WO2016136492A1

WO2016136492A1 - Wireless terminal and base station

Info

Publication number: WO2016136492A1
Application number: PCT/JP2016/054077
Authority: WO
Inventors: 剛洋榮祝; 空悟守田
Original assignee: 京セラ株式会社
Priority date: 2015-02-27
Filing date: 2016-02-12
Publication date: 2016-09-01

Abstract

A UE to be used in a mobile communication system for directly transmitting data between UE. The UE directly transmits a control signal containing data allocation information to another UE, and thereafter, directly transmits data according to the allocation information to the other UE. When transmitting emergency data as the data, the UE includes information indicating transmission of emergency data in the control signal.

Description

Wireless terminal and base station

The present invention relates to a radio terminal and a base station used in a mobile communication system that supports inter-device proximity service (D2D ProSe).

In 3GPP (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, specifications are being developed for inter-device proximity service (D2D ProSe: Device to Device Proximity Service).

As the D2D ProSe mode, two modes of direct discovery (Sidelink Direct Discovery) and direct communication (Sidelink Direct Communication) are defined.

Here, “Sidelink Direct Discovery” is a mode in which a partner is searched by directly transmitting a discovery signal that does not designate a specific destination between wireless terminals. “Sidelink Direct Communication” is a mode in which data is directly transmitted between wireless terminals by designating a specific destination (destination group).

On the other hand, machine type communication (MTC), in which a wireless terminal communicates without a human being in a mobile communication system, has attracted attention. As one form of such communication, there is vehicle-to-vehicle (V2V) communication in which communication is performed directly between vehicles. In addition, it has been studied to realize V2V communication using the function of D2D ProSe (see Non-Patent Documents 1 and 2).

The wireless terminal according to the first feature is used in a mobile communication system that directly transmits data between wireless terminals. The wireless terminal includes a transmission unit that directly transmits a control signal including the data allocation information to another wireless terminal, and then directly transmits the data to the other wireless terminal according to the allocation information. When transmitting emergency data as the data, the transmission unit includes information indicating that the emergency data is transmitted in the control signal.

The wireless terminal according to the second feature is a wireless terminal used in a mobile communication system that directly transmits data between wireless terminals. The wireless terminal receives a control signal including the data allocation information directly from another wireless terminal, and then receives a data directly from the other wireless terminal according to the allocation information; an emergency unit; A control unit that recognizes that the emergency data is transmitted from the other wireless terminal when information indicating that data is transmitted is included in the control signal.

The wireless terminal according to the third feature is used in a mobile communication system that directly transmits data between wireless terminals. The wireless terminal directly transmits a control signal including the data allocation information to another wireless terminal, and then directly transmits the data to the other wireless terminal according to the allocation information; A controller for notifying a base station of information indicating that the emergency data is transmitted in order to receive radio resource allocation for transmitting the emergency data when transmitting emergency data as data.

The base station according to the fourth feature is used in a mobile communication system that directly transmits data between wireless terminals. The base station receives, from the wireless terminal, information indicating that emergency data is transmitted as data to be directly transmitted between wireless terminals, and the emergency data according to the information received by the receiving unit. A control unit that preferentially allocates radio resources for transmission to the radio terminals.

1 is a configuration diagram of an LTE system. It is a protocol stack figure of a radio | wireless interface. It is a block diagram of a radio frame. It is a protocol stack figure of "Sidelink Direct Communication". It is a figure for demonstrating the process of the MAC layer in "Sidelink Direct Communication." It is a block diagram of eNB. It is a block diagram of UE. It is a figure which shows the structural example of "SCI" concerning 1st Embodiment. It is an operation | movement sequence diagram which concerns on 1st Embodiment. FIG. 10A shows the main parameters included in the “Sidelink UE Information” message, and FIG. 10B shows the main parameters included in the “RRC Connection Reconfiguration” message. It is a figure for demonstrating the specific example of the operation | movement in UE of the receiving side. It is a figure which shows the structural example of "MAC Sub-header" of the data (PDU) handled by a MAC layer. It is an operation | movement sequence diagram which concerns on 2nd Embodiment. It is a figure which shows the specific example of the "Sidelink UE Information" message which concerns on 2nd Embodiment.

