WO2018138854A1

WO2018138854A1 - Base station, wireless communication system, wireless terminal, and wireless communication method

Info

Publication number: WO2018138854A1
Application number: PCT/JP2017/002852
Authority: WO
Inventors: 昂平田
Original assignee: 富士通株式会社
Priority date: 2017-01-27
Filing date: 2017-01-27
Publication date: 2018-08-02

Abstract

The present invention enables a wireless terminal that is in a state different from a line-connected state to perform data communication without transitioning to the line-connected state. Provided is a base station (11) having: a storage unit (11a) in which is stored information (21a) about a wireless terminal (12) that assumes a first state that is a line-connected state, a second state that is a line-disconnected state, or a third state that is different from the first and second states; and a control unit (11b) for receiving information (31) pertaining to uplink data transmission that is transmitted from the wireless terminal (12) in the third state when uplink data transmission occurs, and waiting for uplink data (32) from the wireless terminal (12) by uplink data transmission that uses a predetermined wireless resource (RS) between the wireless terminal (12) and the base station (11).

Description

Base station, radio communication system, radio terminal, and radio communication method

The present invention relates to a base station, a wireless communication system, a wireless terminal, and a wireless communication method.

The connection state between the wireless terminal (UE: User Equipment) and the base station (eNB: Evolved Node B) is the RRC (Radio Resource Control) that controls the wireless network (E-UTRAN: Evolved UMTS Terrestrial Radio Access Network). It is expressed in two states. One of the states is a state of RRC_IDLE, which is a state in which radio resources are disconnected. Another state is a state of RRC_CONNECTED which is a connection state of radio resources.

On the other hand, the connection state between the wireless terminal and the core network is represented by two states of ECM (EPS Connection Management). One of the states is an ECM_IDLE state in which a wireless terminal and a core network are connected via a base station. Another state is a state of ECM_CONNECTED, which is a state in which the wireless terminal and the core network are disconnected via the base station. In LTE (Long Term Evolution), the state transition of the wireless terminal is managed in the RRC state and the ECM state as described above.

An example of such a wireless terminal is an IoT (Internet of Things) terminal. The IoT terminal is equipped with a sensor and intermittently wirelessly transmits data output from the sensor to the base station at a low frequency. A radio terminal having a low communication frequency such as an IoT terminal transitions to the CONNECTED state of RRC and ECM at the timing of communication, and maintains the IDLE state of RRC and ECM during a period of no communication. When such wireless terminals increase, there is a risk that the processing load of disconnection and connection increases on the ECM side (upper layer).

Note that a WTRU (wireless transmission / reception unit) having a sleep mode (RRC DORMANT) different from the IDLE state and the CONNECTED state of RRC has been proposed. The WTRU transitions to sleep mode when the data characteristics or priority matches the sleep mode characteristics or priority. The WTRU in dormant mode executes a mobility procedure controlled by the WTRU and holds a C-RNTI (Cell Radio Radio Network Temporary Identity) for receiving traffic. In addition, a method has been proposed in which a network releases an RRC connection of a wireless terminal when the wireless terminal is inactive during a period defined by a sleep timer.

In addition, a radio terminal that transitions from an RRC_IDLE state and an EMM (EPS （Mobility－Management) -IDLE state to an RRC_CONNECTED state and an EMM-IDLE state has been proposed. After completing the transmission of user data, the wireless terminal transits from the RRC_CONNECTED state and the EMM-IDLE state to the RRC_IDLE state and the EMM-IDLE state. In addition, a method of shifting to the RRC deep idle mode when an MTC (Machine Type Communication) terminal in the RRC_CONNECTED state enters the power saving mode has been proposed.

JP-A-2015-149754 Japanese Unexamined Patent Publication No. 2014-143616 Special table 2016-527848 gazette JP 2016-146675 A

As described above, various proposals have been made for state transition of wireless terminals. In these proposed technologies, when the wireless terminal transmits data in a state where at least the wireless resource is disconnected, the state of the wireless terminal transitions to the RRC_CONNECTED state. For example, in the case of LTE, when UL (UpLink) data transmission is performed in the RRC_CONNECTED state, SR (Scheduling Request), BSR (Buffer Status Report), and the like are performed.

As already described, in a situation where the number of wireless terminals that perform communication infrequently increases, there is a risk that radio resources are frequently secured and released due to state transitions. Such a risk can be suppressed if data communication can be performed without shifting to a line-connected state such as the RRC_CONNECTED state in a state where the radio resource is disconnected.

According to one aspect, an object of the present invention is to enable a wireless terminal in a state different from a line-connected state to perform data communication without transitioning to a line-connected state.
Here, for convenience of explanation, the state transition of LTE is taken as an example, but an existing wireless communication system other than LTE, or a wireless communication system that is defined in the present or the future, or for which preparation of regulations is being advanced. Of course, this technique can also be included in the scope of the subject.

According to one aspect, for a wireless terminal that takes a first state that is a line connection state, a second state that is a line disconnection state, or a third state that is different from the first and second states Receives information related to uplink data transmission transmitted during uplink data transmission from a storage unit storing information and a wireless terminal in the third state, and uses radio resources determined in advance with the wireless terminal There is provided a base station having a control unit that waits for uplink data from a wireless terminal by uplink data transmission.

A wireless terminal in a state different from the line-connected state can perform data communication without making a transition to the line-connected state.
These and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings which illustrate preferred embodiments by way of example of the present invention.

It is the figure which showed an example of the radio | wireless communications system which concerns on 1st Embodiment. It is the figure which showed an example of the radio | wireless communications system which concerns on 2nd Embodiment. It is the block diagram which showed an example of the hardware which can implement | achieve the function of the base station which concerns on 2nd Embodiment. It is the block diagram which showed an example of the hardware which can implement | achieve the function of the radio | wireless terminal which concerns on 2nd Embodiment. It is the figure which showed an example of the state transition diagram regarding the state of line connection. It is the sequence diagram which showed the example of uplink data transmission. It is the block diagram which showed an example of the function which the base station which concerns on 2nd Embodiment has. It is the figure which showed an example of the management information which concerns on 2nd Embodiment. It is the block diagram which showed an example of the function which the radio | wireless terminal which concerns on 2nd Embodiment has. It is the sequence diagram which showed the flow of the process performed at the time of the uplink data transmission in the radio | wireless communications system which concerns on 2nd Embodiment. It is a figure for demonstrating an example of the radio | wireless resource allocated at the time of transmission of special SR. It is a flowchart for demonstrating the operation example (resource allocation) of the base station which concerns on 2nd Embodiment. It is a flowchart for demonstrating the operation example (special SR process) of the base station which concerns on 2nd Embodiment. It is a flowchart for demonstrating the operation example (resource allocation) of the radio | wireless terminal which concerns on 2nd Embodiment. It is a flowchart for demonstrating the operation example (special SR process) of the radio | wireless terminal which concerns on 2nd Embodiment. It is the sequence diagram which showed the example of downlink data transmission. It is the block diagram which showed an example of the function which the base station which concerns on 3rd Embodiment has. It is the figure which showed an example of the management information which concerns on 3rd Embodiment. It is the block diagram which showed an example of the function which the radio | wireless terminal which concerns on 3rd Embodiment has. It is the sequence diagram which showed the flow of the process performed at the time of the downlink data transmission in the radio | wireless communications system which concerns on 3rd Embodiment. It is a flowchart for demonstrating the operation example (resource allocation) of the base station which concerns on 3rd Embodiment. It is a flowchart for demonstrating the operation example (special Paging process) of the base station which concerns on 3rd Embodiment. It is a flowchart for demonstrating the operation example (resource allocation) of the radio | wireless terminal which concerns on 3rd Embodiment. It is a flowchart for demonstrating the operation example (special Paging process) of the radio | wireless terminal which concerns on 3rd Embodiment.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, about the element which has the substantially same function in this specification and drawing, duplication description may be abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. First Embodiment>
The first embodiment will be described with reference to FIG. The first embodiment relates to a wireless communication system in which a wireless terminal in a state different from a line-connected state can perform data communication without transitioning to a line-connected state. FIG. 1 is a diagram illustrating an example of a wireless communication system according to the first embodiment. The wireless communication system 10 illustrated in FIG. 1 is an example of a wireless communication system according to the first embodiment.

As shown in FIG. 1, the wireless communication system 10 includes a base station 11 and a wireless terminal 12. For convenience of explanation, FIG. 1 shows only one wireless terminal (wireless terminal 12), but the wireless communication system 10 may include two or more wireless terminals. The base station 11 is connected to a core network (not shown), which is a backbone network, by wire.

