KR20170000232A - Terminal device and control method thereof - Google Patents

Terminal device and control method thereof Download PDF

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Publication number
KR20170000232A
KR20170000232A KR1020150089228A KR20150089228A KR20170000232A KR 20170000232 A KR20170000232 A KR 20170000232A KR 1020150089228 A KR1020150089228 A KR 1020150089228A KR 20150089228 A KR20150089228 A KR 20150089228A KR 20170000232 A KR20170000232 A KR 20170000232A
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KR
South Korea
Prior art keywords
communication link
data packet
packet
condition
reception
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KR1020150089228A
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Korean (ko)
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KR102000108B1 (en
Inventor
권경석
이병석
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에스케이텔레콤 주식회사
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Priority to KR1020150089228A priority Critical patent/KR102000108B1/en
Publication of KR20170000232A publication Critical patent/KR20170000232A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/04—Arrangements for maintaining operational condition
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W28/00—Network traffic management; Network resource management
    • H04W28/02—Traffic management, e.g. flow control or congestion control
    • H04W28/04—Error control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/06—Terminal devices adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

The present invention relates to a terminal device and a method for operating the same. The present invention discloses the terminal device which can rapidly determine whether a D2D communication link has been disconnected during operating in a D2D mode by using a method suitable for a D2D communication environment and which can minimize a data transmission delay caused by the disconnection of the D2D communication link based on a result of the determination. The present invention also discloses the method for operating the terminal device.

Description

TECHNICAL FIELD [0001] The present invention relates to a terminal device and a terminal device,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a D2D (Device to Device) communication technology, and more particularly, to a D2D communication method in which when a D2D communication link is used to transmit data, And more particularly, to a terminal apparatus and an operation method of a terminal apparatus capable of minimizing a data transmission delay due to a link disconnection.

D2D (Device to Device) communication is a technology for performing direct communication between terminals, unlike cellular communication (hereinafter referred to as cellular communication) in which a terminal transmits data on the basis of a mobile communication network through a base station.

Therefore, a terminal supporting both cellular communication and D2D communication can be connected to a cellular transmission path based on a cellular communication (hereinafter referred to as a cellular link) and a D2D transmission path based on a D2D communication (hereinafter referred to as a D2D communication link D2D link ").

Recently, WLAN Direct (for example, WiFi Direct) is being used for D2D communication.

When WiFi Direct is used for D2D communication, since the transmission coverage of the D2D communication environment is small unlike the cellular communication environment, the D2D communication link may experience a path failure due to the mobility of the user (terminal) If the D2D communication link disconnection occurs, the data transmission is temporarily interrupted, resulting in a delay in data transmission. That is, the D2D communication link is less reliable than the cellular communication link.

Therefore, in the D2D mode for transmitting data using the D2D communication link, it is very important from the reliability point of view to quickly determine whether or not the D2D communication link is disconnected.

Meanwhile, a method of determining whether or not a communication failure occurs in a currently used transport layer is a method of determining based on a plurality of timeout events.

Such an existing method may be suitable for an environment in which communication link is hardly disconnected, such as a cellular communication environment, because it takes a long time to determine whether or not the communication link is disconnected. However, in the D2D communication environment, It is not suitable for an environment where frequent breaks occur.

Accordingly, in the present invention, the data transmission delay due to the D2D communication link disconnection is minimized by quickly determining whether or not the D2D communication link is disconnected in a manner suitable for the D2D communication environment.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method and apparatus for quickly determining whether a D2D communication link is disconnected while operating in a D2D mode for transmitting data using a D2D communication link, The present invention provides a method of operating a terminal device and a terminal device capable of minimizing a data transmission delay due to a D2D communication link disconnection.

In order to achieve the above object, a terminal device according to a first aspect of the present invention is a terminal device for confirming whether or not an acknowledgment (ACK) is not received for a data packet transmitted by a receiver terminal using a first communication link for direct communication between terminals part; A confirming packet transmitting unit for transmitting a confirming packet to the receiving terminal by using a second communication link different from the first communication link when the acknowledgment is not received; And a determination unit for determining whether or not the first communication link is disconnected based on information confirmed from the confirmation attack when an acknowledgment for the confirmation packet is received from the reception terminal.

Preferably, the acknowledgment includes a sequence number of a reception waiting data packet waiting for a next reception according to the sequence number of a data packet received by the receiving terminal over the first communication link, a transmission number Information on the reception amount of the data packet received by the receiving end of the data packets transmitted through the first communication link before the time is included.

