KR20220013336A - Realy seelcting system of powerline communication network based on noma and method thereof - Google Patents

Abstract

The present technology discloses a relay selecting system for a powerline communication network based on non-orthogonal multiple access (NOMA), and a method thereof. According to a specific embodiment, an outage probability (OP) that an achievable data rate is lower than a target rate set based on the quality of service is derived, with respect to a reception signal of a relay node for operating in a DF mode derived from a channel of a powerline communication network, signal attenuation according to the distance between a node and an operating frequency, and white noise, and an optimal relay node is selected as a maximizing solution for the OP. Accordingly, from the point of view of the powerline communication network, a high data transfer rate, high spectral efficiency, better fairness and low transmission power to meet EMC regulations can be ensured, the operation with high spectral efficiency can be realized based on NOMA with a relay node, and robust properties against signal attenuation and noise can be obtained.

Description

The relay selection system and method of DF mode of cooperative multi-connected powerline communication network

The present invention relates to a system and method for selecting a relay in a DF mode of a cooperative multiple-connected powerline communication network, and more particularly, a plurality of relays with cooperative multiple access (NOMA) of a power domain in a powerline communication network. It relates to a technology for selecting an optimal relay node operating in a decorating-forward (DF) mode based on a closed-form OP (Outage Probability) performance estimation among nodes.

The Power-line Communication (PLC) system has grown from a single power line (SISO) to a multiple power line (MIMO) system in the smart grid and Internet-of-things (IoT). In addition, the PLC system can also be implemented in cooperative communication to improve system performance.

However, the PLC system currently has a low data transmission rate due to a defective transmission channel. In other words, the PLC data transmission channel has impulse noise, impedance mismatch (this reduces the transmission signal output and causes multipath fading), frequency selective multipath fading, electromagnetic compatibility (EMC) requirements, high frequency and distance signal attenuation. is degraded due to the presence of

Here, the impedance mismatch causes multi-path fading and loss of signal power transmission of the power cable, thereby reducing the reliability of the PLC network. This limits the transmission capacity of PLC networks to minimize electromagnetic interference (EMI) to other frequency users (eg wireless systems) and to meet electromagnetic compatibility (EMC) regulations.

However, when the transmission power is low, the signal-to-noise ratio (SNR) is lowered at the destination node of the PLC network, and thus the bottleneck related to the PLC channel, noise, and signal propagation needs to be improved for the robust performance of the powerline communication system.

Meanwhile, in Non-Orthogonal Multiple Access (NOMA), multiple destination nodes are simultaneously provided at the same time and using frequency and spatial resources. For the power domain NOMA, the powerline source node S uses location coding (SC), where user data is multiplexed to different power levels, and the destination node uses the power difference of the powerline source node S's transmit signal to perform continuous interference cancellation (SIC) can be used to recover the desired data. In SIC, the decoding order of the received signal of the destination node is determined according to the channel gain. That is, the decoding process is performed continuously, whereby the received data is successively decoded until the destination node obtains the desired data, and thus, the transmission signal of the power line source node is obtained in the combined received data.

Accordingly, the present applicant selects the optimal relay node of the DF mode with the minimum signal-to-noise ratio in a powerline communication system in which at least one relay node is cooperatively multiple access (NOMA). We want to propose a method that can guarantee transmit power, can operate with high spectral efficiency, and is robust against signal attenuation and noise.

Korean Patent No. 1287291 (2013.07.11.)

An object of the present invention is to select an optimal relay node in DF mode with a minimum signal-to-noise ratio in a powerline communication system in which at least one relay node is cooperative multiple access (NOMA), so that high data rate, high spectral efficiency, better fairness and An object of the present invention is to provide a relay selection system and method for DF mode of a cooperative multi-connected power line communication network that can ensure low transmission power, can operate with high spectral efficiency, and are robust against signal attenuation and noise.

Objects of the present invention are not limited to the objects mentioned above, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

The relay selection system of the DF mode of the cooperative multiple-connected powerline network of an embodiment according to an aspect for achieving the above object is a powerline network in which at least one relay node is located between a source node and at least one destination node, Based on the probability that the data transmission rate of the non-orthogonal multiple access (NOMA) relay node is lower than the target speed, an optimal relay node is selected among at least one relay node, and the power line source node amplified through the selected optimal relay node It is characterized in that it is provided to include a control unit for transmitting the transmission signal to the destination node.