The base station 11 includes a storage unit 11a and a control unit 11b. The wireless terminal 12 includes a storage unit 12a and a control unit 12b.
The

storage units

11a and 12a are, for example, volatile storage devices such as RAM (Random Access Memory), or nonvolatile storage devices such as HDD (Hard Disk Drive) and flash memory. The

control units

11b and 12b are, for example, processors such as a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), and a field programmable gate array (FPGA), or a processor including a plurality of processors. Is a set of For example, the control unit 11b executes a program stored in the storage unit 11a or another memory. For example, the control unit 12b executes a program stored in the storage unit 12a or another memory.

The base station 11 and / or the wireless terminal 12 changes the state of the wireless terminal 12 to a first state that is a line connection state, a second state that is a line disconnection state, and a first and second state. Are managed in one of different third states.

The line connection state (first state) refers to the case where the radio resource is in the connected state and is also in the connected state in the upper layer. The state of RRC_CONNECTED and the state of ECM_CONNECTED are examples of the line connection state. On the other hand, the line disconnection state (second state) refers to, for example, a case where the radio resource is in a disconnected state and the upper layer is also in a disconnected state. The RRC_IDLE state and the ECM_IDLE state are examples of the line disconnection state.

The third state refers to, for example, the case where the radio resource is in a disconnected state and the upper layer is in a connected state. The RRC_IDLE state and the ECM_CONNECTED state are examples of the third state. For convenience of explanation, the RRC and ECM states are illustrated, but the first state, the second state, and the third state are states other than RRC and ECM (for example, current generation or next generation other than LTE). It may be defined by a radio resource defined by a standard or the like and a connection state of an upper layer).

Hereinafter, for convenience of explanation, the first state may be referred to as state # 1, the second state as state # 2, and the third state as state # 3.
FIG. 1 illustrates a situation where the wireless terminal 12 in the third state transmits uplink data (UL Data) 32.

In the storage unit 11a of the base station 11, information 21a about a wireless terminal and information 21b about a wireless resource are stored. The storage unit 12a of the wireless terminal 12 stores information 22a on the wireless terminal and information 22b on the wireless resource. The

information

21a and 22a on the wireless terminal includes information on the state of the wireless terminal 12. The radio resource information 21b and 22b includes information related to the radio resource RS determined in advance between the base station 11 and the radio terminal 12.

The information regarding the state of the wireless terminal 12 and the information regarding the wireless resource RS are shared between the base station 11 and the wireless terminal 12 when the wireless terminal 12 transitions to the third state, for example.
The information related to the radio resource RS includes, for example, a radio resource used for transmission of information (UL information) 31 related to uplink data transmission (to be described later), a radio resource used for uplink data transmission, and timing of uplink data transmission.

The radio resource used to transmit the information 31 related to uplink data transmission can be set to a size of 1 RE (Resource Element) or less, for example. In addition, the radio resource used for transmitting the information 31 related to uplink data transmission is determined in advance when the wireless terminal 12 is in the first state, or determined in advance when the wireless terminal 12 transitions to the third state, for example. Alternatively, the base station 11 is determined and notified to the wireless terminal 12 by a paging message.

The radio resource used for uplink data transmission can be set to a size that is equal to or smaller than a preset maximum size, for example. The maximum size may be set in advance as a fixed value according to the performance of the wireless communication system 10, the slice, the wireless terminal 12, or may be determined by the wireless terminal 12 or the base station 11 according to the performance. The radio resource used for uplink data transmission is determined in advance, for example, when the radio terminal 12 transitions to the third state, or is notified from the radio terminal 12 when information 31 related to uplink data transmission is transmitted.

The timing of uplink data transmission can be expressed by, for example, the time at which uplink data transmission is performed, the time from transmission of information 31 related to uplink data transmission to transmission of uplink data, and the like.
When the wireless terminal 12 performs uplink data transmission in the third state, the control unit 12b of the wireless terminal 12 transmits information 31 related to uplink data transmission to the base station 11. The information 31 regarding uplink data transmission is information for notifying the existence of uplink data transmission using the radio resource RS shared in advance between the base station 11 and the radio terminal 12. It should be noted that condition designation such as MCS (Modulation and Coding Scheme) may be performed at the timing of transmitting information 31 related to uplink data transmission.

When the control unit 11b of the base station 11 receives the information 31 related to the uplink data transmission transmitted from the wireless terminal 12, the controller 11b waits for the uplink data 32 from the wireless terminal 12. The control unit 12b of the radio terminal 12 performs uplink data transmission using a radio resource RS determined in advance with the base station 11.

As described above, in the radio communication system 10, the radio resource RS to be used when performing uplink data transmission in the third state is determined in advance, and information shared between the base station 11 and the radio terminal 12 Uplink data transmission is performed based on the above. Therefore, the wireless terminal 12 in the third state can perform uplink data transmission without transitioning to the first state.

The first embodiment has been described above.
<2. Second Embodiment: UL>
Next, a second embodiment will be described. The second embodiment relates to a wireless communication system in which data communication can be performed without a wireless terminal in a state different from a line connected state changing to a line connected state. For convenience of explanation, the case of uplink data transmission in the second embodiment and the case of downlink data transmission in the third embodiment will be described. The techniques of the second and third embodiments to be described later can be combined, and a wireless communication system equipped with both techniques can be realized.

[2-1. system]
The wireless communication system 100 will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a wireless communication system according to the second embodiment. Note that the wireless communication system 100 illustrated in FIG. 2 is an example of a wireless communication system according to the second embodiment.

2, the wireless communication system 100 includes a base station (gNB) 101 and wireless terminals (UE) 102, 103,. The base station 101 is connected to a core network that is a backbone network by wire. Although two

wireless terminals

102 and 103 are clearly shown in FIG. 2, the number of wireless terminals included in the wireless communication system 100 is arbitrary.

The base station 101 has hardware as shown in FIG. 3, for example. FIG. 3 is a block diagram illustrating an example of hardware capable of realizing the functions of the base station according to the second embodiment. As shown in FIG. 3, the base station 101 includes an antenna 101a, an RF (Radio frequency) circuit 101b, a BB (Baseband) circuit 101c, an NIF (Network interface) circuit 101d, a CPU 101e, and a memory 101f.

The RF circuit 101b executes processing such as modulation / demodulation and frequency conversion on a radio band signal (RF signal). The BB circuit 101c executes encoding / decoding processing, AD (Analog to Digital) / DA (Digital to Analog) conversion processing, and the like for a baseband signal (BB signal). The NIF circuit 101d is a communication circuit connected to the core network.

The CPU 101e controls the operation of the base station 101 using programs and data stored in the memory 101f. The CPU 101e is an example of a processor, and can be replaced with a DSP, ASIC, FPGA, or the like. The memory 101f is, for example, an HDD, an SSD (Solid State Drive), a RAM, a ROM (Read Only Memory), or the like.

The wireless terminal 102 has, for example, hardware as shown in FIG. FIG. 4 is a block diagram illustrating an example of hardware capable of realizing the function of the wireless terminal according to the second embodiment. As shown in FIG. 4, the wireless terminal 102 includes an antenna 102a, an RF circuit 102b, a BB circuit 102c, a CPU 102d, and a memory 102e.

The RF circuit 102b executes processing such as modulation / demodulation and frequency conversion on the RF signal. The BB circuit 102c executes encoding / decoding processing, AD / DA conversion processing, and the like for the BB signal. The CPU 102d controls the operation of the wireless terminal 102 using a program and data stored in the memory 102e.

The CPU 102d is an example of a processor, and can be replaced with a DSP, ASIC, FPGA, or the like. The memory 102e is, for example, an HDD, SSD, RAM, ROM, or the like. The hardware of the wireless terminal 103 is substantially the same as that of the wireless terminal 102.

Hereinafter, description will be given by taking the wireless communication system 100 as an example.
[2-2. function]
The functions of the base station 101 and the

wireless terminals

102, 103, ... will be described. In the following description, for convenience of explanation, functions of the wireless terminal 102 will be described, and the functions of the wireless terminals 103,... Are the same as those of the wireless terminal 102, and detailed description thereof will be omitted.

(Example of state transition & uplink data transmission)
First, the state transition of the wireless terminal 102 will be described with reference to FIG. FIG. 5 is a diagram showing an example of a state transition diagram regarding the state of line connection. For convenience of explanation, the RRC state will be described as an example, but the scope of application of the technology according to the second embodiment is not limited to LTE. For example, the RRC_CONNECTED state is an example of a connection state of radio resources, and the RRC_IDLE state is an example of a disconnection state of radio resources.

