Base station device and terminal station device

Abstract

To improve efficiency of data communication during an RRC inactive mode.SOLUTION: A base station device has a communication unit that can implement communication when a terminal station device is in a predetermined state, and a control unit that can perform control to have communication with the terminal station device implemented using an interval in which an area where the terminal station device decodes a control signal to implement the communication is valid corresponding to a first interval corresponding to first communication and a second interval corresponding to second communication of the communication. The second interval is initiated by the terminal station device transmitting data corresponding to the second communication, and is an interval until an RRC (Radio Resource Control) message, which sets suspend and is transmitted from the communication unit, is received by the terminal station device.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a base station device, a terminal station device, a wireless communication system, and a wireless communication method. [Background technology]

[0002] In today's networks, traffic from mobile devices (smartphones and feature phones) accounts for the majority of network resources, and the traffic used by mobile devices is expected to continue to expand in the future.

[0003] On the other hand, there is a demand for supporting services with diverse requirements in line with the development of IoT (Internet of Things) services (for example, monitoring systems for transportation systems, smart meters, devices, etc.). Therefore, in the communication standard for 5th generation mobile communications (5G or NR (New Radio)), in addition to the standard technologies of 4G (4th generation mobile communications) (for example, Non-Patent Documents 1 to 13), technologies that realize even higher data rates, larger capacities, and lower latency are required.

[0004] Regarding the fifth generation communication standard, technical studies are being conducted in working groups (for example, TSG-RAN WG1, TSG-RAN WG2, etc.) of the Third Generation Partnership Project (3GPP).

[0005] Generally, in a wireless communication system, processing of the RRC (Radio Resource Control) layer is performed. In the RRC layer processing, for example, connection is set, changed, and released between a base station device and a terminal station device. For example, in LTE (Long Term Evolution) or LTE-A (LTE-Advanced), which are standard technologies for 4G, RRC connected mode (RRC_CONNECTED) and RRC idle mode (RRC_IDLE) are defined as the states of the RRC layer. The RRC connected mode is, for example, a mode in which data communication can be performed between the base station device and the terminal station device. The RRC idle mode is, for example, a mode in which data communication is not performed between the base station device and the terminal station device, and a mode in which the terminal station device is in a power saving state.

[0006] In 5G, in addition to the RRC connected mode and the RRC idle mode, the introduction of the RRC inactive mode (RRC_INACTIVE) is being considered. The RRC inactive mode is a mode that has the same low power consumption as the RRC idle mode and can quickly transition to the RRC connected mode when transmitting data. In the RRC inactive mode, information about data communication with the terminal station device is held in the base station device. The information about data communication includes information such as the location of the terminal station device, communication capabilities, various parameters, and an identifier (terminal ID) of the terminal station device. In this way, since the information about data communication is held in the base station device, even in the RRC inactive mode, the core network considers the terminal station device to be connected to the base station device. As a result, when the terminal station device returns from the RRC inactive mode to the RRC connected mode, the transmission and reception of signals between the base station device and the core network is omitted, and a quick transition to the RRC connected mode is realized. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] 3GPP TS 36.133 V16.6.0(2020-06)

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[0008] The RRC inactive mode is a mode in which no data communication is performed between a base station device and a terminal station device, except for data communication essential for performing or maintaining communication, but recently, it has been considered to realize transmission of data (e.g., small data) during the RRC inactive mode. That is, it is considered that small data such as failure information of the terminal station device and measurement values ​​by a sensor are transmitted from the terminal station device to the base station device during the RRC inactive mode.

[0009] For the transmission of small data, it is being considered to use either the RACH method using random access or the CG (Configured Grant) method using preset radio resources. In the RACH method, the terminal station device transmits a message including a preamble to the base station device in the same manner as the random access when establishing synchronization with the base station device, and transmits the small data by including it in one of these messages. On the other hand, in the CG method, the terminal station device is configured in advance by the base station device with radio resources to be used for transmission, and when small data is generated, the terminal station device transmits the small data using the preset radio resources.

[0010] However, data communication in the RRC inactive mode has a problem of poor control efficiency. That is, in the RRC inactive mode, the terminal station device turns off the power supply to the wireless communication unit and enters a power saving state except when it is essential, but for example, when transmitting small data, switching between on and off of the power supply occurs in a short time.

[0011] For example, when small data is transmitted from a terminal station device during the RRC inactive mode, the terminal station device turns on the power supply to the wireless receiving circuit to receive a control channel (e.g., a Physical Downlink Control CHannel (PDCCH)) that controls retransmission corresponding to the small data. The power supply to the wireless receiving circuit is also turned on to receive, for example, an ACK of a TCP (Transmission Control Protocol) or a Status Report of an RLC (Radio Link Control) layer. Furthermore, during the RRC inactive mode, the terminal station device receives a periodic paging signal in a paging frame to check the presence or absence of downlink data from the base station device.

[0012] Thus, during the RRC inactive mode when the power supply to the wireless receiving circuit is turned off, the power supply to the wireless receiving circuit is frequently turned on, causing on / off switching in a short period of time, reducing control efficiency.

[0013] The disclosed technology has been developed in consideration of these points, and aims to provide a base station device, a terminal station device, a wireless communication system, and a wireless communication method that can improve the efficiency of data communication during RRC inactive mode. [Means for solving the problem]

[0014] In one aspect, the base station device disclosed in the present application has a communication unit capable of performing communication when the terminal station device is in a predetermined state, and a control unit capable of controlling the performance of the communication with the terminal station device using a first interval corresponding to a first communication among the communications and an interval corresponding to a second communication among the communications, in which an area for decoding a control signal for the terminal station device to perform the communication is enabled, the second interval being a interval that is started when the terminal station device transmits data corresponding to the second communication and that lasts until an RRC (Radio Resource Control) message for setting a suspend, transmitted from the communication unit, is received by the terminal station device. Effect of the Invention

[0015] According to one aspect of the base station device, the terminal station device, the wireless communication system, and the wireless communication method disclosed in the present application, it is possible to achieve an effect of improving the efficiency of data communication during the RRC inactive mode. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a block diagram showing a configuration of a base station apparatus according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing a configuration of the terminal station device according to the first embodiment. [Diagram 3] FIG. 3 is a sequence diagram showing an example of a wireless communication method. [Figure 4] FIG. 4 is a sequence diagram showing another example of a wireless communication method. [Diagram 5] FIG. 5 is a sequence diagram showing an example of a small data transmission method. [Figure 6] FIG. 6 is a sequence diagram showing a specific example of the wireless communication method according to the second embodiment. [Figure 7] FIG. 7 is a sequence diagram showing another specific example of the wireless communication method according to the second embodiment. [Figure 8] FIG. 8 is a sequence diagram showing yet another specific example of the wireless communication method according to the second embodiment. [Figure 9] FIG. 9 is a sequence diagram showing a specific example of the wireless communication method according to the third embodiment. [Figure 10] FIG. 10 is a sequence diagram showing another specific example of the wireless communication method according to the third embodiment. [Figure 11] FIG. 11 is a sequence diagram showing yet another specific example of the wireless communication method according to the third embodiment. [Figure 12] FIG. 12 is a sequence diagram showing a specific example of the wireless communication method according to the fourth embodiment. [Figure 13]FIG. 13 is a sequence diagram showing another specific example of the wireless communication method according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of a base station device, a terminal station device, a wireless communication system, and a wireless communication method disclosed in the present application will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

[0018] (Embodiment 1) 1 is a block diagram showing a configuration of a base station device 100 according to embodiment 1. The base station device 100 shown in FIG.