The confirmation packet may include information on a link identifier for the first communication link and a transmission time for transmitting the confirmation packet.

Preferably, the determination unit determines whether or not a first condition that a data packet having a sequence number of the reception waiting data packet exists among data packets transmitted to the receiving end using the first communication link, And determining that the first communication link is disconnected if at least one of a second condition that a reception amount of the data packet is smaller than a transmission amount of the data packet transmitted to the receiver is equal to or greater than a predetermined value is satisfied.

Preferably, the determination unit determines whether the first condition is satisfied, the third condition that at least one of the first condition and the second condition is satisfied, the transmission window of the first communication link is full, If the at least one of the fourth conditions for confirming the absence of the acknowledgment of the data packet transmitted to the receiving end using the first communication link is satisfied, it can be determined that the first communication link is disconnected.

Advantageously, said second communication link may be a communication link for cellular communication.

Preferably, when it is determined that the first communication link is disconnected, a data packet having a sequence number of the reception waiting data packet and a subsequent data packet are transmitted to the receiving terminal using the second communication link, And a packet transmission control unit for retransmitting the data packet for which the acknowledgment has not been acknowledged to the receiving end by using the first communication link when it is determined that the communication link is not disconnected.

According to a second aspect of the present invention, there is provided a method of operating a terminal device, the method comprising the steps of: confirming whether or not an acknowledgment has been received on a data packet transmitted to a receiver terminal using a first communication link for direct communication between terminals; step; A confirming packet transmitting step of transmitting a confirming packet to the receiving terminal using a second communication link different from the first communication link when the ek not received is confirmed; And a determination step of determining whether or not the first communication link is disconnected based on information confirmed from the confirmation attack when an acknowledgment for the confirmation packet is received from the reception terminal.

Preferably, the acknowledgment includes a sequence number of a reception waiting data packet waiting for a next reception according to the sequence number of a data packet received by the receiving terminal over the first communication link, a transmission number Information on the reception amount of the data packet received by the receiving end of the data packets transmitted through the first communication link before the time is included.

Preferably, the determining step may include a first condition that a data packet having a sequence number of the reception waiting data packet exists in a data packet transmitted to the receiving end using the first communication link, The first communication link can be determined to be disconnected if at least one of the second condition that the reception amount of the data packet is smaller than or equal to the transmission amount of the data packet transmitted to the receiver is satisfied.

Advantageously, the determination step further comprises a third condition in which at least one of the first condition and the second condition is satisfied and the transmission window of the first communication link is full, When the at least one of the fourth conditions for confirming whether or not the acknowledgment is not received is further satisfied with respect to the data packet transmitted to the receiving end using the first communication link after transmitting the packet for the first communication link, have.

Thus, according to the operation method of the terminal device and the terminal device according to the present invention, it is possible to promptly determine whether or not the D2D communication link is disconnected while operating in the D2D mode for transmitting data using the D2D communication link, Thereby minimizing the data transmission delay caused by the data transmission.

1 is an exemplary diagram showing a communication environment to which the present invention is applied.
2 is a configuration diagram illustrating a configuration of a terminal device according to a preferred embodiment of the present invention.
3 is a flowchart illustrating an operational flow of a terminal device according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

First, FIG. 1 shows a communication environment to which the present invention is applied.

As shown in FIG. 1, in the present invention, in addition to cellular communication (hereinafter, referred to as cellular communication) in which terminals 10 and 20 transmit data on the basis of a mobile communication network through a base station, (Hereinafter referred to as " D2D communication ") in which data is transmitted based on communication.

The terminals 10 and 20 are connected to a cellular transmission path based on a cellular communication (hereinafter referred to as a cellular link) b and a D2D transmission path based on a D2D communication (hereinafter referred to as a D2D communication link D2D link )) (A) can be selected and used.

For example, the terminal 10 and the terminal 20 can select and use the cellular communication link b to transmit the mutual data, wherein the operation mode of the terminal 10, 20 can be referred to as a cellular mode.

The terminal 10 and the terminal 20 can select and use the D2D communication link a to transmit the mutual data. The operation mode of the terminals 10 and 20 may be referred to as a D2D mode.

Recently, WLAN Direct (for example, WiFi Direct) is being used for D2D communication.

