First wireless communication device and second wireless communication device

Abstract

Provided is a first wireless communication device having a control unit that has a first mode in which data communication with a second wireless communication device can be executed and a second mode in which limited data communication can be executed, and that, at a time in the second mode when the second wireless communication device can receive data, includes first data and a code relating to message authentication into a downlink channel, which does not accompany a corresponding uplink channel, and can transmit the same to the second wireless communication device.

Description

[Technical Field]

[0001] The present invention relates to a first wireless communication device and a second wireless communication device. [Background technology]

[0002] A terminal device in a wireless communication system has multiple states defined for the connection with a base station device. For example, the terminal device has an RRC_CONNECTED state (a communicating state), an RRC_IDLE state (an unconnected state), and an RRC_INACTIVE state (a suspended state).

[0003] In the RRC_INACTIVE state, the terminal device achieves power saving by turning off the radio unit. In the RRC_INACTIVE state, the terminal device turns on the radio unit at the timing when paging (e.g., RAN Paging) is received, and receives the paging. Paging is a message that calls the terminal device. When the terminal device turns on the radio unit to receive paging, it performs measurement to aggregate the timing when the radio unit is turned on, thereby reducing power consumption caused by turning the radio unit on and off.

[0004] When an opportunity to transmit uplink small data (Small Data Transmission: SDT) occurs in the RRC_INACTIVE state, the terminal device transmits data using, for example, one of three methods. The small data includes, for example, a small amount of data ranging from a few bytes to a few hundred bytes. The three methods are, for example, the 4-step RACH method, the 2-step RACH method, and the Configured Grant method.

[0005] Techniques relating to SDT for terminal devices are described in the following prior art documents. [Prior art documents] [Non-patent literature]

[0006] [Non-patent document 01] 3GPP TS36.133 LTE-A Radio Measurement Specification [Non-patent document 02] 3GPP TS36.300 LTE-A Overview Specifications [Non-patent document 03] 3GPP TS36.211 LTE-A PHY Channel Specification [Non-patent document 04] 3GPP TS36.212 LTE-A PHY Coding Specification [Non-patent document 05] 3GPP TS36.213 LTE-A PHY Procedure Specification [Non-patent document 06] 3GPP TS36.214 LTE-A PHY Measurement Specification [Non-patent document 07] 3GPP TS36.321 LTE-A MAC Specification [Non-patent document 08] 3GPP TS36.322 LTE-A RLC Specification [Non-patent document 09] 3GPP TS36.323 LTE-A PDCP Specification [Non-Patent Document 10] 3GPP TS36.331 LTE-A RRC Specification [Non-Patent Document 11] 3GPP TS36.413 LTE-A S1 Specification [Non-Patent Document 12] 3GPP TS36.423 LTE-A X2 Specification [Non-Patent Document 13] 3GPP TS36.425 LTE-A Xn Specification [Non-Patent Document 14] 3GPP TR36.912 NR Radio Access Overview [Non-Patent Document 15] 3GPP TR38.913 NR Requirements [Non-Patent Document 16] 3GPP TR38.913 NR Requirements [Non-Patent Document 17] 3GPP TR38.801 NR Network Architecture Overview [Non-Patent Document 18] 3GPP TR38.802 NR PHY Overview [Non-Patent Document 19] 3GPP TR38.803 NR RF Overview [Non-Patent Document 20] 3GPP TR38.804 NR L2 Overview [Non-Patent Document 21] 3GPP TR38.900 NR High Frequency Overview [Non-Patent Document 22] 3GPP TS38.300 NR Overview Specifications [Non-Patent Document 23] 3GPP TS37.340 NR Multiple Access Overview Specification [Non-Patent Document 24] 3GPP TS38.201 NR PHY Specification Overview [Non-Patent Document 25] 3GPP TS38.202 NR PHY Service Overview Specification [Non-Patent Document 26] 3GPP TS38.211 NR PHY Channel Specification [Non-Patent Document 27] 3GPP TS38.212 NR PHY Coding Specification [Non-patent document 28] 3GPP TS38.213 NR PHY Data Channel Procedure Specification [Non-Patent Document 29] 3GPP TS38.214 NR PHY Control Channel Procedure Specification [Non-Patent Document 30] 3GPP TS38.215 NR PHY Measurement Specification [Non-Patent Document 31] 3GPP TS38.321 NR MAC Specification [Non-Patent Document 32] 3GPP TS38.322 NR RLC Specification [Non-Patent Document 33] 3GPP TS38.323 NR PDCP Specification [Non-Patent Document 34] 3GPP TS37.324 NR SDAP Specification [Non-Patent Document 35] 3GPP TS38.331 NR RRC Specification [Non-Patent Document 36] 3GPP TS38.401 NR Architecture Overview Specification [Non-Patent Document 37] 3GPP TS38.410 NR Core Network Overview Specification [Non-Patent Document 38] 3GPP TS38.413 NR Core Network AP Specification [Non-Patent Document 39] 3GPP TS38.420 NR Xn Interface Overview Specification [Non-Patent Document 40] 3GPP TS38.423 NR XnAP Specification [Non-Patent Document 41] 3GPP TS38.470 NR F1 Interface Overview Specification [Non-Patent Document 42] 3GPP TS38.473 NR F1AP Specification Summary of the Invention [Problem to be solved by the invention]

