KR102105554B1 - Method and apparatus for device-to-device direct communication - Google Patents

Abstract

A method of direct communication between devices is provided. The device performs scheduling and data transmission of at least one frame among a plurality of frames included in the superframe, a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and resources. It is set as frame type 0 that is sectioned as a data area for data, and the remaining frames in a plurality of frames are set as frame type 1 that is sectioned as a synchronization area and a data area.

Description

Method and apparatus for direct communication between devices {METHOD AND APPARATUS FOR DEVICE-TO-DEVICE DIRECT COMMUNICATION}

The present invention relates to a method and apparatus for direct communication between devices.

Recently, interest in device-to-device (D2D) direct communication for adjacency-based application services is increasing, and various technologies supporting direct communication have been proposed.

In a wireless communication system such as a wireless LAN, carrier sensing is performed for direct communication between devices, which consumes a lot of energy and resources due to carrier sensing. In particular, as the number of devices increases, the probability of occupying a resource decreases, and the probability of collision with other devices in the occupied resource increases, resulting in a decrease in resource utilization efficiency.

There is a method of avoiding collision with another device based on carrier sensing, but when there are many devices, a signal for avoiding collision consumes almost all resources, and thus there is a problem in that it is impossible to transmit traffic to be actually transmitted.

An object of the present invention is to provide a method and apparatus for direct communication between devices that can efficiently utilize resources.

According to an embodiment of the present invention, a method of direct communication of a device in direct communication between devices is provided. In the direct communication method, at least one frame among a plurality of frames included in a superframe, a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and scheduling of resources And setting the frame type 0 sectioned into a data area for data transmission, setting the remaining frames in the plurality of frames to the sync area and frame type 1 sectioned into the data area, and the sync area. And transmitting / receiving signals in the discovery area, the peering area, and the data area.

At this time, the frame set to the frame type 0 may be the first frame of the superframe.

The sync region may be located at the front of each frame.

Transmitting and receiving the signal may include repeatedly transmitting a synchronization signal in the synchronization area.

The direct communication method may include determining a channel state through interference sensing in at least one of the discovery area, the peering area, and the data area, and uses resources in a section in which the channel state is determined to be idle. It may further include a step.

The direct communication method may further include transmitting a blocking signal for preventing intrusion of other types of devices in the section using the resource.

The transmitting of the blocking signal may include transmitting the blocking signal through at least one subcarrier.

The discovery area may include a plurality of resource unit groups, each of which includes a plurality of resource units, and an interference sensing period that is located in front of each resource unit group and performs the interference sensing.

The peering area may include a peering request / response section for setting a peering identity (PID) and a PID broadcast section for PID broadcast. In this case, the peering request / response section includes a plurality of first resource unit groups, each of which includes a plurality of resource units, and a first interference sensing section that is located in front of each of the first resource unit groups and performs the interference sensing. can do. In addition, the PID broadcast period may include a second resource unit group including a plurality of resource units, and a second interference sensing period located in front of the second resource unit group and performing the interference sensing.

The data area may include a scheduling period for resource scheduling and a data period for data burst transmission. In this case, the scheduling period may include a resource unit group including a plurality of resource units, and an interference sensing period located in front of the resource unit group and performing the interference sensing. In addition, the data period may include a plurality of data burst periods and a feedback period corresponding to each of the plurality of data burst periods, and the number and length of the data burst periods may vary according to the result of the scheduling.

According to another embodiment of the present invention, a method of direct communication of a device in direct communication between devices is provided. The direct communication method includes setting a superframe and transmitting and receiving signals in the superframe. At this time, the superframe includes a plurality of frames, and the plurality of frames included in the superframe includes a type 0 frame and a type 1 frame. The type 0 frame is divided into a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and a data area for scheduling and data transmission of resources. The type 1 frame is divided into the synchronization area and the data area.

In this case, the first frame of the superframe may be the type 0 frame, and the remaining frames may be the type 1 frame.

The sync region may be located at the front of each frame.

At least one area of the discovery area, the peering area, and the data area may include a first section for determining a channel state through interference sensing, and a second section following the first section and having a plurality of resource units. It can contain.