[0019] The network IF 110 is connected by wire to a core network (not shown), and transmits and receives signals to and from devices that make up the core network.

[0020] The processor 120 is a control unit that includes, for example, a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor), and controls the entire base station device 100. The processor 120 also sets the area of ​​the radio resource for decoding the control signal for the terminal station device to perform communication with the base station device 100 and the time period in which this area is valid in the terminal station device. That is, the processor 120 sets, for example, an area corresponding to the first communication of the terminal station device and an area corresponding to the second communication of the terminal station device, and controls the terminal station device to perform communication by using each of the areas intermittently. The processor 120 notifies the terminal station device of information on the setting of the above-mentioned area by transmitting control information via the wireless communication unit 140, and controls the communication by the terminal station device.

[0021] The memory 130 includes, for example, a random access memory (RAM) or a read only memory (ROM), and stores information used in processing by the processor 120.

[0022] The wireless communication unit 140 performs wireless communication with the opposing terminal station device. The wireless communication unit 140 transmits control information including information on section settings to the terminal station device. The wireless communication unit 140 also receives data transmitted from the terminal station device. Note that the wireless communication unit 140 can also communicate with the terminal station device when the opposing terminal station device transitions to a predetermined state.

[0023] 2 is a block diagram showing a configuration of the terminal station device 200 according to the embodiment 1. The terminal station device 200 shown in FIG.

[0024] The wireless communication unit 210 performs wireless communication with the opposing base station device 100. The wireless communication unit 210 receives control information from the base station device 100, for example, including information regarding the setting of a time interval during which a region of wireless resources for decoding a control signal is valid. The wireless communication unit 210 also transmits, for example, small data to the base station device 100. Note that the wireless communication unit 210 can communicate with the base station device 100 even when the terminal station device 200 transitions to a predetermined state.

[0025] The processor 220 is a control unit that includes, for example, a CPU, an FPGA, or a DSP, and controls the entire terminal station device 200. The processor 220 also receives settings from the base station device 100 regarding a radio resource area for decoding a control signal for the terminal station device 200 to perform communication and a time period during which this area is valid. That is, the processor 220 controls the communication by setting, for example, an area corresponding to the first communication of the terminal station device 200 and an area corresponding to the second communication of the terminal station device 200, and by using each area intermittently. At this time, the processor 220 controls the communication depending on the state of the data communication.

[0026] The memory 230 includes, for example, a RAM or a ROM, and stores information used in processing by the processor 220.

[0027] Next, a wireless communication method performed by the base station device 100 and the terminal station device 200 configured as above will be described with reference to FIGS.

[0028] Fig. 3 is a sequence diagram showing an example of a wireless communication method. Here, it is assumed that the terminal station device 200 transitions to a predetermined state in which power supply to the wireless communication unit 210 is reduced to achieve low power consumption. Fig. 3 shows time intervals in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off. As shown in Fig. 3, the base station device 100 transmits control information including information on setting an interval corresponding to the first communication of the terminal station device 200 and an interval corresponding to the second communication of the terminal station device 200 (hereinafter referred to as "interval setting information") (step S101).

[0029] When the terminal station device 200 receives the interval setting information, it turns on the wireless receiving circuit in the interval corresponding to the first communication and receives a control signal related to the first communication from the base station device 100 (step S102). Then, the terminal station device 200 turns off the wireless receiving circuit when the interval corresponding to the first communication has elapsed.

[0030] Thereafter, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 uses the radio resource CG set in advance by the base station device 100 to carry out a second communication to transmit the small data SD to the base station device 100 (step S103). In addition, the terminal station device 200 starts a timer 301 corresponding to the second communication in accordance with the section setting information, and turns on the radio receiving circuit in the section until the timer 301 expires.

[0031] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a control signal to the terminal station device 200 in response to the small data SD (step S104). Since the terminal station device 200 has its wireless receiving circuit turned on until the timer 301 expires, the terminal station device 200 can receive the control signal in step S104. Then, when the timer 301 expires, the terminal station device 200 turns off its wireless receiving circuit.

[0032] The first communication may be periodic. After that, the terminal station device 200 turns on the wireless receiving circuit during the period corresponding to the first communication that is periodically performed, and receives a control signal related to the first communication from the base station device 100 (step S105). Then, the terminal station device 200 turns off the wireless receiving circuit after the period corresponding to the first communication has elapsed.

[0033] In this way, the terminal station device 200 controls the period during which the wireless receiving circuit is turned on in accordance with the settings made by the base station device 100, so that the terminal station device 200 can receive a control signal in response to the transmission of small data SD, and can minimize the frequency at which the wireless receiving circuit is switched on and off, thereby improving the efficiency of data communication.

[0034] Fig. 4 is a sequence diagram showing another example of a wireless communication method. In Fig. 4, the same parts as in Fig. 3 are denoted by the same reference numerals. In Fig. 4 as well, it is assumed that the terminal station device 200 transitions to a predetermined state in which the power supply to the wireless communication unit 210 is reduced and power consumption is reduced. As shown in Fig. 4, the base station device 100 transmits control information including zone setting information (step S101).

[0035] When the terminal station device 200 receives the interval setting information, it turns on the wireless receiving circuit in the interval corresponding to the first communication and receives a control signal related to the first communication from the base station device 100 (step S102). In addition, the terminal station device 200 starts the timer 302 in response to the interval setting information and keeps the wireless receiving circuit on in the interval until the timer 302 expires.

[0036] Thereafter, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 carries out a second communication to transmit the small data SD to the base station device 100 using the radio resource CG previously set by the base station device 100 (step S103).

[0037] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a control signal to the terminal station device 200 in response to the small data SD (step S104). Since the terminal station device 200 has its wireless receiving circuit turned on until the timer 302 expires, the terminal station device 200 can receive the control signal in step S104. Then, when the timer 302 expires, the terminal station device 200 turns off its wireless receiving circuit.

[0038] Thereafter, the terminal station device 200 turns on the wireless receiving circuit during the period corresponding to the first communication, and receives a control signal related to the first communication from the base station device 100 (step S105). Then, the terminal station device 200 turns off the wireless receiving circuit after the period corresponding to the first communication has elapsed.

[0039] In the example shown in Fig. 4, the first communication may be a periodic communication, and the radio resource CG may be a periodic resource. That is, the period of the first communication that is periodically performed and the period of the periodic radio resource CG have a corresponding time length. The timer 302 is set to expire at a predetermined time according to these periods.

[0040] In this way, according to the setting by the base station device 100, the wireless receiving circuit is turned on continuously in the section corresponding to the first communication and the section corresponding to the second communication regarding the small data SD, so that the terminal station device 200 can receive a control signal corresponding to the transmission of the small data SD and can minimize the frequency at which the wireless receiving circuit is switched on and off, thereby improving the efficiency of data communication.

[0041] As described above, according to this embodiment, the terminal station device controls the period during which the wireless receiving circuit is turned on in accordance with the settings made by the base station device and performs communication intermittently, so that the terminal station device can receive a control signal in response to the transmission of small data, and can minimize the frequency at which the wireless receiving circuit is switched on and off, thereby improving the efficiency of data communication.