[0007] However, the transmission method in a base station device when downlink small data occurs for a terminal device in the RRC_INACTIVE state is currently under discussion at standardization meetings and the like.

[0008] For example, it is conceivable that a terminal device transitions from an RRC_INACTIVE state to an RRC_CONNECTED state by executing a series of procedures, and transmits small data after the state transition. However, in this case, it is not possible to transmit small data efficiently, because it is necessary to turn on the radio unit of the terminal device and execute a series of procedures for the state transition.

[0009] Therefore, one disclosure provides a first wireless communication device and a second wireless communication device that efficiently transmit small data to a terminal device in an RRC_INACTIVE state. [Means for solving the problem]

[0010] The first wireless communication device has a first mode in which data communication with a second wireless communication device can be performed, and a second mode in which limited data communication (e.g., communication of a limited amount of data or communication for a limited time) can be performed, and has a control unit that can include a code related to message authentication and first data in a downlink channel that does not have a corresponding uplink channel and transmit the data to the second wireless communication device at a timing when the second wireless communication device can receive data in the second mode. [Effects of the Invention]

[0011] One disclosure enables efficient transmission of small data to a terminal device in the RRC_INACTIVE state. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing an example of wireless communication in a wireless communication system 3. As shown in FIG. [Figure 2] FIG. 2 is a diagram showing an example of the configuration of the wireless communication system 10. As shown in FIG. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of the terminal device 100. As shown in FIG. [Figure 4] FIG. 4 illustrates an example of the configuration of the base station device 200. As shown in FIG. [Figure 5] FIG. 5 is a diagram showing an example of a paging cycle of the terminal device 100 in the RRC_INACTIVE state. [Figure 6] FIG. 6 is a diagram showing an example of a sequence of the first method. [Figure 7] FIG. 7 is a diagram showing an example of a sequence of the second method. [Figure 8] FIG. 8 is a diagram showing an example of a sequence of the second method. [Figure 9] FIG. 9 is a diagram showing an example of a sequence of the third method. [Figure 10] FIG. 10 is a diagram showing an example of a sequence of the third method. [Figure 11] FIG. 11 is a diagram illustrating an example of data transmission triggered by SPS. [Figure 12] FIG. 12 is a diagram showing an example of a paging cycle corresponding to the downlink SDT method. [Figure 13] FIG. 13 is a diagram showing an example of an SPS period corresponding to the downstream SDT method. [Figure 14] FIG. 14 is a diagram illustrating an example of a calculation formula for the HARQ process ID. [Figure 15] FIG. 15 is a diagram illustrating an example of the configuration of a New DL CCCH. DETAILED DESCRIPTION OF THE INVENTION

[0013] [First embodiment] The wireless communication system 3 includes a first wireless communication device 1 and a second wireless communication device 2. The first wireless communication device 1 and the second wireless communication device 2 are wirelessly connected to each other and transmit and receive data wirelessly. The first wireless communication device 1 and the second wireless communication device 2 support a first mode and a second mode.

