KR20210157821A - Method and apparatus for transmitting and receiving signal in two-way full-duplex relay network - Google Patents

Abstract

The present invention relates to a method for transmitting and receiving a signal in a two-way full-duplex relay network to remove self-interference and an apparatus thereof. According to one embodiment of the present invention, a communication method for a replay in a two-way full-duplex relay network comprises the following steps: storing, in a first time slot, a received signal (r_∈) including a first signal (x_S1) received from a first source node (S_1), a second signal (x_S2) received from a second source node (S_2), and a self-interference signal of the relay (R) in a buffer; applying a first reception beamforming vector to the signal stored in the buffer to remove influence of the self-interference signal of the relay and the second signal to detect the first signal; removing the detected first signal from the signal stored in the buffer and applying a second reception beamforming vector to detect the second signal; and transmitting a signal (x_R) acquired by combining the detected first signal and the detected second signal to the first source node and the second source node in a second time slot.

Description

Method and apparatus for transmitting and receiving signals in a full-duplex bidirectional relay network

The present disclosure relates to wireless communication, and more particularly, to a method and apparatus for transmitting and receiving a signal in a wireless communication system including a full-duplex bidirectional relay.

Full-duplex communication is a technology for transmitting and receiving signals using the same time and frequency resources. In full-duplex communication, since a signal transmitted from a device may act as interference to a receiver of the device, a method for eliminating self-interference is required.

Bidirectional relay communication may support information exchange between two devices by a relay transferring a signal received from the first device to a second device and transferring a signal received from the second device to the first device.

Conventionally, there is no method in which all devices (or nodes) of a network support full-duplex communication including a bidirectional relay.

It is an object of the present disclosure to provide a method and an apparatus for bidirectional full-duplex relay communication.

An additional technical object of the present disclosure is to provide a method and apparatus for eliminating self-interference in a bidirectional full-duplex relay communication method and increasing overall system performance.

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be able

A communication method of a relay in a full-duplex bidirectional relay network according to an aspect of the present disclosure, a first signal (x _{S1 ) received from a first source node (S 1} ) in a first time slot, a second source node (S ₂ ) _{Storing the received signal (r ∈} ) including the second signal (x _S2 ) and the self-interference signal of the relay (R) received from the buffer; detecting the first signal by applying a first reception beamforming vector to the signal stored in the buffer to remove the influence of the self-interference signal and the second signal of the relay; removing the detected first signal to the signal stored in the buffer and then detecting the second signal by applying a second reception beamforming vector; _{and transmitting a signal (x R} ) obtained by combining the detected first signal and the detected second signal to the first source node and the second source node in a second time slot.

A relay device for performing communication in a full-duplex bidirectional relay network according to an additional aspect of the present disclosure includes: a transceiver; Memory; and a processor. The processor includes a first signal (x _{S1 ) received from a first source node (S 1} ) and a second signal (x _S2 ) received from a second source node (S ₂ ) in a first time slot through the transceiver _{and storing the received signal (r ∈} ) including the self-interference signal of the relay (R) in the memory; detecting the first signal by applying a first reception beamforming vector to the signal stored in the memory to cancel the influence of the self-interference signal of the relay and the second signal; removing the detected first signal to the signal stored in the memory and then detecting the second signal by applying a second reception beamforming vector; _{A signal (x R} ) obtained by combining the detected first signal and the detected second signal may be configured to be transmitted to the first source node and the second source node in a second time slot through the transceiver. .

The features briefly summarized above with respect to the present disclosure are merely exemplary aspects of the detailed description of the present disclosure that follows, and do not limit the scope of the present disclosure.

According to the present disclosure, a method and apparatus for bidirectional full-duplex relay communication may be provided.

According to the present disclosure, a method and apparatus for removing self-interference in a bidirectional full-duplex relay communication method and increasing overall system performance may be provided.

The effects obtainable in the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present disclosure belongs from the description below. will be.

1 is a diagram for explaining full-duplex communication to which the present disclosure can be applied.
2 is a diagram for explaining a self-interference signal of full-duplex communication to which the present disclosure can be applied.
3 is a diagram illustrating an example of a relay network to which the present disclosure can be applied.
4 is a diagram for explaining steps of two-way communication to which the present disclosure can be applied.
5 is a diagram illustrating an example of a system model to which the present disclosure can be applied.
6 is a diagram illustrating the configuration of a relay device and a terminal device according to the present disclosure.
7 is a diagram illustrating an outage probability in contrast to examples of the present disclosure.
8 is a diagram illustrating an outage probability in the case of examples according to the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present disclosure pertains can easily implement them. However, the present disclosure may be embodied in several different forms and is not limited to the embodiments described herein.