[Outline of Embodiment]
In the V2V communication, it is assumed that data including a traffic safety message (V2V message) is transmitted by “Sidelink Direct Communication”.

However, since a low delay is required for transmission of the V2V message, there is a concern that such a low delay request cannot be satisfied in “Sidelink Direct Communication”.

Therefore, the embodiment provides a wireless terminal and a base station that can appropriately transmit data requiring low delay by “Sidelink Direct Communication”.

The wireless terminal according to the first embodiment is used in a mobile communication system that directly transmits data between wireless terminals. The wireless terminal includes a transmission unit that directly transmits a control signal including the data allocation information to another wireless terminal, and then directly transmits the data to the other wireless terminal according to the allocation information. When transmitting emergency data as the data, the transmission unit includes information indicating that the emergency data is transmitted in the control signal.

In the first embodiment, the control signal includes a destination field that can store a destination identifier that specifies a destination of the data. The information indicating that the emergency data is transmitted is an emergency flag included in the control signal separately from the destination field.

In the first embodiment, the control signal includes a destination field that can store a destination identifier that specifies a destination of the data. Information indicating that the emergency data is transmitted is included in the destination field.

In the first embodiment, the information indicating that the emergency data is transmitted is a broadcast identifier indicating that a specific destination is not specified.

The wireless terminal according to the first embodiment is used in a mobile communication system that directly transmits data between wireless terminals. The wireless terminal receives a control signal including the data allocation information directly from another wireless terminal, and then receives a data directly from the other wireless terminal according to the allocation information; an emergency unit; A control unit that recognizes that the emergency data is transmitted from the other wireless terminal when information indicating that data is transmitted is included in the control signal.

The wireless terminal according to the second embodiment is used in a mobile communication system that directly transmits data between wireless terminals. The wireless terminal directly transmits a control signal including the data allocation information to another wireless terminal, and then directly transmits the data to the other wireless terminal according to the allocation information; A controller for notifying a base station of information indicating that the emergency data is transmitted in order to receive radio resource allocation for transmitting the emergency data when transmitting emergency data as data.

In the second embodiment, the control unit includes, in the notification message, information indicating that the emergency data is transmitted when transmitting a notification message regarding direct communication between wireless terminals to the base station.

In the second embodiment, the control unit includes, in the request message, information indicating that the emergency data is transmitted when transmitting a request message for establishing a connection with the base station to the base station. .

The base station according to the second embodiment is used in a mobile communication system that directly transmits data between wireless terminals. The base station receives, from the wireless terminal, information indicating that emergency data is transmitted as data to be directly transmitted between wireless terminals, and the emergency data according to the information received by the receiving unit. A control unit that preferentially allocates radio resources for transmission to the radio terminals.

In the second embodiment, the information indicating that the emergency data is transmitted is included in a notification message regarding direct communication between wireless terminals.

In the second embodiment, information indicating that the emergency data is transmitted is included in a request message for establishing a connection with the base station.

[First Embodiment]
(Mobile communication system)
Hereinafter, the LTE system that is the mobile communication system according to the first embodiment will be described. FIG. 1 is a diagram illustrating a configuration of an LTE system.

As shown in FIG. 1, the LTE system includes a UE (User Equipment) 100, an E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) 10, and an EPC (Evolved Packet Core) 20.

UE 100 corresponds to a wireless terminal. The UE 100 is a mobile communication device, and performs radio communication with a cell (serving cell). The configuration of the UE 100 will be described later.

E-UTRAN 10 corresponds to a radio access network. The E-UTRAN 10 includes an eNB 200 (evolved Node-B). The eNB 200 corresponds to a base station. The eNB 200 is connected to each other via the X2 interface. The configuration of the eNB 200 will be described later.

The eNB 200 manages one or a plurality of cells and performs radio communication with the UE 100 that has established a connection with the own cell. The eNB 200 has a radio resource management (RRM) function, a routing function of user data (hereinafter simply referred to as “data”), a measurement control function for mobility control / scheduling, and the like. “Cell” is used as a term indicating a minimum unit of a radio communication area, and is also used as a term indicating a function of performing radio communication with the UE 100.

