KR101007453B1 - Transmission Probability Calculation Apparatus and Method for Selecting GPS Relay in Distributed Method - Google Patents

Abstract

The present invention provides a method for selecting an optimal QoS relay among a plurality of relays in a distributed manner in a relay communication in which a relay node receiving data of a source performs data retransmission when a wireless channel state of an wireless communication environment is unstable. The present invention relates to a transmission probability calculating apparatus and a method thereof.

Transmission transmission apparatus according to the present invention, the data storage unit 121 for collecting data from the source; A channel distribution information determining unit 122 recognizing channel distribution information between the source and the retransmission relay; A decoding set determination unit 123 for determining whether the channel distribution information is included in a contention relay group and selecting a primary relay; A channel information collecting unit 131 for receiving a transmission acknowledgment (ACK) message and a retransmission request (NACK) message from a destination; A transmission set determining unit 132 for selecting a secondary relay based on a channel gain between the destination and the relay; A relay grouping unit 133 for classifying the QoS relay group estimated from the primary and secondary relay screening operations in consideration of the channel gain between the destination and the relay; And a transmission probability calculator 134 for calculating an optimal transmission probability through the section differentiated by the classification.

QoS relay, primary relay, secondary relay,

Description

Transmission probability calculating apparatus and method for single QoS relay selection in a distributed manner

The present invention relates to a transmission probability calculation apparatus for selecting a QoS relay in a distributed manner and a method for selecting a QoS relay in a distributed manner. More particularly, the present invention relates to a method for selecting a QoS relay in a distributed manner. In a relay communication in which a received relay node performs data retransmission, a transmission probability calculating device for selecting an optimal QoS relay among a plurality of relays in a distributed manner and a method of selecting a QoS relay in a distributed manner. It is about.

Selecting a relay node having a channel that preferably operates in a cooperative relay communication system is a very important problem for stable communication.

In relay communication, a method of selecting a relay node to participate in retransmission includes opportunistic single relay selection and multiple relay selection to obtain diversity effects. There is a way.

The method of selecting a plurality of relays is basically operated by a centralized relay selection algorithm under the control of a super node, and is a destination node due to cooperative transmission between participating relays. A control signal for providing channel state information (CSI) feedback or multiple access (MA) orthogonality between channels is required.

Aggelos Bletsas et al., “Cooperative Diversity with Opportunistic Relaying,” (WCNC 2006) states that opportunistic single relay selection is superior to multiple relay selection. Based on these findings, the present invention describes an effective method and apparatus for selecting one optimal relay.

The method of selecting one optimal relay includes a centralized relay node selection algorithm having a central controller that knows channel information of all relay nodes to participate in, and the relay nodes are distributed in their own way. As a result, there is a distributed relay node selection algorithm that can be selected in competition.

In the case of the central control relay node selection method, the relay node having the best performance can be selected because the channel state among the relays participating in the retransmission can be selected under the control of the central control unit. However, as the number of relay nodes increases, the burden on the central control unit to control the entire channel information increases, and a problem arises in practically implementing a device for having information of all relay nodes.

(여기서,

는 (1) 릴레이와 소스, 릴레이와 목적지 둘 중에서 나쁜 채널 이득, (2) 둘의 조화평균(harmonic mean))의 레졸루션(resolution, 즉 λ)을 증가시켜야 하기 때문에, 하나의 릴레이가 선택될 시간이 길어지는 단점이 발생한다.The present invention proposes a distributed relay node selection algorithm in which all relay nodes compete in a distributed manner so that the relay node having the best channel can be selected. Representative researches on distributed relay node selection algorithms include Aggelos Bletsas et al. “A simple cooperative diversity method based on network path selection,” (IEEE JSAC Vol. 24, March 2006, MIT media lab). In this paper, a number of relays are described in terms of minimizing collisions with each other in a distributed manner by collecting channel information from sources and destinations. However, if the number of competing relays increases, a timer set in proportion to the inverse of the collected channel information to reduce the probability of collision

(here,

Since (1) must increase the resolution of the bad channel gain between the relay and source, both relay and destination, and (2) the harmonic mean of the two, i. This lengthening disadvantage occurs.

In other words, there is a need for a method of controlling λ that determines a timer of a participating relay according to the number of competing relays, and in this case, when the number of participating relays increases, the access delay time of the timer using the channel gain increases. It is inevitable.