[0014] The first wireless communication device 1 has a first processor. The first processor executes a program stored in the first wireless communication device 1 and establishes a control unit. The second wireless communication device 2 has a second processor. The second processor executes a program stored in the second wireless communication device 2 and establishes a second control unit. The processing performed by the first wireless communication device 1 described below may be interpreted as being executed by the control unit. The processing performed by the second wireless communication device 2 described below may be interpreted as being executed by the second control unit.

[0015] The first mode is a mode in which data communication can be performed. In the first mode, the first wireless communication device 1 can transmit data to the second wireless communication device 2 at any timing, for example.

[0016] The second mode is a mode in which limited data communication (for example, communication of a limited amount of data or communication for a limited time) can be performed. In the second mode, the first wireless communication device 1 can transmit data at a timing when the second wireless communication device 2 can receive the data, for example.

[0017] 1 is a diagram showing an example of wireless communication in a wireless communication system 3. A second wireless communication device 2 transitions from a first mode (S1) to a second mode (S2). The transition from the first mode to the second mode is triggered by, for example, the reception (transmission) of a predetermined message.

[0018] During the second mode, data to be transmitted to the second wireless communication device 2 arrives (occurs) at the first wireless communication device 1 (S3). When the second wireless communication device becomes capable of receiving messages (S4), the first wireless communication device 1 transmits the arrived data to the second wireless communication device 2 (S5).

[0019] The data is transmitted using a downlink channel. In addition to the data, the downlink channel can include a code for message authentication. The code for message authentication is a code that enables authentication of the included message. A message with a message authentication code can be considered to have higher security than a message without a message authentication code.

[0020] Furthermore, the downlink channel can be transmitted without a paired (corresponding) uplink channel. For example, the second wireless communication device 2 can transmit data, etc., using the downlink channel without receiving the corresponding uplink channel (either before or after).

[0021] The first wireless communication device 1 receives the downlink channel and acquires the data, and then maintains the second mode (S2).

[0022] [Second embodiment] A second embodiment will be described.

[0023] <About the wireless communication system 10> 2 is a diagram showing an example of the configuration of a wireless communication system 10. The wireless communication system 10 includes a base station device 200 and a terminal device 100. The wireless communication system 10 is, for example, a wireless communication system that supports uplink and downlink SDT in an RRC_INACTIVE state.

[0024] The terminal device 100 is a communication device that is wirelessly connected to the base station device 200 and transmits and receives data, and is, for example, a smartphone or a tablet terminal.

[0025] The base station device 200 supports, for example, various communication generations (for example, 5G and Beyond 5G). The base station device 200 may be configured as a single device or may be configured as multiple devices such as a CU (Central Unit) and a DU (Distributed Unit).

[0026] 2, there is one terminal device 100, but there may be multiple terminal devices. In the following embodiments, downlink small data transmission from the base station device 200 to the terminal device 100 will be described as an example, but similar processing can be applied to data transmission other than small data, uplink data transmission, and communication between terminal devices. Note that "small" refers to data of a predetermined size or less, for example. The predetermined size refers to a size that can be transmitted in the method described below (for example, a size corresponding to the channel size, the radio frame size, etc.).

[0027] <Configuration example of terminal device 100> 3 is a diagram illustrating an example of the configuration of the terminal device 100. The terminal device 100 includes a CPU (Central Processing Unit) 110, a storage 120, a memory 130, a wireless communication circuit 150, and an antenna 151.

[0028] The storage 120 is an auxiliary storage device that stores programs and data, such as a flash memory, a hard disk drive (HDD), or a solid state drive (SSD). The storage 120 stores a terminal communication program 121 and a terminal-side small data communication program 122.

[0029] The memory 130 is an area into which the programs stored in the storage 120 are loaded. The memory 130 may also be used as an area in which the programs store data.

[0030] The wireless communication circuit 150 is a device that performs wireless communication with the base station device 200 and other terminal devices 100. The wireless communication circuit 150 has an antenna 151. The antenna 151 includes, for example, a directional antenna that can control the direction of transmission and reception of radio waves.