The EPC 20 corresponds to a core network. The EPC 20 includes an MME (Mobility Management Entity) / S-GW (Serving-Gateway) 300. MME performs various mobility control etc. with respect to UE100. The S-GW performs data transfer control. The MME / S-GW 300 is connected to the eNB 200 via the S1 interface. The E-UTRAN 10 and the EPC 20 constitute a network.

FIG. 2 is a protocol stack diagram of a radio interface in the LTE system. As shown in FIG. 2, the radio interface protocol is divided into the first to third layers of the OSI reference model, and the first layer is a physical (PHY) layer. The second layer includes a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, and a PDCP (Packet Data Convergence Protocol) layer. The third layer includes an RRC (Radio Resource Control) layer.

The physical layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control signals are transmitted between the physical layer of the UE 100 and the physical layer of the eNB 200 via a physical channel.

The MAC layer performs data priority control, retransmission processing by hybrid ARQ (HARQ), random access procedure, and the like. Data and control signals are transmitted between the MAC layer of the UE 100 and the MAC layer of the eNB 200 via a transport channel. The MAC layer of the eNB 200 includes a scheduler that determines an uplink / downlink transport format (transport block size, modulation / coding scheme (MCS)) and an allocation resource block to the UE 100.

The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and the physical layer. Data and control signals are transmitted between the RLC layer of the UE 100 and the RLC layer of the eNB 200 via a logical channel.

The PDCP layer performs header compression / decompression and encryption / decryption.

The RRC layer is defined only in the control plane that handles control signals. Messages for various settings (RRC messages) are transmitted between the RRC layer of the UE 100 and the RRC layer of the eNB 200. The RRC layer controls the logical channel, the transport channel, and the physical channel according to establishment, re-establishment, and release of the radio bearer. When there is a connection (RRC connection) between the RRC of the UE 100 and the RRC of the eNB 200, the UE 100 is in the RRC connected state (connected state), and otherwise, the UE 100 is in the RRC idle state (idle state).

The NAS (Non-Access Stratum) layer located above the RRC layer performs session management and mobility management.

FIG. 3 is a configuration diagram of a radio frame used in the LTE system. In the LTE system, OFDMA (Orthogonal Frequency Division Multiplexing Access) is applied to the downlink, and SC-FDMA (Single Carrier Frequency Multiple Access) is applied to the uplink.

As shown in FIG. 3, the radio frame is composed of 10 subframes arranged in the time direction. Each subframe is composed of two slots arranged in the time direction. The length of each subframe is 1 ms, and the length of each slot is 0.5 ms. Each subframe includes a plurality of resource blocks (RB) in the frequency direction and includes a plurality of symbols in the time direction. Each resource block includes a plurality of subcarriers in the frequency direction. One symbol and one subcarrier constitute one resource element (RE). Further, among radio resources (time / frequency resources) allocated to the UE 100, a frequency resource can be specified by a resource block, and a time resource can be specified by a subframe (or slot).

In the downlink, the section of the first few symbols of each subframe is an area mainly used as a physical downlink control channel (PDCCH) for transmitting a downlink control signal. Details of the PDCCH will be described later. The remaining part of each subframe is an area that can be used mainly as a physical downlink shared channel (PDSCH) for transmitting downlink data.

In the uplink, both ends in the frequency direction in each subframe are regions used mainly as physical uplink control channels (PUCCH) for transmitting uplink control signals. The remaining part of each subframe is an area that can be used as a physical uplink shared channel (PUSCH) mainly for transmitting uplink data.

(Sidelink Direct Communication)
In the following, “Sidelink Direct Communication” will be mainly described for D2D ProSe. In D2D ProSe, a plurality of UEs 100 transmit and receive various signals via direct radio links that do not go through the eNB 200. Such a direct radio link is referred to as a “side link”. As modes of D2D ProSe, two modes of “Sidelink Direct Discovery” and “Sidelink Direct Communication” are defined.

“Sidelink Direct Discovery” is a mode in which a destination is searched by directly transmitting a discovery signal that does not designate a specific destination between UEs. “Sidelink Direct Communication” is a mode in which data is directly transmitted between UEs by designating a specific destination (destination group). The resource allocation type of “Sidelink Direct Communication” includes “Mode 1” in which the eNB 200 specifies the radio resource of “Sidelink Direct Communication”, and “Mode 2” in which the UE 100 selects the radio resource of “Sidelink Direct Communication”, There is. In the following, “Sidelink Direct Communication” in mode 1 is mainly assumed.