When the WiFi Direct is used for D2D communication, the D2D communication link may experience a path failure due to the mobility of the user (terminal) because the transmission coverage of the D2D communication environment is small unlike the cellular communication environment . If the D2D communication link disconnection occurs, a temporary interruption of data transmission results in a data transmission delay. That is, the D2D communication link is less reliable than the cellular communication link.

Therefore, in the D2D mode for transmitting data using the D2D communication link, it is very important from the reliability point of view to quickly determine whether or not the D2D communication link is disconnected.

Meanwhile, a method of determining whether or not a communication failure occurs in a currently used transport layer is a method of determining based on a plurality of timeout events.

Such an existing method may be suitable for an environment in which communication link is hardly disconnected, such as a cellular communication environment, because it takes a long time to determine whether or not the communication link is disconnected. However, in the D2D communication environment, It is not suitable for an environment where frequent breaks occur.

Accordingly, in the present invention, the data transmission delay due to the D2D communication link disconnection is minimized by quickly determining whether or not the D2D communication link is disconnected in a manner suitable for the D2D communication environment.

More specifically, the present invention proposes a terminal device for realizing a method of the present invention for quickly determining whether or not a D2D communication link is disconnected in a manner suitable for a D2D communication environment.

Hereinafter, a configuration of a terminal device according to a preferred embodiment of the present invention will be described in detail with reference to FIG.

Prior to a specific description with reference to FIG. 2, it is assumed that the terminal device 100 according to the present invention supports cellular communication and D2D communication.

At this time, the terminal device 100 assumes that the interface used for the D2D communication is different from the cellular communication. For example, it can be assumed that WLAN Direct (e.g., WiFi Direct) is used for D2D communication.

Accordingly, the terminal apparatus 100 can selectively use a cellular communication-based cellular communication link and a D2D communication-based D2D communication link.

The terminal device 100 according to the present invention includes a first communication unit 160 for D2D communication and a second communication unit 170 for cellular communication and includes an input unit 180 for user input, An output unit 190 for outputting various outputs (e.g., images, sounds, etc.) according to D2D communication so that the user can identify the devices, and a control unit 150 for controlling all operations of the terminal device 100. [

Accordingly, the communication using the D2D communication, that is, the D2D communication link is performed through the first communication unit 160, and the communication using the cellular communication, that is, the cellular communication link is performed through the second communication unit 170 And that the D2D communication and the cellular communication are performed under the control of the control unit 150. [

The method of the present invention for quickly determining whether or not the D2D communication link is disconnected in a manner suitable for the D2D communication environment can be realized by the control unit 150 of the terminal device 100. [

2, the terminal device 100 of the present invention, in particular, the control unit 150, transmits an ACK to the data packet transmitted by the receiving end using the first communication link for direct communication between the terminals, A confirmation packet transmission unit 120 for transmitting a confirmation packet to the receiver using a second communication link different from the first communication link when the acknowledgment is not received, And a determination unit (130) for determining whether or not the first communication link is disconnected based on information confirmed from the confirmation fork when an acknowledgment for the confirmation packet is received from the reception terminal.

The confirmation unit 110 confirms whether or not an acknowledgment (ACK) is not received for the data packet transmitted by the receiving end using the first communication link for direct communication between terminals, that is, the D2D communication link.

When operating in the D2D mode, the terminal device 100 of the present invention transmits data (packets) at the receiving end using the D2D communication link.

At this time, the terminal device 100 may be the terminal 10 shown in FIG. 1 or the terminal 20 as a side terminal for transmitting data.

Hereinafter, for convenience of description, the terminal device 100 of the present invention corresponds to the terminal 10 of FIG. 1, referring to the time when the terminal 10 transmits data and the terminal 20 receives data , It is assumed that the terminal 20 of FIG. 1 is a receiving terminal.

That is, when operating in the D2D mode, the terminal device 100 of the present invention transmits data (packets) to the receiving terminal 20 using the D2D communication link (a).

At this time, the confirming unit 110 confirms whether or not the data packets transmitted to the receiving terminal 20 using the D2D communication link (a) are not received.

More specifically, the confirming unit 110 waits for receiving ack for a predetermined time (T) from the transmission time point for a data packet transmitted to the receiving terminal 20 by using the D2D communication link (a).

At this time, the predetermined time T may be greater than the RTT (Round Trip Time) of the D2D communication and smaller than the RTO (Retransmission Timeout) of the D2D communication.

