KR101221280B1 - Retransmission method for cooperative arq in manet and cooperative ad-hoc network system - Google Patents

Abstract

PURPOSE: A method for retransmitting a cooperative ARQ(Automatic Repeat Request) in an MANET(Mobile Ad Hoc Network) environment and a cooperative ad-hoc network system thereof are provided to quickly select a proper relay before the transmission of an error frame by providing a cooperative ARQ retransmission method. CONSTITUTION: A cognitive relay selects itself as one of a candidate relay group for cooperative transmission between a transmitting node and a receiving node(S1). The necessity of cooperative transmission between the transmitting node and the receiving node is determined based on received power of an NACK signal and an ACK of the receiving node for a frame transmitted by the transmitting node(S2). The transmitting node selects a cooperative recognition relay from a candidate relay group(S3). The cooperative recognition relay retransmits data received from a previous time slot to the transmitting node(S4). [Reference numerals] (S1) Selecting a candidate relay group(R_I) by a cognitive relay(R_i) for cooperative transmission by sensing an SINR of a signal transmitted from a transmitting node(S) and a receiving node(D); (S2) Determining the necessity of cooperative transmission between the transmitting node(S) and the receiving node(D) based on received power of an NACK signal and an ACK of the receiving node(D) for a frame transmitted by the transmitting node(S); (S3) Selecting a cooperative recognition relay from a candidate relay group selected in the S1 step when the necessity of cooperative transmission is determined in the S2 step; (S4) Retransmitting data received from a previous time slot in the cooperative recognition relay selected in the S3 step to the transmitting node(D)

Description

RE-RANSMISSION METHOD FOR COOPERATIVE ARQ IN MANET AND COOPERATIVE AD-HOC NETWORK SYSTEM}

The present invention relates to a cooperative ARQ retransmission method in a mobile ad hoc network (MANET). In particular, the present invention relates to an ARQ retransmission method that actively suggests retransmission to a transmitting node before receiving feedback from a receiving node in a cognitive relay.

In order to provide data transmission and various services in real time, a high quality wireless communication environment is required. In particular, in the packet wireless communication environment of the MANET, many frame errors occur due to factors such as transmission power limitation and user mobility, and there have been considerations for an automatic repeat request (ARQ) algorithm in order to reduce them.

Meanwhile, in order to improve performance in a wireless fading channel, researches on cooperative communication for establishing a virtual multi-input multi-output (MIMO) environment using terminals having one antenna have been conducted. In such cooperative communication, each node not only transmits its own data but also serves as an alternative path to other nodes in communication, thereby improving communication quality.

Recently, research has been actively conducted on a method of combining ARQ algorithm and cooperative communication technology to transmit high capacity data in real time by reducing frame error and delay. Veluppillai Mahinthan and Jon W. Mark combine the ARQ retransmission technology with a system in which two subscribers collaborate, allowing the transmitting node to retransmit an errored frame through the ACK and NACK feedback received from the receiving node. A CD-ARQ algorithm has been proposed (Veluppillai Mahintan, Humphrey Rutagemwa, Jon W. Mark and sherman Shen, "Cross-layer performance study of cooperative diversity system with ARQ," IEEE trans. Veh. Technol., Vol. 58, no. 2, pp. 705-718, Feb., 2009). However, the relay always retransmits the frame of the transmitting node irrespective of the ARQ feedback information of the receiving node, causing unnecessary retransmission, which is used in the next generation mobile communication system that needs to transmit a large amount of data in real time. There was a problem.

Megradad Dianati and Xuemin Shen, meanwhile, proposed NCSW algorithms that operate in wireless ad hoc network environments (Mehrdad Dianati, Xinhua Ling, Kshirasagar Naik, and Sherman Shen, "A node-cooperative ARQ schemes for wireless ad-hoc"). networks, "IEEE trans. Veh. Technol., vol. 55, no. 3, pp. 1032-1044, May., 2006.). NCSW is an algorithm that reduces the retransmission frame error by causing the relay to retransmit the corresponding frame where an error occurs instead of the transmitting node when the receiving node transmits a NACK feedback signal. However, since the relay starts retransmission after receiving a feedback signal from the receiving node, there is a problem that it is difficult to use for a service requiring fast retransmission when an error occurs.

A cooperative ARQ retransmission method and a cooperative ad hoc network system in a MANET environment according to the present invention aim to solve the following problems.

First, sensing the SINR of a signal transmitted by a transmitting node using a cognitive relay is intended to provide a cooperative ARQ retransmission method.

Second, it is intended to provide a relay for retransmission to the transmitting node in advance before receiving the feedback signal.

Third, it is intended to minimize unnecessary cooperative communication proposals by optimizing the relay sensing threshold according to the change of the wireless channel.