FIG. 4 is a protocol stack diagram of “Sidelink Direct Communication”. As shown in FIG. 4, the “Sidelink Direct Communication” protocol stack includes a physical (PHY) layer, a MAC layer, an RLC layer, and a PDCP layer. Between the physical layer of UE (A) and the physical layer of UE (B), a control signal is transmitted via the physical side link control channel (PSCCH), and data is transmitted via the physical side link shared channel (PSSCH). Is transmitted. Further, a synchronization signal or the like may be transmitted via a physical side link broadcast channel (PSBCH). Data is transmitted between the MAC layer of UE (A) and the MAC layer of UE (B) via a transport channel called a side link shared channel (SL-SCH). Between the RLC layer of UE (A) and the RLC layer of UE (B), data is transmitted through a logical channel called a side link traffic channel (STCH).

FIG. 5 is a diagram for explaining the processing of the MAC layer in “Sidelink Direct Communication”. As shown in FIG. 5, the MAC layer on the transmission side assigns logical channel priorities to the data on the STCH (Logical Channel Priority), multiplexes the data, and passes the data to the physical layer via the HARQ entity. . On the other hand, the MAC layer on the receiving side receives data on the SL-SCH by the HARQ entity, performs PDU filtering based on the destination identifier, and then separates (De-Multiplexing) and passes the data to the RLC layer.

In the following description, the UE 100 on the data transmission side is denoted as UE 100-1, and the UE 100 on the data reception side is denoted as UE 100-2.

(V2V message)
Hereinafter, a message (V2V message) for “Load Safety” will be described.

The message length of the V2V message is 45 bytes, 49 bytes, 99 bytes, 166 bytes, 427 bytes, 507 bytes, or 600 bytes in the case of “Basic Safety Message for DSRC” defined by “The Society of the Automotive Engineers”. Yes (see "SAE J2735: (R) Dedicated Short Range Communication (DSRC) Message Set Dictionary"). Note that the V2V message includes, for example, the following information elements (see “700 MHz band highway traffic system experimental vehicle-to-vehicle communication message guideline ITS FORUM RC-013 1.0 version”).

-Vehicle information: 1. Vehicle ID, 2. Message ID, 3. Increment counter, 4. Data length-Message content confirmation time information-Location information: 1. Latitude, latitude, altitude, 2. Location acquisition information (measurement standards, etc.) ),
-Vehicle status information: 1. Vehicle speed, azimuth, acceleration, 2. Speed acquisition information, acceleration acquisition information-Vehicle attribute information: 1. Vehicle size, application type

• Low delay is required for V2V message transmission. For example, it is required to be within 100 ms from data generation to transmission. Therefore, it is important to speed up the processing related to the V2V message.

(base station)
The eNB 200 (base station) according to the first embodiment will be described below. FIG. 6 is a block diagram of the eNB 200. As illustrated in FIG. 6, the eNB 200 includes a transmission unit 210, a reception unit 220, a control unit 230, and a backhaul communication unit 240.

The transmission unit 210 performs various transmissions under the control of the control unit 230. The transmission unit 210 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output from the control unit 230 into a radio signal and transmits it from the antenna.

The receiving unit 220 performs various types of reception under the control of the control unit 230. The receiving unit 220 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 230.

The control unit 230 performs various controls in the eNB 200. The control unit 230 includes a processor and a memory. The memory stores a program executed by the processor and information used for processing by the processor. The processor includes a baseband processor that performs modulation / demodulation and encoding / decoding of the baseband signal, and a CPU (Central Processing Unit) that executes various processes by executing programs stored in the memory. The processor executes various processes and the various communication protocols described above.

The backhaul communication unit 240 is connected to the neighboring eNB 200 via the X2 interface, and is connected to the MME / S-GW 300 via the S1 interface. The backhaul communication unit 240 is used for communication performed on the X2 interface, communication performed on the S1 interface, and the like.

(Wireless terminal)
Below, UE100 (radio | wireless terminal) which concerns on 1st Embodiment is demonstrated. UE100 which concerns on 1st Embodiment is mainly mounted in a vehicle.