[0042] In the above-mentioned embodiment 1, as an example, the first communication performed periodically may be, for example, transmission and reception of a paging signal, and the second communication may be transmission and reception of small data. In addition, the control signal received by the terminal station device 200 regarding the second communication may be transmitted using a control channel such as a PDCCH. In this case, a radio resource area specific to each terminal station device 200 (i.e., a terminal specific search space (USS: UE-specific Search Space)) may be set in the control channel. Furthermore, in the example shown in FIG. 4, the period of the first communication and the period of the periodic radio resource CG are set to have a corresponding time length. Specifically, for example, when the subcarrier interval is 15 KHz, the period of the periodic radio resource CG may be 320 ms*14 symbols*N (N=1, 2, 3, 4).

[0043] (Embodiment 2) Incidentally, in a wireless communication system using FR2 (Frequency Range 2) including frequency bands such as millimeter wave bands, it is considered that a base station device will form beams in multiple directions to deploy cells, and a terminal station device will select a beam with a large reception power to communicate with the base station device. In this case, for example, when a terminal station device transmits small data in a CG method using a preset radio resource, the terminal station device will transmit the small data using the radio resource that was set before selecting the optimal beam.

[0044] Specifically, as shown in FIG. 5, the base station device 100 sets the radio resource CG that the terminal station device 200 can use to transmit the small data SD by using, for example, broadcast information such as a master information block (MIB) or a system information block (SIB), or individual control information of the RRC layer (step S10). The terminal station device 200 sets the radio resource CG according to the broadcast information or individual control information received from the base station device 100, and when the small data SD occurs, transmits the small data SD using the radio resource CG that arrives immediately after the small data SD occurs (step S20). At this time, the terminal station device 200 selects a beam to be used for transmitting the small data SD from a plurality of beams formed by the base station device 100, but since the radio resource CG is set in advance, there is a certain restriction on the selection of the beam. In addition, a relatively long time may have passed from the time the radio resource CG is set until the terminal station device 200 transmits the small data SD, and the terminal station device 200 may move during this time. For this reason, the radio resource CG used to transmit the small data SD is not necessarily the optimal radio resource.

[0045] Therefore, in the second embodiment, a case where the efficiency of data communication is improved by using an optimal beam and radio resources will be described. In particular, in the second embodiment, a case where the radio resource CG used for transmitting the small data SD is set by using a four-step random access procedure will be described.

[0046] The configurations of the base station device 100 and the terminal station device 200 according to the second embodiment are the same as those of the base station device 100 (FIG. 1) and the terminal station device 200 (FIG. 2) according to the first embodiment. Fig. 6 is a sequence diagram showing a specific example of a wireless communication method according to the second embodiment. Here, it is assumed that the terminal station device 200 transitions to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 6 shows time periods in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0047] The base station device 100 transmits control information including interval setting information regarding setting of an interval corresponding to a paging frame and an interval corresponding to communication of small data (step S201). The interval setting information may include, for example, information on the time when the paging frame is provided, information on the setting time of a timer that starts when small data is transmitted, etc. In addition, as the control information including the interval setting information, for example, broadcast information such as MIB or SIB, or individual control information of the RRC layer is used.

[0048] When the terminal station device 200 receives the period setting information, for example, in a period corresponding to a paging frame, the terminal station device 200 turns on a wireless receiving circuit and receives a control signal such as a PDCCH related to paging from the base station device 100. Then, the terminal station device 200 turns off the wireless receiving circuit when the period corresponding to the paging frame has elapsed.

[0049] Thereafter, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 selects an optimal beam from among the multiple beams formed by the base station device 100, and transmits a message (MSG1) including a preamble corresponding to the selected beam to the base station device 100 (step S202). After transmitting MSG1, the terminal station device 200 turns on a wireless receiving circuit to receive a message corresponding to MSG1.

[0050] The base station device 100 receiving MSG1 determines a timing advance value (hereinafter referred to as a "TA value") for adjusting the transmission timing of the terminal station device 200, and assigns a Temporary C-RNTI (Cell-Radio Network Temporary Identifier), which is a temporary identifier, to the terminal station device 200. Then, the base station device 100 transmits a message (MSG2) including the TA value and the Temporary C-RNTI to the terminal station device 200 (step S203).

[0051] The terminal station device 200 that receives MSG2 including the TA value determines that uplink synchronization has been established, and starts a time alignment timer 311 that specifies the duration of uplink synchronization. After that, until the time alignment timer 311 expires, the processor 220 of the terminal station device 200 can arbitrarily set the radio receiving circuit to on or off. In addition, the terminal station device 200 holds the Temporary C-RNTI included in MSG2 until the time alignment timer 311 expires.

[0052] Then, the terminal station device 200 transmits a message (MSG3) equivalent to an RRC Resume Request to the base station device 100 (step S204). At this time, the terminal station device 200 may transmit a part of the small data SD by including it in MSG3. The base station device 100 receiving MSG3 determines a radio resource CG to be used by the terminal station device 200 to transmit the small data SD, and transmits a message (MSG4) including configuration information of this radio resource CG to the terminal station device 200 (step S205). Note that MSG4 corresponds to RRC Release w / suspendConfig. Here, the radio resource CG is determined in a state in which an optimal beam is selected by the terminal station device 200, and therefore the optimal radio resource CG is set. The radio resource CG may be set in a plurality of time domains.

[0053] After receiving MSG4, the terminal station device 200 transmits a part of the small data SD to the base station device 100 by using the wireless resource CG (step S206). In addition, the terminal station device 200 starts a timer 312 related to the communication of the small data SD in accordance with the interval setting information received in step S201, and turns on a wireless receiving circuit in the interval until the timer 312 expires. Note that, although it is assumed here that interval setting information of a timer or the like is received in step S201, interval setting information of a timer or the like related to the wireless resource CG may be received in step S205.

[0054] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S207). At this time, the base station device 100 masks the PDCCH in response to the value of the Temporary C-RNTI included in MSG2 and transmits it. Since the terminal station device 200 turns on the wireless receiving circuit in the period until the timer 312 expires, the terminal station device 200 can receive the PDCCH control signal in step S207. Furthermore, since the terminal station device 200 holds the Temporary C-RNTI notified by MSG2, the terminal station device 200 can decode the control signal masked in response to the value of the Temporary C-RNTI. Then, the terminal station device 200 turns off the wireless receiving circuit when the timer 312 expires.

[0055] Thereafter, the terminal station device 200 transmits the remaining part of the small data SD to the base station device 100 by using the next radio resource CG (step S208). In addition, the terminal station device 200 starts a timer 313 related to the communication of the small data SD in accordance with the section setting information received in step S201, and turns on the radio receiving circuit during the section until the timer 313 expires.

[0056] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S209). At this time, the base station device 100 masks the PDCCH in response to the value of the Temporary C-RNTI included in MSG2 and transmits it. Since the terminal station device 200 turns on the wireless receiving circuit in the period until the timer 313 expires, the terminal station device 200 can receive the PDCCH control signal in step S209. Furthermore, since the terminal station device 200 holds the Temporary C-RNTI notified by MSG2, the terminal station device 200 can decode the control signal masked in response to the value of the Temporary C-RNTI. Then, the terminal station device 200 turns off the wireless receiving circuit when the timer 313 expires.

[0057] 6, the timers 312 and 313 are started every time the small data SD is transmitted using the radio resource CG, and the period in which the radio receiving circuit is on continues until the timers 312 and 313 expire. As a result, the terminal station device 200 can reliably receive the control signal of the PDCCH for the small data SD even in the RRC inactive mode.