As shown in FIG. 5, the wireless terminal 102 takes an RRC_CONNECTED state 201 and an RRC_IDLE state 202. Further, the wireless terminal 102 takes an intermediate state (Intermediate) different from the RRC_CONNECTED state 201 and the RRC_IDLE state 202. Hereinafter, for convenience of explanation, this intermediate state is referred to as an RRC_INACTIVE state 203. The RRC_INACTIVE state 203 is a state in which radio resources are disconnected while maintaining a connection in an upper layer.

The wireless terminal 102 can perform state transition (connect / release) between the RRC_CONNECTED state 201 and the RRC_IDLE state 202. Further, the wireless terminal 102 can perform state transition (inactive / resume; part (A)) between the RRC_CONNECTED state 201 and the RRC_INACTIVE state 203. Further, the wireless terminal 102 can perform a state transition (release) from the RRC_INACTIVE state 203 to the RRC_IDLE state 202.

When the wireless terminal 102 in the RRC_CONNECTED state 201 transmits uplink data, processing as illustrated in FIG. 6 is performed between the base station 101 and the wireless terminal 102. FIG. 6 is a sequence diagram illustrating an example of uplink data transmission.

(S51) As shown in the state transition diagram of FIG. 5, the wireless terminal 102 can transition from the RRC_INACTIVE state 203 and the RRC_IDLE state 202 to the RRC_CONNECTED state 201. For example, the wireless terminal 102 in the RRC_IDLE state 202 transitions to the RRC_CONNECTED state 201 during uplink data transmission.

(S52) The radio terminal 102 transmits a Scheduling Request (SR) to the base station 101, and requests the base station 101 to allocate radio resources used for uplink data transmission.
(S53) Upon receiving the SR from the radio terminal 102, the base station 101 allocates radio resources used by the radio terminal 102 for uplink data transmission, and transmits a UL Scheduling grant for the SR to the radio terminal 102.

(S54) The wireless terminal 102 that has received the UL Scheduling grant for SR transmits a Buffer State Report (BSR) corresponding to the size of the uplink data to the base station 101.
(S55) The base station 101 that has received the BSR transmits a UL Scheduling grant for the BSR to the wireless terminal 102.

(S56) The wireless terminal 102 that has received the UL Scheduling grant for the BSR transmits uplink data (UL DATA) to the base station 101 using PUSCH (Physical Uplink Shared Channel).

(S57) The base station 101 that has completed the reception of the uplink data transmits an acknowledgment (ACK) for the reception of the uplink data to the wireless terminal 102.
As described above, when uplink data is transmitted in the RRC_CONNECTED state 201, scheduling of radio resources is performed together with transmission and reception of SR and BSR (see FIG. 6A). As described above, when the wireless terminal 102 in the RRC_IDLE state 202 performs uplink data transmission, the state transition to the RRC_CONNECTED state 201 and the above processing associated with uplink data transmission are executed.

On the other hand, if the wireless terminal 102 in the RRC_INACTIVE state 203 can transmit uplink data without transitioning to the RRC_CONNECTED state 201, the processing corresponding to the above state transition can be omitted. Further, if the allocation of radio resources by the SR and the processing related to the BSR can be omitted at the time of uplink data transmission in the RRC_INACTIVE state 203, the processing load associated with the scheduling or the like can be suppressed.

As will be described below, the base station 101 and the wireless terminal 102 according to the second embodiment have a function of enabling the wireless terminal 102 in the RRC_INACTIVE state 203 to perform uplink data transmission without transitioning to the RRC_CONNECTED state 201. It has.

(base station)
First, the function of the base station 101 will be described with reference to FIG. FIG. 7 is a block diagram illustrating an example of functions of the base station according to the second embodiment.

7, the base station 101 includes a storage unit 111, a radio processing unit 112, a state transition processing unit 113, a resource determination unit 114, a special SR reception unit 115, and a data reception unit 116.

The function of the storage unit 111 can be realized by the memory 101f described above. The function of the wireless processing unit 112 can be realized by the antenna 101a, the RF circuit 101b, and the BB circuit 101c described above. The functions of the state transition processing unit 113, the resource determination unit 114, the special SR reception unit 115, and the data reception unit 116 can be realized by the CPU 101e described above.

Management information 111a is stored in the storage unit 111. The management information 111a has contents as shown in FIG. FIG. 8 is a diagram illustrating an example of management information according to the second embodiment. As shown in FIG. 8, in the management information 111a, identification information of a wireless terminal (INACTIVE UE) in the RRC_INACTIVE state 203, information on special SR resources, and information on data resources are stored in association with each other.

In the example of FIG. 8, for convenience of explanation, a code is described in the column of identification information of ACTIVEINUE. For example, an ID used by the base station 101 for management of a wireless terminal or an International Mobile Subscriber Identity (IMSI) ) Etc. can be used as identification information.

The special SR resource is a radio resource used for transmitting notification information transmitted from the radio terminal 102 to the base station 101 prior to uplink data transmission in the RRC_INACTIVE state 203. Hereinafter, for convenience of explanation, this notification information is referred to as a special SR. The information on the special SR resource includes, for example, information such as the frequency used for transmission of the special SR and the time indicating the transmission timing of the special SR.

The data resource is a radio resource used for uplink data transmission in the RRC_INACTIVE state 203. The data resource information includes, for example, information such as a frequency used for uplink data transmission and a time indicating uplink data transmission timing. In addition, as information indicating the transmission timing of the uplink data, the elapsed time from the transmission time of the special SR may be included in the management information 111a.

The radio processing unit 112 executes processing of an RF signal input to the base station 101 via the antenna 101a, an RF signal output from the base station 101 via the antenna 101a, and a BB signal corresponding to these RF signals. To do. The state transition processing unit 113 executes processing related to the state transition of the

wireless terminals

102, 103,. The resource determination unit 114 executes processing for determining radio resources used for transmission of the special SR and uplink data.

The special SR receiving unit 115 receives the special SR via the radio processing unit 112 and notifies the data receiving unit 116 of the allocated radio resource for uplink data transmission corresponding to the special SR. The data reception unit 116 controls the radio processing unit 112 to receive the uplink data using the allocated radio resource notified from the special SR reception unit 115, and executes processing of the uplink data such as transfer to the core network.

For example, when transitioning the wireless terminal 102 to the RRC_INACTIVE state 203, the state transition processing unit 113 requests the resource determination unit 114 to determine a resource for special SR and a resource for data. Upon receiving this request, the resource determination unit 114 executes processing for determining the special SR resource and the data resource, and uses the information on the determined special SR resource and data resource as identification information of the wireless terminal 102. Correspondingly recorded in the management information 111a.

Also, the resource determination unit 114 notifies the wireless terminal 102 of the determined special SR resource and data resource via the wireless processing unit 112, and shares information on the special SR resource and data resource.

In addition, it can be modified so that the determination of the special SR resource and the data resource is performed on the wireless terminal 102 side. In this case, the resource determination unit 114 receives the special SR resource and the data resource from the wireless terminal 102 via the wireless processing unit 112, and transmits the received information on the special SR resource and the data resource to the wireless terminal 102. The management information 111a is recorded in association with the identification information.

When the special SR is received from the wireless terminal 102 by the wireless processing unit 112, the special SR receiving unit 115 reads the data resource information corresponding to the special SR from the management information 111a, and sends the read information to the data receiving unit 116. Notice. The data reception unit 116 waits for uplink data with the radio resource indicated by the notified data resource information, and processes the uplink data received via the radio processing unit 112.

The base station 101 has the above functions.
(Wireless terminal)
Next, functions of the wireless terminal 102 will be described with reference to FIG. FIG. 9 is a block diagram illustrating an example of functions of the wireless terminal according to the second embodiment.

As illustrated in FIG. 9, the wireless terminal 102 includes a storage unit 121, a wireless processing unit 122, a state transition processing unit 123, a resource determination unit 124, a special SR transmission unit 125, and a data transmission unit 126.

The function of the storage unit 121 can be realized by the memory 102e described above. The function of the wireless processing unit 122 can be realized by the antenna 102a, the RF circuit 102b, and the BB circuit 102c described above. The functions of the state transition processing unit 123, the resource determination unit 124, the special SR transmission unit 125, and the data transmission unit 126 can be realized by the CPU 102d described above.

The storage unit 121 stores management information 121a. The management information 121a stores information on special SR resources and data resources.
The special SR resource is a radio resource used for transmitting notification information (special SR) transmitted from the radio terminal 102 to the base station 101 prior to uplink data transmission in the RRC_INACTIVE state 203. The information on the special SR resource includes, for example, information such as the frequency used for transmission of the special SR and the time indicating the transmission timing of the special SR.