Preferably, in a power line communication network in which at least one relay node is located between the source node and the at least one destination node, the source node transmits the overlapped data by multiplexing the user data using different amounts of power through overlap coding; a relay node that receives the transmission signal from the source node, performs DF mode, decodes the received signal, reconstructs the superimposed signal, and transmits it to the target destination load; a destination node for recovering the user data; and selects an optimal relay node among at least one relay node based on the probability that the data transmission rate of the non-0thogonal multiple access (NOMA) relay node is lower than the target rate, and the source amplified through the selected optimal relay node and a control unit that transmits the transmission signal of the node to the destination node.

Preferably, the control unit includes a probability OP ( Derivation means for deriving Outage Probability) and selection means for selecting an optimal relay node operating in DF mode as a maximizing solution for the probability (OP).

The control unit uses the signal-to-noise ratio for the communication signal at each source node and the relay node and the target data rate of each user, and applies the minimization operator to derive the probability of power failure (OP) between the destination node and the cooperatively multi-connected relay node do.

In addition, the control unit amplifies the overlapped transmission signal based on a predetermined amplification coefficient, and then selects an optimal relay node to deliver the amplified transmission signal to the destination nodes N and F in the second slot, and the destination nodes N and F transmit data. To recover and detect the desired data, successive interference cancellation (SIC) is used to recover the desired data.

According to another embodiment, a relay selection method of a cooperative multi-connected powerline network includes a channel of the powerline network, a distance between a node and an operating frequency in the control unit of the powerline network in which at least one relay node is located between a source node and at least one destination node Deriving a probability (OP) that the achievable data transmission rate is lower than the target rate based on the quality of service with respect to the signal attenuation and the received signal of the relay node derived from white noise; and selecting an optimal relay node operating in a DF mode as a maximizing solution for the probability OP.

According to one embodiment, for the received signal of the relay node operating in the DF mode derived from the channel of the power line communication network, the signal attenuation according to the distance between the node and the operating frequency, and white noise, the achievable data rate is based on the quality of service. By deriving the probability (OP) that is lower than the set target speed and selecting the optimal relay node as a maximizing solution for the derived probability (OP), high data rate, high spectral efficiency, better It can ensure fairness and low transmission power, and can operate with high spectral efficiency through relay node cooperative multiple access, and is robust against signal attenuation and noise.

1 is a diagram showing the configuration of a power line communication system to which an embodiment is applied.
2 and 3 are OP comparison diagrams for each destination node of the system according to an embodiment.
4 is a comparative diagram illustrating a data rate of a system according to an exemplary embodiment.

Specific structural or functional descriptions presented in the embodiments of the present invention are only exemplified for the purpose of describing embodiments according to the concept of the present invention, and the embodiments according to the concept of the present invention may be implemented in various forms. In addition, it should not be construed as being limited to the embodiments described herein, and should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Meanwhile, in the present invention, terms such as first and/or second may be used to describe various components, but the components are not limited to the terms. The above terms are used only for the purpose of distinguishing one component from other components, for example, within the scope without departing from the scope of the rights according to the concept of the present invention, the first component may be named as the second component, Similarly, the second component may also be referred to as the first component.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In describing the embodiment of the present invention, if it is determined that the description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the description thereof is omitted.

In one embodiment at least one relay node can be deployed in amplification and forwarding (AF) or decoding and forwarding (DF) mode. The AF relay node transmits the amplified signal of the source message to the target node. Conversely, the DF relay node decrypts the source message and forwards the re-encoded signal to the destination node. Due to the decoding, the DF relay node is better than the AF relay node with a low signal-to-noise ratio (SNR). Accordingly, the operation of at least one relay node applied to an embodiment in the DF mode will be described as an example.

The relay selection system of the DF mode of the cooperative multi-connected powerline communication network according to an embodiment of the present invention is a powerline communication network in which at least one relay node is located between a source node and at least one destination node. a source node that multiplexes user data using a relay node that receives the transmission signal from the source node, performs DF mode, decodes the received signal, reconstructs the superimposed signal, and transmits it to the target destination load; a destination node for recovering the user data; and selects an optimal relay node among at least one relay node based on the probability that the data transmission rate of the non-0thogonal multiple access (NOMA) relay node is lower than the target rate, and the source amplified through the selected optimal relay node and a control unit that transmits the transmission signal of the node to the destination node.

The control unit determines the probability that the achievable data rate is lower than the target rate set based on the quality of service for the received signal derived from the signal attenuation and white noise according to the distance between the channel of the power line communication network, the node and the operating frequency (Outage Probability) It includes derivation means for deriving , and selection means for selecting an optimal relay node operating in DF mode as a maximizing solution for the probability OP.