In describing the embodiments of the present disclosure, if it is determined that a detailed description of a well-known configuration or function may obscure the gist of the present disclosure, a detailed description thereof will be omitted. And, in the drawings, parts not related to the description of the present disclosure are omitted, and similar reference numerals are attached to similar parts.

In the present disclosure, when it is said that a component is "connected", "coupled" or "connected" with another component, it is not only a direct connection relationship, but also an indirect connection relationship in which another component exists in the middle. may also include. In addition, when a component is said to "include" or "have" another component, it means that another component may be further included without excluding other components unless otherwise stated. .

In the present disclosure, terms such as first, second, etc. are used only for the purpose of distinguishing one component from other components, and do not limit the order or importance between the components unless otherwise specified. Accordingly, within the scope of the present disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment is referred to as a first component in another embodiment. can also be called

In the present disclosure, components that are distinguished from each other are for clearly describing respective characteristics, and do not necessarily mean that the components are separated. That is, a plurality of components may be integrated to form one hardware or software unit, or one component may be distributed to form a plurality of hardware or software units. Accordingly, even if not specifically mentioned, such integrated or dispersed embodiments are also included in the scope of the present disclosure.

In the present disclosure, components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, an embodiment composed of a subset of components described in one embodiment is also included in the scope of the present disclosure. In addition, embodiments including other components in addition to components described in various embodiments are also included in the scope of the present disclosure.

The present disclosure relates to communication between network nodes in a wireless communication system. The network node may include one or more of a base station, a terminal, or a relay. The term base station (BS) may be replaced with terms such as fixed station, Node B, eNodeB (eNB), ng-eNB, gNodeB (gNB), and access point (AP). . A terminal may be replaced with terms such as User Equipment (UE), Mobile Station (MS), Mobile Subscriber Station (MSS), Subscriber Station (SS), and non-AP station (non-AP STA).

A wireless communication system may support communication between a base station and a terminal or may support communication between terminals. In communication between the base station and the terminal, a downlink (DL) means communication from the base station to the terminal. Uplink (UL) refers to communication from a terminal to a base station. Inter-terminal communication may include various communication methods or services such as Device-to-Device (D2D), Vehicle-to-everything (V2X), Proximity Service (ProSe), and sidelink communication. In the communication between terminals, the terminal may be implemented in the form of a sensor node, a vehicle, a disaster warning device, or the like.

In addition, examples of the present disclosure may be applied to a wireless communication system including a relay or a relay node (RN). When a relay is applied to communication between a base station and a terminal, the relay may function as a base station for the terminal, and the relay may function as a terminal for the base station. Meanwhile, when the relay is applied to communication between terminals, the relay may function as a base station for each terminal.

The present disclosure may be applied to various multiple access schemes of a wireless communication system. For example, multiple access schemes include Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA). , OFDM-FDMA, OFDM-TDMA, OFDM-CDMA, Non-Orthogonal Multiple Access (NOMA), and the like. In addition, a wireless communication system to which the present disclosure can be applied may support a Time Division Duplex (TDD) scheme in which uplink and downlink communications use distinct time resources, and Frequency Division (FDD) uses distinct frequency resources. Duplex) method may be supported.

In the present disclosure, transmitting or receiving a channel includes the meaning of transmitting or receiving information or a signal through a corresponding channel. For example, transmitting the control channel means transmitting control information or a signal through the control channel. Similarly, to transmit a data channel means to transmit data information or a signal over the data channel.

Hereinafter, embodiments of the present disclosure for bidirectional full-duplex relay communication will be described.

Examples of the present disclosure relate to a method for removing self-interference occurring in a full-duplex two-way communication system and effectively exchanging information between source nodes.

1 is a diagram for explaining full-duplex communication to which the present disclosure can be applied.

2 is a diagram for explaining a self-interference signal of full-duplex communication to which the present disclosure can be applied.