FIG. 7 is a block diagram of the UE 100. As illustrated in FIG. 7, the UE 100 includes a reception unit 110, a transmission unit 120, and a control unit 130.

The receiving unit 110 performs various types of reception under the control of the control unit 130. The receiving unit 110 includes an antenna and a receiver. The receiver converts a radio signal received by the antenna into a baseband signal (received signal) and outputs the baseband signal to the control unit 130.

The transmission unit 120 performs various transmissions under the control of the control unit 130. The transmission unit 120 includes an antenna and a transmitter. The transmitter converts the baseband signal (transmission signal) output from the control unit 130 into a radio signal and transmits it from the antenna.

The control unit 130 performs various controls in the UE 100. The control unit 130 includes a processor and a memory. The memory stores a program executed by the processor and information used for processing by the processor. The processor includes a baseband processor that performs modulation / demodulation and encoding / decoding of the baseband signal, and a CPU (Central Processing Unit) that executes various processes by executing programs stored in the memory. The processor may include a codec that performs encoding / decoding of an audio / video signal. The processor executes various processes and the various communication protocols described above.

First, the operation when the UE 100 is the data transmission side (UE 100-1) will be described. Transmitting section 120 transmits a control signal including data allocation information directly to UE 100-2 via “PSCCH”. A control signal including data allocation information is referred to as side link control information (SCI). Then, the transmission unit 120 directly transmits data to the UE 100-2 according to the allocation information via “PSSCH”.

In the first embodiment, when transmitting emergency data (V2V message) as data, the transmission unit 120 includes information (Emergency Flag) indicating that emergency data is transmitted in “SCI”.

FIG. 8 is a diagram illustrating a configuration example of “SCI” according to the first embodiment. As shown in FIG. 8, “SCI” is “Frequency Hopping flag”, “Resource block assignment and hopping resource allocation”, “Time resource pattern”, “Modulation timing”, “Modulation timing”, “Modulation timing”, “Modification timing” Each field includes “ID” and “Emergency Flag”. For example, when the “Emergency Flag” field is “1”, it indicates that emergency data is to be transmitted. When the “Emergency Flag” field is “0”, it indicates that emergency data is not transmitted.

The 8-bit “Group destination ID” corresponds to a destination field that can store a destination identifier that specifies a data destination. The “Group destination ID” field stores a destination identifier (destination group identifier).

Next, the operation when the UE 100 is the data receiving side (UE 100-2) will be described.

The reception unit 110 receives “SCI” including data allocation information directly from the UE 100-1 and then receives data directly from the UE 100-1 according to the allocation information.

When information (Emergency Flag) indicating that emergency data is transmitted is included in “SCI”, the control unit 130 recognizes that emergency data is transmitted from the UE 100-1. In this case, it is preferable that the control unit 130 performs processing for receiving emergency data corresponding to “SCI” regardless of “Group destination ID”. Further, when “Emergency Flag” is included in “SCI”, the control unit 130 may perform preparations for emergency response (vehicle control, sensor confirmation, or the like).

(Operation sequence)
Hereinafter, an operation sequence according to the first embodiment will be described. FIG. 9 is an operation sequence diagram according to the first embodiment. In the initial state of FIG. 9, it is assumed that UE 100-1 is in an idle state and has decided to transmit emergency data (V2V message).

As shown in FIG. 9, in step S101, the eNB 200 broadcasts system information including each parameter of “Sidelink Direct Communication” in its own cell. Such system information is referred to as system information block type 18 (SIB18). The UE 100-1 receives “SIB18”.

In step S102, the UE 100-1 establishes an RRC connection with the eNB 200, and transitions to a connected state.

In step S103, the UE 100-1 transmits a notification message (Sidelink UE Information) related to “D2D ProSe” to the eNB 200. FIG. 10A shows main parameters included in the “Sidelink UE Information” message. As shown in FIG. 10A, the “Sidelink UE Information” message includes a transmission request (comTxResourceReq) of “Sidelink Direct Communication”. The eNB 200 receives “Sidelink UE Information”.