The data resource is a radio resource used for uplink data transmission in the RRC_INACTIVE state 203. The data resource information includes, for example, information such as a frequency used for uplink data transmission and a time indicating uplink data transmission timing. As information indicating the transmission timing of the uplink data, an elapsed time from the transmission time of the special SR may be included in the management information 121a.

The wireless processing unit 122 executes processing of an RF signal input to the wireless terminal 102 via the antenna 102a, an RF signal output from the wireless terminal 102 via the antenna 102a, and a BB signal corresponding to these RF signals. To do. The state transition processing unit 123 executes processing related to state transition of the wireless terminal 102. The resource determination unit 124 executes processing for determining radio resources used for transmission of the special SR and uplink data.

The special SR transmission unit 125 transmits the special SR via the wireless processing unit 122, and notifies the base station 101 that there is uplink data to be subjected to uplink data transmission corresponding to the special SR. The data transmission unit 126 controls the radio processing unit 122 to transmit uplink data using radio resources determined between the radio terminal 102 and the base station 101.

For example, when the wireless terminal 102 transitions to the RRC_INACTIVE state 203, the state transition processing unit 123 requests the resource determination unit 124 to determine a special SR resource and a data resource. The resource determination unit 124 that has received this request executes processing for sharing information on the special SR resource and the data resource with the base station 101. Then, the resource determination unit 124 records information on the determined special SR resource and data resource in the management information 121a.

In addition, it can be modified so that the determination of the special SR resource and the data resource is performed on the wireless terminal 102 side. In this case, the resource determination unit 124 determines the special SR resource and the data resource, and transmits information on the special SR resource and the data resource to the base station 101 via the radio processing unit 112.

The special SR transmission unit 125 transmits the special SR to the base station 101 via the wireless processing unit 122. At this time, the special SR transmission unit 125 refers to the management information 121a, transmits the special SR using the special SR resource, and requests the data transmission unit 126 to transmit the uplink data corresponding to the special SR. Upon receiving this request, the data transmission unit 126 refers to the management information 121a, and the wireless processing unit 122 transmits uplink data using the data resource.

The wireless terminal 102 has the above functions.
As described above, the base station 101 and the wireless terminal 102 share the special SR resource and the data resource when transiting to the RRC_INACTIVE state 203. By this sharing, the transmission of the special SR and the transmission of the uplink data are realized using the shared special SR resource and data resource without causing the state of the wireless terminal 102 to transition to the RRC_CONNECTED state 201.

Note that the radio resource for special SR transmission may be set to a size equivalent to one RE (Resource Element) or a plurality of radio terminals multiplexed on one RE.
In addition, as a method for determining radio resources for special SR transmission, a method other than the method in which the base station 101 and / or the radio terminal 102 determine at the timing of transition to the RRC_INACTIVE state 203 can be adopted as a modification. For example, a method in which the base station 101 and / or the wireless terminal 102 determines in advance when the wireless terminal 102 is in the RRC_CONNECTED state 201, a method in which the base station 101 determines in advance and notifies the wireless terminal 102 with a paging message, etc. It can be adopted as the above modification.

Moreover, the maximum size of the uplink data transmitted in the RRC_INACTIVE state 203 may be set. This maximum size can be determined, for example, in a dialogue performed between the base station 101 and the wireless terminal 102 when transitioning to the RRC_INACTIVE state 203. The maximum size may be fixed depending on the performance of the wireless communication system 100, the slice, the wireless terminal 102, or the base station 101 and / or the wireless terminal 102 may be determined within an allowable range. .

As a method for determining a radio resource for uplink data transmission, a method other than the method in which the base station 101 and / or the radio terminal 102 determine at the timing of transition to the RRC_INACTIVE state 203 can be adopted as a modified example. For example, a method of determining when the wireless terminal 102 transmits the special SR and notifying the base station 101 can be adopted as a modification. Note that a condition such as MCS may be specified at the time of this notification.

In addition, the base station 101 that has received the special SR may perform scheduling adjustment so that radio resources for transmission of uplink data corresponding to the special SR are not allocated to other radio terminals. Also, the radio resource for uplink data transmission by the radio terminal 102 that has transmitted the special SR may be separated from the radio resource allocated when the radio terminal 102 transmits uplink data in the RRC_CONNECTED state 201, or may be shared. Good. In this manner, functions can be added or modified for the base station 101 and the wireless terminal 102.

[2-3. Process flow]
Next, the flow of processing executed by the base station 101 and the wireless terminal 102 will be described.
(Processing sequence)
First, a process from a transition from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 to transmission of uplink data in the RRC_INACTIVE state 203 will be described with reference to FIG. FIG. 10 is a sequence diagram showing a flow of processing executed when uplink data is transmitted in the wireless communication system according to the second embodiment.

(S101) The wireless terminal 102 is in the RRC_CONNECTED state 201. From this state, the wireless terminal 102 starts transition from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 by the function of the state transition processing unit 123.

(S102) The state transition processing unit 123 of the wireless terminal 102 notifies the base station 101 of transition to the RRC_INACTIVE state 203, and transmits a request signal for requesting execution of processing associated with the transition to the base station 101. To do. Hereinafter, this request signal is referred to as INACTIVE_REQUEST.

(S103) The state transition processing unit 113 of the base station 101 receives the request signal from the wireless terminal 102. In addition, the state transition processing unit 113 requests the resource determination unit 114 to determine the special SR resource and the data resource. The resource determination unit 114 determines a special SR resource and a data resource, and records information on the special SR resource and the data resource in the management information 111a.

The special SR resource is set to a size of 1 RE (see FIG. 11) or less than 1 RE. FIG. 11 is a diagram for describing an example of radio resources allocated when a special SR is transmitted. Note that RB is an abbreviation for Resource Block, and RE is an abbreviation for Resource Element. 1 RE includes a CP (Cyclic-Prefix) region (T _CP ) and a user data region (T _U ), and has a length of about several bits according to the modulation scheme.

Further, the resource determination unit 114 transmits information on the special SR resource and the data resource to the wireless terminal 102 as a response to the INACTIVE_REQUEST via the wireless processing unit 112. At this time, the resource determination unit 114 may notify the wireless terminal 102 of the maximum size of data to be transmitted as uplink data corresponding to the special SR.

Hereinafter, a response to INACTIVE_REQUEST will be referred to as INACTIVE_RESPONSE. In the example of FIG. 10, it is assumed that the maximum size information is included in INACTIVE_RESPONSE.

(S104) The state transition processing unit 123 of the wireless terminal 102 transitions to the RRC_INACTIVE state 203 state.
(S105) The resource determination unit 114 of the base station 101 may notify the radio terminal 102 of the special SR resource by a paging message.

For example, if the special SR resource is changed after the special SR resource is transmitted by INACTIVE_RESPONSE, the change of the special SR resource is notified to the wireless terminal 102 by the paging message. Alternatively, the special SR resource may not be notified by INACTIVE_RESPONSE, and the special SR resource may be notified by a paging message. Further, when the special SR resource is notified by INACTIVE_RESPONSE and the special SR resource is not changed, the notification of the special SR resource in S105 may be omitted.

(S106) The special SR transmission unit 125 of the wireless terminal 102 transmits the special SR using the special SR resource, and notifies the base station 101 of the uplink data transmission schedule corresponding to the special SR. In addition, when the maximum size is notified by INACTIVE_RESPONSE, the special SR can be modified to notify the change of the maximum size. Further, the special SR transmission unit 125 may change the transmission timing of the uplink data using the special SR.

The special SR reception unit 115 of the base station 101 that has received the special SR notifies the data reception unit 116 of radio resources for the uplink data corresponding to the special SR, and waits for the uplink data. By using the special SR, the base station 101 omits the scheduling process of assigning radio resources for uplink data transmission corresponding to the special SR. Further, since the maximum size is set in advance, waiting for BSR is also omitted. However, scheduling adjustment is performed so that other radio terminals are not assigned to radio resources for uplink data transmission corresponding to the special SR.

(S107) The data transmission unit 126 of the wireless terminal 102 refers to the management information 121a, and transmits the uplink data corresponding to the special SR to the base station 101 at the transmission timing of the uplink data determined as the data resource. Since the maximum size of uplink data is set in advance, transmission of BSR is omitted.

(S108) When the uplink data is correctly received, the data receiving unit 116 of the base station 101 transmits an ACK for notifying that the reception is completed to the wireless terminal 102. In addition, the data reception unit 116 executes processing for uplink data such as transfer to the core network. When the process of S108 is completed, the series of processes shown in FIG.