The existing wireless communication system uses time division multiplexing (TDD) for dividing uplink and downlink resources in the time domain or frequency division multiplexing (FDD) for dividing uplink and downlink signals in the frequency domain. Interference between link signals is avoided. Recently, a full duplex communication technology for transmitting and receiving signals using the same time and frequency resources has been proposed. Full-duplex communication can achieve up to twice the frequency usage efficiency compared to half-duplex communication. However, a transmission signal of a source node performing full-duplex communication may act as interference to its own receiver. This self-interference (loopback interference) signal, compared to a signal received from other nodes that are relatively far away, the signal strength is very large. Therefore, if the self-interference signal is not effectively removed, the communication performance is seriously deteriorated.

3 is a diagram illustrating an example of a relay network to which the present disclosure can be applied.

4 is a diagram for explaining steps of two-way communication to which the present disclosure can be applied.

Cooperative communication through the relay node can increase the coverage of the network and achieve high transmission rate and quality of service (QoS). In addition, if two-way communication using two time slots is considered, frequency use efficiency can be further increased. In this case, the relay receives and processes signals from two source nodes, a first source node and a second source node (source1 and source2) (first phase or first time slot), and then again two source nodes By transmitting a signal (second stage or second time slot), information can be exchanged between two source nodes.

In the example of FIG. 3 , H _SR represents a channel from a source node to a relay. H _RD represents a channel from a relay (relay) to a destination (destination) node. H _SD represents a channel from a source node to a destination node. However, since the present disclosure does not consider direct signal transmission and reception through a channel between the source node and the destination node, and considers transmission and reception of signals between the source node and the destination node via a relay, H _SD and H _DS may not be considered. have.

Conventionally, a unidirectional relay system in which only a relay node supports full-duplex communication and a source node and a destination node do not support full-duplex communication has been proposed. However, if all nodes support full-duplex communication and perform bidirectional communication using two timeslots, frequency use efficiency can be greatly improved.

In addition, the prior art of designing a filter for processing a signal in two-way communication has also been proposed. However, since this bidirectional communication considers that all nodes do not support full-duplex communication, efficiency can be further increased through full-duplex communication.

In the present disclosure, a bidirectional relay network in which all nodes support full-duplex communication is considered.

A method of transmitting a signal from a relay to each node considers a DF (Decode and Forward) relay method.

The relay should effectively detect two different signals received from each node while canceling the self-interference in the first step of FIG. 4 .

When each source node transmits a signal using similar power, an error floor occurs even in a high signal-to-noise ratio (SNR) region in the outage probability performance of the entire system and the performance There is a problem of this deterioration.

In order to solve this problem, the present disclosure proposes a technique of using a buffer (or memory) of a finite size in a relay.

Beamforming (SNR) that completely eliminates self-interference at each node while effectively detecting signals received from other source nodes in the relay and maximizing the instantaneous SNR or signal-to-noise and interference ratio (SINR) between each node. beamforming) is proposed.

Accordingly, even if each node uses similar power, an error floor does not exist in the SNR region where the outage probability of the system is high, and a diversity order can be obtained in proportion to the number of antennas.

5 is a diagram illustrating an example of a system model to which the present disclosure can be applied

In FIG. 5 , it is assumed that all nodes of the network (eg, source 1, relay, and source 2) support full-duplex communication. Also, in the present disclosure, it is assumed that all nodes completely know the channel.

In the example of FIG. 5 , Hab represents a channel from a to b. a or b may be one of S ₁ (source 1), S ₂ (source 1), and R (relay). If a=b, it indicates a channel experienced by the self-interference signal of the corresponding node.

In the example of FIG. 5 , t _a represents a transmit precoding matrix (or transmit beamforming vector) of a, and r _a represents a receive precoding matrix (or receive beamforming vector) of a.

In the example of FIG. 5 , w _R denotes a reception precoding matrix (or reception beamforming vector) of _{the relay, and W T} denotes a transmission precoding matrix (or transmission beamforming vector) of the relay.

The signal received by the relay (r _∈ ), that is, the signal from the source 1, the signal from the source 2, and the self-interference signal received by the relay may be expressed as in Equation 1 below.

In Equation 1, P _a represents the transmit power of the node a. x _a represents the signal (or message or data) transmitted by node a. n _a represents the noise detected by node a.

및

를 만족한다. in Equation 1

and

is satisfied with

Signal (r _R) applied to the received signal (r _∈) relay in which a reception beam forming _(R w) in the equation (1) can be expressed by equation (2).