[0058] In this embodiment, the small data SD is transmitted by two radio resource CGs, but the radio resource CG may be set three or more times, and the small data SD may be transmitted by using each radio resource CG. If the small data SD can be transmitted by one radio resource CG, the small data SD may not be transmitted in step S208. In this case, instead of the small data SD, for example, buffer status information (BSR: Buffer Status Report) indicating the state of the buffer of the terminal station device 200 may be transmitted by using the radio resource CG.

[0059] Fig. 7 is a sequence diagram showing another specific example of the wireless communication method according to the second embodiment. In Fig. 7, the same parts as in Fig. 6 are given the same reference numerals, and detailed description thereof will be omitted. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which the power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 7 shows a time period in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0060] When the base station device 100 transmits control information including interval setting information (step S201), the terminal station device 200 turns on a wireless receiving circuit during an interval corresponding to a paging frame, for example, and turns off the wireless receiving circuit when the interval corresponding to the paging frame has elapsed. After that, when small data SD to be transmitted from the terminal station device 200 is generated, the terminal station device 200 selects an optimal beam from among multiple beams formed by the base station device 100, and transmits MSG1 to the base station device 100 (step S202). After transmitting MSG1, the terminal station device 200 turns on a wireless receiving circuit to receive a message corresponding to MSG1.

[0061] The base station device 100 that receives MSG1 transmits MSG2 including the TA value and the Temporary C-RNTI to the terminal station device 200 (step S203). The terminal station device 200 that receives MSG2 including the TA value starts the time adjustment timer 311. In addition, the terminal station device 200 holds the Temporary C-RNTI included in MSG2 until the time adjustment timer 311 expires.

[0062] Then, the terminal station device 200 transmits MSG3 to the base station device 100 (step S204). At this time, the terminal station device 200 may transmit MSG3 including a part of the small data SD. After transmitting MSG3, the terminal station device 200 starts a contention resolution timer 314 and attempts to detect reception of MSG4 until the contention resolution timer 314 expires. At this time, the terminal station device 200 treats the contention resolution timer 314 as a timer equivalent to the timers 312 and 313 described above, and turns on the wireless receiving circuit in the period until the contention resolution timer 314 expires (case 1). Alternatively, in order to separate the roles of the timers, the terminal station device 200 may define a timer other than the contention resolution timer 314 and treat the timer as a timer equivalent to the timers 312 and 313 described above. In this case, the terminal station device 200 turns on the wireless receiving circuit in the period until the other defined timer expires (case 2).

[0063] In case 1, the terminal station device 200 may extend the set time of the collision resolution timer 314 that starts when MSG3 is transmitted, according to the interval setting information received in step S201. Specifically, the set time of the collision resolution timer 314 is extended by the time specified by the interval setting information so that the set time of the collision resolution timer 314 expires after the time to wait for the reception of the PDCCH control signal after the radio resource CG has elapsed. Note that, although the maximum set time of the collision resolution timer 314 is currently specified as 64 subframes (corresponding to 64 ms), a longer set time may be set in the collision resolution timer 314 as necessary. When the terminal station device 200 starts the collision resolution timer 314, it turns on the wireless receiving circuit in the interval until the collision resolution timer 314 expires. Hereinafter, the description of this embodiment will be continued assuming that the set time of the collision resolution timer 314 is extended.

[0064] The base station device 100 that receives MSG3 determines the radio resource CG that the terminal station device 200 will use to transmit the small data SD, and transmits MSG4 including setting information of the radio resource CG to the terminal station device 200 (step S205). After receiving MSG4, the terminal station device 200 transmits a part of the small data SD to the base station device 100 using the radio resource CG (step S206).

[0065] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S207). Since the terminal station device 200 keeps the wireless receiving circuit on until the extended collision resolution timer 314 expires, the terminal station device 200 can receive the PDCCH control signal in step S207.

[0066] Thereafter, the terminal station device 200 transmits the remaining part of the small data SD to the base station device 100 using the next radio resource CG (step S208). The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S209). Since the terminal station device 200 keeps the wireless receiving circuit on during the period until the extended collision resolution timer 314 expires, the terminal station device 200 can receive the PDCCH control signal in step S209. Then, the terminal station device 200 turns off the wireless receiving circuit when the collision resolution timer 314 expires.

[0067] 7, the set time of the collision resolution timer 314 is extended, and the period in which the radio receiving circuit is on continues until the PDCCH control signals for all of the multiple radio resource CGs are received. As a result, the radio receiving circuit is not temporarily turned off after each radio resource CG, and on / off switching is suppressed, thereby further improving control efficiency.

[0068] Fig. 8 is a sequence diagram showing yet another specific example of the wireless communication method according to the second embodiment. In Fig. 8, the same parts as in Fig. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 8 shows time periods in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0069] When the base station device 100 transmits control information including interval setting information (step S201), the terminal station device 200 turns on a wireless receiving circuit during an interval corresponding to a paging frame, for example, and turns off the wireless receiving circuit when the interval corresponding to the paging frame has elapsed. After that, when small data SD to be transmitted from the terminal station device 200 is generated, the terminal station device 200 selects an optimal beam from among multiple beams formed by the base station device 100, and transmits MSG1 to the base station device 100 (step S202). After transmitting MSG1, the terminal station device 200 turns on a wireless receiving circuit to receive a message corresponding to MSG1.

[0070] The base station device 100 that receives MSG1 transmits MSG2 including the TA value and the Temporary C-RNTI to the terminal station device 200 (step S203). The terminal station device 200 that receives MSG2 including the TA value starts the time adjustment timer 311. In addition, the terminal station device 200 holds the Temporary C-RNTI included in MSG2 until the time adjustment timer 311 expires.

[0071] Then, the terminal station device 200 transmits MSG3 to the base station device 100 (step S204). At this time, the terminal station device 200 may transmit MSG3 including a part of the small data SD. Furthermore, when transmitting MSG3, the terminal station device 200 starts a collision resolution timer for waiting for reception of MSG4, and turns on the wireless receiving circuit during the period until the collision resolution timer expires. Note that, although the maximum set time of the collision resolution timer is currently specified as 64 subframes (equivalent to 64 ms), a longer set time may be set in the collision resolution timer as necessary.

[0072] The base station device 100 receiving MSG3 determines the radio resource CG to be used by the terminal station device 200 to transmit the small data SD, and transmits RRC layer reconfiguration information (e.g., RRC Reconfiguration) including configuration information of this radio resource CG to the terminal station device 200 (step S211). At this time, the base station device 100 sets the radio resource CG at the time until MSG4 is transmitted. Here, the radio resource CG is determined with the terminal station device 200 selecting the optimal beam, and therefore the optimal radio resource CG is set. The radio resource CG may be set in a plurality of time domains.

[0073] After receiving the reconfiguration information, the terminal station device 200 transmits the small data SD to the base station device 100 using the radio resource CG set at the time before receiving MSG4 (step S212). The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S213). At this time, the base station device 100 masks the PDCCH in response to the value of Temporary C-RNTI included in MSG2 and transmits it. Since the terminal station device 200 keeps the radio receiving circuit on during the period until the collision resolution timer that waits for reception of MSG4 expires, the terminal station device 200 can receive the PDCCH control signal in step S213. Furthermore, since the terminal station device 200 holds the Temporary C-RNTI notified by MSG2, the terminal station device 200 can decode the control signal masked in response to the value of Temporary C-RNTI.

[0074] Thereafter, the base station device 100 transmits MSG4 corresponding to MSG3 to the terminal station device 200 before the collision resolution timer of the terminal station device 200 expires (step S205). After receiving MSG4, the terminal station device 200 turns off the wireless receiving circuit when the collision resolution timer expires.