In step S104, the eNB 200 transmits an individual RRC message (RRC Connection Reconfiguration) including various parameters related to “D2D ProSe” to the UE 100-1. FIG. 10B shows the main parameters included in the “RRC Connection Reconfiguration” message. As shown in FIG. 10B, the “RRC Connection Reconfiguration” message includes a setting parameter (SL-CommConfig) of “Sidelink Direct Communication”. The UE 100-1 receives the “RRC Connection Reconfiguration” message.

In step S105, the UE 100-1 transmits a buffer status report (Prose BSR) indicating the transmission data amount of “Sidelink Direct Communication” to the eNB 200. The eNB 200 receives “Prose BSR”. However, step S105 may be omitted.

In step S106, the eNB 200 transmits downlink control information (DCI) including allocation resource information (scheduling information) for "Sidelink Direct Communication" to the UE 100-1. Such “DCI” is referred to as “DCI format 5”. The UE 100-1 receives “DCI”.

In step S107, the UE 100-1 transmits “SCI” including “Emergency Flag” to the UE 100-2. The UE 100-2 starts a process for receiving emergency data corresponding to “SCI” regardless of the “Group destination ID”.

In step S108 and subsequent steps, the UE 100-1 transmits emergency data (V2V message) to the UE 100-2 using the radio resource indicated by “SCI”. The UE 100-2 receives the emergency data (V2V message) based on “SCI”.

(Specific example of receiver operation)
FIG. 11 is a diagram for explaining a specific example of the operation in the UE 100-2.

As shown in FIG. 11, the UE 100-1 detects the occurrence of an accident (vehicle accident) and generates a V2V message related to the accident. The UE 100-1 transmits “SCI” including “Emergency Flag”. The UE 100-2 receives “SCI” including “Emergency Flag”. The UE 100-2 determines that an accident has occurred nearby, and starts preparations for emergency response (vehicle control, sensor confirmation, etc.).

UE 100-1 transmits emergency data (V2V message) using the radio resource indicated by "SCI". The UE 100-2 receives emergency data (V2V message) corresponding to “SCI” regardless of “Group destination ID” in “SCI”. The UE 100-2 grasps the details of the accident based on the emergency data (V2V message).

[Modification of First Embodiment]
In the present modification, information indicating that emergency data is transmitted is included in a destination field (“Group destination ID” field) in “SCI”. That is, in the present modification, the “Emergency Flag” field is unnecessary.

In this modified example, the information indicating that emergency data is transmitted is a broadcast identifier indicating that a specific destination is not specified.

As shown in FIG. 8, the 8-bit “Group destination ID” corresponds to a destination field that can store a destination identifier that designates a data destination. Normally, the “Group destination ID” field stores a destination identifier (destination group identifier). In this modified example, when transmitting emergency data (V2V message), the transmission unit 120 of the UE 100-1 includes a broadcast identifier in the “Group destination ID” field.

FIG. 12 is a diagram illustrating a configuration example of “MAC Sub-header” of data (PDU) handled in the MAC layer. As shown in FIG. 12, “MAC Sub-header” includes a “DST” field for storing a destination identifier (destination group identifier). The “DST” field is 2 octets (16 bits).

The destination identifier is 24 bits as a whole. Of the 24 bits, 6 bits are stored in the “Group destination ID” field of “SCI”, and 16 bits of the 24 bits are stored in the “DST” field of “MAC Sub-header”. Thereby, primary filtering is performed in the physical layer on the reception side, and secondary filtering is performed in the MAC layer on the reception side.

For example, the broadcast identifier is composed of all 24 bits of “1”. In this case, the “Group destination ID” field is all “1”, and the “DST” field of “MAC Sub-header” is also all “1”. Here, both “Group destination ID” set to “1” and “DST” set to “1” all constitute a broadcast identifier.

When the UE 100-2 receives “SCI” in which the broadcast identifier is stored in the “Group destination ID” field, the UE 100-2 recognizes that the emergency data (V2V message) is transmitted from the UE 100-1, and passes the primary filtering. Then, when receiving emergency data (V2V message) in which the broadcast identifier is stored in the “DST” field of “MAC Sub-header”, the UE 100-2 passes the secondary filtering.

[Second Embodiment]
The second embodiment will be described mainly with respect to differences from the first embodiment. The second embodiment is an embodiment for accelerating the processing until receiving a resource assignment for “Sidelink Direct Communication” from the eNB 200.