The problem of the present invention is not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

In the method of cooperative ARQ retransmission in the MANET environment according to the present invention, the recognition relay R _i senses the SINR of the signal transmitted by the transmitting node S and the receiving node D, and thus a candidate relay set R _I for cooperative transmission. ) Is selected, the cooperation between the transmitting node (S) and the receiving node (D) on the basis of the received power of the ACK and NACK signal of the receiving node (D) for the frame immediately transmitted by the transmitting node (S). Step S2 is determined whether or not transmission is necessary, if it is determined that the cooperative transmission is necessary in step S2 cooperative recognition relay selected in step S3 and step S3 where the cooperative recognition relay is selected from the candidate relay set (R _I ) selected in step S1 S4 step of retransmitting the data received in the previous time slot in the next time slot of OFDM to the receiving node (D).

The candidate relay set R _I in step S1 is characterized by the following equation.

는 송신 노드가 프레임을 전송하는 타임 슬롯 내 R_i의 수신 SINR,

는 송신 노드에서 전송한 신호가 수신 노드에 디코딩 가능한 SINR의 최소 문턱값,

는 송신 노드에서 전송한 신호가 수신 노드에 디코딩 가능한 SINR의 최대 문턱값,

는 수신 노드가 프레임을 전송하는 타임 슬롯 내 R_i의 수신 SINR,

는 인식 릴레이(R_i)에서 프레임을 전송하는 경우 수신 노드에서 디코딩이 가능한 SINR의 문턱값이다.here,

Is the received SINR of R _{i in} the time slot in which the transmitting node transmits the frame,

Is a minimum threshold of SINR that a signal transmitted from a transmitting node can decode to a receiving node,

Is the maximum threshold of SINR that a signal transmitted from a transmitting node can decode to a receiving node,

Is the received SINR of R _{i in} the time slot in which the receiving node transmits the frame,

Is a threshold value of the SINR that can decode at the receiving node when transmitting a frame from aware relays (R _i).

The recognition relay R _i belonging to the candidate relay set R _I may transmit the RTS to the transmitting node S.

) 이하로 감지되면 협력 전송이 필요하다고 판단하고, S3 단계에서 처음 수신된 RTS의 노드 ID를 통해 선택된 협력 인식 릴레이에 CTS가 전송되는 것을 특징으로 한다.In step S2, the reception power of the ACK and NACK signals of the reception node D is determined as a reference threshold (

When it is detected as below, it is determined that cooperative transmission is necessary, and the CTS is transmitted to the cooperative recognition relay selected through the node ID of the RTS first received in step S3.

The distance between the candidate relay set (R _I) aware relays (R _i) belonging to the recognition relay (R _i) and the transmitting node (S) is inversely proportional to the distance, recognizes the relay (R _i) and a receiving node (D) between the Set a timer proportional to and transmit the RTS when the timer reaches zero.

When two or more recognition relays R _i belonging to the candidate relay set R _I transmit the RTS at the same time, the transmitting node S compares the group ID of the received RTS with its own group ID, If the ID does not match, the received RTS is ignored and waits for the ACK and NACK responses of the receiving node D for the corresponding frame.

값과

값은 초기에 임의의 값으로 설정되고, 이 후 송신 노드(S)의 CTS 신호와 수신 노드의 ACK 및 NACK 신호를 기준으로 최적화되는 것을 특징으로 한다.

Value and

The value is initially set to an arbitrary value, and is then optimized based on the CTS signal of the transmitting node S and the ACK and NACK signals of the receiving node.

로 조절되고,

로 조절되며, 여기서 δ _△는 문턱값 단위변화량을 의미하는 것을 특징으로 한다.If the cooperative aware relay transmits an RTS to the transmitting node S and fails to receive the CTS from the transmitting node S,

Adjusted to

It is adjusted to, wherein δ _△ is characterized in that the threshold unit amount of change.

로 조절되고,

로 조절되며, 여기서 δ _△는 문턱값 단위변화량을 의미하는 것을 특징으로 한다.When it is determined that cooperative transmission is unnecessary in step S2 and the cooperative recognition relay is not selected in step S3, a NACK is transmitted from the receiving node D for the frame.

Adjusted to

It is adjusted to, wherein δ _△ is characterized in that the threshold unit amount of change.

와

가 2 타입 슬롯 만에 동일한 값으로 변경된 경우, δ _△ = (1/2) x δ _△ 로 변경되는 것을 특징으로 한다.

Wow

Is changed to the same value only in the two type slots, δ _Δ = (1/2) x δ _Δ .

According to the present invention, a cooperative ad-hoc network system includes a transmitting node S for transmitting a data frame, a receiving node D for receiving a data frame, and a transmitting node S and a receiving node D for transmitting. An acknowledgment relay (R _i ) constituting a set of candidate relays (R _I ) for cooperative transmission by sensing the SINR of the signal, wherein the acknowledgment of the receiving node (D) for the frame transmitted immediately before the transmitting node (S) And determining whether cooperative transmission is necessary by determining whether cooperative transmission is necessary between the transmitting node S and the receiving node D based on the reception power of the NACK signal, and in the candidate relay set R _I. Select to perform a cooperative ARQ retransmission.

The candidate relay set (R _I ) definition, the cooperative aware relay selection, and the cooperative ARQ retransmission through the same are the same as the above-described cooperative ARQ retransmission method.

The cooperative ARQ retransmission method and cooperative ad hoc network system in the MANET environment according to the present invention have the following effects.