[0075] 8, the terminal station device 200 transmits small data SD using the radio resource CG and receives a control signal of the PDCCH during the time period from the transmission of MSG3 until the expiration of the collision resolution timer for waiting for the reception of MSG4. Therefore, the terminal station device 200 only needs to monitor the PDCCH during the time period from the transmission of MSG3 until the reception of MSG4, and does not need to set a new timer for waiting for the reception of a control signal of the PDCCH for the transmission of the small data SD.

[0076] As described above, according to the present embodiment, after the small data is generated, the radio resource for transmitting the small data is set using the four-step random access procedure, and a section is provided in which the radio receiving circuit of the terminal station device is continuously turned on even after the small data is transmitted. Therefore, the terminal station device can receive a control signal corresponding to the transmission of the small data, and can improve the efficiency of data communication by minimizing the frequency at which the radio receiving circuit is switched on and off. In addition, since the small data is transmitted using the optimal radio resource that is set after the optimal beam is selected, the reception quality of the small data can be improved.

[0077] (Embodiment 3) In the third embodiment, a case will be described in which the radio resource CG used for transmitting the small data SD is set by using a two-step random access procedure.

[0078] The configurations of the base station device 100 and the terminal station device 200 according to the third embodiment are the same as those of the base station device 100 (FIG. 1) and the terminal station device 200 (FIG. 2) according to the first embodiment. Fig. 9 is a sequence diagram showing a specific example of a wireless communication method according to the third embodiment. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 9 shows time periods in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0079] The base station device 100 transmits control information including interval setting information regarding setting of an interval corresponding to a paging frame and an interval corresponding to communication of small data (step S301). The interval setting information may include, for example, information on the time when the paging frame is provided, information on the setting time of a timer that starts when small data is transmitted, etc. In addition, as the control information including the interval setting information, for example, broadcast information such as MIB or SIB, or individual control information of the RRC layer is used.

[0080] When the terminal station device 200 receives the period setting information, for example, in a period corresponding to a paging frame, the terminal station device 200 turns on a wireless receiving circuit and receives a control signal such as a PDCCH related to paging from the base station device 100. Then, the terminal station device 200 turns off the wireless receiving circuit when the period corresponding to the paging frame has elapsed.

[0081] Thereafter, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 selects an optimal beam from among the multiple beams formed by the base station device 100, and transmits a message (MSGA) including a preamble corresponding to the selected beam to the base station device 100 (step S302). At this time, the terminal station device 200 may transmit a part of the small data SD by including it in the MSGA. The MSGA is a message that combines MSG1 and MSG3 in the four-step random access procedure described in the second embodiment. After transmitting the MSGA, the terminal station device 200 turns on a wireless receiving circuit to receive a message corresponding to the MSGA.

[0082] The base station device 100 that receives the MSGA determines a TA value for adjusting the transmission timing of the terminal station device 200, and assigns an identifier, C-RNTI (Cell-Radio Network Temporary Identifier), to the terminal station device 200. Then, the base station device 100 transmits a message (MSGB) including the TA value and C-RNTI to the terminal station device 200 (step S303). The MSGB is a message that combines MSG2 and MSG4 in the four-step random access procedure described in the second embodiment, but here, RRC Release w / suspendConfig is not transmitted in MSG4.

[0083] The terminal station device 200 that receives the MSGB including the TA value determines that uplink synchronization has been established, and starts the time adjustment timer 321 that specifies the duration of uplink synchronization. After that, until the time adjustment timer 321 expires, the processor 220 of the terminal station device 200 can arbitrarily set the radio receiving circuit to on or off. In addition, the terminal station device 200 holds the C-RNTI included in the MSGB until the time adjustment timer 321 expires.

[0084] After transmitting the MSGB, the base station device 100 determines the radio resource CG to be used by the terminal station device 200 to transmit the small data SD, and transmits individual control information including setting information of the radio resource CG to the terminal station device 200 (step S304). This individual control information corresponds to RRC Release w / suspendConfig. Here, the radio resource CG is determined in a state in which an optimal beam is selected by the terminal station device 200, so that the optimal radio resource CG is set. The radio resource CG may be set in a plurality of time domains.

[0085] After receiving the individual control information, the terminal station device 200 transmits a part of the small data SD to the base station device 100 using the radio resource CG (step S305). In addition, the terminal station device 200 starts a timer 322 related to communication of the small data SD in accordance with the section setting information received in step S301, and turns on the radio receiving circuit during the section until the timer 322 expires.

[0086] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S306). At this time, the base station device 100 masks the PDCCH in response to the value of the C-RNTI included in the MSGB and transmits it. Since the terminal station device 200 turns on the wireless receiving circuit in the period until the timer 322 expires, the terminal station device 200 can receive the PDCCH control signal in step S306. Furthermore, since the terminal station device 200 holds the C-RNTI notified by the MSGB, the terminal station device 200 can decode the control signal masked in response to the value of the C-RNTI. Then, the terminal station device 200 turns off the wireless receiving circuit when the timer 322 expires.

[0087] Thereafter, the terminal station device 200 transmits the remaining part of the small data SD to the base station device 100 by using the next radio resource CG (step S307). In addition, the terminal station device 200 starts a timer 323 related to the communication of the small data SD in accordance with the section setting information received in step S301, and turns on the radio receiving circuit during the section until the timer 323 expires.

[0088] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S308). At this time, the base station device 100 masks the PDCCH in response to the value of the C-RNTI included in the MSGB and transmits it. Since the terminal station device 200 turns on the wireless receiving circuit in the period until the timer 323 expires, the terminal station device 200 can receive the PDCCH control signal in step S308. Furthermore, since the terminal station device 200 holds the C-RNTI notified by the MSGB, the terminal station device 200 can decode the control signal masked in response to the value of the C-RNTI. Then, the terminal station device 200 turns off the wireless receiving circuit when the timer 323 expires.

[0089] 9, the timers 322 and 323 start every time the small data SD is transmitted using the radio resource CG, and the period in which the radio receiving circuit is on continues until the timers 322 and 323 expire. As a result, the terminal station device 200 can reliably receive the control signal of the PDCCH for the small data SD even in the RRC inactive mode.

[0090] In this embodiment, the small data SD is transmitted by two radio resource CGs, but the radio resource CG may be set three or more times, and the small data SD may be transmitted by using each radio resource CG. If the small data SD can be transmitted by one radio resource CG, the small data SD may not be transmitted in step S307. In this case, instead of the small data SD, for example, buffer status information (BSR) indicating the state of the buffer of the terminal station device 200 may be transmitted by using the radio resource CG.

[0091] Fig. 10 is a sequence diagram showing another specific example of the wireless communication method according to the third embodiment. In Fig. 10, the same parts as those in Fig. 9 are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 10 shows time periods in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0092] When the base station device 100 transmits control information including interval setting information (step S301), the terminal station device 200 turns on a wireless receiving circuit during an interval corresponding to a paging frame, for example, and turns off the wireless receiving circuit when the interval corresponding to the paging frame has elapsed. After that, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 selects an optimal beam from among the multiple beams formed by the base station device 100, and transmits an MSGA to the base station device 100 (step S302). At this time, the terminal station device 200 may transmit a part of the small data SD by including it in the MSGA.