[0031] The CPU 110 is a processor that loads a program stored in the storage 120 into the memory 130, executes the loaded program, configures each unit, and realizes each process.

[0032] The CPU 110 establishes a second communication unit and performs terminal communication processing by executing the terminal communication program 121. The terminal communication processing is processing for wirelessly connecting to the base station device 200 or other terminal devices 100 and performing wireless communication.

[0033] The CPU 110 executes the terminal-side small data communication program 122 to construct a second control unit and perform terminal-side small data communication processing. The terminal-side small data communication processing is processing for controlling transmission and reception of small data between the terminal device 100 and the base station device 200. In the terminal-side small data communication processing, the terminal device 100 supports both uplink and downlink SDT methods. Uplink SDT methods include, for example, the 4-step RACH method, the 2-step RACH method, and the Configured Grant method. Details of the downlink SDT method will be described later.

[0034] The CPU 110 constructs a second control unit and performs uplink small data transmission processing by executing an uplink small data transmission module 1221 included in the terminal side small data communication program 122. The uplink small data transmission processing is processing that occurs when small data occurs in the terminal device 100 in the RRC_INACTIVE state, and is processing that transmits the small data to the base station device 200. The uplink small data transmission processing corresponds to the uplink SDT method.

[0035] The CPU 110 constructs a second control unit and performs downlink small data reception processing by executing a downlink small data reception module 1222 included in the terminal-side small data communication program 122. The downlink small data reception processing is processing that occurs when small data occurs in the base station device 200 while the terminal device 100 is in the RRC_INACTIVE state, and is processing that receives the small data from the base station device 200. The downlink small data reception processing corresponds to the downlink SDT method.

[0036] <Configuration Example of Base Station Device 200> 4 is a diagram illustrating an example of the configuration of the base station device 200. The base station device 200 includes a CPU 210, a storage 220, a memory 230, a wireless communication circuit 250, and an antenna 251.

[0037] The storage 220 is an auxiliary storage device such as a flash memory, HDD, or SSD that stores programs and data. The storage 220 stores a base station communication program 221 and a base station side small data communication program 222.

[0038] The memory 230 is an area into which the programs stored in the storage 220 are loaded. The memory 230 may also be used as an area in which the programs store data.

[0039] The wireless communication circuit 250 is a device that performs wireless communication with the terminal device 100. The wireless communication circuit 250 has an antenna 251. The antenna 251 includes, for example, a directional antenna that can control the direction of transmission and reception of radio waves.

[0040] The CPU 210 is a processor that loads a program stored in the storage 220 into the memory 230, executes the loaded program, configures each unit, and realizes each process.

[0041] The CPU 210 establishes a communication unit and performs communication processing by executing the base station communication program 221. The base station communication processing is processing for performing wireless communication with the terminal device 100. In the base station communication processing, the base station device 200 establishes a wireless connection with the terminal device 100, transmits data and control signals to the terminal device 100, and receives data from the terminal device 100.

[0042] The CPU 210 executes the base station side small data communication program 222 to construct a control unit and perform base station side small data communication processing. The base station side small data communication processing is processing for controlling the transmission and reception of small data between the terminal device 100 and the base station device 200. In the base station side small data communication processing, the base station device 200 supports both uplink and downlink SDT methods. Uplink SDT methods include, for example, the 4-step RACH method, the 2-step RACH method, and the Configured Grant method. Details of the downlink SDT method will be described later.

[0043] The CPU 210 constructs a control unit and performs uplink small data reception processing by executing an uplink small data reception module 2221 included in the base station side small data communication program 222. The uplink small data reception processing is processing that occurs when small data occurs in the terminal device 100 in the RRC_INACTIVE state, and is processing that receives the small data from the terminal device 100. The uplink small data reception processing corresponds to the uplink SDT method.

[0044] The CPU 210 constructs a control unit and performs downlink small data transmission processing by executing a downlink small data transmission module 2222 included in the base station side small data communication program 222. The downlink small data transmission processing is processing that occurs when small data occurs in the base station device 200 while the terminal device 100 is in the RRC_INACTIVE state, and is processing that transmits the small data to the terminal device 100. The downlink small data transmission processing corresponds to the downlink SDT method.