In an ad hoc OFDMA communication network, a cognitive relay senses the SINR of a signal, thereby providing a cooperative ARQ retransmission method in which a receiving node proposes cooperative transmission before transmitting a feedback signal. This improves frame rate by quickly selecting the appropriate relay before retransmitting an error frame. Through simulations to be described later it was confirmed that the method according to the present invention can reduce the frame transmission time and improve the frame loss rate.

Figure 1 is a schematic model for an ad hoc network system, Figure 1 (a) shows a cooperative ad hoc network model, Figure 1 (b) shows a schematic structure of a cooperative ad hoc network system according to the present invention.
2 is a schematic flowchart of a cooperative ARQ retransmission method in a MANET environment according to the present invention.
3 is a configuration diagram of a slot used in the cooperative ARQ method according to the present invention.
4 illustrates a process in which a cooperative ARQ retransmission algorithm according to the present invention is operated.
5 illustrates a sample function representing a transmission time for each frame for evaluating the performance of the present invention.
6 is a graph showing the efficiency according to the SD channel for showing the effect of the present invention.
7 is a graph showing the possibility of frame loss according to the SD channel for explaining the effect of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, A, B, etc. may be used to describe various components, but the components are not limited by the terms, but merely for distinguishing one component from other components. Only used as For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

As used herein, the singular forms "a,""an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is to be understood that the present invention means that there is a part or a combination thereof, and does not exclude the presence or addition possibility of one or more other features or numbers, step operation components, parts or combinations thereof.

Hereinafter, referring to the drawings, a cooperative ARQ retransmission method and a cooperative ad hoc network system in a MANET environment will be described in detail.

Prior to the detailed description of the drawings, it is to be clear that the division of the components in the present specification is only divided by the main function of each component. That is, two or more components to be described below may be combined into one component, or one component may be provided divided into two or more for each function. Each of the components to be described below may additionally perform some or all of the functions of other components in addition to the main functions of the components, and some of the main functions of each of the components are different. Of course, it may be carried out exclusively by. Therefore, the existence of each component described through this specification should be interpreted functionally, and for this reason, the configuration of the components according to the cooperative ad hoc network system 100 of the present invention can achieve the object of the present invention. It should be clearly noted that within limits, it may differ from FIG. 1 (b).

First, a brief description of a communication network system in which the present invention is used. The present invention relates to a cooperative ARQ transmission method used in an ad hoc network system or an ad hoc network system using the method.

Figure 1 is a schematic model for an ad hoc network system, Figure 1 (a) shows a cooperative ad hoc network model, Figure 1 (b) shows a schematic structure of a cooperative ad hoc network system according to the present invention.

Figure 1 (a) represents a cooperative ad-hoc OFDMA communication network system. All nodes are randomly distributed in the network, and the channels between nodes are assumed to be Rayleigh fading environment. As shown in FIG. 1 (b), the cooperative communication group is composed of nodes located within one hop distance of the transmitting nodes S and 110, and each transmitting group uses multiple transmitting nodes S, which use the same frequency. It is assumed that there are 110 nodes and receiving nodes D and 130. At this time, the cooperative communication group is a group consisting of transmitting nodes (S, 110) for data transmission, and as shown in FIG. 1 (b), one transmitting node (S, 110) and one receiving node (D, 130). And a relay (R _i , i = 1, ..., N) capable of cooperative retransmission.

In the present invention, a frame-based real-time multimedia transmission is considered, and an optional retransmission protocol is used to reduce execution time for real-time transmission. In addition, the recognition relay (R _i , 120) having a cognitive radio (CR) function of the communication signal (traffic signal) transmitted by the transmitting node (S, 110) and the receiving node (D, 130) in its service area Detect the strength of the signal power. In this case, even in the case of relays having similar distances between the transmitting node S and 110 and the receiving node D and 130, the strength of the signal power measured due to factors such as the terrain and the building is different from each other.

,

는 아래의 수학식 1과 같이 표현될 수 있다.
When the transmitting node (S, 110) transmits a frame to the receiving node (D, 130), the signal received at the receiving node (D, 130) and any relay recognition relay (R _i , 120)

,

May be expressed as Equation 1 below.

로 정의할 때, 송신 노드(S, 110)가 프레임을 전송하는 타임 슬롯(time slot)동안 수신 노드(D, 130)의 수신 SINR,

와 인식 릴레이(R_i, 120)의 수신 SINR,

는 아래의 수학식 2와 같이 표현될 수 있다.Where h _{S , D} , h _{S , Ri} is a Rayleigh fading channel characteristic function between the transmitting node (S, 110) and the receiving node (D, 130), and between the transmitting node (S, 110), respectively, and x _S is the transmitting the signal transmitted by the node _{(S, 110), n D} , n Ri indicates a white Gaussian noise, each received in a receiving node (D, 130) and recognizes the relay (R _i, 120). Also, x _S power

When defined as, the receiving SINR of the receiving node (D, 130) during the time slot (time slot) for transmitting the frame (S, 110),

And the received SINR of the recognition relay (R _i , 120),

May be expressed as Equation 2 below.