In addition, assuming that the self-interference signal in the relay is completely removed by applying appropriate reception beamforming in Equation 2, the signal r _R ′ from which the self-interference signal is removed can be expressed as Equation 3 .

The relay may detect the received signal by applying a Successive Interference Cancellation (SIC) technique to the received signal. SIC performance is determined according to the decoding order of the received signal.

When the distance from the relay to the source 1 is closer than the distance from the relay to the source 2, or the channel environment between the relay and the source 1 is better than the channel environment between the relay and the source 2 in the situation where the source 2 has mobility, etc. can be assumed. For example, the relay may detect the signal from source 1 before the signal from source 2.

In this case, the signal-to-noise and interference ratio (SINR) for the signal from each source in the relay can be expressed as Equation (4).

In Equation 4, γ _ab represents the SINR of the signal received by the node b from the node a.

As shown in Equation 4, even if the magnetic interference is completely removed from the relay, if the power of the signal received by the relay from source 2 is large, the SINR of the signal received by the relay from source 1 may seriously degrade performance. have.

In order to solve this problem, the present disclosure proposes a method of completely separating a self-interference signal from a relay and a signal received from each source by the relay using a buffer in the relay.

Specifically, the relay stores the _{received signal r ∈} in the buffer, and then applies the first receive beamforming vector w _{R1 appropriate to the r ∈} signal to remove the influence of the self-interference self-interference signal and the signal received from the source 2. have. _{In this case, the SINR for the signal (x S1} ) transmitted from the source 1 detected by the relay may be expressed as Equation 5.

_{In r ∈} stored in the buffer, _{the second reception beamforming vector w R2} may be applied to remove the self-interference signal after removing the influence on the signal from the source 1 detected by the relay. _{In this case, the SINR for the signal (x S2} ) transmitted from the source 2 detected by the relay may be expressed as Equation (6).

A signal x _{R obtained by synthesizing signals x S1} and x _S2 transmitted from two source nodes detected by the relay may be expressed as Equation 7 below. The composite signal may be sent to each source.

In Equation 7, α _a represents a synthesis ratio applied to a signal that the relay intends to transmit to node a.

R signal _S1 to a signal received from the relay to remove the self interference from the source 1 is applied to the receiving beam forming vector r _S1 it can be expressed as Equation (8).

_{In Equation 8, since the signal x S1} transmitted by the source 1 to the relay in the previous time slot is a signal that the source 1 already knows, the signal r _S1 ' from which the influence is removed can be expressed as in Equation 9.

이다.in Equation 9

to be.

_{In addition, the SINR for the signal that the source 1 receives from the relay (that is, the signal x S2} transmitted from the source 2 to the relay in the first step is transmitted from the relay to the source 1 in the second step) is as shown in Equation 10 can be expressed

_{Next, the signal x S1} transmitted from the source 1 is transmitted to the source 2 through the relay may be detected in a manner similar to the above-described example. That is, in Equations 8 to 10, the signal transmitted to the source 2 may be expressed by substituting the source 2 for the items described with reference to the source 1 and the source 1 for the items described with the source 2 as the reference.

Specifically, the r signal _S2 to a signal received from the relay to remove the self interference from the source 2, applying the reception beam forming vector r _S2 can be expressed as Equation (11).

_{In Equation 11, since the signal x S2} transmitted by the source 2 to the relay in the previous time slot is a signal that the source 2 already knows, the signal r _S2 ' from which the influence is removed can be expressed as in Equation 12.

이다.in Equation 12

to be.

_{In addition, the SINR for the signal that the source 2 receives from the relay (that is, the signal x S1} transmitted from the source 1 to the relay in the first step is transmitted from the relay to the source 2 in the second step) is as shown in Equation 13 can be expressed

Hereinafter, a beamforming design according to the present disclosure will be described.

Table 1 below exemplarily shows a beamforming design method (or algorithm) of the entire system when a buffer is used in the relay according to the present disclosure.