(Sending wireless terminal)
Hereinafter, UE 100-1 (radio terminal on the transmission side) according to the second embodiment will be described.

The control unit 130 of the UE 100-1 according to the second embodiment receives an allocation of radio resources for transmitting emergency data (V2V message) in the case of transmitting emergency data by “Sidelink Direct Communication”. Information indicating transmission of data is notified to the eNB 200.

In the second embodiment, the control unit 130 transmits information indicating that emergency data is to be transmitted when a notification message (“Sidelink UE Information” message) regarding “D2D ProSe” is transmitted to the eNB 200, and a “Sidelink UE Information” message. Include in

(base station)
Hereinafter, the eNB 200 (base station) according to the second embodiment will be described.

The receiving unit 220 of the eNB 200 according to the second embodiment receives, from the UE 100-1, information indicating that emergency data (V2V message) is to be transmitted by “Sidelink Direct Communication”. The control unit 230 of the eNB 200 preferentially allocates radio resources for transmitting emergency data to the UE 100-1 according to the information received by the reception unit 220.

(Operation sequence)
Hereinafter, an operation sequence according to the second embodiment will be described. FIG. 13 is an operation sequence diagram according to the second embodiment. Here, differences from the first embodiment will be mainly described, and redundant description will be omitted.

As shown in FIG. 13, in step S201, the eNB 200 transmits “SIB18” by broadcast in its own cell. The UE 100-1 receives “SIB18”.

In step S202, the UE 100-1 establishes an RRC connection with the eNB 200, and transitions to a connected state.

In step S203, the UE 100-1 transmits “Sidelink UE Information” to the eNB 200. In the second embodiment, “Sidelink UE Information” includes emergency data information indicating that emergency data is to be transmitted (want to be transmitted) by “Sidelink Direct Communication”. The emergency data information may be information stored in a new field (“Cause” field or “Emergency Flag” field) of “Sidelink UE Information”. Alternatively, the emergency data information may be a specific identifier included in the “SL-DestinationInfoList” shown in 10 (a). “SL-DestinationInfoList” can include a maximum of 16 destination identifiers. For example, the broadcast identifier may be used as emergency data information by including a broadcast identifier (see “Modification of First Embodiment”) in “SL-DestinationInfoList”. From the emergency data information, the eNB 200 grasps that the UE 100-1 wants to transmit emergency data, and prepares radio resources to be preferentially allocated to the UE 100-1.

In step S204, the eNB 200 transmits an individual RRC message (RRC Connection Reconfiguration) including various parameters related to “D2D ProSe” to the UE 100-1. The UE 100-1 receives the “RRC Connection Reconfiguration” message. The “RRC Connection Reconfiguration” message may include an acknowledgment (Ack) for emergency data information or information indicating that quick radio resource allocation is performed.

In this sequence, transmission of “Prose BSR” from the UE 100-1 to the eNB 200 is omitted. For example, the eNB 200 allocates radio resources with the lowest possible delay regardless of the buffer state of the UE 100-1.

In step S205, the eNB 200 transmits, to the UE 100-1, downlink control information (DCI) including allocation resource information (scheduling information) for “Sidelink Direct Communication”. The UE 100-1 receives “DCI”. The subsequent operations (steps S206 to S207) are the same as those in the first embodiment.

(Specific example of Sidelink UE Information)
FIG. 14 is a diagram illustrating a specific example of a “Sidelink UE Information” message according to the second embodiment. A portion surrounded by a broken line in FIG. 14 is a new field.

As shown in FIG. 14, the “Sidelink UE Information” message includes a “commTxCause” field that indicates the reason for transmitting “Sidelink Direct Communication”. In the “commTxCause” field, for example, “emergency”, “high Priority Access”, “mt-Access”, “mo-Signaling”, “mo-Data”, or “delayTolerantAccess” is set. Here, “emergency” indicates an emergency call. “High Priority Access” indicates that Access class is 11-15 (11: PLMN Use, 12: Security Service, 13: Public Utilities (e.g. water / gas suppliers), 14: Emergency Services, 15: PLMN Staff). “Mt-Access” indicates paging response. “Mo-Signaling” indicates a control signal such as tracking area update. “Mo-Data” indicates normal data transmission. “DelayTolerantAccess” indicates a low priority signal.