[0045] <Paging Cycle> 5 is a diagram showing an example of a paging cycle of the terminal device 100 in the RRC_INACTIVE state. The paging cycle indicates, for example, a period in which paging (for example, RAN paging) is transmitted from the base station device 200.

[0046] In the RRC_INACTIVE state, the terminal device 100 turns off the radio frequency (RF) unit (S10). The terminal device 100 turns on the radio frequency unit in accordance with the timing for receiving a paging message (S11). Then, the terminal device 100 searches for a paging message and waits for reception of the paging message (S12).

[0047] The base station apparatus 200 transmits a paging message at a predetermined timing (S13). The paging message is transmitted to the terminal apparatuses 100 in the same paging group and includes, for example, DCI format 1_0.

[0048] The terminal device 100 receives a paging message while waiting for reception of the paging message (S13). Then, the terminal device 100 performs measurement (S14) and turns off the radio unit (S15).

[0049] Then, when the paging cycle has elapsed, the terminal device 100 turns on the radio unit again (S16), and repeats the following steps: waiting for reception of a paging message (S17), receiving the paging message (S18), performing measurement (S19), and turning off the radio unit (S20).

[0050] In the RRC_INACTIVE state, the terminal device 100 reduces power consumption by turning on the radio unit in accordance with the paging cycle and keeping the radio unit off at other times. Furthermore, the terminal device 100 also performs measurement when the radio unit is turned on to receive paging. This allows the terminal device 100 to reduce the number of times the radio unit is turned on and off, thereby reducing power consumption.

[0051] <Downstream SDT method> The downlink SDT method will be described. In the following description, it is assumed that downlink data (small data) to be transmitted to the terminal device 100 is generated in the base station device 200, and that the terminal device 100 is in the RRC_INACTIVE state when the data is generated.

[0052] <1. 1st method> The first method is a method in which the base station device 200 causes the terminal device 100 to transition to the RRC_CONNECTED state and transmits data.

[0053] 6 is a diagram showing an example of a sequence of the first method. The terminal device 100 is in an RRC_INACTIVE state (S30). The base station device 200 has downlink small data to transmit to the terminal device 100 (S31).

[0054] The base station device 200 transmits a paging message to the terminal device 100 (S32). The terminal device 100 turns on the radio unit to receive the paging message.

[0055] Then, the base station device 200 executes an RRC resumption procedure (a procedure for transitioning from the RRC_INACTIVE state to the RRC_CONNECTED state) with the terminal device 100 (S33), and transitions the terminal device 100 to the RRC_CONNECTED state (S34).

[0056] Then, the base station device 200 transmits small data to the terminal device 100 that has entered the RRC_CONNECTED state (S35).

[0057] <2.Second method> 7 is a diagram showing an example of a sequence of the second scheme. In the second scheme, a new message for downlink data transmission is defined. The new message is defined as, for example, a new downlink Common Control Channel (hereinafter referred to as New DL CCCH).

[0058] The base station device 200 transmits an RRC Release (or an RRC Connection Release) (S40). The RRC Release is a message that triggers the terminal device 100 to transition to the RRC_INACTIVE state. The RRC Release includes, for example, information about the downlink SDT method. The information about the downlink SDT method includes, for example, all or part of the downlink SDT method to be used, data transmission timing, information about the New DL CCCH, etc. Note that the RRC Release is just an example, and messages that include information about the downlink SDT method are not limited to this.

[0059] The terminal device 100 receives the RRC Release, performs a predetermined process (sequence), transitions to the RRC_INACTIVE state (S42), and turns off the radio unit (S41). When the terminal device 100 is in the RRC_INACTIVE state, small data to be transmitted to the terminal device 100 arrives at the base station device 200 (S43).

[0060] The terminal device 100 turns on the radio unit at the timing when it receives the paging, for example (S44). The base station device 200 transmits data using a New DL CCCH in accordance with the timing when the terminal device 100 turns on the radio unit (S45).

