KR20200102029A - Collaborative request repeat method in communication for internet of things and apparatus thereof - Google Patents

Abstract

According to the present invention, disclosed are a cooperative retransmission method in Internet of things (IoT) communications and an apparatus thereof. According to the present invention, the cooperative retransmission method in IoT communications comprises the steps of: transmitting a feedback signal to a relay node and a source node when a gateway fails to receive a packet transmitted from the source node; retransmitting the packet to the gateway during a temporary period after the relay node receives the feedback signal; detecting an operation state of the relay node during a temporary period after the source node receives the feedback signal; and retransmitting the packet to the gateway after a temporary period according to the detection result after the source node detects the operation state of the relay node. According to the invention, not only can the packet transmission efficiency be increased, but also the consumption of the battery can be reduced.

Description

Cooperative retransmission method and device for internet of things communication {COLLABORATIVE REQUEST REPEAT METHOD IN COMMUNICATION FOR INTERNET OF THINGS AND APPARATUS THEREOF}

The present invention relates to a cooperative retransmission method and apparatus therefor in IoT communication, and more particularly, in IoT communication to increase packet transmission efficiency when retransmitting packets when data is transmitted through cooperative communication in IoT communication. It relates to a cooperative retransmission method and apparatus thereof.

In general, the Internet is evolving from a human-centered connection network in which humans create and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with cloud servers, is also emerging.

In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied.

In the IoT environment, intelligent IT (Internet Technology) services that create new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is the field of smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart home appliance, advanced medical service, etc. through the convergence and combination of existing IT (information technology) technology and various industries. Can be applied to.

The background technology of the present invention is disclosed in Korean Patent Application Publication No. 2018-0105555 (published on September 28, 2018, method for setting downlink control information for cooperative network communication).

When data is transmitted from the terminal to the gateway (destination) in the above IoT communication, if the decoding fails, a retransmission request (ARQ, Autonomous Repeat request) is made to the terminal. At this time, the terminal that has requested retransmission may retransmit the information transmitted before that, or may deliver additional information capable of lowering the packet error rate in the next transmission by combining the information transmitted before that.

Here, cooperative communication is a method in which a repeater assists signal transmission to communicate a signal transmitted from one terminal, and when there is a retransmission request to one terminal (source node) in the IoT environment, another terminal (hereinafter, relay Node) can act as a repeater.

For example, when the source node sends a signal to the gateway, the relay node and the source node cooperate to communicate. If the gateway fails to receive a packet, the gateway requests a packet retransmission to the source node or relay node, NACK (Negative; Negative). Acknowledge) signal. Thereafter, the source node or the relay node receiving the packet retransmission request in the next time slot transmits the same information or additional information back to the gateway.

Here, as a method to reduce the error rate of packet transmission, a forward error correction method in which an error occurring in the transmission process is detected and corrected at the receiving end by adding redundant bits to the information of the source node (hereinafter referred to as FEC method) There is this.

In addition, there is a Hybrid Autonomous Repeat Request (HARQ) method that combines the error detection feature of the FEC method and the advantage of securing accuracy through retransmission request of the ARQ method.

When applying this HARQ cooperative communication method, the method of transmitting a feedback (NACK) signal is largely a method of sending a packet to a source node that has transmitted a packet, a method of sending it to a relay node, and a method of broadcasting to the source node and the relay node. It can be broadly divided by way of sending.

Each of the three methods of transmitting a feedback (NACK) signal has different problems.

First, if NACK is transmitted to the source node as in the first method, the diversity effect using the relay node cannot be obtained. If NACK is transmitted to the relay node as in the second method, the relay node transmits the packet of the transmitting node (gateway). If the reception is not successful, the source node does not recognize the retransmission request, and a delay may occur if the standby state continues.

In addition, in the case of transmitting NACK by broadcasting as in the third method, if the source node and the relay node receive the NACK and the relay node succeeds in decoding, the gateway must allocate resources and retransmit it. Overhead) occurs, and if the retransmission is immediately retransmitted without the resource allocation of the gateway, it is transmitted to the same gateway at the same time, so there is a problem that collision between carriers may occur.