The present invention has been made to solve the above problems, and an object of the present invention is to minimize the probability of collision by selecting the optimal QoS relay group in relay communication and controlling the transmission probability in consideration of the number of contention relays. And at the same time to provide a method and apparatus for minimizing the access time delay.

It is an object of the present invention to provide a method of selecting an optimal QoS relay group from participating relay groups by setting QoS thresholds.

An object of the present invention is to provide a method for selecting an optimal QoS relay by applying a differentiated transmission probability based on the size of the selected relay group and the probability to be included in the transmission set (transmission set) of each relay.

An object of the present invention is to provide a method of resetting the QoS threshold down and satisfying the required QoS through multiple relay cooperation when no relay satisfies the QoS threshold.

Transmission transmission apparatus according to the present invention, the data storage unit 121 for collecting data from the source; A channel distribution information determining unit 122 recognizing channel distribution information between the source and the retransmission relay; A decoding set determination unit 123 for determining whether the channel distribution information is included in a contention relay group and selecting a primary relay; A channel information collecting unit 131 for receiving a transmission acknowledgment (ACK) message and a retransmission request (NACK) message from a destination; A transmission set determining unit 132 for selecting a secondary relay based on a channel gain between the destination and the relay; A relay grouping unit 133 for classifying the QoS relay group estimated from the primary and secondary relay screening operations in consideration of the channel gain between the destination and the relay; And a transmission probability calculator 134 for calculating an optimal transmission probability through the section differentiated by the classification.

Transmission probability calculation apparatus and method for selecting QoS relay in a distributed manner according to the present invention, when the data communication is stopped due to unstable radio channel status between source and destination, selects the optimal QoS relay and retransmits By improving the communication system performance, data communication downtime can be overcome.

In a system such as a mesh network, a relay communication of a cellular environment, an ad hoc network, and the like, the method may be used to select an optimal node considering service QoS among competing nodes.

1 is an exemplary configuration diagram of an apparatus for calculating a transmission probability according to the present invention.

Transmission probability calculation apparatus according to the present invention comprises a data storage unit 121 for collecting data from the source; A channel distribution information determining unit 122 recognizing channel distribution information between the source and the retransmission relay; A decoding set determination unit 123 for determining whether the channel distribution information is included in a contention relay group and selecting a primary relay; A channel information collecting unit 131 for receiving a transmission acknowledgment (ACK) message and a retransmission request (NACK) message from a destination; A transmission set determining unit 132 for selecting a secondary relay based on a channel gain between the destination and the relay; A relay grouping unit 133 for classifying the QoS relay group estimated from the primary and secondary relay screening operations in consideration of the channel gain between the destination and the relay; And a transmission probability calculator 134 that calculates an optimal transmission probability through the section differentiated by the classification.

2 is a flowchart illustrating a method of calculating a transmission probability according to the present invention.

As shown in FIG. 2, the method of calculating a transmission probability according to the present invention greatly calculates the transmission probability for controlling the minimum collision probability and access delay based on step 1 of performing channel data collection for calculating probability and collected channel information. It is divided into two stages.

When the relay participates in performing the relay function, the relay initialization is performed in the relay start 110 state. This includes receiving data from a source, initializing a storage medium for recording the received data for a period of time, receiving a NACK signal for entering a relay contention mode, and initializing the received signal storage medium. After the relay initialization is performed, the relay collects data sent from the source to the destination, and the collected data is recorded in the storage medium according to the destination address. When data from the source is successfully received at the destination, the destination sends an ACK signal to the relay, and the relay removes data from the storage medium if there is data corresponding to the received ACK signal. If it fails to receive data from the source at the destination, the destination sends a NACK signal to the relay, and if the relay has data corresponding to the received NACK signal, step 2 is performed and is optimal for competition with neighboring relays. Calculate the transmission probability of.

Step 1 of recognizing a relay network radio channel state in a method for calculating a transmission probability includes storing data of a source in the data storage unit 121 (S1), and physical relay distribution and channel distribution between a base station and a terminal. Determining information by the channel distribution information determining unit 122 (S2); And a step S3 of determining, by the decoding set determining unit 123, a channel state between the relay and the corresponding source.