In step 1 of Table 1, as described with reference to FIG. 5, W _T corresponds to a transmission beamforming matrix in the relay. In the present disclosure, since it is assumed that each source node transmits one stream to the relay, the relay may decode and then synthesize the two streams received from the source 1 and the source 2 . When the relay synthesizes two different streams _{and transmits them to each source node using the W T} beamforming matrix, the SINR value of the stream received by each source node is maximized and at the same time, the relay is linked with _{w R} In order to remove the self-interference signal, _{beamforming matrices of W T} and w _R may be designed, respectively. Here, it is assumed that the size of the _{W T beamforming matrix is N tR} × 2, and N _tR corresponds to the number of transmit antennas of the relay. In addition, t _S1 is a transmission beamforming vector in the source node 1, and it _{is assumed that the size is N tS1} × 1, and N _tS1 corresponds to the number of transmission antennas of the source 1. In addition, t _S2 is a transmit beamforming vector in the source node 2, and it _{is assumed that the size is N tS2} × 1, and N _tS2 corresponds to the number of transmit antennas of the source 2 .

As specified in steps 2 and 13 of Table 2, the processes of steps 3 to 12 may be repeated until the SINR value is maximized and the self-interference signal is converged to a beamforming matrix or beamforming vector from which the self-interference signal is removed.

In order to remove the self-interference signal and _{the signal for x S2} in the relay, a reception beamforming vector corresponding to a null space for both channels must be applied. The corresponding null space can be expressed as Equation (14). In Equation 14, NrR corresponds to the number of receive antennas of the relay.

과 같이 표현될 수 있다. In step 3 of Table 3, the zero space for self interference (SI) and user interference (IUI) in the relay (R) may be expressed as Equation 14. Here, R ₁ may correspond to a space spanning the self-interference signal of the relay and signals transmitted from the source 2 (ie, received by the relay). The _{null space for R 1} is in Equation 14

can be expressed as

_{In the relay, w R1} may be applied to decode _{x S1} , which is a signal transmitted from source 1. Here, when the relay _{decodes x S1} , the self-interference signal and the signal x _S2 received from the source 2 may act as user interference. _{An optimal reception beamforming matrix w R} for removing such self-interference and user interference can be designed.

In step 4 of Table 1, the transmit beamforming vector t _S1 of the source 1 may be designed as in Equation 15 such that the SNR of the signal received by the relay from the source 1 is maximized.

공간 내에서 설계되므로, 소스 1으로부터 릴레이로의 채널에 w_R1이 곱해진 유효 채널(effective channel)의 이득이 최대가 되도록 소스 1의 송신 빔포밍 벡터가 설계될 수 있다. 즉, t_S1은 유효 채널 행렬의 최대 고유 값에 해당하는 고유 벡터가 되도록 설계될 수 있다.The relay's receive beamforming matrix w _R1 is

Since it is designed in space, the transmit beamforming vector of the source 1 may be designed such that the gain of the effective channel obtained by multiplying the channel from the source 1 to the relay by w _{R1 is maximized.} That is, t _S1 may be designed to be an eigenvector corresponding to the maximum eigenvalue of the effective channel matrix.

공간 내에서, 소스 1의 송신 빔포밍 벡터와, 소스 1으로부터 릴레이로의 채널의 곱인 h_S1R에 정렬되도록 설계될 수 있다. 예를 들어, w_R1은 수학식 16과 같이 설계될 수 있다.In step 5 of Table 1, w _R1 in Equation 15 may be designed such that the SNR of the signal received by the relay from the source 1 becomes the maximum. Specifically, w _R1 is

In space, it can be designed to align to _{h S1R which} is the product of the transmit beamforming vector of source 1 and the channel from source 1 to the relay. For example, w _R1 may be designed as in Equation 16.

_{The signal x S1} transmitted from source 1 to the relay is decoded _{based on t S1} which is the transmit beamforming vector of source 1 calculated in steps 4 and 5 of Table 1 and _{w R1} which is the receive beamforming matrix from source 1 in the relay. can The relay can decode _{x S2} after removing the influence of _{x S1} from the received signal stored in the buffer.

The relay's self-interference signal component still exists _{in the signal from which the influence of x S1} is removed from the signal stored in the relay's buffer, which may act as interference when decoding _{x S2.} Therefore, in order to design the reception beamforming matrix w _{R1 for decoding x S2} in the relay, it may be considered to remove the self-interference signal.

는 수학식 17과 같이 표현될 수 있다. In step 6 of Table 1, the zero space for self-interference (SI) in the relay (R)

can be expressed as in Equation 17.

In step 7 of Table 1, the transmit beamforming vector t _S2 of the source 2 may be designed as in Equation 18 such that the SNR of the signal received by the relay from the source 2 is maximized.