Note that the flow of the processing illustrated in FIG. 10 is an example, and for example, the transition from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 can be modified according to an instruction from the base station 101. In this case, transmission / reception of INACTIVE_REQUEST and INACTIVE_RESPONSE is transformed into information notification from the base station 101 to the wireless terminal 102. For example, in this information notification, a transition instruction to the RRC_INACTIVE state 203, a special SR resource, and a data resource are notified.

Also, the number of dialogs performed between the base station 101 and the wireless terminal 102 when changing from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 can be changed. It is possible to modify the instruction to transition to the RRC_INACTIVE state 203, information on special SR resources, and information on data resources in a plurality of dialogs. Such a modification naturally belongs to the technical scope of the second embodiment.

(Operation example of base station)
Here, the operation of the base station 101 will be further described with reference to FIGS. 12 and 13. FIG. 12 is a flowchart for explaining an operation example (resource allocation) of the base station according to the second embodiment. FIG. 13 is a flowchart for explaining an operation example (special SR process) of the base station according to the second embodiment.

First, referring to FIG.
(S111) The state transition processing unit 113 starts executing a process associated with the transition (INACTIVE) of the wireless terminal 102 to the RRC_INACTIVE state 203.

(S112) The state transition processing unit 113 determines whether or not to perform radio resource allocation (allocation for small data) for uplink data transmission in the RRC_INACTIVE state 203. When the allocation for small data is performed, the process proceeds to S113. On the other hand, when the small data allocation is not performed, the series of processes shown in FIG. 12 ends.

In the process of conversion to INACTIVE, dialogue between the base station 101 and the wireless terminal 102 (for example, INACTIVE_REQUEST and INACTIVE_RESPONSE in FIG. 10) is performed. For example, in the dialog, the base station 101 and / or the wireless terminal 102 determines whether or not to perform uplink data transmission in the RRC_INACTIVE state 203 after being converted into INACTIVE.

(S113) The state transition processing unit 113 requests the resource determination unit 114 to determine a special SR resource and a data resource. The resource determination unit 114 determines the special SR resource and the data resource in the dialog with the wireless terminal 102, and records the determined information on the special SR resource and the data resource in the management information 111a.

Also, the resource determination unit 114 transmits information on the determined special SR resource and data resource to the wireless terminal 102. For example, information on the special SR resource and the data resource is transmitted by INACTIVE_RESPONSE. Through these processes, information on the special SR resource and the data resource is shared between the base station 101 and the wireless terminal 102. When the process of S113 is completed, the series of processes illustrated in FIG.

Reference is now made to FIG.
(S121) The wireless processing unit 112 receives a signal from the wireless terminal 102. The signal received by the wireless processing unit 112 includes, for example, a normal SR and the like other than the special SR and the uplink data corresponding to the special SR described so far.

(S122) The wireless processing unit 112 determines whether or not the received signal is a special SR. If the received signal is a special SR, the process proceeds to S123. On the other hand, if the received signal is not a special SR, the process proceeds to S127.

(S123) The data receiving unit 116 refers to the management information 111a and identifies a data resource corresponding to the received special SR. Further, the data receiving unit 116 secures the specified data resource. Then, the data receiving unit 116 waits for uplink data corresponding to the special SR with the reserved data resource.

(S124) The data receiving unit 116 determines whether or not the waiting uplink data has been received. When uplink data is received with the data resource secured in S123, the process proceeds to S125. On the other hand, when the uplink data is not received by the data resource secured in S123, the series of processes illustrated in FIG. 13 ends. Note that, when uplink data is not received, the data reception unit 116 may return NACK (Negative ACK) to the wireless terminal 102.

(S125) The data receiving unit 116 transmits an ACK for notifying that the uplink data corresponding to the special SR is correctly received using the data resource secured in S123 to the wireless terminal 102.

(S126) The data reception unit 116 transmits the received uplink data to the core network (CN). When the process of S126 is completed, the series of processes shown in FIG.
(S127) The data reception unit 116 executes processing (normal processing) according to the content of the received signal in a timely manner. For example, when a normal SR is received, the data reception unit 116 executes a process for the normal SR as a normal process. When the process of S127 is completed, the series of processes shown in FIG.

(Example of wireless terminal operation)
Next, the operation of the wireless terminal 102 will be further described with reference to FIGS. 14 and 15. FIG. 14 is a flowchart for explaining an operation example (resource allocation) of the wireless terminal according to the second embodiment. FIG. 15 is a flowchart for explaining an operation example (special SR process) of the wireless terminal according to the second embodiment.

First, referring to FIG.
(S131) The state transition processing unit 123 starts execution of a process associated with the transition (INACTIVE conversion) of the wireless terminal 102 to the RRC_INACTIVE state 203.

(S132) The state transition processing unit 123 determines whether or not to perform assignment of radio resources for uplink data transmission (assignment for small data) in the RRC_INACTIVE state 203. When the allocation for small data is performed, the process proceeds to S133. On the other hand, when the allocation for small data is not performed, the series of processes shown in FIG. 14 ends.

(S133) The state transition processing unit 123 requests the resource determination unit 124 to determine the special SR resource and the data resource. The resource determination unit 124 requests the base station 101 to determine the special SR resource and the data resource in the dialog with the base station 101, and sends information on the determined special SR resource and data resource to the base station 101. Receive from. Then, the resource determination unit 124 records information on the special SR resource and the data resource in the management information 121a.

For example, the information on the special SR resource and the data resource is transmitted from the base station 101 to the wireless terminal 102 by INACTIVE_RESPONSE. Then, the information on the special SR resource and the data resource received by the wireless terminal 102 is stored in the management information 121a. Through these processes, information on the special SR resource and the data resource is shared between the base station 101 and the wireless terminal 102. When the process of S133 is completed, the series of processes illustrated in FIG.

Reference is now made to FIG.
(S141) When uplink data transmission occurs in the RRC_INACTIVE state 203, the data transmission unit 126 performs the processing after S142.

(S142) The data transmission unit 126 determines whether or not the uplink data to be transmitted is small size data. For example, the data transmission unit 126 determines whether the data size of the uplink data (Data) is smaller than a preset threshold value Th1. The threshold value Th1 may be set in advance as a fixed value, or may be dynamically changed by the base station 101 and / or the wireless terminal 102. If the uplink data is small size data, the process proceeds to S143. On the other hand, if the uplink data is not small size data, the process proceeds to S147.

(S143) The special SR transmission unit 125 refers to the management information 121a, and transmits the special SR for notifying uplink data transmission to the base station 101 using the special SR resource.
(S144) The data transmission unit 126 refers to the management information 121a, and transmits uplink data corresponding to the special SR transmitted by the special SR transmission unit 125 to the base station 101 using the data resource.

(S145) The data transmission unit 126 determines whether or not an ACK indicating completion of reception of the transmitted uplink data has been received from the base station 101. If ACK is received, the process proceeds to S147. On the other hand, if no ACK is received, the process proceeds to S146.

(S146) The data transmission unit 126 determines whether the number of retries for special SR transmission (S143) and uplink data transmission (S144) is smaller than a predetermined value N (for example, N = 3). If the number of retries is less than N, the process proceeds to S143. In this case, the special SR transmission (S143) and uplink data transmission (S144) processes are re-executed (retry). On the other hand, if the number of retries is not smaller than N, the process proceeds to S147.

(S147) The state transition processing unit 123 executes processing for transitioning to the RRC_CONNECTED state 201. In this case, uplink data is transmitted by an uplink data transmission process (see FIG. 6) normally performed in the RRC_CONNECTED state 201. When the process of S147 is completed, the series of processes illustrated in FIG.

The second embodiment has been described above.
As described above, uplink data can be transmitted without transition from the RRC_INACTIVE state 203 to the RRC_CONNECTED state 201 by using the special SR. Also, the method using the special SR is more than the case of applying the concept of Grant Free in which the radio resource used for uplink data transmission is fixedly secured in the RRC_INACTIVE state 203 so that any radio terminal can use it. Wireless resource usage efficiency is high. Also, transmission of PDCCH (Physical Downlink Control Channel) for allocating and releasing radio resources to the radio terminal that has transmitted the special SR can be omitted.

<3. Third Embodiment: DL>
Next, a third embodiment will be described. In the third embodiment, a case of downlink data transmission will be described. The techniques of the second and third embodiments can be combined. In addition, duplication description may be abbreviate | omitted about the element which is common in 2nd Embodiment.