On the other hand, if the relay node succeeds in decoding in the second and third methods as above, only the additional information of the source node is transmitted to the gateway, and other resources (time and frequency band) are allocated and transmitted to send the information of the relay node. There is a problem that is not efficient in resource allocation. In other words, considering the situation in which the source node and the relay node each need to transmit the collected information in the sensor network environment, it is a resource to transmit only the additional information of the source node without transmitting the information of the relay node in the retransmission request to the source node. Time and frequency band) can be viewed as a loss from the point of view of allocation.

The present invention was conceived to improve the above problems, and an object of the present invention according to an aspect of the present invention is, when transmitting data through cooperative communication in IoT communication, when retransmitting a packet, a retransmission packet at a relay node and a It is to provide a cooperative retransmission method and apparatus therefor in Internet of Things communication, which enables the transmission of the information of the relay node together and the source node to transmit the retransmission packet if the retransmission is not made in a tentative period, thereby increasing the packet transmission efficiency.

Cooperative retransmission method in Internet of Things communication according to an aspect of the present invention includes: transmitting a feedback signal to a relay node and a source node when a gateway fails to receive a packet transmitted from a source node; Retransmitting the packet to the gateway during a temporary period after the relay node receives the feedback signal; Sensing an operating state of the relay node during a temporary period after the source node receives the feedback signal; And retransmitting the packet to the gateway after a provisional period according to the detection result after the source node senses the operation state of the relay node.

In the present invention, the step of transmitting the feedback signal to the relay node and the source node is characterized in that the gateway transmits the feedback signal in a broadcasting manner.

In the present invention, the step of retransmitting the packet by the relay node to the gateway is characterized in that the relay node combines the retransmission packet with additional information of the relay node in a chain form and transmits it.

In the present invention, the step of retransmitting the packet by the relay node to the gateway is characterized in that the relay node retransmits the packet when the packet is successfully decoded by receiving the packet transmitted from the source node.

In the present invention, the sensor node and the relay node are characterized in that they operate with the same operation period within the same group.

In the present invention, the step of retransmitting the packet by the relay node to the gateway is characterized in that the relay node transmits the payload portion of the source node using header information of the retransmission packet.

In the IoT communication according to another aspect of the present invention, the cooperative retransmission device transmits a packet to a relay node and a gateway, and when a feedback signal is received from the gateway, detects the operation state of the relay node during a provisional period, and then according to the detection result. A source node for retransmission to the gateway; A relay node that decodes the packet transmitted from the source node and transmits it to the gateway, and retransmits the packet transmitted from the source node to the gateway during a temporary period when a feedback signal is received from the gateway; And a gateway for requesting retransmission by transmitting a feedback signal to the source node and the relay node when the packet is received from the source node and fails.

In the present invention, the gateway is characterized in that it transmits the feedback signal to the relay node and the source node in a broadcasting method.

In the present invention, the relay node is characterized in that when retransmitting the packet to the gateway, the additional information of the relay node is combined with the retransmission packet in a chain form and transmitted.

In the present invention, the relay node is characterized by retransmitting the packet when it receives the packet transmitted from the source node and successfully decodes it.

In the present invention, the relay node transmits the payload portion of the source node using header information of the retransmission packet when retransmitting the packet to the gateway.

In the present invention, the source node, the relay node, and the gateway are characterized in that they operate with the same operation period within the same group.

In the cooperative retransmission method and apparatus therefor in IoT communication according to an aspect of the present invention, when data is transmitted from IoT communication to cooperative communication, when retransmitting a packet, the relay node transmits information of the relay node together with the retransmission packet at a provisional period. By allowing the source node to transmit the retransmission packet if the retransmission is not performed in a tentative period, the packet transmission efficiency can be increased, and the operation cycle within the group is made equal by forming a group between the source node and the relay node. Can reduce the consumption of.

1 is a block diagram showing a cooperative retransmission apparatus in IoT communication according to an embodiment of the present invention.
2 is an exemplary diagram illustrating an operation cycle for each group of a cooperative retransmission device in IoT communication according to an embodiment of the present invention.
3 is a flowchart illustrating a cooperative retransmission method in IoT communication according to an embodiment of the present invention.
4 is an exemplary diagram showing a retransmission packet through a cooperative retransmission method in IoT communication according to an embodiment of the present invention.