[0061] The terminal device 100 searches for a New DL CCCH when the radio unit is ON and receives the transmitted New DL CCCH (S45). Then, when the terminal device 100 completes the predetermined processing, it turns off the radio unit (S46). The terminal device 100 can receive small data while maintaining the RRC_INACTIVE state.

[0062] Furthermore, when small data to be transmitted in the RRC_INACTIVE state arrives (S47), the base station device 200 transmits the data using a New DL CCCH (S49) in accordance with the timing when the terminal device 100 turns on the radio unit (S48). The terminal device 100 searches for a New DL CCCH when the radio unit is turned on, and receives the transmitted New DL CCCH (S49).

[0063] As a result, the terminal device 100 can receive small data while maintaining the RRC_INACTIVE state.

[0064] In RAN conforming to 3GPP, CCCH cannot be said to be a secure message (channel). New DL CCCH secures messages by having a message authentication code (authentication code) such as MAC-I. Compared to paging, which is transmitted to an unspecified number of people and does not have an authentication code, New DL CCCH can be said to have a higher security message because it contains a message authentication code.

[0065] Fig. 8 is a diagram showing an example of a sequence of the second method. In the sequence of Fig. 8, the terminal device 100 can (may) transmit a reception acknowledgement (ACK) for data received on the New DL CCCH. Processing S50 to processing S55 are the same as processing S40 to processing S45 in Fig. 7.

[0066] If the terminal device 100 has successfully received the data, it transmits an ACK to the base station device 200 (S56). At this time, the terminal device 100 uses the uplink SDT method for transmitting the ACK. In either of the uplink SDT methods, the terminal device 100, for example, includes an ACK (small data) in an RRC Resume Request and transmits it to the base station device 200 (S56).

[0067] In the second scheme, the base station device 200 can transmit small data while maintaining the RRC_INACTIVE state of the terminal device 100. Furthermore, since the New DL CCCH has a message authentication code, data transmission using the old security settings (security settings already in place) is possible without implementing a security (confidentiality) procedure.

[0068] <3. Third method> 9 is a diagram showing an example of a sequence in the third scheme. In the third scheme, the base station apparatus 200 transmits small data using a PDCCH order.

[0069] The base station apparatus 200 transmits an RRC release (S60). The RRC release includes, for example, information about the downlink SDT mode.

[0070] The terminal device 100 receives the RRC Release, performs a predetermined process (sequence), transitions to the RRC_INACTIVE state (S62), and turns off the radio unit. When the terminal device 100 is in the RRC_INACTIVE state, small data to be transmitted to the terminal device 100 arrives at the base station device 200 (S62).

[0071] The base station device 200 transmits a PDCCH order (S63). The PDCCH order is a message that triggers the terminal device 100 to perform random access (RA).

[0072] Upon receiving the PDCCH order, the terminal device 100 transmits Msg1 to the base station device 200 (S64). Msg1 is, for example, an RA preamble.

[0073] Upon receiving Msg1 (S64), the base station device 200 transmits Msg2 to the terminal device 100 (S65). Msg2 is, for example, an RA response corresponding to Msg1.

[0074] Upon receiving Msg2 (S65), the terminal device 100 transmits Msg3 to the base station device 200 (S66). Msg3 is, for example, an RRC message of layer 3, and includes identification information and authentication information of the terminal device 100. Msg3 is, for example, a Scheduled Transmission.

[0075] Upon receiving Msg3 (S66), the base station device 200 includes small data in Msg4 and transmits the Msg4 to the terminal device 100 (S67). Msg4 is, for example, a message for controlling the state of the terminal device 100. Msg4 is, for example, Contention Resolution.

[0076] Fig. 10 is a diagram showing an example of a sequence of the third method. In the sequence of Fig. 10, the terminal device 100 transmits a reception confirmation (ACK: ACKnowledgement) for the data received in Msg 4. Processes S70 to S77 are the same as processes S60 to S67 in Fig. 9.

[0077] If the terminal device 100 has successfully received the data, it transmits an ACK to the base station device 200 (S78). At this time, the terminal device 100 uses the uplink SDT method for transmitting the ACK. In either of the uplink SDT methods, the terminal device 100, for example, includes an ACK (small data) in an RRC Resume Request and transmits the RRC Resume Request to the base station device 200 (S78).