,

는 수신 노드(D, 130)와 인식 릴레이(R_i, 120)에서 수신된 잡음 전력이다.
Here, M means a set of all nodes existing in the communication group,

,

Is the noise power received at the receiving node (D, 130) and the recognition relay (R _i , 120).

와 인식 릴레이(R_i, 120)의 수신 SINR,

는 아래의 수학식 3과 같이 표현될 수 있다.
In addition, during the time slot in which the receiving node (D, 130) transmits a frame, the receiving SINR of the transmitting node (S, 110),

And the received SINR of the recognition relay (R _i , 120),

May be expressed as Equation 3 below.

In the present invention, the relay selected by the transmitting node (S, 110) for the cooperative transmission is defined as a cooperative aware relay (R _i ^* ), and in the time slot in which R _i ^* transmits a packet, the transmitting node (S, 110) is Assume that no packet is sent.

In a wireless communication environment, even if the position of a node is constant, channel fluctuations over time are severe due to the effects of Rayleigh fading and shadow fading. Therefore, even in the wireless communication environment at the beginning of data transmission, even if the position of the node is constant, the channel fluctuates with time due to the influence of Rayleigh fading and shadow fading. Therefore, the method of selecting the recognition relay (R _i , 120) at the beginning of data transmission and using the same recognition relay (R _i , 120) for all frame transmissions of the transmitting node (S, 110) is performed according to the time slot of the transmitting frame. _{S , D} , h _{S , Ri} , h _{D , S} , and h _{D , Ri} Since the value changes, it may act as a factor of reducing cooperative diversity gain. In addition, the method of starting cooperative transmission with the NACK signal of the receiving node (D) 130 may reduce the performance of real-time multimedia communication because the error frame is retransmitted after a predetermined time slot.

The present invention proposes an ARQ method for selecting a recognition relay (R _i , 120) using RTS and CTS, which are short time slots, for low retransmission error rate and fast retransmission of an error frame, and minimizing delay.

2 is a schematic flowchart of a cooperative ARQ retransmission method in a MANET environment according to the present invention.

In the cooperative ARQ retransmission method according to the present invention, a recognition relay (R _i ) senses the SINR of a signal transmitted by a transmitting node (S, 110) and a receiving node (D, 130) and a candidate relay set (R _I) for cooperative transmission. ) Is selected, the transmitting node (S, 110) and the receiving node on the basis of the received power of the ACK and NACK signals of the receiving node (D, 130) for the frame immediately transmitted by the transmitting node (S, 110). In step S2 where it is determined whether cooperative transmission is necessary between (D, 130), and when it is determined that cooperative transmission is necessary in step S2, the cooperative recognition relay R _i , 120 in the candidate relay set R _I selected in step S1. Step S3 and step S4 of retransmitting the data received in the previous time slot in the cooperative recognition relay R _i (120) selected in step S3 to the receiving node (D, 130) in the next time slot of OFDM. It includes.

In the step S1, the candidate relay set R _I is represented by Equation 4 below. Determining a candidate relay set and selecting a cooperative aware relay (R _i , 120) to be used for the final cooperative ARQ is one of the core configurations of the present invention.

는 송신 노드(S, 110)가 프레임을 전송하는 타임 슬롯 내 인식 릴레이(R_i, 120)의 수신 SINR,

는 송신 노드(S, 110)에서 전송한 신호가 수신 노드(D, 130)에 디코딩 가능한 SINR의 최소 문턱값,

는 송신 노드(S, 110)에서 전송한 신호가 수신 노드(D, 130)에 디코딩 가능한 SINR의 최대 문턱값,

는 수신 노드(D, 130)가 프레임을 전송하는 타임 슬롯 내 인식 릴레이(R_i, 120)의 수신 SINR,

는 인식 릴레이(R_i, 120)에서 프레임을 전송하는 경우 수신 노드(D, 130)에서 디코딩이 가능한 SINR의 문턱값이다.here,

Is the received SINR of the recognition relay Ri _i 120 in the time slot in which the transmitting node S 110 transmits the frame;

Is the minimum threshold of SINR that the signal transmitted from the transmitting node (S, 110) can decode to the receiving node (D, 130),

Is the maximum threshold of SINR the signal transmitted from the transmitting node (S, 110) can decode to the receiving node (D, 130),

Is received SINR at the receiving nodes (D, 130) a time slot within aware relays (R _i, 120) for transmitting a frame,

Is a threshold of SINR that can be decoded by the receiving node (D, 130) when the frame is transmitted by the recognition relay (R _i , 120).

와

는 인식 릴레이(R_i, 120)가 센싱한 이전 프레임의 피드백 신호에 의해 타임 슬롯마다 경험적으로 결정되게 된다.At this time,

Wow

Is by a feedback signal of a previous frame is aware relays (R _i, 120) sensing to be determined empirically for each time slot.

값를 측정하여

가 문턱값보다 높은 값이면 재전송을 하기 위하여 송신 노드(S, 110)에 RTS를 전송한다.In addition, when the receiving nodes D and 130 are experiencing severe fading, a large amount of transmission power is required to maintain channel quality. Therefore, it recognized by the power-saving viewpoint relay (R _i, 120), even if the excessively large value

Measure the value

If R is higher than the threshold value, the RTS is transmitted to the transmitting node (S, 110) for retransmission.