Hereinafter, a method and apparatus for cooperative retransmission in Internet of Things communication according to the present invention will be described with reference to the accompanying drawings. In this process, the thickness of the lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention and may vary according to the intention or custom of users or operators. Therefore, definitions of these terms should be made based on the contents throughout the present specification.

1 is a block diagram showing a cooperative retransmission device in IoT communication according to an embodiment of the present invention, and FIG. 2 is a diagram illustrating an operation cycle for each group of a cooperative retransmission device in IoT communication according to an embodiment of the present invention It is an exemplary diagram for.

As shown in FIG. 1, the cooperative retransmission apparatus in IoT communication may include a source node 10, a relay node 20, and a gateway 30.

The source node 10 transmits the packet to the relay node 20 and the gateway 30, and when a feedback (NACK) signal is received from the gateway 30, it detects the operation state of the relay node 20 during a provisional period. Then, it may be retransmitted to the gateway 30 according to the detection result.

The relay node 20 decodes the packet transmitted from the source node 10 and transmits it to the gateway 30. When a feedback signal is received from the gateway 30, the relay node 20 transmits the packet transmitted from the source node 10 during a provisional period. It can be retransmitted to the gateway 30.

Here, the relay node 20 may retransmit the packet if the packet transmitted from the source node 10 is received and decoding is successful, and when the packet is retransmitted to the gateway 30, the relay node 20 is added to the retransmitted packet. Information can be combined and transmitted in a chain.

That is, the relay node 20 may transmit only the payload portion of the source node 10 by using the header information of the retransmission packet when retransmitting the packet to the gateway 30.

If the gateway 30 receives a packet from the source node 20 and fails, the gateway 30 transmits a feedback signal to the source node 10 and the relay node 20 in a broadcasting manner to request retransmission.

On the other hand, the source node 10, the relay node 20, and the gateway 30 are distributed in a similar area, have similar types, or are grouped in a random way to make the operation cycles of the sensor nodes in the group the same or similar. , It can reduce battery consumption.

For example, as shown in FIG. 2, when a group is formed through two sensor nodes as in group A, operation starts at the same time, and when one sensor node operates as the source node 10, the remaining sensor nodes May transmit a packet to the gateway 30 through cooperative retransmission while operating as the relay node 20 or vice versa.

As described above, according to the cooperative retransmission apparatus in IoT communication according to an embodiment of the present invention, not only can obtain a diversity effect through cooperative communication between nodes in IoT communication, but also receive reliability of packets through cooperative retransmission method. In this process, by forming a group between sensor nodes and making the operation periods similar, it is possible to obtain an effect of increasing the reception performance at the gateway without increasing battery consumption.

In addition, the relay node can connect and transmit the retransmission packet of the source node and its own packet information at the same time to increase the transmission efficiency. When the relay node retransmits the packet, the packet of the source node can be transmitted as it is, but only the payload section is extracted. Accordingly, transmission efficiency may be improved by transmitting only the payload portion together with the header information of the relay node.

3 is a flowchart illustrating a cooperative retransmission method in IoT communication according to an embodiment of the present invention, and Fig. 4 is an example showing a retransmission packet through cooperative retransmission method in IoT communication according to an embodiment of the present invention Is also.

As shown in FIG. 3, in the cooperative retransmission method in IoT communication according to an embodiment of the present invention, first, the source node 10 transmits a packet to the relay node 20 and the gateway 30 (S10).

In the present embodiment, a case of transmitting a packet using a convolutional code and a QPSK (Qaudrature Phase Shift Keying) modulation method will be described as an example. It is also applicable to the case of applying other modulation and decoding methods.

Assuming that nodes have a random distribution, a group may be formed to transmit information sensed by nodes having the same period or pattern. For example, as shown in FIG. 2, two nodes may be included in one group. At this time, one of the two nodes may be configured as a source node 10 and the other may be configured as a relay node 20.

In this case, the source node 10 and the relay node 20 operate with the same operation period within the same group, thereby reducing battery consumption.