[0078] In the third scheme, the base station device 200 can transmit small data using the PSCCH order. The terminal device 100 can receive the small data while maintaining the RRC_INACTIVE state.

[0079] <Modification of the second method> In the second scheme, the base station apparatus 200 transmits a New DL CCCH when the radio unit is turned on at the paging reception timing. In a modified example, a transmission trigger other than paging-triggered data transmission is defined. For example, data transmission triggered by SPS (semi-persistent scheduling) is defined.

[0080] 11 is a diagram showing an example of data transmission triggered by SPS. The base station apparatus 200 transmits an RRC release (or an RRC connection release) (S80). The RRC release includes, for example, information about the downlink SDT mode.

[0081] The terminal device 100 receives the RRC Release, performs a predetermined process (sequence), transitions to the RRC_INACTIVE state (S81), and turns off the radio unit. When the terminal device 100 is in the RRC_INACTIVE state, small data to be transmitted to the terminal device 100 arrives at the base station device 200 (S82).

[0082] The terminal device 100 turns on the radio unit at the timing of receiving the SPS message (S83) and searches for the PDSCH (S84).

[0083] The base station device 200 includes small data in a New DL CCCH and transmits it to the terminal device 100 at the same time that the terminal device 100 turns on the radio unit in the SPS (S85). After that, the base station device 200 repeats the same processing whenever data is generated (processing S86 to processing S89).

[0084] <Paging cycle corresponding to the downlink SDT method> To accommodate the SDT triggering paging, a paging cycle corresponding to the downlink SDT method is defined. Figure 12 is a diagram showing an example of a paging cycle corresponding to the downlink SDT method. In Figure 12, "PagingCycle" indicates an example of a paging cycle in conventional RAN paging, and "PagingCycleSDT" indicates an example of a paging cycle corresponding to the downlink SDT method.

[0085] For example, PagingCycleSDT may require an interval shorter than PagingCycle. Therefore, PagingCycleSDT is defined to have an interval shorter than PagingCycle. PagingCycleSDT corresponds to an interval corresponding to the transmission period of the measurement signal (for example, rf5) or rf16, which is not supported conventionally. Note that spare is not necessarily required. If there are other useful values, for example, rf24, which is an intermediate value between rf16 and rf32, may be added. Rf24 is just one example.

[0086] <SPS cycle corresponding to the downstream SDT method> To accommodate SPS-triggered SDT, an SPS period corresponding to the downstream SDT method is defined. Fig. 13 is a diagram showing an example of an SPS period corresponding to the downstream SDT method. In Fig. 13, "periodicity ENUMERATED" indicates an example of a conventional SPS period, and "periodicitySDT ENUMERATED" indicates an example of an SPS period corresponding to the downstream SDT method.

[0087] For example, there are cases where periodicitySDT ENUMERATED is required to have an interval shorter than periodicity ENUMERATED. Therefore, periodicitySDT ENUMERATED is defined to have an interval shorter than periodicity ENUMERATED.

[0088] The SPS period corresponding to the downlink SDT scheme is, for example, shorter than the scheduling period (period of semi-static scheduling) in the RRC Connected state.

[0089] <Calculation formula of HARQ process ID> FIG. 14 is a diagram showing an example of a calculation formula of HARQ process ID. The HARQ process ID is, for example, an identifier for identifying data. The HARQ process ID is included in, for example, the New DL CCCH. Also, the HARQ process ID is associated with the data, for example. As described above, when the periodicity corresponds to a shorter period (for example, less than 10 msec), the calculation formula of the HARQ process ID also needs to correspond to less than 10 msec. Note that spare is not always necessary. If there are other useful values, for example, rf6, rf7, rf9 may be added. These values are just examples.

[0090] Equation (1) is an example of a calculation formula of a conventional HARQ process ID.

[0091] Equation (2) is an example of a calculation formula of a new HARQ process ID. Equation (2) does not use the numberOfSlotsPerFrame (for example, the number of consecutive slots included in one radio frame) in the calculation.