3 is a slot configuration diagram used for the cooperative ARQ method. Using the RTS, CTS frame shown in Figure 3 is S is determined whether or not recognition cooperative transmission for the relay (R _i, 120).

를 결정한다. 송신 노드(S, 110)는 이전 프레임의 피드백 신호가

이하로 감지되면 협력전송을 하기로 결정하고, 처음 수신된 RTS의 노드 ID를 통하여 인식 릴레이(R_i, 120)를 선택하여 도 4와 같이 CTS를 전송한다. 인식 릴레이(R_i, 120)가 송신 노드(S, 110)로부터 CTS를 수신하면 인식 릴레이(R_i, 120)는 이전 타임 슬롯에 수신한 데이터를 OFDM의 다음 타임 슬롯에서 수신 노드(D, 130)에 재전송한다.
The transmitting node (S, 110) between the transmitting node (S, 110) and the receiving node (D, 130) through the received power of the ACK, NACK signal of the receiving node (D, 130) for the previously transmitted frames Threshold for judging whether the cooperative transmission by empirically determining the channel status;

. The transmitting node (S, 110) is the feedback signal of the previous frame

If it detects below, it decides to perform cooperative transmission, selects the recognition relay (R _i , 120) through the node ID of the first received RTS, and transmits the CTS as shown in FIG. 4. When the recognition relay (R _i , 120) receives the CTS from the transmitting node (S, 110), the recognition relay (R _i , 120) receives the data received in the previous time slot in the next time slot of the OFDM node (D, 130) Resend to).

A process of selecting the final cooperative aware relay in the candidate relay set R _I will be described in more detail. The recognition relay R _i belonging to the candidate relay set R _I transmits the RTS to the transmitting node S 110.

Aware relays (R _i, 120) is a transmitting node (S, 110) and a receiving node (D, 130) that when the sensing of the SINR of a signal transmitting the value is present in the range of predetermined threshold value, the sending node (S, 110 By sending RTS to), it actively proposes itself as a candidate relay for cooperative transmission. In this case, in order to prevent collisions by transmitting RTS simultaneously from two or more nodes, it is preferable to use an adaptive back-off method.

The adaptive backoff method is a method of transmitting an RTS after waiting for a predetermined time according to a timer value owned by the recognition relay (R _i , 120) after sensing the signal and immediately transmitting the RTS. .

Aware relays (R _i, 120) held by the timer aware relays (R _i, 120) and the transmitting node (S, 110) in inverse proportion to the distance between, it recognizes the relay (R _i, 120) and a receiving node (D, 130 Set the time proportional to the distance between). Aware relays (R _i, 120) will send an RTS to the time of the timer becomes zero.

On the other hand, when two or more recognition relays R _i and 120 belonging to the candidate relay set R _I transmit the RTS at the same time point, the transmitting node S and 110 transmits the group ID of the received RTS and its group ID. In comparison, if the group IDs do not match, the received RTS is ignored and the ACK and NACK responses of the receiving node (D) 130 for the corresponding frame are waited.

If the threshold for determining the recognition relay (R _i , 120) to belong to the candidate relay set (R _I ) is greater than the optimal value, the signal transmitted from the transmitting node (S, 110) is sufficiently decoded at the receiving node (D, 130). In spite of being good enough, the recognition relay (R _i , 120) transmits the RTS. Since the receiving node (D, 130) has already received the frame from the transmitting node (S, 110), the frame retransmitted by the recognition relay (R _i , 120) is ignored, which is a bad signal from the recognition relay (R _i , 120) Indicates that an unnecessary retransmission was performed. If the threshold value is smaller than the optimum value, the RTS transmission is performed even though the receiving node (D, 130) receives a value lower than the SINR satisfying the QoS and needs to retransmit the recognition relay (R _i , 120). The situation does not occur.

This means that the feedback signal aware relays (R _i, 120) a retransmission decision error of the threshold value generating a receiving node (D, 130) by at were not correctly predicted. Therefore, in order to reduce the occurrence of false signal and retransmission decision error according to the threshold value, the threshold value of R _i for determining the candidate relay set R _I should be determined as an optimal value.

값과

값은 초기에 임의의 값으로 설정되고, 이 후 송신 노드(S, 110)의 CTS 신호와 수신 노드(D, 130)의 ACK 및 NACK 신호를 기준으로 최적화되는 방법을 제안한다.In the present invention,

Value and

The value is initially set to an arbitrary value, and then a method is optimized based on the CTS signal of the transmitting node (S, 110) and the ACK and NACK signals of the receiving node (D, 130).

If you can not receive the CTS from the sending node (S, 110) cooperate aware relays (R _i, 120) in were RTS sent to the sending node (S, 110), the threshold value of the recognition relay (R _i, 120) Optimum Since the case is larger than the value, the threshold value is adjusted as in Equation 5 below.

Here, δ _Δ means a threshold unit amount of change. This threshold unit change amount has a constant reference value according to the network system environment.