를 사용할 수 있다. 부호비트의 천공비율은 2/3로 한다. 이때, 천공이란, 부호율을 높이기 위해 일부 비트를 제외하고 전송하는 방법을 말한다. 예컨대, k 비트의 메시지 정보를 수학식 1과 같다고 할 때, 위의 2/3의 부호율을 갖는 부호화 비트는 수학식 2와 같이 나타낼 수 있다. Here, the polynomial of the convolutional sign is

You can use The puncturing ratio of the code bit is 2/3. At this time, puncturing refers to a method of excluding some bits to increase the code rate. For example, when k-bit message information is assumed to be the same as in Equation 1, the coded bit having a code rate of 2/3 above can be expressed as in Equation 2.

After receiving the packet transmitted in step S10, the relay node 20 and the gateway 30 demodulate the received packet and then perform Viterbi decoding (S20).

Here, Viterbi decoding refers to a process of calculating a path metric using branch metrics excluding puncturing bits, and selecting an optimal survival path through an Add, Compare and Select (ACS) process. After the decoding process, the error is verified using a Cyclic Redundancy Check (CRC).

If the gateway 30 fails to decrypt in S20. A feedback (NACK; Negative Acknowledge) signal is transmitted to the source node 10 and the relay node 20 (S30).

Here, the gateway 30 transmits the feedback signal to the relay node 20 and the source node 10 in a broadcasting manner.

When the relay node 20 receiving the feedback signal transmitted in step S30 successfully decodes the packet of the source node 10, the packet received from the source node 10 may be retransmitted as it is during a provisional period, The parity bit may be transmitted to the gateway 30 (S40).

For example, the parity bit can be expressed as in Equation 3.

At this time, when the relay node 20 retransmits the packet to the gateway 30, the additional information collected by the relay node 20 may be combined and transmitted in a chain form.

That is, when the relay node 20 retransmits a packet to the gateway 30, the payload portion of the source node 10 may be transmitted using the header information of the retransmission packet as shown in FIG. 4.

Here, if the size of the header is large, transmitting the header twice causes waste in terms of the efficiency of communication resources, so in this embodiment, the relay node 20 receives the packet of the source node 10 as above. After extracting only the payload portion, the retransmission packet and the additional information of the relay node 20 are both transmitted in one header.

Then, the gateway 30 combines the packet retransmitted from the relay node 20 and the packet received from the source node 10, separately Viterbi-decodes the additional information of the relay node 20, and then corrects the packet error with CRC bits. If the check is normal, the ACK signal is transmitted to the relay node 20 and the source node 10 (S50).

Meanwhile, after receiving the feedback signal, the source node 10 detects the operation state of the relay node 20 during the provisional period and retransmits the packet to the gateway 30 after the provisional period according to the detection result.

In this embodiment, in order to prevent carrier collision due to simultaneous transmission between nodes, the source node 10, which has received a feedback (NACK) signal, sets a provisional period to detect a carrier without retransmitting immediately, and then the relay node 20 during the provisional period. ) Detects whether the decoding is successful and retransmission occurs.

Here, the provisional period can be set by any one or more of node-to-node distance, channel status, and RTT (Round Trip Time), and when transmission of other nodes is not performed during the set temporary period, the source node 10 ) Transmits a packet to the gateway 30 after a provisional period.

In addition, in step S40, the code rate may be adjusted by applying puncture to the relay node 20 as well. For example, if the polynomial convolutional code used in the above soson node 10 is used and perforation of the same ratio is applied, the code information of the relay node 20 can be expressed as Equation 4.

In addition, before the gateway 30 transmits the feedback, a packet capable of estimating a channel state between the relay node 20 and the gateway 30 may be transmitted. The gateway 30 may selectively transmit a feedback (NACK) signal to the source node 10 or the relay node 20 according to an arbitrary channel estimation method. As a result, the gateway 30 can select a reasonable channel environment. That is, the channel is estimated using the channel estimation packet, and according to the result, the gateway 30 may request a retransmission packet by specifying the source node 10 or the relay node 20, or the source node 10 ) And the relay node 20 may request a retransmission packet.

On the other hand, when the relay node 20 is moved and an obstacle exists between the source node 10 and a hidden node problem occurs, the source node 10 does not properly detect the signal of the relay node 20, It may be erroneously determined that the relay node 20 does not transmit the retransmission packet.

Therefore, if the transmission of the packet between the source node 10 and the relay node 20 is not detected due to the movement of the relay node 20 or other factors, and the source node 10 retransmits the packet, the gateway 30 ), a signal collision may occur.