[Modification Example of Second Embodiment]
Instead of the “Sidelink UE Information” message, the “RRC connection request” message may include emergency data information indicating that emergency data is to be transmitted (want to be transmitted) by “Sidelink Direct Communication”. The “RRC connection request” message is transmitted from the UE 100-1 to the eNB 200 in step S202 of FIG. The “RRC connection request” message corresponds to a request message for establishing a connection with the eNB 200.

[Other Embodiments]
In the first embodiment and the second embodiment described above, the V2V message is exemplified as emergency data. However, the present invention can be applied to transmission of emergency data other than V2V messages.

In the first embodiment and the second embodiment described above, the LTE system is exemplified as the mobile communication system. However, the present invention is not limited to LTE systems. The present invention may be applied to a system other than the LTE system.

[Cross-reference]
The entire contents of Japanese Patent Application No. 2015-37504 (February 27, 2015) are incorporated herein by reference.

The present invention is useful in the communication field.

Claims

A wireless terminal used in a mobile communication system for directly transmitting data between wireless terminals,
A transmission unit that directly transmits a control signal including the data allocation information to another wireless terminal, and then directly transmits the data to the other wireless terminal according to the allocation information;
In the case where emergency data is transmitted as the data, the transmitting unit includes information indicating that the emergency data is transmitted in the control signal.
The control signal includes a destination field capable of storing a destination identifier that specifies a destination of the data;
The wireless terminal according to claim 1, wherein the information indicating that the emergency data is transmitted is an emergency flag included in the control signal separately from the destination field.
The control signal includes a destination field capable of storing a destination identifier that specifies a destination of the data;
The wireless terminal according to claim 1, wherein information indicating that the emergency data is transmitted is included in the destination field.
4. The wireless terminal according to claim 3, wherein the information indicating that the emergency data is transmitted is a broadcast identifier indicating that a specific destination is not specified.
A wireless terminal used in a mobile communication system for directly transmitting data between wireless terminals,
A receiving unit that directly receives the data from the other wireless terminal according to the allocation information after receiving the control signal including the data allocation information directly from the other wireless terminal;
In the case where information indicating that emergency data is transmitted is included in the control signal, a controller that recognizes that the emergency data is transmitted from the other wireless terminal;
A wireless terminal comprising:
The control signal includes a destination field capable of storing a destination identifier that specifies a destination of the data;
The wireless terminal according to claim 5, wherein the information indicating that the emergency data is transmitted is an emergency flag included in the control signal separately from the destination field.
The control signal includes a destination field capable of storing a destination identifier that specifies a destination of the data;
The wireless terminal according to claim 5, wherein information indicating that the emergency data is transmitted is included in the destination field.
The wireless terminal according to claim 7, wherein the information indicating that the emergency data is transmitted is a broadcast identifier indicating that a specific destination is not specified.
A wireless terminal used in a mobile communication system for directly transmitting data between wireless terminals,
A transmission unit that directly transmits a control signal including the data allocation information to another wireless terminal, and then transmits the data directly to the other wireless terminal according to the allocation information;
In the case of transmitting emergency data as the data, a control unit for notifying a base station of information indicating that the emergency data is transmitted in order to receive radio resource allocation for transmitting the emergency data;
A wireless terminal comprising:
The wireless terminal according to claim 9, wherein the control unit includes, in the notification message, information indicating that the emergency data is transmitted when a notification message related to direct communication between wireless terminals is transmitted to the base station.
The control unit according to claim 9, wherein when the request message for establishing a connection with the base station is transmitted to the base station, the control unit includes information indicating that the emergency data is transmitted in the request message. Wireless terminal.
A base station used in a mobile communication system for directly transmitting data between wireless terminals,
A receiving unit that receives information indicating that emergency data is transmitted as data to be transmitted directly between wireless terminals from the wireless terminal;
A control unit that preferentially allocates radio resources for transmitting the emergency data to the radio terminal according to information received by the reception unit;
A base station comprising:
The base station according to claim 12, wherein the information indicating that the emergency data is transmitted is included in a notification message regarding direct communication between wireless terminals.
The base station according to claim 12, wherein the information indicating that the emergency data is transmitted is included in a request message for establishing a connection with the base station.