If it is determined that the cooperative transmission is unnecessary in step S2 and the cooperative recognition relay (R _i , 120) is not selected in step S3, but the NACK is transmitted from the receiving node (D, 130) for the frame, the recognition relay (R _i , 120) is a case where the threshold value is smaller than the optimal value, the threshold value is adjusted as in Equation 6 below.

At this time, if the optimal value of δ and the value of _△ inadequate threshold exists between the _△ δ, is repeated (ping-pong) developing a threshold value of aware relays (R _i, 120) continue to be changed is generated. In order to solve this problem, when the threshold value returns to the same value in only two time slots, the algorithm is performed by reducing the δ _Δ value in half. The threshold adjustment algorithm in the recognition relay can be expressed as the following pseudo code.

Hereinafter, the cooperative ad hoc network system 100 according to the present invention will be described. The cooperative ad hoc network system of the present invention is an ad hoc network system using the aforementioned cooperative ARQ retransmission method. Duplicated descriptions of the cooperative ARQ retransmission method in the above-described MANET environment will be briefly described.

As described above, Fig. 1 (b) shows a schematic structure of a cooperative ad hoc network system according to the present invention.

The cooperative ad hoc network system according to the present invention includes a transmitting node (S, 110) for transmitting a data frame, a receiving node (D, 130) for receiving a data frame, a transmitting node (S, 110) and a receiving node (D, 130). And a recognition relay (R _i , 120) configured to sense the SINR of the signal transmitted by the candidate relay set (R _I ) for cooperative transmission.

Between the transmitting nodes S and 110 and the receiving nodes D and 130 based on the received power of the ACK and NACK signals of the receiving nodes D and 130 for the frame transmitted immediately before the transmitting nodes S and 110. when determined that the cooperative transmission to determine whether the required cooperative transmission is required, is characterized in that by selecting a candidate set of relay (R _I) cooperate aware relays (R _i, 120) in performing the cooperative ARQ retransmission.

As shown in FIG. 1 (b), the RTSs are transmitted from the recognition relays R1 and R2 belonging to the candidate relay set to the transmitting nodes S and 110, and then the final cooperative recognition relay is transmitted from the transmitting nodes S and 110. FIG. ARQ retransmission is performed through the recognition relay (R1) receiving the selected CTS.

The method of determining the candidate relay set (R _I ), the method of selecting the cooperative aware relay, the threshold adjustment method for determining the candidate relay set, and the like are all the same as the above-described cooperative ARQ retransmission method in the MANET environment.

Experiment to prove the effectiveness of the present invention

는 아래의 수학식 7과 같다.
When the transmitting node (S, 110) transmits a frame and then receives a feedback signal from the receiving node (D, 130), the mutual between the receiving node (D, 130) and the transmitting node (S, 110) channel Mutual information,

Is the same as Equation 7 below.

를 비교하여 피드백 신호가 보다 더 좋으면 협력전송 요청을 거절한다. 따라서 인식 릴레이(R_i, 120)에서 RTS를 전송하였지만 송신 노드(S, 110)의 CTS를 수신하지 못할 확률, P_FA는 아래의 수학식 8과 같다.
When the transmitting node (S, 110) receives the cooperative transmission request of the recognition relay (R _i , 120), the SINR of the feedback signal of the receiving node (D, 130) for the previous frame and

Compare with and reject the cooperative transmission request if the feedback signal is better. Thus aware relays (R _i, 120) the probability, P _FA does not receive the CTS from the sending node (S, 110) but transmit the RTS is shown in equation (8) below.

는 아래의 수학식 9와 같다.
In addition, when the transmitting node (S, 110) transmits a frame to the receiving node (D, 130), mutual information between the transmitting node (S, 110) and the receiving node (D, 130) channel,

Is the same as Equation 9 below.

는 아래의 수학식 10과 같다.
When the recognition relay R _i 120 retransmits the frame, the receiving nodes D and 130 sum and decode the frames of the received transmission node S 110 and the frames of the retransmitted recognition relay R _i 120. At this time, mutual information,

Is the same as Equation 10 below.

는 인식 릴레이(R_i, 120)가 오류 프레임을 재전송할 때 수신 노드(D, 130)에서 수신한 SINR을 뜻한다.
here,

Denotes the SINR received by the receiving node (D, 130) when the recognition relay (R _i , 120) retransmits the error frame.

If the probability that the transmission node (S, 110) does not properly transmit the frame is defined as P _SF , P _SF is expressed by Equation 11 below.

Where r is the minimum data rate required per frame. In addition, when P _SF performs retransmission, if P _RF is defined as a probability that a corresponding frame may not be properly transmitted, P _RF is expressed by Equation 12 below.

In Equation 12, the first term reflects retransmission by information repetition.

은 아래의 수학식 13과 같이 유도된다. If the maximum number of retransmissions of the same frame is n, and frames that fail after n times are ignored, then the average number of slots per frame,

Is derived as in Equation 13 below.

는 아래의 수학식 14와 같이 유도된다.
Therefore, if the ratio of time slots used to transmit a frame is defined as transmission efficiency, the transmission efficiency,

Is derived as in Equation 14 below.