The control unit uses the signal-to-noise ratio for the communication signal at each source node and the relay node and the target data rate of each user, and applies a minimization operator to it to apply a minimization operator to the power failure probability (OP) between the destination node and the cooperatively multi-connected relay node. ) is derived.

In addition, the control unit amplifies the overlapped transmission signal based on a predetermined amplification coefficient, and then selects an optimal relay node to deliver the amplified transmission signal to the destination nodes N and F in the second slot, and the destination nodes N and F transmit data. To recover and detect the desired data, successive interference cancellation (SIC) is used to recover the desired data.

Hereinafter, a relay selection system of a DF mode based on cooperative multiple access in a powerline communication network according to an embodiment will be described in detail with reference to the accompanying drawings.

1 is a diagram showing the configuration of a cooperative multiple-connected powerline communication system to which an embodiment is applied, FIGS. 2 and 3 are the cooperative multiple-access (DF NOMA) powerline communication system shown in FIG. 1 (hereinafter referred to as DF NOMA communication system) ), the existing time division multiple access (TDMA) powerline communication system (hereinafter abbreviated as TDMA communication system), and the existing cooperative multiple access powerline communication system (hereinafter referred to as the Direct NOMA communication system) for each destination node It is an OP comparison graph, and FIG. 4 is a graph comparing processing performance of the systems for each of the DF NOMA communication system shown in FIG. 1, the conventional TDMA communication system, and the existing Direct NOMA communication system.

1 to 4 , a cooperative multiple access (NOMA) powerline communication system according to an embodiment is a powerline source node S _, and at least one relay node R ₁ to R _N, and at least one destination node N, It may contain F.

It goes without saying that the cooperative multiple access (NOMA) powerline communication system is only a preferred embodiment, and some components may be added or deleted as necessary. In addition, each component of the cooperative multiple access (NOMA) powerline communication system shown in FIG. 1 represents functional elements that are functionally separated, and a plurality of components may be implemented in a form that is integrated with each other in an actual physical environment. take note of

Here, considering a power line source node S _, and a network for mutual communication between at least one relay node R ₁ to R _N and at least one destination node N, F, each node is configured as a PLC system, and each relay node R ₁ ~ R _N is assumed to operate in DF mode.

And the power line source node S transmits a transmission signal by applying the NOMA protocol transmitted in two time slots. Here, the powerline source node S multiplexes the two destination nodes N and F using different amounts of power during overlap coding. That is, the superposition coded transmission signal generated in the first slot can be expressed by the following equation.

,

, 그리고

는 각각 목적지 노드

의 전송신호이고, 목적지 노드

의 전송신호이며, 전체 전송 전력이다.here,

,

, and

are each destination node

is the transmission signal of the destination node

is the transmission signal of , and is the total transmission power.

And, since the destination node F is farther away than the destination node N, more power is allocated to the destination node F than the destination node N. In this case, the power distribution for the respective powers a ₁ and a ₂ of the two destination nodes N and F satisfies a ₁ >a ₂ and a ₁ +a ₂ =1.

On the other hand, the power line source node S is modeled by lognormal fading considering the discontinuous and irregular effects caused by the connected load. The probability density function (PDF), cumulative distribution function (CDF), and complementary cumulative distribution function (CCDF) for all PLC channels h can be expressed by the following Equations 1 to 3, respectively.

[Equation 1]

[Equation 2]

[Equation 3]

와

는 평균과

의 분산이고

은 스케일링 상수이며

은 가우시안

함수이다.here,

Wow

is the average and

is the dispersion of

is the scaling constant

Silver Gaussian

It is a function.

And, the attenuation of the transmission signal of the power line source node in the distance between the relay node and the destination node and the node and the operating frequency can be specified from the Zimmerman-Dostert model. can be expressed as

[Equation 4]

,

, 그리고

는 각각 거리 (in m), 주파수 (in MHz), 그리고 감쇠계수의 지수이다.

, 와

은 각각 실험 데이터에서 얻은 감쇠 상수들이다.here,

,

, and

are the exponents of distance (in m), frequency (in MHz), and damping factor, respectively.

, Wow

are the attenuation constants obtained from the experimental data, respectively.

Also, the noise of the power line source node S is non-Gaussian, modeled using a Bernouli-Gaussian random process, and is the sum of the ambient noise and the impulse noise. The total noise of all PLC nodes can be inferred from Equation 5 below.