For example, the wireless communication system 100 includes the elements illustrated in FIG. 2 as in the second embodiment. Further, the functions of the base station 101 and the wireless terminal 102 can be realized by the hardware shown in FIGS. 3 and 4, respectively, as in the second embodiment. Further, the state of the wireless terminal 102 transitions as in the example illustrated in FIG. 5 as in the second embodiment.

[3-1. function]
The functions of the base station 101 and the

wireless terminals

(Example of downlink data transmission)
First, a process when performing downlink data transmission when the wireless terminal 102 is in the RRC_IDLE state 202 will be described with reference to FIG. FIG. 16 is a sequence diagram illustrating an example of downlink data transmission.

(S61, S62) mt (mobile termination) -access is performed by paging from the base station 101 side (core network), and the state of the wireless terminal 102 transitions from the RRC_IDLE state 202 to the RRC_CONNECTED state 201.

(S63) The radio terminal 102 that has transitioned to the RRC_CONNECTED state 201 transmits a CQI report (Channel Quality Indicator Report) to the base station 101.
(S64) The base station 101 allocates radio resources used for downlink data transmission based on the CQI report received from the radio terminal 102, and notifies the assigned radio resources to the radio terminal 102 (DL Resource Allocation).

(S65) The base station 101 transmits downlink data to the radio terminal 102 using the allocated radio resource. When the process of S65 is completed, the series of processes illustrated in FIG.
As described above, when the wireless terminal 102 is in the RRC_IDLE state 202, a transition to the RRC_CONNECTED state 201 is performed as shown in (A). Also, as shown in (B), transmission / reception of CQI reports and scheduling of radio resources are performed. Thus, when the wireless terminal 102 is in the RRC_IDLE state 202, state transition is performed, and scheduling for downlink data transmission is performed.

On the other hand, if downlink data transmission can be performed without causing the wireless terminal 102 in the RRC_INACTIVE state 203 to transition to the RRC_CONNECTED state 201, the processing corresponding to the above (A) can be omitted. In addition, when the size of the downlink data is small, it may not be necessary to strictly consider the quality of the cell. In such a case, the processing corresponding to the above (B) can be omitted.

The base station 101 and the wireless terminal 102 according to the third embodiment have a function of realizing downlink data transmission in which processing corresponding to the above (A) and (B) is omitted when the wireless terminal 102 is in the RRC_INACTIVE state 203. To do.

(base station)
The function of the base station 101 will be described with reference to FIG. FIG. 17 is a block diagram illustrating an example of functions of the base station according to the third embodiment.

As illustrated in FIG. 17, the base station 101 includes a storage unit 111, a radio processing unit 112, a state transition processing unit 113, a resource determination unit 114, a special paging transmission unit 117, and a data transmission unit 118. Note that the base station 101 may further include a special SR receiver 115 and a data receiver 116 according to the second embodiment (a modification in which the second and third embodiments are combined).

The function of the storage unit 111 can be realized by the memory 101f described above. The function of the wireless processing unit 112 can be realized by the antenna 101a, the RF circuit 101b, and the BB circuit 101c described above. The functions of the state transition processing unit 113, the resource determination unit 114, the special paging transmission unit 117, and the data transmission unit 118 can be realized by the CPU 101e described above.

Management information 111b as shown in FIG. 18 is stored in the storage unit 111. FIG. 18 is a diagram illustrating an example of management information according to the third embodiment. As shown in FIG. 18, the management information 111b includes identification information of a wireless terminal in the RRC_INACTIVE state 203, and a radio resource (hereinafter referred to as special paging) for notifying the wireless terminal 102 of the start of downlink data transmission ( Special paging resource) information. The management information 111b stores data resource information used for downlink data transmission corresponding to special paging.

wireless terminals

102, 103,.

The resource determination unit 114 executes a process for determining a radio resource for special paging and a radio resource used for transmission of downlink data. The special paging transmission unit 117 transmits special paging via the radio processing unit 112 and notifies the radio terminal 102 of the downlink data transmission. The data transmission unit 118 transmits downlink data corresponding to special paging to the wireless terminal 102 via the wireless processing unit 112.

For example, when the wireless terminal 102 is transitioned to the RRC_INACTIVE state 203, the state transition processing unit 113 requests the resource determining unit 114 to determine a special paging resource and a data resource. Upon receiving this request, the resource determination unit 114 executes processing for determining the special paging resource and the data resource. Further, the resource determining unit 114 records the determined information on the special paging resource and the data resource in the management information 111b in association with the identification information of the wireless terminal 102.

Further, the resource determination unit 114 notifies the wireless terminal 102 of the determined special paging resource and data resource via the wireless processing unit 112, and shares information on the special paging resource and the data resource. For example, the resource determination unit 114 transmits information on special paging resources and data resources by INACTIVE_RESPONSE. Through these processes, information on special paging resources and data resources is shared with the wireless terminal 102.

When transmitting the downlink data after the information on the special paging resource and the data resource is shared, the data transmission unit 118 requests the special paging transmission unit 117 to transmit special paging. Upon receiving this request, the special paging transmission unit 117 transmits the special paging to the wireless terminal 102 using the special paging resource via the wireless processing unit 112. Then, the data transmission unit 118 transmits downlink data to the wireless terminal 102 via the wireless processing unit 112 using data resources.

The base station 101 has the above functions.
(Wireless terminal)
Next, functions of the wireless terminal 102 will be described with reference to FIG. FIG. 19 is a block diagram illustrating an example of functions of the wireless terminal according to the third embodiment.

As illustrated in FIG. 19, the wireless terminal 102 includes a storage unit 121, a wireless processing unit 122, a state transition processing unit 123, a resource determination unit 124, a special paging receiving unit 127, and a data receiving unit 128. Note that the wireless terminal 102 may further include a special SR transmission unit 125 and a data transmission unit 126 according to the second embodiment (a modification in which the second and third embodiments are combined).

The function of the storage unit 121 can be realized by the memory 102e described above. The function of the wireless processing unit 122 can be realized by the antenna 102a, the RF circuit 102b, and the BB circuit 102c described above. The functions of the state transition processing unit 123, the resource determination unit 124, the special paging reception unit 127, and the data reception unit 128 can be realized by the CPU 102d described above.

The storage unit 121 stores management information 121b. The management information 121b stores special paging resource information and data resource information.
The special paging resource is a radio resource used for transmitting notification information (special paging) transmitted from the base station 101 to the radio terminal 102 prior to downlink data transmission in the RRC_INACTIVE state 203. The information on the special paging resource includes, for example, information such as the frequency used for the special paging transmission and the time indicating the special paging transmission timing.

The data resource of the management information 121b is a radio resource used for transmitting downlink data in the RRC_INACTIVE state 203. The data resource information includes, for example, information such as a frequency used for downlink data transmission and a time indicating downlink data transmission timing. As information indicating the transmission timing of the downlink data, an elapsed time from the transmission time of the special paging may be included in the management information 121b.

The wireless processing unit 122 executes processing of an RF signal input to the wireless terminal 102 via the antenna 102a, an RF signal output from the wireless terminal 102 via the antenna 102a, and a BB signal corresponding to these RF signals. To do. The state transition processing unit 123 executes processing related to state transition of the wireless terminal 102.

The resource determination unit 124 executes processing for determination of radio resources used for special paging and downlink data transmission. The special paging receiving unit 127 receives special paging via the wireless processing unit 122 and recognizes that there is downlink data corresponding to the special paging. The data receiving unit 128 waits for downlink data transmitted by the data resource of the management information 121b.

For example, when the wireless terminal 102 transitions to the RRC_INACTIVE state 203, the state transition processing unit 123 requests the resource determination unit 124 to perform processing regarding determination of special paging resources and data resources. The resource determination unit 124 that has received this request executes processing for sharing information on the special paging resource and the data resource with the base station 101. Then, the resource determination unit 124 records information on the determined special paging resource and data resource in the management information 121b.

The special paging receiving unit 127 receives special paging from the base station 101 via the wireless processing unit 122. At this time, the special paging receiving unit 127 refers to the management information 121b and receives special paging using the special paging resource. Further, the special paging receiving unit 127 requests the data receiving unit 128 to wait for downlink data corresponding to the special paging. Upon receiving this request, the data receiving unit 128 waits for reception of downlink data by the data resource, and processes the received downlink data.

The wireless terminal 102 has the above functions.
As described above, the base station 101 and the wireless terminal 102 share the special paging resource and the data resource when transitioning to the RRC_INACTIVE state 203. By this sharing, transmission of special paging and transmission of downlink data is realized using the shared special paging resource and data resource without changing the state of the wireless terminal 102 to the RRC_CONNECTED state 201. According to the above method, mt-access is not performed in downlink data transmission.