[0093] After transmitting MSGA, the terminal station device 200 starts a response window (msgB-ResponseWindow) 324 and tries to detect reception of MSGB until the response window 324 ends. At this time, the terminal station device 200 treats the response window 324 as a timer equivalent to the timer 322 and timer 323 described above, and turns on the wireless receiving circuit during the period until the response window 324 ends (Case 1). Alternatively, in order to separate the roles of the timers, the terminal station device 200 may define a timer other than the response window 324 and treat the timer as a timer equivalent to the timer 322 and timer 323 described above. In this case, the terminal station device 200 turns on the wireless receiving circuit during the period until the other defined timer expires (Case 2).

[0094] In case 1, the terminal station device 200 may extend the setting time of the response window 324 for waiting for reception of MSGB according to the interval setting information received in step S301. Specifically, the setting time of the response window 324 is extended by the time specified by the interval setting information so that the response window 324 expires after the time for waiting for reception of the PDCCH control signal after the radio resource CG has elapsed. Note that, although the maximum setting time of the response window 324 for MSGB is currently specified as 1320 slots, the response window 324 may be set to a longer setting time as necessary. When the response window 324 starts, the terminal station device 200 turns on the wireless receiving circuit for the interval until the response window 324 ends. Hereinafter, the description of this embodiment will be continued assuming that the setting time of the response window 324 is extended.

[0095] The base station device 100 that receives the MSGA transmits the MSGB including the TA value and the C-RNTI to the terminal station device 200 (step S303). The terminal station device 200 that receives the MSGB including the TA value starts the time adjustment timer 321. In addition, the terminal station device 200 holds the C-RNTI included in the MSGB until the time adjustment timer 321 expires.

[0096] After transmitting the MSGB, the base station device 100 determines the radio resource CG to be used by the terminal station device 200 to transmit the small data SD, and transmits individual control information including setting information of the radio resource CG to the terminal station device 200 (step S304). After receiving the individual control information, the terminal station device 200 transmits a part of the small data SD to the base station device 100 using the radio resource CG (step S305).

[0097] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S306). Since the terminal station device 200 keeps the wireless receiving circuit on during the period until the extended response window 324 ends, the terminal station device 200 can receive the PDCCH control signal in step S306.

[0098] Thereafter, the terminal station device 200 transmits the remaining part of the small data SD to the base station device 100 using the next radio resource CG (step S307). The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S308). Since the terminal station device 200 keeps its wireless receiving circuit on during the period until the extended response window 324 expires, it is able to receive the PDCCH control signal in step S308. Then, the terminal station device 200 turns off its wireless receiving circuit when the response window 324 ends.

[0099] 10, the set time of the response window 324 for MSGB is extended, and the period during which the radio receiving circuit is on continues until PDCCH control signals for all of the multiple radio resources CG are received. As a result, the radio receiving circuit is not temporarily turned off after each radio resource CG, and on / off switching is suppressed, thereby further improving control efficiency.

[0100] Fig. 11 is a sequence diagram showing yet another specific example of the wireless communication method according to the third embodiment. In Fig. 11, the same parts as in Fig. 9 are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 11 shows time periods in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0101] When the base station device 100 transmits control information including the interval setting information (step S301), the terminal station device 200 turns on the wireless receiving circuit in the interval corresponding to the paging frame, for example, and turns off the wireless receiving circuit when the interval corresponding to the paging frame has elapsed. After that, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 selects an optimal beam from among the multiple beams formed by the base station device 100 and transmits MSGA to the base station device 100 (step S302). At this time, the terminal station device 200 may transmit a part of the small data SD by including it in the MSGA. In addition, when transmitting MSGA, the terminal station device 200 starts a response window for waiting for reception of MSGB, and turns on the wireless receiving circuit in the interval until the response window ends. The maximum setting time of the response window is currently specified as 1320 slots, but a response window with a longer setting time may be set as necessary.

[0102] The base station device 100 that receives the MSGA transmits an MSGB including a TA value and a C-RNTI to the terminal station device 200 (step S303). However, RRC Release w / suspendConfig is not transmitted in this MSGB. The terminal station device 200 that receives the MSGB including the TA value starts a time adjustment timer 321. In addition, the terminal station device 200 holds the C-RNTI included in the MSGB until the time adjustment timer 321 expires.

[0103] After transmitting MSGB, the base station device 100 determines the radio resource CG to be used by the terminal station device 200 to transmit the small data SD, and transmits RRC layer reconfiguration information (e.g., RRC Reconfiguration) including configuration information of the radio resource CG to the terminal station device 200 (step S311). At this time, the base station device 100 sets the radio resource CG at the time until the individual control information corresponding to MSG4 is transmitted. Here, the radio resource CG is determined in a state in which an optimal beam is selected by the terminal station device 200, and therefore the optimal radio resource CG is set. The radio resource CG may be set in a plurality of time domains.

[0104] After receiving the reconfiguration information, the terminal station device 200 transmits the small data SD to the base station device 100 using the radio resource CG set at the time before receiving the individual control information (step S312). The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S313). At this time, the base station device 100 masks the PDCCH in response to the value of the C-RNTI included in the MSGB and transmits it. Since the terminal station device 200 turns on the radio receiving circuit in the section until the response window for waiting for reception of the MSGB ends, it can receive the PDCCH control signal in step S313. Furthermore, since the terminal station device 200 holds the C-RNTI notified by the MSGB, it can decode the control signal masked in response to the value of the C-RNTI.

[0105] Thereafter, the base station device 100 transmits individual control information corresponding to MSG4 to the terminal station device 200 until the response window of the terminal station device 200 ends (step S304). After receiving the individual control information, the terminal station device 200 turns off the wireless receiving circuit when the response window ends.

[0106] 11, the terminal station device 200 transmits small data SD using the radio resource CG and receives a PDCCH control signal during the period from the transmission of MSGA until the end of the response window for waiting for reception of MSGB. Therefore, the terminal station device 200 only needs to monitor the PDCCH during the period from the transmission of MSGA until the reception of RRC Release w / suspendConfig, which is individual control information corresponding to MSG4, and does not need to set a new timer for waiting for reception of a PDCCH control signal for the transmission of small data SD.

[0107] As described above, according to the present embodiment, after the small data is generated, the radio resource for transmitting the small data is set using the individual control information, and a section is provided in which the radio receiving circuit of the terminal station device is continuously turned on even after the small data is transmitted. Therefore, the terminal station device can receive a control signal corresponding to the transmission of the small data, and can improve the efficiency of data communication by minimizing the frequency at which the radio receiving circuit is switched on and off. In addition, since the small data is transmitted using the optimal radio resource that is set after the optimal beam is selected, the reception quality of the small data can be improved.

[0108] (Embodiment 4) In the fourth embodiment, another case will be described in which the radio resource CG used for transmitting the small data SD is set by using a two-step random access procedure.

[0109] The configurations of the base station device 100 and the terminal station device 200 according to the fourth embodiment are the same as those of the base station device 100 (FIG. 1) and the terminal station device 200 (FIG. 2) according to the first embodiment. FIG. 12 is a sequence diagram showing a specific example of a wireless communication method according to the fourth embodiment. In FIG. 12, the same parts as those in FIG. 9 are given the same reference numerals, and detailed explanations thereof will be omitted. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. FIG. 12 shows a time period in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0110] When the base station device 100 transmits control information including interval setting information (step S301), the terminal station device 200 turns on a wireless receiving circuit during an interval corresponding to a paging frame, for example, and turns off the wireless receiving circuit when the interval corresponding to the paging frame has elapsed. After that, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 selects an optimal beam from among a plurality of beams formed by the base station device 100, and transmits an MSGA to the base station device 100 (step S302). At this time, the terminal station device 200 may transmit a part of the small data SD by including it in the MSGA. After transmitting the MSGA, the terminal station device 200 turns on a wireless receiving circuit to receive a message corresponding to the MSGA.