The acknowledgment unit 110 can confirm that there is a data packet in which a certain period of time T has elapsed as a result of waiting for reception of an acknowledge for a predetermined time T from the transmission time point, .

On the other hand, it is preferable that the terminal apparatus 100 and the reception terminal 20 maintain the cellular communication link (b) even while operating in the D2D mode using the D2D communication link as described above.

The acknowledgment packet transmission unit 120 transmits the acknowledgment packet to the acknowledgment receiving unit 120 using a second communication link, for example, a cellular communication link b, different from the first communication link, that is, the D2D communication link a, And transmits a confirmation packet to the terminal 20.

That is, when the acknowledgment is not received from the acknowledgment unit 110, the acknowledgment packet transmission unit 120 uses the second communication link, i.e., the cellular communication link (b), which is held uninterrupted even while operating in the D2D mode , And can transmit the confirmation packet to the receiving terminal 20.

At this time, the verification packet (V_Packet) includes information on the transmission time of the first communication link, that is, the link identifier for the D2D communication link (a) and the confirmation packet (V_Packet).

Upon receiving the confirmation packet (V_Packet) through the cellular communication link (b), the reception terminal (20) confirms the confirmation packet (V_Packet) for the confirmation packet (V_Packet) based on the information contained in the confirmation packet Verification Ack (hereinafter referred to as V_Ack) to the terminal device 100 (reply).

At this time, the confirmation etch (V_Ack) includes the sequence number of the reception waiting data packet waiting for the next reception in accordance with the sequence number of the data packet received by the reception terminal 20 via the first communication link, that is, the D2D communication link , Information on the reception amount of the data packet received by the receiving terminal 20 among the data packets transmitted through the D2D communication link (a) before the transmission time of the confirmation packet (V_Packet) is included.

More specifically, the receiving terminal 20, which has received the confirmation packet V_Packet via the cellular communication link b, generates a confirmation address V_Ack based on the link identifier confirmed from the confirmation packet V_Packet ) To identify the D2D communication link (a) to be acknowledged.

Accordingly, the receiving terminal 20 recognizes the sequence number of the waiting data packet waiting for the next reception in accordance with the sequence number of the data packet received from the terminal device 100 via the identified D2D communication link (a).

Based on the transmission time of the confirmation packet (V_Packet) confirmed from the confirmation packet (V_Packet), the reception terminal 20 transmits the confirmation packet (V_Packet) to the terminal device 100 via the D2D communication link And recognizes the reception amount of the data packet received by the receiving terminal 20 among the transmitted data packets.

That is, since the transmission time of the corresponding data packet is recorded in the data packet transmitted from the terminal device 100, the reception terminal 20 transmits the data packet received from the terminal device 100 via the D2D communication link (a) (V_Packet) before the transmission time of the confirmation packet (V_Packet).

Thereafter, the receiving terminal 20 transmits an acknowledgment (V_Ack) including information on the sequence number of the reception waiting data packet recognized as described above and the reception amount of the data packet to the terminal And returns it to the device 100.

The determination unit 130 determines whether or not the D2D communication link a is received based on the information confirmed from the confirmation use V_Ack when the confirmation use V_Ack for the confirmation packet V_Packet is received from the reception terminal 20, Or not.

That is, the determination unit 130 confirms the D2D reception state related information of the reception terminal 20, that is, the sequence number of the reception waiting data packet and the reception amount of the data packet, from the confirmation fork (V_Ack) It can be determined whether or not the communication link (a) is disconnected.

The determination process of the determination unit 130 will be described in more detail as follows.

The determination unit 130 determines whether or not a data packet having a sequence number of a reception waiting data packet exists in a data packet transmitted to the reception terminal 20 using the first communication link, that is, the D2D communication link (a) If at least one of the second conditions in which the reception amount of the data packet is smaller than or equal to a predetermined value (for example, X%) than the transmission amount of the data packet transmitted to the reception terminal 20 using the D2D communication link (a) (a).

That is, the determination unit 130 determines whether or not the data packet having the sequence number of the reception waiting data packet identified from the confirmation fork (V_Ack) in the data packet transmitted to the reception terminal 20 using the D2D communication link If the first condition exists, it can be determined that the D2D communication link (a) is disconnected.