Note that the radio resource for special paging transmission may be a normal physical channel such as PDSCH (Physical Downlink Shared Shared Channel), or may be separately reserved for special paging transmission.

Also, as a method for determining radio resources for special paging transmission, a method other than the method in which the base station 101 determines at the timing of transition to the RRC_INACTIVE state 203 can be adopted as a modified example. For example, a method in which the base station 101 and / or the wireless terminal 102 determines in advance when the wireless terminal 102 is in the RRC_CONNECTED state 201, a method in which the base station 101 determines in advance and notifies the wireless terminal 102 with a paging message, etc. It can be adopted as the above modification.

Moreover, the maximum size of the downlink data transmitted in the RRC_INACTIVE state 203 may be set. This maximum size can be determined, for example, in a dialogue performed between the base station 101 and the wireless terminal 102 when transitioning to the RRC_INACTIVE state 203. The maximum size may be fixed depending on the performance of the wireless communication system 100, the slice, the wireless terminal 102, or the base station 101 and / or the wireless terminal 102 may be determined within an allowable range. . In this manner, functions can be added or modified for the base station 101 and the wireless terminal 102.

[3-2. Process flow]
Next, the flow of processing executed by the base station 101 and the wireless terminal 102 will be described.
(Processing sequence)
First, processing from the transition from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 to the transmission of downlink data in the RRC_INACTIVE state 203 will be described with reference to FIG. FIG. 20 is a sequence diagram showing a flow of processing executed when downlink data is transmitted in the wireless communication system according to the third embodiment.

(S201) The wireless terminal 102 is in the RRC_CONNECTED state 201. From this state, the wireless terminal 102 starts transition from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 by the function of the state transition processing unit 123.

(S202) The state transition processing unit 123 of the wireless terminal 102 notifies the base station 101 of the transition to the RRC_INACTIVE state 203, and sends a request signal (INACTIVE_REQUEST) for requesting execution of processing associated with the transition to the base station. 101.

(S203) The state transition processing unit 113 of the base station 101 receives the request signal from the wireless terminal 102. In addition, the state transition processing unit 113 requests the resource determination unit 114 to determine a special paging resource and a data resource. The resource determination unit 114 determines a special paging resource and a data resource, and records information on the special paging resource and the data resource in the management information 121b.

Further, the resource determination unit 114 transmits information including at least a part of the special paging resource and the data resource via the wireless processing unit 112 to the wireless terminal 102 as a response (INACTIVE_RESPONSE) to INACTIVE_REQUEST. At this time, the resource determination unit 114 may notify the wireless terminal 102 of the maximum size of downlink data corresponding to special paging. In the example of FIG. 20, INACTIVE_RESPONSE includes data resources and maximum size information.

(S204) The state transition processing unit 123 of the wireless terminal 102 transitions to the RRC_INACTIVE state 203.
(S205) When the downlink data is smaller than the maximum size, the special paging transmission unit 117 of the base station 101 transmits special paging for notifying the execution of downlink data transmission to the radio terminal 102 using the special paging resource. .

At this time, the special paging transmission unit 117 may notify the wireless terminal 102 of a change in downlink data transmission timing and maximum size. The special paging receiving unit 127 of the wireless terminal 102 receives special paging using the special paging resource, and waits for the arrival of downlink data using the data resource corresponding to the special paging.

(S206) The data transmission unit 118 of the base station 101 refers to the management information 111b, and transmits the downlink data corresponding to the special paging to the wireless terminal 102 at the transmission timing of the downlink data determined as the data resource. Since the downlink data is smaller than the maximum size, the process for the CQI report is omitted.

(S207) When the data reception unit 128 of the wireless terminal 102 receives the downlink data correctly, the data reception unit 128 transmits an ACK for notifying that the reception is completed to the base station 101. In addition, the data reception unit 128 executes processing for downlink data. When the process of S207 is completed, the series of processes shown in FIG.

Note that the processing flow shown in FIG. 20 is an example, and for example, the transition from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 can be modified according to an instruction from the base station 101. In this case, transmission / reception of INACTIVE_REQUEST and INACTIVE_RESPONSE is transformed into information notification from the base station 101 to the wireless terminal 102. For example, in this information notification, a transition instruction to the RRC_INACTIVE state 203, a special paging resource, and a data resource are notified.

Also, the number of dialogs performed between the base station 101 and the wireless terminal 102 when changing from the RRC_CONNECTED state 201 to the RRC_INACTIVE state 203 can be changed. It is possible to modify the instruction to transition to the RRC_INACTIVE state 203, information on special paging resources, and information on data resources in a plurality of dialogs. Such a modification naturally belongs to the technical scope of the third embodiment.

(Operation example of base station)
Here, the operation of the base station 101 will be further described with reference to FIGS. 21 and 22. FIG. 21 is a flowchart for explaining an operation example (resource allocation) of the base station according to the third embodiment. FIG. 22 is a flowchart for explaining an operation example (special paging process) of the base station according to the third embodiment.

First, referring to FIG.
(S211) The state transition processing unit 113 starts executing a process associated with the transition (INACTIVE) of the wireless terminal 102 to the RRC_INACTIVE state 203.

(S212) The state transition processing unit 113 determines whether or not to perform radio resource allocation (allocation for small data) for downlink data transmission in the RRC_INACTIVE state 203.

In the case of performing allocation for small data, the process proceeds to S213. On the other hand, when the small data allocation is not performed, the series of processes shown in FIG.
In the process of making INACTIVE, a dialog (for example, INACTIVE_REQUEST, INACTIVE_RESPONSE in FIG. 20) is performed between the base station 101 and the wireless terminal 102. For example, in the dialog, the base station 101 and / or the wireless terminal 102 determines whether or not to perform downlink data transmission in the RRC_INACTIVE state 203 after being converted into INACTIVE.

(S213) The state transition processing unit 113 requests the resource determination unit 114 to determine a special paging resource and a data resource. The resource determining unit 114 determines the special paging resource and the data resource in the dialog with the wireless terminal 102, and records the determined information on the special paging resource and the data resource in the management information 111b.

Further, the resource determining unit 114 transmits information on the determined special paging resource and data resource to the wireless terminal 102.
For example, information on special paging resources and data resources is transmitted by INACTIVE_RESPONSE. Through these processes, information on special paging resources and data resources is shared between the base station 101 and the wireless terminal 102. When the process of S213 is completed, the series of processes illustrated in FIG.

Reference is now made to FIG.
(S221) When downlink data transmission occurs in a situation where the wireless terminal 102 is in the RRC_INACTIVE state 203, the data transmission unit 118 performs the processing from S222 onward.

(S222) The data transmission unit 118 determines whether or not the downlink data to be transmitted is small size data. For example, the data transmission unit 118 determines whether the data size of the downlink data (Data) is smaller than a preset threshold value Th2. Note that the threshold value Th <b> 2 may be set in advance as a fixed value, or may be dynamically changed by the base station 101 and / or the wireless terminal 102. If the downlink data is small size data, the process proceeds to S223. On the other hand, if the downlink data is not small data, the process proceeds to S227.

(S223) The special paging transmission unit 117 refers to the management information 111b and transmits special paging for notifying downlink data transmission to the wireless terminal 102 using the special paging resource.

(S224) The data transmission unit 118 refers to the management information 111b, and transmits the downlink data corresponding to the special paging transmitted by the special paging transmission unit 117 to the wireless terminal 102 using the data resource.

(S225) The data transmission unit 118 determines whether or not an ACK indicating completion of reception of the transmitted downlink data has been received from the wireless terminal 102. If ACK is received, the process proceeds to S227. On the other hand, if ACK is not received, the process proceeds to S226.

(S226) The data transmission unit 118 determines whether or not the number of retries for special paging transmission (S223) and downlink data transmission (S224) is smaller than a predetermined value N (for example, N = 3).

If the number of retries is less than N, the process proceeds to S223. In this case, the special paging transmission (S223) and downlink data transmission (S224) processes are re-executed (retry). On the other hand, if the number of retries is not smaller than N, the process proceeds to S227.

(S227) The state transition processing unit 113 executes processing for transitioning the state of the wireless terminal 102 to the RRC_CONNECTED state 201. In this case, downlink data is transmitted by the downlink data transmission process (see FIG. 16) normally performed in the RRC_CONNECTED state 201. When the process of S227 is completed, the series of processes shown in FIG.

(Example of wireless terminal operation)
Next, the operation of the wireless terminal 102 will be further described with reference to FIGS. 23 and 24. FIG. 23 is a flowchart for explaining an operation example (resource allocation) of the wireless terminal according to the third embodiment. FIG. 24 is a flowchart for explaining an operation example (special paging processing) of the wireless terminal according to the third embodiment.