Transmitting and receiving the signal may include using resources of the second section when the channel state is determined to be idle in the first section, and different types in the second section when using the resource. It may include the step of transmitting a blocking signal to prevent the intrusion of the device.

According to another embodiment of the present invention, a direct communication apparatus in direct communication between devices is provided. The direct communication device includes a frame generating unit for setting a superframe, and a transmitting and receiving unit for transmitting and receiving signals in the superframe. At this time, the superframe includes a plurality of frames, and the plurality of frames included in the superframe includes a type 0 frame and a type 1 frame. The type 0 frame is divided into a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and a data area for scheduling and data transmission of resources. The type 1 frame is divided into the synchronization area and the data area.

In this case, the first frame of the superframe may be the type 0 frame, and the remaining frames may be the type 1 frame.

The sync region may be located at the front of each frame.

At least one area of the discovery area, the peering area, and the data area may include a first section for determining a channel state through interference sensing, and a second section following the first section and having a plurality of resource units. It can contain.

The transmission / reception unit uses resources of the second section when it is determined that the channel state is idle in the first section, and prevents intrusion of other types of devices in the second section when using the resources. It can transmit a blocking signal for.

According to an embodiment of the present invention, it is possible to provide direct communication between devices for a large number of devices within a limited resource.

1 is a diagram illustrating a direct communication system between devices according to an embodiment of the present invention.
2 is a view showing a frame structure in a device-to-device direct communication system according to an embodiment of the present invention.
3 is a diagram illustrating an example of a method of operating a fixed format frame in a device-to-device direct communication system according to an embodiment of the present invention.
4 is a diagram illustrating another example of a method of operating a fixed format frame in a device-to-device direct communication system according to an embodiment of the present invention.
5 is a diagram illustrating a synchronization area of a frame structure according to an embodiment of the present invention.
6 is a diagram illustrating interference sensing in a device-to-device direct communication system according to an embodiment of the present invention.
7 is a diagram illustrating a discovery area in a frame structure of a direct communication system between devices according to an embodiment of the present invention.
8 is a diagram illustrating a peering area in a frame structure of a direct communication system between devices according to an embodiment of the present invention.
9 is a diagram illustrating a data area in a frame structure of a direct communication system between devices according to an embodiment of the present invention.
10 is a block diagram of a direct communication apparatus in a device-to-device direct communication system according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

1 is a view showing a direct communication system between devices according to an embodiment of the present invention, Figure 2 is a view showing a frame structure in a direct communication system between devices according to an embodiment of the present invention, Figure 3 is a view A diagram showing an example of a method of operating a fixed format frame in a device-to-device direct communication system according to an embodiment of the present invention, and FIG. 4 is a frame of a fixed format in a device-to-device direct communication system according to an embodiment of the present invention It is a view showing another example of how to operate.

Referring to FIG. 1, a plurality of devices DV1, DV2, DV3, DV4, DV5, DV6, and DV7 participate in direct communication between devices. At this time, a one-to-one communication may be performed between the device (DV1 to DV7, DV3 to DV5, DV5 to DV7, DV3 to DV7), or between one device (DV2) and multiple devices (DV1, DV4, DV6). One-to-many communication may be performed. These devices DV1-DV7 perform direct communication between devices in an unlicensed band.

2, in a frame structure for direct communication between devices in an unlicensed band, superframes appear continuously, a plurality of superframes form an ultraframe, and each superframe includes a plurality of frames. Includes. For example, an ultraframe may include 16 superframes, and a superframe may include 10 frames. In this case, the ultra frame may have a length of 3.2 s, the super frame may have a length of 200 ms, and the frame may have a length of 20 ms.

Frames can be classified into two types of frames according to their use: frame type 0 and frame type 1. The type 0 frame includes a synchronization region, a discovery region, a peering region, and a data region, and a type 1 frame includes a synchronization region and a discovery region. Only the first frame (frame # 0) in each superframe may be frame type 0, and the remaining frames may be frame type 1. Frames have a fixed length, ie a fixed structure, regardless of type, and are sectioned according to type.