Alternatively, the determination unit 130 determines whether the reception amount of the data packet confirmed from the confirmation fork (V_Ack) is greater than the transmission amount of the data packet transmitted to the reception terminal 20 using the D2D communication link (a) X%) is satisfied, it can be determined that the D2D communication link (a) is disconnected. Here, a constant (e.g., X%) can be changed and set to an arbitrary value.

Of course, the determination unit 130 may determine the disconnection of the D2D communication link (a) only if all of the first condition and the second condition described above are satisfied or both of the first condition and the second condition described above are satisfied .

On the other hand, the above-mentioned first condition and second condition are conditions resulting from the D2D reception state related information of the reception terminal 20 confirmed by the confirmation use (V_Ack) received from the reception terminal 20.

Furthermore, the determination unit 130 determines whether or not at least one of the first condition and the second condition due to the confirmation fork (V_Ack) received from the reception terminal 20 is satisfied, It is possible to determine whether or not the D2D communication link (a) is disconnected by further considering the following third condition and fourth condition resulting from the state related information.

For example, when at least one of the first condition and the second condition is satisfied and the transmission window of the first communication link, that is, the D2D communication link (a) is in a full state At least one of the fourth conditions in which the acknowledgment is not received for the data packet transmitted to the receiving terminal 20 by using the D2D communication link (a) after transmitting the third condition, the confirmation packet (V_Packet) , It may be determined that the D2D communication link (a) is disconnected.

That is, when the at least one of the first condition and the second condition is satisfied and the transmission window of the first communication link, that is, the D2D communication link (a) is in a full state 3 condition is satisfied, it can be determined that the D2D communication link (a) is disconnected.

In addition, when at least one of the first condition and the second condition described above is satisfied and the determination unit 130 transmits the confirmation packet (V_Packet) to the receiving terminal 20 using the D2D communication link (a) If the fourth condition that the acknowledgment is not received for the transmitted data packet is satisfied, it can be determined that the D2D communication link (a) is disconnected.

Of course, when at least one of the first condition and the second condition described above is satisfied and all of the third condition and the fourth condition described above are satisfied or the third condition and the fourth condition described above are all satisfied It may be determined that the D2D communication link (a) is disconnected.

Here, when determining whether or not the D2D communication link (a) is disconnected, the greater the number of satisfied conditions among the above-described four conditions, namely, the first condition, the second condition, the third condition, and the fourth condition, Will increase.

As described above, according to the present invention, unlike the conventional method of determining whether or not the communication link is disconnected based on a plurality of timeout events, even if only one unacknowledgment is received for a data packet during operation in the D2D mode, (V_Ack) / confirmation (V_Ack) for confirmation packet (V_Packet) / confirmation via another communication link (cellular communication link) and suspends D2D communication It is possible to quickly determine whether or not the link is disconnected.

As described above, according to the present invention, it is possible to quickly determine whether or not the D2D communication link is disconnected in a manner suitable for the D2D communication environment.

The terminal device 100 according to the present invention may further include a packet transmission control unit 440 as shown in FIG.

When it is determined that the first communication link, that is, the D2D communication link (a) is disconnected, the packet transmission control unit 440 transmits the data packet having the sequence number of the reception waiting data packet and the subsequent data packet to the second communication link, And transmits it to the receiving terminal 20 using the link b.

That is, when it is determined that the D2D communication link (a) is disconnected, the packet transmission control unit 440 removes the outstanding data packet from which the Ack is not received in the transmission window of the D2D communication link (a) Transmits the data packet having the sequence number of the reception waiting data packet confirmed from the acknowledge (V_Ack) and the subsequent data packet to the receiving terminal 20 using the cellular communication link (b).

On the other hand, when it is not determined that the D2D communication link (a) is disconnected, the packet transmission control unit 440 transmits a data packet in which the acknowledgment has not been acknowledged in the confirmation unit 110, (20).

That is, if it is not determined that the D2D communication link (a) is disconnected, there is a possibility that the data packet has been lost due to reasons other than the disconnection of the D2D communication link (a). Therefore, The data packet in which the acknowledgment has not been acknowledged is transmitted to the receiving terminal 20 using the D2D communication link (a).

As described above, according to the terminal device of the present invention, it is possible to quickly determine whether or not the D2D communication link is disconnected in a manner suitable for the D2D communication environment while operating in the D2D mode, Thereby minimizing the data transmission delay caused by the data transmission.