In the method for calculating the transmission probability, determining the access probability according to the recognized relay radio channel state may include collecting, by the ACK / NACK channel information collecting unit 131, information on success and failure of data reception from a destination ( S4); The transmission set determining unit 132 determining whether the relay is included in the transmission set based on the collected channel information (S5); Classifying the relay in the relay grouping unit 133 to control a collision due to contention when there are a plurality of relays included in the transmission set (S6); And calculating a transmission probability by the differentiated transmission probability calculator 134 for each classified relay (S7).

The channel distribution information determining unit 122 collects and preserves channel state between the source and the relay as channel state information related to the physical position of the relay distributed between the source and the destination. In an embodiment of the invention the distribution of relays takes into account path loss, shadowing and short-term fading in the channel state with respect to the source and destination of the target (the ACK / NACK signal is received). Accordingly, the channel distribution of the data from the source received by the relay, the ACK and the NACK from the destination are determined by the transmission power, mobility, distance, etc. of the source and destination. In other words, it is preferable to include the channel distribution information determination stage 122 considering the channel distribution of the signal received from the relay according to the environment of the system to be applied. The criterion of such information determination may provide information for channel state determination in a central control node such as a base station. The same channel information and differentiated channel information may be provided to the installed relay group collectively.

The decoding set determination unit 123 determines whether the relay participates in the communication between the source and the destination by determining a channel state between the source and the relay, and the source provides a QoS threshold value β _s ( broadcast) to include in the decoding set if the probability to meet a predetermined target data rate R (bps / Hz) in the distribution of channel gains collected at any relay i of the M relays is higher than the QoS threshold; If not, the relay function will be deactivated.

를 파라미터로 하는 지수적인 분포를 가진다. 릴레이는 선택된 소스와의 채널 파라미터

를 계산하고, 수학식 2를 만족하는 지를 체크한다. 수학식 2를 만족하지 않는 릴레이는 비활성화된다. In equation 1, for Rayleigh scattering, the probability that the relay is included in the decoding set

It has an exponential distribution with. Relay is a channel parameter with the selected source.

Calculate and check whether the equation (2) is satisfied. Relays that do not satisfy Equation 2 are deactivated.

The decoding set determination unit 123 of the activated relay group basically assumes the data relay function of the decode-transfer method, and if there is no error through the CRC checksum of the data received from the source, it is recorded in the storage medium by the corresponding destination address. do. When extended to the amplification-transmission relay, only the relay in the case of exceeding a predetermined signal-to-noise ratio (SNR) participates in the competition, and the change in data size to be transmitted involves such a reset of the signal-to-noise ratio. In the embodiment of the present invention, when there is data in which the source address of the NACK signal from the destination and the destination address of the pre-stored data are identical, the transmission relay group to which the data of step 2 is to be transmitted is determined and the transmission probability calculation process for each relay is performed. Done.

The ACK / NACK channel information collecting unit 131 determines whether the relay stores decoding data corresponding to the NACK, and if there is no data corresponding to the NACK signal, step 2 is not performed. The reason why such data and ACK / NACK management method should be added is that in case of 802.11 ad hawk mode or mesh network environment, since there are different sources and destinations, data collected by source and destination collected in data transmission are collected. This is because NACK channel gain management is required. Accordingly, the decoding set determination unit 123 manages channel information between the source and the relay, and the ACK / NACK channel information collecting unit 131 preserves the channel information between the relay and the destination. Is required. Appropriate protocols and algorithms for the orthogonal channel and synchronization method between any destinations and relays should be involved here.

In a system such as a mesh network, a relay communication of a cellular environment, an ad hoc network, and the like, a method of selecting an optimal routing node considering service QoS among competing nodes may be used. In this case, the decoding set determining unit 123 and the ACK / NACK channel information collecting unit 131 or the transmission set determining unit 132 select a transmission power, a transmission rate, and a QoS threshold for each source and destination to select an optimal QoS relay. It is desirable to preserve.

)를 수집한다. 수집된 채널 상태는 목적지로부터의 송신 파워, 이동성, 거리 등을 고려한 값으로 릴레이와 목적지와의 평균 채널 상태를 제공한다. 해당 목적지는 QoS 임계값 (β_d )을 제공(broadcast) 하여 상술한 디코딩 셋에 포함된 임의의 릴레이 i에서 수집된 채널 이득의 분포에서 사전 설정된 목표 데이터 비율 R(bps/Hz)을 만족하기 위한 확률이 QoS 임계값보다 높은 경우 전송 셋에 포함시키고, 그렇지 않은 경우 해당 목적지로의 릴레이 기능을 비활성화하게 된다. The ACK / NACK channel information collecting unit 131 receives channel information between the relay and the destination by receiving ACK and NACK signals from the destination.