[Equation 5]

는 임펄스 노이즈 확률이고 분산

와

은 각각 주변 잡음의 전력과 주변 임펄스 잡음의 전력이다.here

is the impulse noise probability and the variance

Wow

are the power of the ambient noise and the power of the ambient impulse noise, respectively.

Each relay node R ₁ to R _N receiving the transmission signal from the power line source node S performs the DF mode in which the source message is decoded and the re-encoded signal is transmitted to the target node. Due to the decoding, the DF relay node is better than the AF relay node with a low signal-to-noise ratio (SNR). For example, relay nodes R ₁ to R _N are Attenuating the signal according to the distance between the channel, the node and the operating frequency of the power line network to decode the superimposed transmission signal to the source message and generate a re-encoded signal, and to deliver the transmission signal to the destination node N, F in the next second slot; and deriving a probability (OP) that the achievable data transmission rate is lower than the target rate based on the quality of service for the received signal of the relay node derived from white noise, and operating in DF mode as a maximizing solution for the probability (OP) and a control unit 100 for selecting an optimal relay node.

Hereinafter, an optimal relay node selection process performed by the control unit 100 will be described.

When the powerline source node S transmits a QoS (quality of service) matrix at a fixed data rate, we derive an outage probability (OP), which is the probability that the achievable data rate of the communication system is lower than the QoS-based target rate. The performance of the powerline communication system is determined using the OP. For example, reliable communication is not guaranteed when the power line communication system is out of operation. That is, OP is obtained based on closed-form estimation using the lognormal distribution characteristic. An optimal relay node is selected as a maximization solution for the obtained OP.

That is, the closed state means that the blackout probability (OP) between the destination node and the cooperatively multi-connected relay node can be expressed in a closed form as shown in Equations 6 and 7, respectively.

[Equation 6]

[Equation 7]

이고,here,

ego,

이다.

to be.

와

는 각각 소스 노드와 릴레이 노드 각각의 전송 신호 대 잡음비 SNR이다.

와

은 각각 사용자

와

의 목표 데이터 전송률이다.

은 최대화 연산자이다.here

Wow

is the transmission signal-to-noise ratio SNR of each source node and relay node, respectively.

Wow

is each user

Wow

is the target data rate of

is the maximization operator.

Accordingly, the control unit 100 overlaps the transmission signal with the transmission signal of the power line source node S based on the maximized solution of the blackout probability (OP) between the destination nodes N and F and the cooperatively multi-connected relay nodes R ₁ to R _N (source message) , and selects an optimal relay node in DF mode to deliver data including the re-encoded signal to destination nodes N and F, and transmits data to the selected optimal relay node. Accordingly, the optimal relay node of the DF mode restores the received data by the destination nodes N and F. Destination nodes N, F directly recover data because more power is allocated. First, the destination nodes N, F can recover the desired data using successive interference cancellation (SIC) to recover the data and detect the desired data.

In this case, the throughput of the system may be estimated using the above-described OP in a power line communication system including at least one relay node that is cooperatively multi-connected. In this case, the throughput τ of the system can be expressed by Equation 7 below.

[Equation 7]

2 and 3 are diagrams showing the OPs of each destination node F and N of a powerline communication system having an AF relay node that is cooperatively multi-connected. Referring to FIGS. 2 and 3, a cooperative multiple-access (AF NOMA) power line Communication system (hereinafter abbreviated as DF NOMA power communication system), time division multiple access (TDMA) power line communication system (hereinafter abbreviated as TDMA power communication system), and multiple access (NOMA) power line communication system (hereinafter direct NOMA power) For the OP for each communication system), it can be seen that the DF NOMA power communication system has very good closed-type OP performance compared to the TDMA power communication system and the Direct NOMA power communication system. That is, it can be confirmed that the DF NOMA power communication system shows better performance than the TDMA communication system and the Direct NOMA power communication system.

dB)과 시나리오와 좋지 않은 페이딩 (

dB) 시나리오 모두에서 뚜렷하다. 또한 제안된 DF NOMA 전력선 통신 시스템은 주어진 OP 값을 충족하기 위해 더 적은 전력을 사용한다. TDMA 전력선 통신 시스템과 Direct NOMA 전력선 통신 시스템은

dB일 때, OP 값의

을 달성하기 위해 3dB와 10dB의 전력을 더 필요로 한다. 따라서 제안된 제안된 DF NOMA 전력선 통신 시스템은 간섭이 감소하므로 다른 주파수 사용자와의 간섭을 개선할 수 있다. 목적지 노드