In frame type 1, the discovery area is an area for discovering other devices for direct communication between devices, a peering area is an area for connection between devices, and a data area determines (schedules) which devices will use which resources. This is the area for transmitting data. In frame type 2, a data area is formed at the positions of the discovery area and the peering area. As described above, the discovery area, the peering area, and the data area are determined in the frame, and each device wakes up in the area corresponding to the action to be performed after synchronization, thereby performing the corresponding action, thereby saving energy. At this time, in order to synchronize the devices, regardless of the type of frame, the frame includes a fixed area for transmitting and receiving a synchronization signal, that is, a synchronization area. The sync region may be located at the front of the frame.

At this time, as illustrated in FIG. 3, frames having a fixed structure may be continuously arranged. In this case, when another signal exists at the start position of the sync region, a frame having the sync region can be emptied.

Alternatively, as illustrated in FIG. 4, when another signal exists at the start position of the sync region, a frame having the sync region may start after the other signal ends. That is, a variable gap may exist between two frames having a fixed structure. In this case, if no other signal exists at the start position of the sync region, a frame having the sync region may be started consecutively with the previous frame.

5 is a diagram illustrating a synchronization area of a frame structure according to an embodiment of the present invention.

Referring to FIG. 5, regardless of the type of frame, the synchronization area has a predetermined length (eg, 0.288 ms) and is located at the front of the frame. Each device performs a synchronization procedure by transmitting or receiving a synchronization signal in the synchronization area. As shown in FIG. 5, in order to increase reliability in the synchronization region, the synchronization signal is repeatedly transmitted, and the synchronization signal may be hopped in the frequency domain.

6 is a diagram illustrating interference sensing in a device-to-device direct communication system according to an embodiment of the present invention.

Referring to FIG. 6, unlike the synchronization area, the discovery area, the peering area, and the data area include an interference sensing (IS) section and a resource unit (RU). At this time, a plurality of resource units may be continuously arranged following one IS period.

Each device detects interference in the IS section to determine whether the channel state is a busy state or an idle state. When the channel state is idle, the corresponding device occupies a resource unit following the IS section and transmits a signal. If the channel state is in use, the device does not occupy the resource unit following the IS section.

On the other hand, when a plurality of resource units are continuously arranged in an IS section, even if devices for direct communication between devices occupy the resource unit and transmit a signal, there may be an unused resource unit among the plurality of resource units. In this case, in order to prevent other types of terminals from occupying an unused resource unit, devices attempting to use the plurality of resource units may transmit a blocking signal from the plurality of resource units. The blocking signal may be transmitted through at least one subcarrier. In addition, a plurality of resource units for transmission of a blocking signal may be referred to as blocking units.

As described above, according to an embodiment of the present invention, since different types of terminals can be prevented from occupying resources through a blocking signal, devices can perform distributed operations.

7 is a diagram illustrating a discovery area in a frame structure of a direct communication system between devices according to an embodiment of the present invention.

Referring to FIG. 7, the discovery area is used for the device to announce its own information, and may be located after the synchronization area with a certain length (eg, 1.568 ms). The discovery area includes a plurality of discovery resource units (RUs) for a plurality of devices, for example, 64 discovery resource units (DRUs # 0- # 63). A guard interval (GI) may exist after each discovery resource unit. The guard interval can be used for transition time and synchronization errors between discovery resource units.

Also, the discovery area includes a plurality of IS periods, and a plurality of discovery resource units, for example, eight discovery resource units, are successively disposed after each IS period. At this time, eight discovery resource units may form one discovery blocking unit.

Each discovery resource unit is divided into a preamble period and a discovery period in the time domain. For example, the preamble section may include two orthogonal frequency division multiplexing (OFDM) symbols, and the discovery section may include three OFDM symbols. At this time, at least one subcarrier of the discovery resource unit may be used to transmit a blocking signal, and FIG. 7 shows that two subcarriers are used to transmit a blocking signal. In the preamble section, automatic gain control (AGC), timing and frequency synchronization, and a preamble for channel estimation are transmitted. In the discovery section, a discovery signal for transmission of information related to discovery is transmitted.