[0092] Equation (3) is an example of a calculation formula of a new HARQ process ID. Equation (3) is a calculation formula that diverts the calculation formula of CG (Configured Grant).

[0093] In Equation (1), since the HARQ process identifiers less than 10 ms have the same value, each HARQ process could not be identified. In Equations (2) and (3), since the HARQ process identifiers less than 10 ms have different values, each HARQ process can be identified.

[0094] <Configuration of New DL CCCH> 15 is a diagram showing an example of the configuration of a New DL CCCH. The New DL CCCH may be defined as, for example, a smallDataCCCH. The New DL CCCH is specified as, for example, an SRB1. The New DL CCCH uses, for example, one spare bit. Unlike other DL-CCCHs, the New DL CCCH is a DL-CCCH that can be transmitted immediately by the base station apparatus 200 (for which no paired UL-CCCH exists).

[0095] The New DL CCCH includes, for example, the following information elements:

[0096] I-RNTI (40 bits) or Short-I-RNTI (24 bits): I-RNTI and Short-I-RNTI are identifiers (identification information) that identify the terminal device 100. They are used to identify the terminal device 100.

[0097] resumeMAC-I (16 bits): Used to authenticate messages (improves security). An example of a message authentication code.

[0098] DL data: Data to be sent (small data)

[0099] Note that the base station apparatus 200 may determine whether data can be transmitted in SDT depending on the size of the data.

[0100] Furthermore, the base station device 200 performs, for example, Layer 2 protocol configuration for the terminal device 100 using an RRC release. The base station device 200 includes, for example, parameters of the PDCP / RLC / MAC entity for SRB1 in the RRC release. Note that, for some parameters, for example, DefaultConfig may be used.

[0101] Furthermore, the terminal device 100 may autonomously resume Layer 2 at the timing of performing downlink SDT. In this case, the terminal device 100 may autonomously perform the procedure described in TS38.331 Section 5.3.13.3.

[0102] [Other embodiments] The requirements described in the first embodiment, the second embodiment, and other embodiments may be combined with each other, and may be used in different ways depending on, for example, wireless conditions, system requirements, etc. [Explanation of symbols]

[0103] 1: First wireless communication device 2: Second wireless communication device 3: Wireless communication system 10: Wireless communication system 100: Terminal device 110:CPU 120: Storage 121: Terminal communication program 122: Terminal side small data communication program 1221: Uplink small data transmission module 1222: Downstream small data receiving module 130: Memory 150: Wireless communication circuit 151: Antenna 200:Base station equipment 210:CPU 220: Storage 221: Base station communication program 222: Base station side small data communication program 2221: Uplink small data receiving module 2222: Downstream small data transmission module 230: Memory 250: Wireless communication circuit 251: Antenna

Claims

1. a first wireless communication device, a control unit having a first mode in which data communication with a second wireless communication device can be performed and a second mode in which limited data communication can be performed, and capable of transmitting a code related to message authentication and first data corresponding to the limited data communication to the second wireless communication device in a downlink channel not accompanied by a corresponding uplink channel at a first timing when the second wireless communication device can receive data in the second mode; A first wireless communication device comprising:

2. The first timing is a cycle shorter than a cycle for calling the second wireless communication device. The first wireless communication device according to claim 1 .

3. The first timing has a cycle shorter than a cycle of quasi-static scheduling that can be set in the first mode. The first wireless communication device according to claim 1 .

4. The first data includes an identifier that can identify the first data. The first wireless communication device according to claim 3 .

5. The downlink channel includes identification information that identifies the second wireless communication device. The first wireless communication device according to claim 1 .

6. The second mode is a mode in which the second wireless communication device activates a wireless unit that enables data reception at a predetermined timing, and deactivates the wireless unit when a series of processes at the predetermined timing is completed. The first wireless communication device according to claim 1 .

7. a second wireless communication device, a first mode in which data communication with a first wireless communication device can be performed and a second mode in which limited data communication can be performed; a second control unit that can receive a downlink channel without a corresponding uplink channel, including a message authentication code and first data corresponding to the limited data communication, at a timing when the second wireless communication device can receive data in the second mode; A second wireless communication device comprising:

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