Collect). The channel state collected provides the average channel state between the relay and the destination in consideration of the transmission power, mobility, and distance from the destination. The destination broadcasts a QoS threshold β _d to satisfy a predetermined target data rate R (bps / Hz) in the distribution of channel gains collected at any relay i included in the decoding set described above. If the probability is higher than the QoS threshold, it is included in the transmission set, otherwise the relay function to the destination is deactivated.

를 파라미터로 가지는 지수적인 분포를 가진다. 릴레이는 선택된 소스와의 채널 파라미터

를 계산하고 수학식 5를 만족하는 지를 확인한다. 수학식 5를 만족하지 않는 릴레이는 비활성화된다. Equation 4, in the case of Rayleigh scattering, the probability that the relay is included in the transmission set

It has an exponential distribution with. Relay is a channel parameter with the selected source.

Calculate and check if the equation 5 is satisfied. Relays that do not satisfy Equation 5 are deactivated.

,

는 소스와 릴레이 사이, 목적지와 릴레이 사이의 경로 손실을 고려한 이격 거리에 비례한다. 해당하는 소스와 목적지로부터의 QoS 임계값이 설정되면 수학식 3과 수학식 5와 같이

와

의 각각의 상한값

와

가 결정된다. 따라서 소스와 목적지 사이의 거리(

)에 따라 도4와 같이 중첩된 구간이 결정된다. 수학식 2, 수학식 5에 의해 중첩된 구간에 포함된 릴레이만 경쟁에 참여하게 된다. 중첩된 구간에서 선택된 QoS 릴레이의 경우 작동 정지 확률의 상한은 수학식 7과 같다.here

,

Is proportional to the separation distance considering the path loss between the source and the relay and the destination and the relay. When QoS thresholds from corresponding sources and destinations are set, Equations 3 and 5

Wow

The upper limit of each

Wow

Is determined. Therefore, the distance between the source and the destination (

), Overlapping sections are determined as shown in FIG. 4. Only relays included in the overlapped sections by Equation 2 and Equation 5 participate in the competition. For the QoS relay selected in the overlapped interval, the upper limit of the downtime probability is expressed by Equation 7.

셋을 구성할 수 있다. 본 발명에서는 중첩된 구간에 다수 개의 릴레이가 존재하는 경우, 도5에 도시된 바와 같이, 릴레이 그룹핑부 (133)에서

제어를 통해 구간별로 릴레이를 활성화시켜, 경쟁하는 릴레이 수를 제어함으로써 충돌 확률을 제어한다.As a result, since the upper limit probability of the down operation of the selected relay is determined according to the QoS thresholds set from the source and the destination,

You can configure a set. In the present invention, when a plurality of relays in the overlapping section, as shown in Figure 5, in the relay grouping unit 133

By controlling the relay for each section through the control, the collision probability is controlled by controlling the number of races to compete.

It is preferable to store the set QoS threshold information for each source-by-source destination in the channel distribution information determining unit 122. As shown in FIG. 3, it is determined whether a relay exists in an overlapping section configured with a set value (320). ). If the relay exists in the overlapped interval, the optimal QoS relay is selected (350). If no relay exists in the overlapped section, the destination node may increase the relay group included by lowering the QoS threshold 330. In this case, since the likelihood of not satisfying the QoS is high, it is preferable to select 350 a multi-relay cooperative scheme or to extend the multi-hop relay scheme.

delete

값에 따라 우선순위를 부여한다. 우선순위가 가장 높은 릴레이는 경쟁 없이 (낮은 경쟁 확률로) 채널을 확보하여 선택되고, 우선순위가 가장 낮은 릴레이는 참여하는 릴레이와 경쟁하여 (높은 경쟁 확률로) 채널을 확보해야 한다.When there are a plurality of relays in the overlapped section, it is preferable to select a relay 340 having the highest probability of being included in the transmission set. The relay set included in the transmission set is the average channel parameter received from the relay.

Priority is given according to the value. The relay with the highest priority is selected by securing the channel (with low competition probability) without competition, and the relay with the lowest priority must compete with the participating relay (with high competition probability) to secure the channel.