공간 내에서 설계되므로, 소스 2로부터 릴레이로의 채널에 w_R2가 곱해진 유효 채널(effective channel)의 이득이 최대가 되도록 소스 2의 송신 빔포밍 벡터가 설계될 수 있다. 즉, t_S2는 유효 채널 행렬의 최대 고유 값에 해당하는 고유 벡터가 되도록 설계될 수 있다.The relay's receive beamforming matrix w _R2 is

Since it is designed in space, the transmit beamforming vector of the source 2 may be designed so that the gain of the effective channel obtained by multiplying the channel from the source 2 to the relay by w _{R2 is maximized.} That is, t _S2 may be designed to be an eigenvector corresponding to the maximum eigenvalue of the effective channel matrix.

공간 내에서, 소스 2의 송신 빔포밍 벡터와, 소스 2로부터 릴레이로의 채널의 곱인 h_S2R에 정렬되도록 설계될 수 있다. 예를 들어, w_R2는 수학식 19와 같이 설계될 수 있다.In step 8 of Table 1, w _R2 in Equation 18 may be designed such that the SNR of the signal received by the relay from the source 2 becomes the maximum. Specifically, w _R2 is

In space, it can be designed to align to _{h S2R , which} is the product of the transmit beamforming vector of source 2 and the channel from source 2 to the relay. For example, w _R2 may be designed as in Equation 19.

_{Based on t S2} , which is the transmit beamforming vector of source 2 calculated in steps 7 and 8 of Table 1, _{and w R2} , which is the receive beamforming matrix from source 2 in the relay, the signal x _S2 transmitted from source 2 to the relay is decoded. can

The reception beamforming vector at each source and the transmission beamforming matrix in the relay may be designed similarly to the above process.

및

로 표현될 수 있다. 여기서, N_rS1 및 N_rS2는 각각 소스 1 및 소스 2의 수신 안테나 개수에 해당할 수 있다. Specifically, in step 9 of Table 1, in a manner similar to the zero space in the relay of steps 3 and 6, the null space for magnetic interference (SI) at _{source 1 (S 1} ) and source 2 (S _{2 ) is} each

and

can be expressed as Here, N _rS1 and N _rS2 may correspond to the number of reception antennas of the source 1 and the source 2, respectively.

In step 10 of Table 1, in a manner similar to the design of the transmit beamforming matrix of source 1 and source 2 to the relay in steps 4 and 7, the transmit beamforming matrix w _T,S1 from the relay to the source 1 , and from the relay A transmit beamforming matrix w _T,S2 to source 1 may be designed.

In step 11 of table 1, the relay of step 5 and step 8 receive the receive beamforming vector r _S1 from the relay of source 1 , and the relay of source 2 in a similar way to the design of the receive beamforming matrix from source 1 and source 2 A receive beamforming vector r _S2 from can be designed.

In step 12 of Table 1, the transmit beam forming matrix of relays W _T, the transmit beamforming matrix from the relay to the source 1 w _{T, S1} and transmission beamforming matrix to source 2 from the relay w _T, be designed on the basis of the _S2 can Here, in this example, when transmitting from the relay to each source node, the optimized power allocation is not considered and the same power is distributed (ie, w _T,S1 and w _T,S2 are multiplied by the same coefficient value). A forming matrix W _T can be designed.

According to the above-described embodiments of the present disclosure, in a two-way communication system in which nodes in a wireless communication system support full-duplex communication, even if self-interference is completely removed and the SNR gain of each link is maximized, a transmission/reception beamforming technique of each node This can be designed

In addition, in a bi-directional communication system in which all nodes support full-duplex communication, the relay uses a buffer to completely separate self-interference and signals from both sources, so the outage probability is dramatically reduced compared to the system in which the relay does not use a buffer. can be improved with

6 is a diagram illustrating the configuration of a relay device and a terminal device according to the present disclosure.

The relay device 600 may include a processor 610 , an antenna unit 620 , a transceiver 630 , and a memory 640 .

The processor 610 performs baseband-related signal processing and may include an upper layer processing unit 611 and a physical layer processing unit 615 . The higher layer processing unit 611 may process the operation of the MAC layer, the RRC layer, or higher layers. The physical layer processing unit 615 may process operations (eg, downlink transmission signal processing, uplink reception signal processing, etc.) of the PHY layer. The processor 610 may control the overall operation of the relay device 600 in addition to performing baseband-related signal processing.