[0111] The base station device 100 that receives the MSGA determines a TA value for adjusting the transmission timing of the terminal station device 200, and assigns a C-RNTI, which is an identifier, to the terminal station device 200. The base station device 100 also determines a radio resource CG that the terminal station device 200 uses to transmit the small data SD, and transmits a message (MSGB) including configuration information of the radio resource CG, the TA value, and the C-RNTI to the terminal station device 200 (step S401). The MSGB is a message that combines MSG2 and MSG4 in the four-step random access procedure described in the second embodiment.

[0112] The terminal station device 200 that receives the MSGB including the TA value determines that uplink synchronization has been established, and starts the time adjustment timer 331 that specifies the duration of uplink synchronization. After that, until the time adjustment timer 331 expires, the processor 220 of the terminal station device 200 can arbitrarily set the radio receiving circuit to on or off. In addition, the terminal station device 200 holds the C-RNTI included in the MSGB until the time adjustment timer 331 expires.

[0113] After receiving the MSGB, the terminal station device 200 transmits a part of the small data SD to the base station device 100 using the radio resource CG (step S305). In addition, the terminal station device 200 starts a timer 322 related to communication of the small data SD in accordance with the section setting information received in step S301, and turns on the radio receiving circuit during the section until the timer 322 expires.

[0114] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S306). At this time, the base station device 100 masks the PDCCH in response to the value of the C-RNTI included in the MSGB and transmits it. Since the terminal station device 200 turns on the wireless receiving circuit in the period until the timer 322 expires, the terminal station device 200 can receive the PDCCH control signal in step S306. Furthermore, since the terminal station device 200 holds the C-RNTI notified by the MSGB, the terminal station device 200 can decode the control signal masked in response to the value of the C-RNTI. Then, the terminal station device 200 turns off the wireless receiving circuit when the timer 322 expires.

[0115] Thereafter, the terminal station device 200 transmits the remaining part of the small data SD to the base station device 100 by using the next radio resource CG (step S307). In addition, the terminal station device 200 starts a timer 323 related to the communication of the small data SD in accordance with the section setting information received in step S301, and turns on the radio receiving circuit during the section until the timer 323 expires.

[0116] The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S308). At this time, the base station device 100 masks the PDCCH in response to the value of the C-RNTI included in the MSGB and transmits it. Since the terminal station device 200 turns on the wireless receiving circuit in the period until the timer 323 expires, the terminal station device 200 can receive the PDCCH control signal in step S308. Furthermore, since the terminal station device 200 holds the C-RNTI notified by the MSGB, the terminal station device 200 can decode the control signal masked in response to the value of the C-RNTI. Then, the terminal station device 200 turns off the wireless receiving circuit when the timer 323 expires.

[0117] 12, the timers 322 and 323 start every time the small data SD is transmitted using the radio resource CG, and the period in which the radio receiving circuit is on continues until the timers 322 and 323 expire. As a result, the terminal station device 200 can reliably receive the control signal of the PDCCH for the small data SD even in the RRC inactive mode.

[0118] In this embodiment, the small data SD is transmitted by two radio resource CGs, but the radio resource CG may be set three or more times, and the small data SD may be transmitted by using each radio resource CG. If the small data SD can be transmitted by one radio resource CG, the small data SD may not be transmitted in step S307. In this case, instead of the small data SD, for example, buffer status information indicating the status of the buffer of the terminal station device 200 may be transmitted by using the radio resource CG.

[0119] Fig. 13 is a sequence diagram showing another specific example of the wireless communication method according to the fourth embodiment. In Fig. 13, the same parts as those in Figs. 9 and 12 are denoted by the same reference numerals, and detailed description thereof will be omitted. Here, it is assumed that the terminal station device 200 has transitioned to an RRC inactive mode in which power supply to the wireless communication unit 210 is reduced to reduce power consumption. Fig. 13 shows time periods in which the wireless receiving circuit of the wireless communication unit 210 is turned on or off.

[0120] When the base station device 100 transmits control information including interval setting information (step S301), the terminal station device 200 turns on a wireless receiving circuit during an interval corresponding to a paging frame, for example, and turns off the wireless receiving circuit when the interval corresponding to the paging frame has elapsed. After that, when small data SD to be transmitted from the terminal station device 200 occurs, the terminal station device 200 selects an optimal beam from among the multiple beams formed by the base station device 100, and transmits an MSGA to the base station device 100 (step S302). At this time, the terminal station device 200 may transmit a part of the small data SD by including it in the MSGA.

[0121] After transmitting MSGA, the terminal station device 200 starts a response window 324 and tries to detect reception of MSGB until the response window 324 ends. At this time, the terminal station device 200 treats the response window 324 as a timer equivalent to the timer 322 and timer 323 described above, and turns on the wireless receiving circuit during the period until the response window 324 ends (Case 1). Alternatively, in order to separate the roles of the timers, the terminal station device 200 may define a timer other than the response window 324 and treat the timer as a timer equivalent to the timer 322 and timer 323 described above. In this case, the terminal station device 200 turns on the wireless receiving circuit during the period until the other defined timer expires (Case 2).

[0122] In case 1, the terminal station device 200 may extend the setting time of the response window 324 for waiting for reception of the MSGB in accordance with the section setting information received in step S301. When the response window 324 starts, the terminal station device 200 turns on the wireless receiving circuit for the section until the response window 324 ends. Hereinafter, the present embodiment will be described assuming that the setting time of the response window 324 is extended.

[0123] The base station device 100 that receives the MSGA transmits the MSGB including the setting information of the radio resource CG, the TA value, and the C-RNTI to the terminal station device 200 (step S401). The terminal station device 200 that receives the MSGB including the TA value starts the time adjustment timer 321. In addition, the terminal station device 200 holds the C-RNTI included in the MSGB until the time adjustment timer 321 expires.

[0124] After receiving the MSGB, the terminal station device 200 transmits a part of the small data SD to the base station device 100 using the radio resource CG (step S305). The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S306). Since the terminal station device 200 keeps its radio receiving circuit on during the period until the extended response window 324 ends, it is able to receive the PDCCH control signal in step S306.

[0125] Thereafter, the terminal station device 200 transmits the remaining part of the small data SD to the base station device 100 using the next radio resource CG (step S307). The base station device 100 that receives the small data SD from the terminal station device 200 transmits a PDCCH control signal in response to the small data SD (step S308). Since the terminal station device 200 keeps its wireless receiving circuit on during the period until the extended response window 324 expires, it is able to receive the PDCCH control signal in step S308. Then, the terminal station device 200 turns off its wireless receiving circuit when the response window 324 ends.

[0126] 13, the setting time of the response window 324 for MSGB is extended, and the period in which the radio receiving circuit is on continues until the PDCCH control signals for all of the multiple radio resources CG are received. As a result, the radio receiving circuit is not temporarily turned off after each radio resource CG, and on / off switching is suppressed, thereby further improving control efficiency.

[0127] As described above, according to the present embodiment, after the small data is generated, a radio resource for transmitting the small data is set using a two-step random access procedure, and a section is provided in which the radio receiving circuit of the terminal station device is continuously turned on even after the small data is transmitted. Therefore, the terminal station device can receive a control signal corresponding to the transmission of the small data, and can improve the efficiency of data communication by minimizing the frequency at which the radio receiving circuit is switched on and off. In addition, since the small data is transmitted using the optimal radio resource that is set after the optimal beam is selected, the reception quality of the small data can be improved.