In order to experiment the effects of the present invention, the frame transmission performance between transmitting nodes (S, 110) and receiving nodes (D, 130) in an ad hoc OFDMA communication network was analyzed. Randomly generated 200 users in a 1km × 1km square ad hoc wireless network, the transmit power of the terminal is 23dBm, and the channel generated between nodes is considered as Rayleigh fading channel model. The packet consists of 1000 bits, and the data rate required by each user is set to 1Mbps, and modeled as the maximum number of retransmissions per frame n = 2 and processing delay d _proc = 1ms.

FIG. 5 illustrates a sample function showing a transmission time for each frame when the reception power of the signal is received at 12 dBm by Rayleigh fading at the reception nodes D and 130. Since the integrated value of the graph represents the total transmission time, the method according to the present invention is compared with the conventional NCSW and QS-CD-ARQ techniques (Fig. 5 (c), 'Proposed CACR ). If you use a scheme , you can see that data can be sent in a shorter time. Hereinafter, the technique of the present invention will be referred to as CACR.

5 (c) shows that by applying adaptive back-off, the success rate of the cooperative transmission can be improved by selecting R having a high cooperative transmission gain. Therefore, the proposed scheme is suitable for transmitting high capacity multimedia data in real time by shortening the transmission time by improving the success rate of fast retransmission and cooperative transmission.

6 shows the efficiency according to the SNR values of the transmitting nodes S and 110. In this case, efficiency represents the ratio of time slots used to transmit the entire frame, and the efficiency becomes 1 when all the frames are transmitted without delay. In FIG. 6, it can be seen that the lower SNR, the better the efficiency of CACR compared to NCSW and QS-CD-ARQ.

This result is because the method of the present invention reduces the frame retransmission delay by determining whether cooperative transmission is faster than the conventional algorithm through cognitive sensing, RTS and CTS. On the other hand, it can be seen that there is a part where QS-CD-ARQ has better efficiency than CACR at high SNR. This is because it acts as a dropping factor.

FIG. 7 shows the frame loss probability of the proposed ARQ retransmission scheme compared with the conventional scheme according to the SNR value of the transmitting node (S, 110). In both the conventional ARQ scheme and the proposed scheme, it can be seen that the probability of frame loss increases as the SNR decreases. Compared with NCSW, QS-CD-ARQ, the CACR of the present invention applies QPSK and has a frame loss probability value improved by 0.037 when the SNR is 5 dB. This result is because the proposed CACR technique selects R for cooperative transmission on a frame-by-frame basis, and thus the probability that the selected R fails to retransmission due to the deterioration of channel conditions due to fading decreases, thus increasing the success rate of cooperative communication. .

The embodiments and drawings attached to this specification are merely to clearly show some of the technical ideas included in the present invention, and those skilled in the art can easily infer within the scope of the technical ideas included in the specification and drawings of the present invention. Modifications that can be made and specific embodiments will be apparent that all fall within the scope of the present invention.

100: cooperative ad hoc network system 110: transmitting node (S)
120: recognition relay (R _i ) 130: receiving node (D)

Claims (20)

In the cooperative ARQ retransmission method of the MANET environment in which the nodes operate as any one of a transmitting node, a receiving node, and a recognition relay for cooperative retransmission,
The recognition relay R _i senses the SINR of the signal transmitted by the transmitting node S and the receiving node D, and between the transmitting node S and the receiving node D according to the sensed SINR. Step S1 of selecting one of a candidate relay set R _I for cooperative transmission;
The cooperative transmission is performed between the transmitting node S and the receiving node D based on the receiving power of the ACK and NACK signals of the receiving node D for the frame immediately transmitted by the transmitting node S. S2 step of determining whether it is necessary;
Step S3, when it is determined in step S2 that cooperative transmission is necessary, the transmitting node S selects a cooperative recognition relay to perform cooperative transmission in the candidate relay set R _I selected in step S1; And
Cooperative ARQ in the MANET environment characterized in that it comprises a step S4 retransmits the data received in the previous time slot (time slot) to the receiving node (D) in the next time slot of the OFDM selected in step S3 Resend method. The method of claim 1,
The candidate relay set R _I in step S1 is represented by the following equation.

(here,

Is the received SINR of R _{i in} the time slot in which the transmitting node S transmits the frame,

Is the minimum threshold of SINR the signal transmitted from the transmitting node S decodable to the receiving node D,

Is the maximum threshold of SINR the signal transmitted from the transmitting node S decodable to the receiving node D,

Is the received SINR of R _{i in} the time slot in which the receiving node D transmits the frame,

It is aware relays (R _i), a receiving node (D) threshold value) of the available SINR decoding in the case of transmitting a frame from The method of claim 2,
Recognition relay R _i belonging to the candidate relay set R _I transmits the RTS to the transmitting node S in order to propose itself as a candidate relay for cooperative transmission. Way. The method of claim 3,
In the step S2, the transmitting node (S) is the receiving power of the ACK and NACK signal of the receiving node (D) is the reference threshold (