The antenna unit 620 may include one or more physical antennas, and when it includes a plurality of antennas, it may support MIMO transmission/reception. The transceiver 630 may include an RF transmitter and an RF receiver. The memory 640 may store operation-processed information of the processor 610 , software related to the operation of the relay device 600 , an operating system, an application, and the like, and may include components such as a buffer.

The processor 610 of the relay device 600 may be configured to implement the operation of the relay in the embodiments described in the present invention.

The physical layer processing unit 515 is a first signal (x _{S1 ) received from the first terminal (S 1} ) in the first time slot through the transceiver 530, the second signal received from the second terminal (S _{2 ) (} x _{S2 ) and the received signal r ∈} including the self-interference signal of the relay R may be stored in the memory 540 or a buffer.

The physical layer processing unit 515 may detect the first signal by applying the first reception beamforming vector to the signal stored in the buffer to remove the influence of the relay self-interference signal and the second signal. Also, the upper layer processing unit 515 may detect the second signal by removing the first signal detected from the signal stored in the buffer and then applying the second reception beamforming vector.

_{The physical layer processing unit 515 may transmit a signal (x R} ) obtained by synthesizing the detected first signal and the detected second signal to the first terminal and the second terminal in the second time slot through the transceiver 530 . have.

The higher layer processing unit 514 may determine a transmission beamforming matrix and a reception beamforming matrix of the relay according to the beamforming design method described with reference to Table 1, for example.

The terminal device 650 may include a processor 660 , an antenna unit 670 , a transceiver 680 , and a memory 690 .

The processor 660 performs baseband-related signal processing and may include an upper layer processing unit 661 and a physical layer processing unit 665 . The higher layer processing unit 661 may process operations of the MAC layer, the RRC layer, or higher layers. The physical layer processor 665 may process PHY layer operations (eg, downlink reception signal processing, uplink transmission signal processing, etc.). The processor 660 may control the overall operation of the terminal device 660 in addition to performing baseband-related signal processing.

The antenna unit 670 may include one or more physical antennas, and when it includes a plurality of antennas, it may support MIMO transmission/reception. The transceiver 680 may include an RF transmitter and an RF receiver. The memory 690 may store information processed by the processor 660 , software related to the operation of the terminal device 650 , an operating system, an application, and the like, and may include components such as a buffer.

The processor 660 of the terminal device 650 may be configured to implement the operation of a source node (eg, source 1 or source 2) or a destination node in the embodiments described in the present invention.

The physical layer processing unit 565 of the first terminal may transmit the first signal to the relay by applying the transmit beamforming vector in the first time slot through the transceiver 530 .

The physical layer processing unit 565 of the first terminal may receive the synthesized signal from the relay in the second time slot through the transceiver 530 and detect the second signal from the synthesized signal by applying a receive beamforming vector.

The upper layer processing unit 561 of the first terminal may determine the transmit beamforming vector and the receive beamforming vector of the first terminal, for example, according to the beamforming design method described with reference to Table 1.

The physical layer processing unit 565 of the second terminal may transmit the second signal to the relay by applying the transmit beamforming vector in the first time slot through the transceiver 530 .

The physical layer processing unit 565 of the second terminal may receive the synthesized signal from the relay in the second time slot through the transceiver 530 and detect the first signal from the synthesized signal by applying a receive beamforming vector.

The upper layer processing unit 561 of the second terminal may determine the transmit beamforming vector and the receive beamforming vector of the second terminal, for example, according to the beamforming design method described with reference to Table 1.

In the operation of the relay device 600 and the terminal device 650 , the descriptions of the relay and the source node in the examples of the present invention may be applied in the same manner, and overlapping descriptions will be omitted.

7 is a diagram illustrating an outage probability in contrast to examples of the present disclosure.

8 is a diagram illustrating an outage probability in the case of examples according to the present disclosure.

7 and 8 show simulation results for comparing diversity orders according to the number of receiving antennas of a relay. It is assumed that the number of antennas is 4 in all nodes except for the number of relay receiving antennas. In addition, it is assumed that the transmission power of the relay is 30 dB, and the transmission power of the source 1 and the transmission power of the source 2 are the same.

The example of FIG. 7 shows the outage probability when the relay does not use the buffer, and the example of FIG. 8 shows the outage probability when the relay uses the buffer.