의 OP 성능이 유사함을 알 수 있다.These performance differences show good fading (

dB) and scenarios and poor fading (

dB) is evident in both scenarios. Also, the proposed DF NOMA powerline communication system uses less power to meet the given OP value. TDMA power line communication system and Direct NOMA power line communication system are

In dB, the OP value of

3dB and 10dB more power is required to achieve . Therefore, the proposed DF NOMA powerline communication system can improve the interference with other frequency users because the interference is reduced. destination node

It can be seen that the OP performance of

4 is a view showing processing performance for each of the DF NOMA power communication system, the TDMA powerline communication system, and the Direct NOMA powerline communication system. Referring to FIG. 4, the throughput of the DF NOMA power communication system decreases as the OP value decreases. It can be seen that the system throughput is increased. In addition, referring to Fig. 4, the throughput of the DF NOMA power communication system, the TDMA power line communication system, and the Direct NOMA power line communication system is reduced because more useful data is damaged as the impulse noise increases from 0.01 to 0.2, but the proposed It can be confirmed that the DF NOMA power communication system is the most powerful against impulse noise.

The DF NOMA power communication system according to an embodiment may realize high spectral efficiency and high data transmission rate in a next-generation PLC system design, and may satisfy the requirements of electromagnetic compatibility (EMC).

Accordingly, according to an embodiment, for the received signal of the relay node operating in the DF mode derived from the signal attenuation according to the distance between the channel of the power line communication network, the distance between the node and the operating frequency, and white noise, the achievable data rate is based on the quality of service By deriving the probability (OP) that is lower than the target speed set by It can guarantee better fairness and low transmission power, and it can operate with high spectral efficiency due to relay node cooperative multiple access, and is robust against signal attenuation and noise.

In another embodiment, the relay selection method of the cooperative AF NOMA powerline communication system includes a channel of the powerline network in the control unit of the powerline network in which at least one relay node is located between a source node and at least one destination node, between the node and the operating frequency. Deriving a probability (OP) that the achievable data transmission rate is lower than the target rate based on the quality of service for the signal attenuation according to the distance and the received signal of the relay node derived from white noise; and selecting an optimal relay node operating in a DF mode as a maximizing solution for the probability (OP), wherein each step of the cooperative DF NOMA powerline communication method is a control unit of the cooperative multi-connected relay node described above As the function performed in (100), detailed references are omitted.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and it will be apparent to those skilled in the art that various substitutions, modifications and changes are possible without departing from the technical spirit of the present invention.

Claims (5)

In a power line communication network in which at least one relay node is located between a source node and at least one destination node,
a source node that multiplexes user data using different amounts of power with overlap coding to transmit the overlapped data;
a relay node that receives the transmission signal from the source node, performs DF mode, decodes the received signal, reconstructs the superimposed signal, and transmits it to the target destination load;
a destination node for recovering the user data; and
Based on the probability that the data transmission rate of the non-0thogonal multiple access (NOMA) relay node is lower than the target speed, an optimal relay node is selected among at least one relay node, and the source node amplified through the selected optimal relay node The relay selection system of the DF mode of the cooperative multi-connected power line communication network, characterized in that it comprises; According to claim 1,
The control unit is
For the received signal derived from the signal attenuation according to the distance between the channel of the power line communication network, the node and the operating frequency, and white noise,
A derivation means for deriving the probability OP (Outage Probability) that the achievable data rate is lower than the target rate set based on the service quality;
and selecting means for selecting an optimal relay node operating in the DF mode as a maximizing solution for the probability (OP). According to claim 1,
The control unit uses the signal-to-noise ratio for the communication signal at each source node and the relay node and the target data rate of each user, and applies a minimization operator to it to determine the probability of a power outage (OP) between the destination node and the cooperatively multi-connected relay node. A relay selection system in DF mode of a cooperative multiple-connected power line communication network, characterized in that deriving. According to claim 1,
The control unit amplifies the overlapped transmission signal based on a predetermined amplification coefficient and then selects an optimal relay node to deliver the amplified transmission signal to the destination nodes N and F in the second slot,
wherein the destination nodes N, F recover the desired data using successive interference cancellation (SIC) to recover the data and detect the desired data. In the control unit of the power line communication network in which at least one relay node is located between the source node and at least one destination node, the signal attenuation according to the distance between the channel of the power line communication network, the node and the operating frequency, and the received signal of the relay node derived from white noise deriving a probability (OP) that the achievable data transmission rate is lower than the target rate based on the quality of service; and
and selecting an optimal relay node operating in the DF mode as a maximizing solution for the probability (OP).

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