As such, according to an embodiment of the present invention, since a plurality of discovery resource units are provided for discovery of a plurality of devices, a large number of devices can be found during one ultraframe period. For example, 1024 discovery resource units are provided during an ultraframe period of 3.2s, so 1024 devices can be discovered.

8 is a diagram illustrating a peering area in a frame structure of a direct communication system between devices according to an embodiment of the present invention.

Referring to FIG. 8, the peering area requests and responds to PID settings for purposes of informing the PID being used by broadcasting a peering identity (PID) for direct communication between devices, and PID setting with a specific device. It is used for the purpose. The peering area includes a peering request / response (REQ / RSP) section and a PID broadcast section. The peering region can be located behind the discovery region with a certain length (eg, 2.108 ms). At this time, the peering REQ / RSP section may have a length of 1.448 ms and the PID broadcast section may have a length of 0.66 ms.

The peering REQ / RSP section includes a plurality of peering REQ / RSP resource units (RUs) for a plurality of devices, for example, 16 peering REQ / RSP resource units, namely 16 peering REQ resource units and 16 peering RSP resource units. It is used to exchange information related to peering, for example PID setting. A guard period (GI) may exist after each peering REQ / RSP resource unit. The peering REQ / RSP section includes a plurality of IS sections, and a plurality of peering REQ / RSP resource units are successively arranged after each IS section. In this case, the four resource units located in front may be peering REQ resource units for requesting peering-related information, or may be a peering RSP resource unit for responding to requests for peering-related information of four resource units located in the back. In addition, four peering REQ resource units may form one peering REQ blocking unit and four peering RSP resource units may form one peering RSP blocking unit.

The peering REQ resource unit is divided into a preamble section and a peering REQ section in the time domain. For example, the preamble period may include 2 OFDM symbols, and the peering REQ period may include 8 OFDM symbols. Similarly, the peering RSP resource unit is divided into a preamble section and a peering RSP section in the time domain. For example, the preamble period may include 2 OFDM symbols, and the peering RSP period may include 8 OFDM symbols. At this time, at least one subcarrier of the peering REQ / RSP resource unit may be used to transmit a blocking signal. In the preamble section, the preamble is transmitted, and in the peering REQ / RSP section, a request / response signal for exchanging peering information is transmitted.

The PID broadcast section includes a plurality of PID broadcast resource units (RUs) for a plurality of devices, for example, 64 PID broadcast resource units, and is used to broadcast the PID being used. A guard period (GI) may exist after each PID broadcast resource unit. In addition, the PID broadcast section includes one IS section, and a plurality of PID broadcast resource units, for example, 64 PID broadcast resource units, are continuously arranged in the IS section. At this time, 64 PID broadcast resource units may form one PID broadcast blocking unit.

Each PID broadcast resource unit may include two OFDM symbols in the time domain. At least one subcarrier of the PID broadcast resource unit may be used to transmit a blocking signal. When a device broadcasts a PID, the device transmitting the PID may not be able to hear the PID broadcast in the corresponding section, so the device broadcasts the PID by shuffling the broadcast pattern. To this end, two broadcast patterns may be repeated in the PID broadcast section.

As described above, according to an embodiment of the present invention, since a plurality of PID broadcast resource units for a plurality of devices are provided, a large number of devices can be activated simultaneously.

9 is a diagram illustrating a data area in a frame structure of a direct communication system between devices according to an embodiment of the present invention.

Referring to FIG. 9, a data area includes a plurality of data channels, and each data channel includes a scheduling period and a data period. Type 1 frames contain more data channels than Type 0 frames. For example, a type 1 frame may have a predetermined length (for example, 19.712 ms) and be located after a sync region, and may include 16 data channels (Data Channels # 0- # 15). A frame of type 0 may have a certain length (eg, 16.016 ms) and be located after the peering area, and may include 13 data channels (Data Channel # 3- # 15). In the data channel, the scheduling period may have a length of 0.258 ms and the data period may have a length of 0.974 ms.