Hereinafter, a method of operating a terminal according to a preferred embodiment of the present invention will be described in detail with reference to FIG. Hereinafter, for convenience of description, reference will be made to the reference numerals mentioned in FIGS. 1 to 2 described above.

The terminal device 100 of the present invention may be the terminal 10 or the terminal 20 shown in Fig. 1 as a side terminal for transmitting data.

Hereinafter, for convenience of description, the terminal device 100 of the present invention corresponds to the terminal 10 of FIG. 1, referring to the time when the terminal 10 transmits data and the terminal 20 receives data , It is assumed that the terminal 20 of FIG. 1 is a receiving terminal.

That is, when operating in the D2D mode, the operation method of the terminal device 100 according to the present invention transmits data (packet) to the receiving terminal 20 using the D2D communication link (a) (S100).

At this time, the operation method of the terminal device 100 according to the present invention checks whether data packets transmitted to the receiving terminal 20 using the D2D communication link (a) are not received or not (S110).

More specifically, an operation method of the terminal device 100 according to the present invention is a method of operating the terminal device 100 using a D2D communication link (a), for a data packet transmitted to the receiving terminal 20, Wait for Eck reception.

The operation method of the terminal device 100 according to the present invention is such that if there is a data packet for which a certain period of time T has elapsed as a result of waiting for reception of an attack for a predetermined time T from the transmission time point, It can be confirmed by the non-EIC non-receipt.

The operation method of the terminal device 100 according to the present invention is such that if the absence of the acknowledgment is confirmed in step S110 (Yes in S110), the second communication link, for example, the cellular communication link b ) To the receiving terminal 20 (S120).

That is, the operation method of the terminal device 100 according to the present invention is such that, if the ACK is not received in step S110 (Yes in S110), the second communication link, that is, the cellular communication link b to send the confirmation packet to the receiving terminal 20.

At this time, the verification packet (V_Packet) includes information on the transmission time of the link identifier and the confirmation packet (V_Packet) for the D2D communication link (a).

The receiving terminal 20 having received the confirmation packet (V_Packet) through the cellular communication link (b) then returns the confirmation fork (V_Ack) on the basis of the link identifier confirmed from the confirmation packet (V_Packet) Can identify the D2D communication link (a) to be identified for.

Accordingly, the receiving terminal 20 recognizes the sequence number of the waiting data packet waiting for the next reception in accordance with the sequence number of the data packet received from the terminal device 100 via the identified D2D communication link (a).

Based on the transmission time of the confirmation packet (V_Packet) confirmed from the confirmation packet (V_Packet), the reception terminal 20 transmits the confirmation packet (V_Packet) to the terminal device 100 via the D2D communication link And recognizes the reception amount of the data packet received by the receiving terminal 20 among the transmitted data packets.

That is, since the transmission time of the corresponding data packet is recorded in the data packet transmitted from the terminal device 100, the reception terminal 20 transmits the data packet received from the terminal device 100 via the D2D communication link (a) (V_Packet) before the transmission time of the confirmation packet (V_Packet).

Thereafter, the receiving terminal 20 transmits an acknowledgment (V_Ack) including information on the sequence number of the reception waiting data packet recognized as described above and the reception amount of the data packet to the terminal And returns it to the device 100.

Accordingly, the operation method of the terminal device 100 according to the present invention receives from the receiving terminal 20 an acknowledgment (V_Ack) for the confirmation packet (V_Packet) transmitted in step S120 (S130).

The operation method of the terminal device 100 according to the present invention is a method of operating the terminal device 100 according to the present invention when receiving an acknowledgment V_Ack from the receiving terminal 20, It is judged whether or not it is disconnected.

More specifically, the operation method of the terminal device 100 according to the present invention is a method of operating the terminal device 100 according to the D2D reception state related information of the receiving terminal 20, that is, the sequence number of the reception waiting data packet, (S140), and it is determined whether or not the D2D communication link (a) is disconnected based on the received amount (S150).

The process of determining whether or not the D2D communication link (a) is disconnected will be described in more detail as follows.

A method of operating a terminal device 100 according to the present invention is a method of operating a terminal device 100 in which a data packet having a sequence number of a waiting data packet exists in a data packet transmitted to a receiving terminal 20 using the D2D communication link (a) If at least one of the second conditions in which the reception amount of the data packet is smaller than or equal to a predetermined value (for example, X%) than the transmission amount of the data packet transmitted to the reception terminal 20 using the D2D communication link (a) It can be determined that the communication link (a) is disconnected.