) Or less, determine that cooperative transmission is necessary,
In the step S3, the transmitting node (S) is a cooperative ARQ retransmission method in the MANET environment, characterized in that for transmitting the CTS to the cooperative recognition relay selected through the node ID of the first received RTS. The method of claim 3,
The recognition relay R _i belonging to the candidate relay set R _I is inversely proportional to the distance between the recognition relay R _i and the transmitting node S, and the recognition relay R _i and the receiving node R _i . D) A method of setting a timer proportional to the distance between, and transmits the RTS when the timer becomes zero, ARQ retransmission method in a MANET environment. The method of claim 5,
When two or more recognition relays R _i belonging to the candidate relay set R _I transmit the RTS at the same time, the transmitting node S compares the group ID of the received RTS with its group ID. And if the group ID does not match, ignores the received RTS and waits for the ACK and NACK responses of the receiving node (D) for the corresponding frame. The method of claim 2,
The recognition relay (R _i ),
remind

Value and

The value is initially set to an arbitrary value, and then adjusted based on the CTS signal of the transmitting node (S) and the ACK and NACK signals of the receiving node (D). The method of claim 7, wherein
The recognition relay (R _i ),
When the RTS is transmitted to the transmitting node S as a cooperative aware relay and the CTS is not received from the transmitting node S,

With the

To the
Where δ _Δ represents a threshold unit change amount. The method of claim 7, wherein
The recognition relay (R _i ),
Since the transmitting node S determines that the cooperative transmission is unnecessary in the step S2, the cooperative transmission has not occurred without selecting the cooperative recognition relay in the step S3, and thereafter, a NACK is received at the receiving node D for the corresponding frame. If sent,

With the

To the
Where δ _Δ represents a threshold unit change amount. 10. The method according to claim 8 or 9,
The recognition relay (R _i ) is the

Wow

Is changed to the same value in only 2 time slots, the δ _Δ = (1/2) * δ _Δ . In a cooperative ad-hoc network system,
A transmitting node S for transmitting a data frame;
A receiving node (D) for receiving the data frame;
Including a recognition relay (R _i ) for sensing the SINR of the signal transmitted by the transmitting node (S) and the receiving node (D) to form a candidate relay set (R _I ) for cooperative transmission,
The transmitting node (S) is a cooperative transmission between the transmitting node (S) and the receiving node (D) based on the received power of the ACK and NACK signals of the receiving node (D) for the frame transmitted immediately before. If it is determined whether the cooperative transmission is necessary by determining whether it is necessary, the cooperative ad hoc network system, characterized in that for requesting cooperative ARQ retransmission by selecting a cooperative recognition relay in the candidate relay set (R _I ). The method of claim 11,
The candidate relay set (R _I ) is a cooperative ad hoc network system, it characterized by the following equation.

(here,

Is the received SINR of R _{i in} the time slot in which the transmitting node S transmits the frame,

Is the minimum threshold of SINR the signal transmitted from the transmitting node S decodable to the receiving node D,

Is the maximum threshold of SINR the signal transmitted from the transmitting node S decodable to the receiving node D,

Is the received SINR of R _{i in} the time slot in which the receiving node D transmits the frame,

It is aware relays (R _i), a receiving node (D) threshold value) of the available SINR decoding in the case of transmitting a frame from The method of claim 12,
And transmitting an RTS to a transmitting node (S) to propose itself as a candidate relay for cooperative transmission of recognition relay (R _i ) belonging to the candidate relay set (R _I ). The method of claim 13,
The transmitting node S,
Receive power of the ACK and NACK signals of the receiving node D is a reference threshold (

) Or less, determine that cooperative transmission is necessary,
And transmitting the CTS to the selected cooperative recognition relay through the node ID of the received RTS. The method of claim 13,
The recognition relay R _i belonging to the candidate relay set R _I is inversely proportional to the distance between the recognition relay R _i and the transmitting node S, and the recognition relay R _i and the receiving node R _i . D) setting a timer proportional to the distance between, and transmitting the RTS when the timer becomes zero. 16. The method of claim 15,
When two or more recognition relays R _i belonging to the candidate relay set R _I transmit the RTS at the same time, the transmitting node S compares the group ID of the received RTS with its group ID. And if the group IDs do not match, ignore the received RTS and wait for the ACK and NACK responses of the receiving node D for the corresponding frame. The method of claim 12,
remind

Value and

The value is initially set to an arbitrary value and then optimized based on the CTS signal of the transmitting node (S) and the ACK and NACK signals of the receiving node (D). 18. The method of claim 17,
The recognition relay (R _i ),
When the RTS is transmitted to the transmitting node S as a cooperative aware relay and the CTS is not received from the transmitting node S,

With the

To the
Wherein δ _Δ is a threshold unit change amount. 18. The method of claim 17,
The recognition relay (R _i ),
When the transmitting node S determines that cooperative transmission is unnecessary and does not select a cooperative recognition relay, but a NACK is transmitted from the receiving node D for the corresponding frame,

With the

To the
Wherein δ _Δ is a threshold unit change amount. 20. The method according to claim 18 or 19,
The recognition relay (R _i ),
remind

Wow

Is changed to the same value in only 2 time slots, the δ _Δ = (1/2) * δ _Δ .

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