The scheduling period is a plurality of DS request / response (DS-REQ / RSP) resource units (RU) for distributed scheduling (DS) among a plurality of devices, for example, 8 DS-REQ / RSP resource units, That is, it includes 8 DS-REQ resource units and 8 DS-RSP resource units. A guard period (GI) may exist after each DS-REQ / RSP resource unit. The scheduling period further includes an IS period, and a plurality of DS-REQ / RSP resource units are continuously arranged after the IS period. At this time, the eight resource units located in front may be DS-REQ resource units for requesting scheduling-related information, or the DS-RSP resource units for response to the scheduling-related request of the eight resource units located in the back. . Eight DS-REQ resource units may form one DS-REQ blocking unit and eight DS-RSP resource units may form one DS-RSP blocking unit. In the scheduling period, the device may occupy resources for data transmission through the exchange of DS-REQ messages and DS-RSP messages.

In addition, the scheduling period may further include an SRI period for transmitting a scheduling request indicator (SRI). SRI is used to indicate the continuous allocation of resources. The SRI section may be located immediately after the IS section, and a protection section may also exist after the SRI section.

The DS-REQ resource unit is divided into a preamble section and a DS-REQ section in the time domain. For example, the preamble period may include two OFDM symbols, and the DS-REQ period may include one OFDM symbol. Similarly, the DS-RSP resource unit is divided into a preamble section and a DS-RSP section in the time domain. For example, the preamble period may include two OFDM symbols, and the DS-RSP period may include one OFDM symbol. The SRI period may include one OFDM symbol in the time domain. At this time, the DS-REQ / RSP resource unit and at least one subcarrier in the SRI section may be used to transmit a blocking signal.

The data period includes a plurality of data burst periods and a plurality of feedback periods. Each feedback period is located after a corresponding data burst period, and a protection period (GI) may exist after the data burst period and the feedback period. The data burst period is a period for transmitting a data burst. The number of data burst periods included in the data period and the length of the data bus periods vary depending on the result of distributed scheduling. That is, when the scheduling period has 8 DS-REQ / RSP resource units, the number of data burst periods is 8 or less according to the scheduling result in the scheduling period. The device that has acquired the resource in the scheduling period transmits data in the data burst period, and the device that has received the data sends an acknowledgment (ACK) for this in the feedback period.

The data burst period is divided into a preamble period, a burst control indicator (BCI) period, and a data period in the time domain. For example, the preamble period may include two OFDM symbols, the BCI period may include one OFDM symbol, and the data period may include a plurality of OFDM symbols. The preamble section transmits a preamble, the data section transmits a data burst, and the BCI section transmits a BCI for indicating the format and modulation and coding scheme (MCS) information of the transmitted data burst. At this time, since the data burst period is a resource secured through scheduling, a blocking signal is not transmitted in the data burst period.

As described above, according to an embodiment of the present invention, it is possible to maintain a signaling overhead that is a ratio of non-data periods for all periods, that is, synchronization, discovery, peering, scheduling, preamble, and feedback periods, at a constant rate. Also, in a non-data section, it is possible to determine whether a signal is transmitted through interference sensing, and when transmitting a signal, a different type of terminal can be blocked through a blocking signal, so that it can coexist with other types of terminals and perform direct communication between devices. .

Next, a direct communication apparatus in a direct communication system between devices according to an embodiment of the present invention will be described with reference to FIG. 10.

10 is a block diagram of a direct communication apparatus in a device-to-device direct communication system according to an embodiment of the present invention.

Referring to FIG. 10, the direct communication device 100 includes a frame generation unit 110 and a transmission / reception unit 120. The direct communication device 100 may be included in a device or may be a device itself.

The frame generator 110 sets the first frame as frame type 0, which is divided into a synchronization area, a discovery area, a peering area, and a data area, and sets the remaining frames to frame type 1, which is divided into a synchronization area and a data area. To create a superframe. In addition, the frame generating unit 110 generates an ultra frame with a plurality of super frames. The transceiver 120 transmits and receives signals according to each area of the superframe.

Accordingly, each device can transmit and receive data bursts for direct communication by synchronizing in the synchronization area, discovering devices in the discovery area, performing connection between devices in the peering area, and occupying resources in the data area. .