That is, the operation method of the terminal device 100 according to the present invention is a method of operating the terminal device 100 according to an embodiment of the present invention. If the first condition that a data packet having a sequence number exists is satisfied, it can be determined that the D2D communication link (a) is disconnected.

Alternatively, the operation method of the terminal device 100 according to the present invention is a method of operating the terminal device 100 using the D2D communication link (a) and the data packet transmitted from the receiving terminal 20 If the second condition that the reception amount is smaller than a predetermined value (e.g., X%) is satisfied, it can be determined that the D2D communication link (a) is disconnected. Here, a constant (e.g., X%) can be changed and set to an arbitrary value.

Of course, the operation method of the terminal device 100 according to the present invention is not limited to the D2D communication link (a) unless both of the first condition and the second condition described above are satisfied or both the first condition and the second condition described above are satisfied. It can be judged as a disconnection.

On the other hand, the above-mentioned first condition and second condition are conditions resulting from the D2D reception state related information of the reception terminal 20 confirmed by the confirmation use (V_Ack) received from the reception terminal 20.

The method of operation of the terminal device 100 according to the present invention further includes the step of determining whether or not at least one of the first condition and the second condition due to the confirmation fork (V_Ack) received from the receiving terminal 20 is satisfied, It is possible to determine whether or not the D2D communication link (a) is disconnected by further considering the following third condition and fourth condition resulting from the D2D transmission state related information of the apparatus 100. [

For example, the operating method of the terminal device 100 according to the present invention is such that at least one of the first condition and the second condition described above is satisfied and the transmission window of the first communication link, that is, the D2D communication link (a) The fourth condition in which the acknowledgment is not received to the data packet transmitted to the receiving terminal 20 by using the D2D communication link (a) after transmitting the checking packet (V_Packet) If at least one of the conditions is satisfied, it may be determined that the D2D communication link (a) is disconnected.

That is, at least one of the first condition and the second condition described above is satisfied, and the transmission window of the first communication link, that is, the D2D communication link (a) If the third condition of the full state is satisfied, it can be determined that the D2D communication link (a) is disconnected.

The operation method of the terminal device 100 according to the present invention is characterized in that at least one of the first condition and the second condition described above is satisfied and the D2D communication link (a) is used after transmitting the confirmation packet (V_Packet) (A) is satisfied if the fourth condition in which the data packet transmitted to the receiving terminal 20 is not acknowledged is confirmed.

Of course, the operation method of the terminal device 100 according to the present invention is a method of operating the terminal device 100, when at least one of the first condition and the second condition described above is satisfied and all of the third condition and the fourth condition described above are satisfied, It may be determined that the D2D communication link (a) is disconnected only if both the condition and the fourth condition are satisfied.

The operation method of the terminal device 100 according to the present invention is a method in which when it is determined that the D2D communication link (a) is disconnected according to the result of the determination in step S150 (Yes in S160) And then transmits the data packet to the receiving terminal 20 using the cellular communication link (b) (S170).

That is, when it is determined that the D2D communication link (a) is disconnected, the operation method of the terminal device 100 according to the present invention is such that, in the transmission window of the D2D communication link (a) And transmits the data packet having the sequence number of the reception waiting data packet confirmed from the confirmation fork (V_Ack) and the subsequent data packet to the reception terminal 20 using the cellular communication link (b).

In the operation method of the terminal device 100 according to the present invention, if it is determined that the D2D communication link a is not disconnected according to the result of the determination in step S150 (No in step S160) And transmits the data packet to the receiving terminal 20 using the D2D communication link (a) (S180).

That is, if it is not determined that the D2D communication link (a) is disconnected, there is a possibility that the data packet has been lost due to reasons other than the disconnection of the D2D communication link (a). Therefore, in accordance with the result determined in step S150, To the receiving terminal 20 by using the D2D communication link (a).

As described above, according to the operation method of the terminal device according to the present invention, it is possible to quickly determine whether or not the D2D communication link is disconnected in a manner suitable for the D2D communication environment while operating in the D2D mode, It is possible to minimize the data transmission delay due to the link disconnection.