[0128] In addition, in the above-mentioned embodiment 4, the terminal station device 200 can also transmit small data SD using the radio resource CG and receive a control signal of the PDCCH until the end of the response window for waiting for reception of the MSGB, as in the embodiment 3 (FIG. 11).

[0129] (Other embodiments) The following is an example of technical matters common to the above-mentioned embodiments. In the above-mentioned embodiments, when small data SD to be transmitted occurs in the terminal station device 200, the small data SD is transmitted using the radio resource CG. Here, the occurrence of small data SD refers to, for example, when a predetermined type of data occurs, or when the size of the generated data satisfies a criterion for determining that the data is small data. In addition, since radio quality is also important, the occurrence of small data SD may include a condition that the radio quality is in a state where transmission of MSG1 and MSGA is possible. The terminal station device 200 performs communication related to the transmission of the small data SD depending on the state of data communication such as whether or not the small data SD occurs.

[0130] From the viewpoint of power consumption, the difference between the setting method (setting 1) in which the radio receiving circuit is repeatedly turned on and off as shown in FIG. 6, FIG. 9, and FIG. 12 and the setting method (setting 2) in which the on interval of the radio receiving circuit is consolidated as shown in FIG. 7, FIG. 8, FIG. 10, FIG. 11, and FIG. 13 will be mentioned. In setting 1, when on and off are repeatedly performed for a long time, power consumption increases at the rising edge of the on interval, so power consumption is larger than that of setting 2. However, since the PDCCH, which is a downlink control signal, is not monitored in the off interval, there is an advantage that power consumption can be reduced from the viewpoint of processing the control signal. On the other hand, setting 2 can reduce power consumption at the rising edge of the on interval, so power consumption is smaller than that of setting 1. However, since the PDCCH is monitored in the on interval, there is a disadvantage that power consumption increases from the viewpoint of processing the control signal. In consideration of such advantages and disadvantages, it is preferable to use the on interval and off interval settings according to settings 1 and 2 separately.

[0131] In each of the above embodiments, quasi-normal communication (for example, various failures) may be managed. For example, when a transmission failure occurs in the RLC (Radio Link Control) layer during small data communication and the maximum number of retransmissions reaches a predetermined threshold, a RLF (Radio Link Failure) occurs. However, in small data communication in the RRC inactive mode, it may be difficult to perform communication using optimal parameters (for example, uplink transmission power, radio resources, transmission timing, etc.), and the number of retransmissions in the RLC layer may increase. For this reason, in small data communication in the RRC inactive mode, even if the maximum number of retransmissions reaches a predetermined threshold, it may be determined that an RLF has not occurred.

[0132] Furthermore, in each of the above embodiments, the lengths of the time adjustment timers 311, 321, and 331 should be set carefully. If there is a provision that the radio resource CG is released when these time adjustment timers expire, even if the terminal station device 200 wishes to continue transmitting small data after the time adjustment timer expires, it will be difficult to transmit the small data because the radio resource CG has been released. Therefore, it is preferable to set the length of the time adjustment timer to a certain extent so that the transmission of small data can be continued. However, there is also a possibility that the length of the time adjustment timer is not set long enough, and it will still be difficult to transmit the small data.

[0133] As one method for fundamentally solving such a situation, the base station device 100 periodically transmits a TA command including a TA value to the terminal station device 200 and restarts the time adjustment timer of the terminal station device 200. For example, if the base station device 100 transmits a TA command at a paging cycle in consideration of reducing the power consumption of the terminal station device 200, it is preferable to set the length of the above-mentioned time adjustment timer to be equal to or longer than the paging cycle. Moreover, regardless of whether the power consumption of the terminal station device 200 is reduced or not, it is preferable for the base station device 100 to transmit a TA command before the time adjustment timer of the terminal station device 200 expires.

[0134] In addition, the above-mentioned embodiments can be appropriately combined and implemented. For example, the various timers, the collision resolution timer, and the response window described in each embodiment may be combined to set the period during which the terminal station device 200 turns on the wireless receiving circuit and monitors the PDCCH. In this case, for example, the period during which the PDCCH is monitored may be set by the maximum or minimum value of the time length of various timers and windows that are set at the same time. [Explanation of symbols]

[0135] 110 Network Interface 120, 220 processors 130, 230 Memory 140, 210 Wireless communication section

Claims

1. a communication unit capable of performing communication when the terminal station device is in a predetermined state; a control unit that controls the communication with the terminal station device by using a section in which an area for decoding a control signal for the terminal station device to perform communication is valid, the section corresponding to a first communication of the communications and a second communication of the communications, the control unit being capable of controlling the communication with the terminal station device; having the second period is a period that starts when the terminal station device transmits data corresponding to the second communication and ends when a Radio Resource Control (RRC) message for setting a suspend state is received by the terminal station device from the communication unit; A base station device comprising:

2. The base station apparatus according to claim 1 , wherein the RRC message for setting the suspend includes an RRC Release with Suspend Config.

3. The base station device according to claim 1 , wherein the control unit causes the terminal station device to perform communication by intermittently using the first interval and the second interval.

4. The base station device according to claim 1 , wherein the communication unit transmits a message of an RRC layer including setting information related to an interval in which the region is valid.

5. 2. The base station apparatus according to claim 1, wherein the first communication is a paging communication, the second communication is a small data communication, and the predetermined state is an RRC inactive mode.

6. a base station device; and a communication unit capable of performing communication when in a predetermined state; a control unit that can control the execution of the communication by using a section in which a region for decoding a control signal for executing the communication is valid, according to a first section corresponding to a first communication of the communications and a second section corresponding to a second communication of the communications; having the second period is a period that starts when the communication unit transmits data corresponding to the second communication and ends when the communication unit receives an RRC message that sets a suspend state from the base station device. A terminal station device comprising:

7. The control unit is A wireless receiving circuit included in the communication unit is turned on in a period corresponding to the first communication which is periodically performed, and a wireless receiving circuit included in the communication unit is turned on in a period corresponding to the second communication including data transmission.

7. The terminal station device according to claim 6,

8. The terminal station according to claim 6 , wherein the control unit causes the terminal station to perform communication by intermittently using the first interval and the second interval.

9. 7. The terminal station device according to claim 6, wherein the first communication is a paging communication, the second communication is a small data communication, and the predetermined state is an RRC inactive mode.

10. a communication unit capable of performing communication when the terminal station device is in a predetermined state; a control unit that controls the communication with the terminal station device by using a section in which an area for decoding a control signal for the terminal station device to perform communication is valid, the section corresponding to a first communication of the communications and a second communication of the communications, the control unit being capable of controlling the communication with the terminal station device; having the second section is a section that starts when the terminal station device transmits data corresponding to the second communication and ends when the terminal station device receives individual control information transmitted from the communication unit. A base station device comprising:

11. a base station device; and a communication unit capable of performing communication when in a predetermined state; a control unit that can control the execution of the communication by using a section in which a region for decoding a control signal for executing the communication is valid, according to a first section corresponding to a first communication of the communications and a second section corresponding to a second communication of the communications; having the second period is a period that starts when the communication unit transmits data corresponding to the second communication and ends when the communication unit receives individual control information from the base station device. A terminal station device comprising:

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