At least some functions of the direct communication method and apparatus according to the embodiment of the present invention described above may be implemented in hardware or software coupled to hardware. For example, a processor implemented as a central processing unit (CPU) or other chipset, microprocessor, etc., performs the function of the frame generating unit 1010, and a physical transceiver (transceiver) 1020 Can perform the function of

Although the embodiments of the present invention have been described in detail above, the scope of rights of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (20)

As a direct communication method of a device in direct communication between devices,
At least one frame among a plurality of frames included in a superframe, a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and data for scheduling and data transmission of resources Setting the frame type to 0, sectioned by region,
Setting the remaining frames in the plurality of frames to frame type 1 sectioned into the synchronization area and the data area,
Transmitting and receiving signals in the synchronization area, the discovery area, the peering area and the data area,
Determining a channel state through interference sensing in at least one of the discovery area, the peering area, and the data area, and
Using resources of the section in which the channel state is determined to be idle.
Direct communication method comprising a. In claim 1,
The frame set as the frame type 0 is the first frame of the superframe, a direct communication method. In claim 1,
The synchronization area is a direct communication method located at the front of each frame. In claim 1,
The transmitting and receiving of the signal includes the step of repeatedly transmitting a synchronization signal in the synchronization area. delete In claim 1,
Further comprising the step of transmitting a blocking signal for preventing the intrusion of other types of devices in the section using the resource
Direct communication method. In claim 6,
The step of transmitting the blocking signal includes transmitting the blocking signal through at least one subcarrier. In claim 6,
The discovery area includes a plurality of resource unit groups each including a plurality of resource units, and a direct communication method including an interference sensing section that is located in front of each resource unit group and performs the interference sensing. In claim 6,
The peering area includes a peering request / response section for setting a peering identity (PID) and a PID broadcast section for PID broadcast,
The peering request / response section includes a plurality of first resource unit groups, each of which includes a plurality of resource units, and a first interference sensing section that is located in front of each of the first resource unit groups and performs the interference sensing,
The PID broadcast section includes a second resource unit group including a plurality of resource units, and a second interference sensing section located in front of the second resource unit group and performing the interference sensing.
Direct communication method. In claim 6,
The data area includes a scheduling interval for resource scheduling and a data interval for data burst transmission,
The scheduling period includes a resource unit group including a plurality of resource units, and an interference sensing period located in front of the resource unit group and performing the interference sensing,
The data section includes a plurality of data burst sections and feedback sections respectively corresponding to the plurality of data burst sections,
The number and length of the data burst periods vary depending on the result of the scheduling
Direct communication method. As a direct communication method of a device in direct communication between devices,
Steps to set up a superframe, and
Transmitting and receiving a signal in the superframe,
The superframe includes a plurality of frames,
The plurality of frames included in the superframe includes a type 0 frame and a type 1 frame,
The type 0 frame is divided into a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and a data area for scheduling and data transmission of resources,
The type 1 frame is divided into the synchronization area and the data area,
At least one of the discovery area, the peering area, and the data area may include a first section for determining a channel state through interference sensing, and a second section following the first section and having a plurality of resource units. Containing
Direct communication method. delete delete delete In claim 11,
Transmitting and receiving the signal,
Using the resource of the second section when it is determined that the channel state is idle in the first section, and
When using the resource, transmitting a blocking signal to prevent the intrusion of other types of devices in the second section
Direct communication method comprising a. As a direct communication apparatus in direct communication between devices,
Frame generation unit to set the super frame, and
It includes a transceiver for transmitting and receiving signals in the superframe,
The superframe includes a plurality of frames,
The plurality of frames included in the superframe includes a type 0 frame and a type 1 frame,
The type 0 frame is divided into a synchronization area for performing a synchronization procedure, a discovery area for discovery of a device, a peering area for connection between devices, and a data area for scheduling and data transmission of resources,
The type 1 frame is divided into the synchronization area and the data area,
At least one of the discovery area, the peering area, and the data area may include a first section for determining a channel state through interference sensing, and a second section following the first section and having a plurality of resource units. Containing
Direct communication device. delete delete delete In claim 16,
The transmission / reception unit uses resources of the second section when it is determined that the channel state is idle in the first section, and prevents intrusion of other types of devices in the second section when using the resource. A direct communication device that transmits a blocking signal for doing so.

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