A method of operating a terminal device according to an embodiment of the present invention may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable recording medium. The computer-readable recording medium may include a program command, a data file, a data structure, and the like, alone or in combination. The program instructions recorded on the recording medium may be those specially designed and constructed for the present invention or may be those known and used by those skilled in the computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

According to the operation method of the terminal device and the terminal device according to the present invention, it is possible to quickly determine whether or not the D2D communication link is disconnected while operating in the D2D mode, thereby minimizing the data transmission delay due to the D2D communication link disconnection. It is an invention that is industrially applicable because it is beyond the limit of the existing technology, and it is not only the use of the related technology, but also the possibility of commercialization or operation of the applied device is sufficient and practically possible.

100: terminal device
110: confirmation unit 120: confirmation packet transmission unit
130: Determination unit 140: Packet transmission control unit

Claims (11)

An acknowledgment unit for confirming whether an acknowledgment (ACK) is not received or not for a data packet transmitted at a receiving end using a first communication link for direct communication between terminals;
A confirming packet transmitting unit for transmitting a confirming packet to the receiving terminal by using a second communication link different from the first communication link when the acknowledgment is not received; And
And a determination unit that determines whether or not the first communication link is disconnected based on information confirmed from the confirmation acknowledgment when the acknowledgment for the confirmation packet is received from the reception terminal. The method according to claim 1,
In the checking stick,
A sequence number of a reception waiting data packet waiting for a next reception according to a sequence number of a data packet received by the receiving terminal over the first communication link, And information on a reception amount of a data packet received by the receiving terminal among the transmitted data packets. The method according to claim 1,
The confirmation packet includes:
A link identifier for the first communication link, and a transmission time for transmitting the confirmation packet. 3. The method of claim 2,
Wherein,
A first condition in which a data packet having a sequence number of the reception waiting data packet exists in a data packet transmitted to the receiving terminal using the first communication link, The second communication link determining unit determines that the first communication link is disconnected if at least one of the second condition that the reception amount of the data packet is smaller than the transmission amount of the first communication link is equal to or greater than a predetermined value is satisfied. 5. The method of claim 4,
Wherein,
Wherein at least one of the first condition and the second condition is satisfied,
A third condition that a transmission window of the first communication link is in a full state; a third condition in which a transmission window of the first communication link is full; a data packet transmitted to the receiving end using the first communication link after transmitting the acknowledgment packet, And determines that the first communication link is disconnected if at least one of the fourth conditions to be confirmed is satisfied. The method according to claim 1,
Wherein the second communication link comprises:
Wherein the terminal is a communication link for cellular communication. 3. The method of claim 2,
Transmitting a data packet having a sequence number of the reception waiting data packet and a subsequent data packet to the receiving terminal using the second communication link when it is determined that the first communication link is disconnected,
Further comprising a packet transmission control unit for retransmitting the data packet in which the acknowledgment of the acknowledgment has been confirmed to the receiving terminal by using the first communication link when it is not determined that the first communication link is disconnected. A confirming step of confirming whether or not an eck has been received for a data packet transmitted by a receiving end using a first communication link for direct communication between terminals;
A confirming packet transmitting step of transmitting a confirming packet to the receiving terminal using a second communication link different from the first communication link when the ek not received is confirmed; And
And a determination step of determining whether or not the first communication link is disconnected based on information confirmed from the confirmation acknowledgment when an acknowledgment for the confirmation packet is received from the reception terminal Lt; / RTI > 9. The method of claim 8,
In the checking stick,
A sequence number of a reception waiting data packet waiting for a next reception according to a sequence number of a data packet received by the receiving terminal over the first communication link, And information on a reception amount of a data packet received by the receiving terminal among the transmitted data packets. 10. The method of claim 9,
Wherein,
A first condition in which a data packet having a sequence number of the reception waiting data packet exists in a data packet transmitted to the receiving terminal using the first communication link, The second communication link is determined to be disconnected when at least one of a second condition in which the reception amount of the data packet is smaller than a transmission amount of the first communication link is equal to or greater than a predetermined value is satisfied. 11. The method of claim 10,
Wherein,
Wherein at least one of the first condition and the second condition is satisfied,
A third condition that a transmission window of the first communication link is in a full state and a third condition that a window of the first communication link is full, Is determined to be a disconnection of the first communication link when at least one of the fourth conditions to be confirmed is satisfied.
KR1020150089228A 2015-06-23 2015-06-23 Terminal device and control method thereof KR102000108B1 (en)

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