In another embodiment of the present invention, in order to perform a dedicated relay function, the source and the destination select an optimal relay in consideration of the channel state, and the selected relay performs the function of transferring information of the corresponding source and the destination. The optimal relay selection method and apparatus can be easily applied even when a dedicated relay is configured.

The above description is merely illustrative of the technical details of the present invention, and those skilled in the art to which the present invention pertains may various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

1 is a diagram showing an exemplary configuration of an apparatus for calculating a transmission probability of a QoS relay.

2 is a flowchart illustrating a method of calculating a transmission probability of a QoS relay.

3 is a flowchart illustrating a method of selecting a relay when a relay is included or not included in an overlapping section configured with a set value.

4 is a diagram illustrating overlapping intervals determined by QoS thresholds set from a source and a destination.

5 is a diagram illustrating adjusting a QoS threshold to control a collision probability of a competing relay.

Claims (13)

Recognizing a relay network radio channel condition; And Determining an access probability according to the recognized relay radio channel state; Step 2 of determining the access probability according to the recognized relay radio channel state, Receiving a transmission acknowledgment (ACK) message and a retransmission request (NACK) message from a destination (S4); Performing a secondary relay screening operation based on the channel gain between the destination and the relay (S5); Classifying the relay in consideration of the channel gain between the destination and the relay in the QoS relay group estimated from the primary and secondary relay screening operations (S6); And Computing the optimal transmission probability through the section differentiated by the classification (S7) characterized in that it comprises a distributed QoS QoS relay selection method. The method of claim 1, In step 1 of recognizing a relay network radio channel state, Collecting data from a source (S1); Determining channel distribution information between the source and the relay (S2); And determining (S3) whether the channel distribution information is included in the contention relay group and performing a primary relay selection operation (S3). delete The method of claim 2, The channel distribution information includes a channel gain between a source and a relay, a data packet address checking process, a power level check, and no CRC error. The method of claim 2, The primary relay screening work, And a means for selecting a relay whose channel parameter satisfies Equation 9 through a transmission rate, a transmission power, and a QoS threshold β _s set from a source.

Where is the channel parameter between the i th relay and the selected source, β _s is the QoS threshold of the source, SNR is the signal-to-noise ratio, and R is the predetermined target data rate. The method of claim 1, The secondary relay screening work, And a means for selecting a relay that satisfies Equation 10 through a transmission rate, a transmission power, and a QoS threshold β _d set from a destination.

Where is the channel parameter between the i th relay and the destination, β _d is the QoS threshold of the destination, SNR is the signal-to-noise ratio, and R is the predetermined target data rate. The method according to any one of claims 5 and 6, And a transmission rate that participates in contention in each relay is set in proportion to Equation (11).

Where is the channel parameter between the ith relay and the selected source, is the channel parameter between the ith relay and the destination, R is the preset target data rate, and SNR is the signal-to-noise ratio. The method of claim 1, The relay grouping step may include: retrieving the relay by reducing the QoS threshold β _d if the destination cannot use a relay that satisfies the QoS and achieving QoS through one or more relay cooperations Method of choosing QoS relay. In the apparatus for calculating the transmission access probability of each relay, A data storage unit for collecting data from a source; A channel distribution information determining unit recognizing channel distribution information between the source and the retransmission relay; A decoding set determining unit which determines whether the channel distribution information is included in a contention relay group and selects a primary relay; A channel information collecting unit receiving a transmission acknowledgment (ACK) message and a retransmission request (NACK) message from a destination; A transmission set discriminating unit which selects a secondary relay based on a channel gain between the destination and the relay; A relay grouping unit for classifying the QoS relay group estimated from the primary and secondary relay screening operations in consideration of the channel gain between the destination and the relay; And And a transmission probability calculator for calculating an optimal transmission probability through the section differentiated by the classification. The method of claim 9, The channel distribution information includes a channel gain between a source and a relay, a data packet address checking process, a power level check, and no CRC error. The method of claim 10, The decoding set determination unit, And a relay selection means for satisfying equation (9) through a transmission rate, a transmission power set from a source, and a QoS threshold value β _s . The method of claim 9, The transmission set determination unit, And a relay selection means for satisfying equation (10) through a transmission rate set from a destination, a transmission power, and a QoS threshold β _d . The method of claim 8, The upper limit value Pr [outtage] of the destination downtime probability through the grouping step is 1- β _s β _d or less.

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