In this case, the source node 10 sends and receives packets of short length, called RTS (1040, Ready To Send) and CTS (1041, Clear To Send), between the relay node 20 and the gateway 30 during a temporary period. It can also detect whether the channel is used or not.

As described above, according to the cooperative retransmission method in IoT communication according to an embodiment of the present invention, not only can obtain a diversity effect through cooperative communication between nodes in IoT communication, but also receive reliability of packets through cooperative retransmission method. In this process, by forming a group between sensor nodes and making the operation periods similar, it is possible to obtain an effect of increasing the reception performance at the gateway without increasing battery consumption.

In addition, the relay node can connect and transmit the retransmission packet of the source node and its own packet information at the same time to increase the transmission efficiency. When the relay node retransmits the packet, the packet of the source node can be transmitted as it is, but only the payload section is extracted. Accordingly, transmission efficiency may be improved by transmitting only the payload portion together with the header information of the relay node.

The implementation described herein may be implemented in, for example, a method or process, an apparatus, a software program, a data stream or a signal. Although discussed only in the context of a single form of implementation (eg, only as a method), the implementation of the discussed features may also be implemented in other forms (eg, an apparatus or program). The device may be implemented with appropriate hardware, software and firmware. The method may be implemented in an apparatus such as a processor, which generally refers to a processing device including, for example, a computer, a microprocessor, an integrated circuit or a programmable logic device, or the like. Processors also include communication devices such as computers, cell phones, personal digital assistants ("PDAs") and other devices that facilitate communication of information between end-users.

The present invention has been described with reference to the embodiments shown in the drawings, but these are only exemplary, and those of ordinary skill in the field to which the present technology pertains that various modifications and other equivalent embodiments are possible. I will understand.

Therefore, the true technical protection scope of the present invention should be determined by the following claims.

10: source node
20: relay node
30: gateway

Claims (12)

Transmitting a feedback signal to the relay node and the source node when the gateway fails to receive the packet transmitted from the source node;
Retransmitting a packet to the gateway during a temporary period after the relay node receives the feedback signal;
Sensing an operating state of the relay node during the provisional period after the source node receives the feedback signal; And
And retransmitting the packet to the gateway after the provisional period according to the detection result after the source node senses the operation state of the relay node.
The method of claim 1, wherein the transmitting of the feedback signal to the relay node and the source node comprises: the gateway transmitting the feedback signal through a broadcasting method.
According to claim 1, wherein the step of retransmitting the packet by the relay node to the gateway, the relay node combines the additional information of the relay node to the retransmission packet in a chain form and transmits the cooperation in IoT communication. Retransmission method.
The method of claim 1, wherein the step of retransmitting the packet by the relay node to the gateway comprises retransmitting the packet when the relay node receives the packet transmitted from the source node and successfully decodes the packet. Cooperation retransmission method.
The method of claim 1, wherein the sensor node and the relay node operate with the same operation period within the same group.
The method of claim 1, wherein the step of retransmitting the packet by the relay node to the gateway comprises transmitting, by the relay node, the payload portion of the source node using header information of the retransmission packet. Cooperation retransmission method.
A source node that transmits a packet to a relay node and a gateway, detects an operation state of the relay node during a temporary period when a feedback signal is received from the gateway, and retransmits it to the gateway according to the detection result;
A relay node for decoding the packet transmitted from the source node and transmitting it to the gateway, and retransmitting the packet transmitted from the source node to the gateway during the provisional period when the feedback signal is received from the gateway; And
And a gateway for requesting retransmission by transmitting the feedback signal to the source node and the relay node when the packet is received from the source node and fails.
8. The apparatus of claim 7, wherein the gateway transmits the feedback signal to the relay node and the source node in a broadcasting method.
8. The apparatus of claim 7, wherein the relay node combines and transmits the additional information of the relay node in a chain form to a retransmission packet when retransmitting the packet to the gateway.
8. The apparatus of claim 7, wherein the relay node retransmits the packet when it receives the packet transmitted from the source node and successfully decodes the packet.
8. The apparatus of claim 7, wherein the relay node transmits the payload portion of the source node using header information of the retransmission packet when retransmitting the packet to the gateway.
8. The apparatus of claim 7, wherein the source node, the relay node, and the gateway operate with the same operation period within the same group.

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