First, referring to FIG.
(S231) The state transition processing unit 123 starts executing a process associated with the transition (INACTIVE conversion) of the wireless terminal 102 to the RRC_INACTIVE state 203.

(S232) The state transition processing unit 123 determines whether or not to perform radio resource allocation (allocation for small data) for downlink data transmission in the RRC_INACTIVE state 203. When the allocation for small data is performed, the process proceeds to S233. On the other hand, when the assignment for small data is not performed, the series of processes shown in FIG. 23 ends.

In the process of conversion to INACTIVE, dialogue between the base station 101 and the wireless terminal 102 (for example, INACTIVE_REQUEST and INACTIVE_RESPONSE in FIG. 20) is performed. For example, in the dialog, the base station 101 and / or the wireless terminal 102 determines whether or not to perform downlink data transmission in the RRC_INACTIVE state 203 after being converted into INACTIVE.

(S233) The state transition processing unit 123 requests the resource determination unit 124 to determine a special paging resource and a data resource.
The resource determination unit 124 requests the base station 101 to determine the special paging resource and the data resource in the dialog with the base station 101, and sends information on the determined special paging resource and data resource to the base station 101. Receive from. Then, the resource determination unit 124 records information on the special paging resource and the data resource in the management information 121b.

For example, information on special paging resources and data resources is transmitted from the base station 101 to the radio terminal 102 by INACTIVE_RESPONSE. Then, information on the special paging resource and the data resource received by the wireless terminal 102 is stored in the management information 121b. Through these processes, information on special paging resources and data resources is shared between the base station 101 and the wireless terminal 102. When the process of S233 is completed, the series of processes illustrated in FIG.

Reference is now made to FIG.
(S241) The wireless processing unit 122 receives a signal from the base station 101. The signal received by the wireless processing unit 122 includes, for example, a normal paging message in addition to the special paging described above and the downlink data corresponding to the special paging.

(S242) The wireless processing unit 122 determines whether or not the received signal is special paging. If the received signal is special paging, the process proceeds to S243. On the other hand, if the received signal is not special paging, the process proceeds to S246.

(S243) The data receiving unit 128 refers to the management information 121b and identifies a data resource corresponding to the received special paging. Further, the data reception unit 128 waits for downlink data corresponding to special paging with the specified data resource.

(S244) The data receiving unit 128 determines whether or not the waiting downlink data has been received. When downlink data is received with the data resource specified in S243, the process proceeds to S245. On the other hand, when downlink data is not received by the data resource specified in S243, the series of processing illustrated in FIG. 24 ends. Note that, when downlink data is not received, the data reception unit 128 may return a NACK to the wireless terminal 102.

(S245) The data receiving unit 128 transmits to the base station 101 an ACK for notifying that the downlink data corresponding to the special paging has been correctly received with the data resource specified in S243. In addition, the data reception unit 128 executes processing for downlink data. When the process of S245 is completed, the series of processes shown in FIG.

(S246) The data receiving unit 128 executes processing (normal processing) according to the content of the received signal in a timely manner. For example, when a normal paging message is received, the data reception unit 128 executes a process for the normal paging message as a normal process. When the process of S246 is completed, the series of processes shown in FIG.

The third embodiment has been described above.
As described above, downlink data transmission can be performed without making the wireless terminal 102 transition from the RRC_INACTIVE state 203 to the RRC_CONNECTED state 201 by using special paging. Also, the method of using special paging has higher utilization efficiency of radio resources than the case of applying the concept of Grant Free in which the radio resources used for downlink data transmission are fixedly secured in the RRC_INACTIVE state 203. Further, the measurement for CQI report by the wireless terminal that has received the special paging can be omitted.

As described in the above description, the techniques of the second and third embodiments described above can be combined. Such combinations and the various modifications described above also belong to the technical scope of the embodiments disclosed in this paper.

Note that the above merely shows the principle of the present invention. In addition, many modifications and changes can be made by those skilled in the art, and the present invention is not limited to the precise configuration and application shown and described above, and all corresponding modifications and equivalents may be And the equivalents thereof are considered to be within the scope of the invention.

DESCRIPTION OF SYMBOLS 10 Radio | wireless communications system 11

Base station

11a, 12a Memory |

storage part

11b, 12b Control part 12 Radio |

wireless terminal

21a, 22a Information about radio | wireless terminal 21b, 22b Information of radio | wireless resource 31 Information regarding uplink data transmission 32 Uplink data RS Radio | wireless resource

Claims

Stores information about a wireless terminal that has a first state that is a line connection state, a second state that is a line disconnection state, or a third state different from the first and second states. A storage unit;
By receiving information related to uplink data transmission transmitted during uplink data transmission from the wireless terminal in the third state, and using the uplink data transmission using radio resources determined in advance with the wireless terminal And a control unit that waits for uplink data from the wireless terminal.
The base station according to claim 1, wherein the information about the wireless terminal is shared between the wireless terminal and the base station when the wireless terminal transitions to the third state.
The information on the wireless terminal includes information on a first wireless resource used by the wireless terminal in the third state for transmission of information on the uplink data transmission, and information on the first wireless resource used by the wireless terminal for transmission of the uplink data. The base station according to claim 2, comprising information related to two radio resources and information related to a transmission timing of the uplink data.
Stores information about a wireless terminal that has a first state that is a line connection state, a second state that is a line disconnection state, or a third state different from the first and second states. A storage unit;
When the wireless terminal is in the third state, the downlink terminal transmits information regarding the downlink data transmission to the wireless terminal during downlink data transmission, and uses the downlink radio resource determined in advance with the wireless terminal. And a control unit that performs data transmission.
A wireless terminal and a base station;
The base station and / or the wireless terminal may change the state of the wireless terminal to a first state that is a line connection state, a second state that is a line disconnection state, and the first and second states. Managed in any one of the third states different from
When the wireless terminal performs uplink data transmission in the third state, the wireless terminal transmits information on the uplink data transmission to the base station,
The base station receives information related to the uplink data transmission transmitted from the wireless terminal, and waits for upstream data from the wireless terminal,
A radio communication system in which the radio terminal performs the uplink data transmission using radio resources determined in advance with the base station.
A wireless terminal and a base station;
The base station and / or the wireless terminal may change the state of the wireless terminal to a first state that is a line connection state, a second state that is a line disconnection state, and the first and second states. Managed in any one of the third states different from
When the wireless terminal is in the third state, the base station transmits information regarding the downlink data transmission to the wireless terminal when performing downlink data transmission,
The wireless terminal receives information on the downlink data transmission transmitted from the base station, and waits for downlink data from the base station,
A radio communication system in which the base station performs the downlink data transmission using radio resources determined in advance with the radio terminal.
Uplink data in the third state among the first state that is a line connection state, the second state that is a line disconnection state, and a third state that is different from the first and second states A storage unit for storing information regarding the uplink data transmission transmitted to the base station when performing transmission;
When performing the uplink data transmission in the third state, the information regarding the uplink data transmission is transmitted to the base station, and the uplink data transmission is performed using radio resources determined in advance with the base station. And a control unit that implements the wireless terminal.
Memory for storing information for managing a first state that is a line connection state, a second state that is a line disconnection state, and a third state that is different from the first and second states And
When in the third state, the base station receives information on the downlink data transmission that is transmitted when the downlink data transmission is performed, and uses the radio resources determined in advance with the base station And a control unit that waits for downlink data transmitted from the base station.
When the base station and / or the wireless terminal, the state of the wireless terminal is defined as a first state that is a line connection state, a second state that is a line disconnection state, and the first and second states. Manage in any of the different third states,
When the wireless terminal performs uplink data transmission in the third state, the wireless terminal transmits information on the uplink data transmission to the base station,
The base station receives information related to the uplink data transmission transmitted from the wireless terminal, and waits for upstream data from the wireless terminal,
A radio communication method in which the radio terminal performs the uplink data transmission using radio resources determined in advance with the base station.
When the base station and / or the wireless terminal, the state of the wireless terminal is defined as a first state that is a line connection state, a second state that is a line disconnection state, and the first and second states. Manage in any of the different third states,
When the wireless terminal is in the third state, the base station transmits information regarding the downlink data transmission to the wireless terminal when performing downlink data transmission,
The wireless terminal receives information on the downlink data transmission transmitted from the base station, and waits for downlink data from the base station,
A radio communication method in which the base station performs the downlink data transmission using radio resources determined in advance with the radio terminal.