Example methods of the present disclosure are expressed as a series of operations for clarity of description, but this is not intended to limit the order in which the steps are performed, and if necessary, each step may be performed simultaneously or in a different order. In order to implement the method according to the present disclosure, other steps may be included in addition to the illustrated steps, other steps may be excluded from some steps, or additional other steps may be included except some steps.

Various embodiments of the present disclosure do not list all possible combinations, but are intended to describe representative aspects of the present disclosure, and the details described in various embodiments may be applied independently or in combination of two or more.

In addition, various embodiments of the present disclosure may be implemented by hardware, firmware, software, or a combination thereof. For implementation by hardware, one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), general purpose It may be implemented by a processor (general processor), a controller, a microcontroller, a microprocessor, and the like.

The scope of the present disclosure includes software or machine-executable instructions (eg, operating system, application, firmware, program, etc.) that cause operation according to the method of various embodiments to be executed on a device or computer, and such software or and non-transitory computer-readable media in which instructions and the like are stored and executable on a device or computer.

Claims (11)

A method of communicating a relay in a full-duplex bidirectional relay network, the method comprising:
A first signal (x _S1 ) received from a first source node (S ₁ ), a second signal (x _S2 ) received from a second source node (S ₂ ) and a magnetic field of the relay (R) in a first time slot Storing the _{received signal (r ∈} ) including the interference signal in a buffer;
detecting the first signal by applying a first reception beamforming vector to the signal stored in the buffer to remove the influence of the self-interference signal and the second signal of the relay;
removing the detected first signal to the signal stored in the buffer and then detecting the second signal by applying a second reception beamforming vector; and
_{A relay communication method comprising transmitting a signal (x R} ) obtained by combining the detected first signal and the detected second signal to the first source node and the second source node in a second time slot. .
The method of claim 1,
The received signal (r _∈ ) is defined by the following equation,

Here, Hab represents a channel from a to b, a or b represents _one of S 1 , S ₂ , R, and represents a channel of a self-interference signal of a or b with a=b,
t _a represents a transmit precoding matrix or transmit beamforming vector of a,
r _a represents a reception precoding matrix or reception beamforming vector of a,
w _R represents a receive precoding matrix or a receive beamforming vector of the relay,
W _T represents the transmit precoding matrix or transmit beamforming vector of the relay,
P _a represents the transmit power of a,
n _a represents the noise detected by a,

and

A relay communication method that satisfies
3. The method of claim 2,
_{A signal (x R} ) obtained by synthesizing the detected first signal and the detected second signal is defined by the following equation,

Here, α _a represents a synthesis ratio applied to a signal transmitted by the relay to a, a relay communication method.
4. The method of claim 3,
A signal r _S1 transmitted from the relay to the first source node and to which the reception beamforming vector of the first source node is applied is defined as in the following equation,

The signal (r _S1 ') obtained by removing the first signal from the first source node is defined as in the following equation,

here,

In, relay communication method.
5. The method of claim 4,
A signal (r _S2 ) transmitted from the relay to the second source node and to which the reception beamforming vector of the second source node is applied is defined by the following equation,

A signal (r _S2 ') obtained by removing the second signal from the second source node is defined by the following equation,

here,

In, relay communication method.
6. The method of claim 5,
The transmit beamforming vector (t _S1 ) of the first source node is defined by the following equation,

The first reception beamforming vector w _R1 is defined as in the following equation,

is defined as the formula below,

,
Relay communication method.
7. The method of claim 6,
The transmit beamforming vector (t _S2 ) of the second source node is defined by the following equation,

The second reception beamforming vector w _R2 is defined as in the following equation,

is defined as the formula below,

,
Relay communication method.
8. The method of claim 7,
_{The transmission beamforming vector (w T, S1} ) of the relay to the first source node is defined as the following equation,

_{The reception beamforming vector r S1} of the first source node is defined by the following equation,

is defined as the formula below,

,
Relay communication method.
9. The method of claim 8,
_{A transmission beamforming vector (w T, S2} ) of the relay to the second source node is defined by the following equation,

_{The reception beamforming vector r S2} of the second source node is defined by the following equation,

is defined as the formula below,

,
Relay communication method.
10. The method of claim 9,
The transmission beamforming matrix (W _T ) of the relay is defined by the following equation,

,
Relay communication method.
A relay device for performing communication in a full-duplex bidirectional relay network, comprising:
transceiver;
Memory; and
including a processor;
The processor is
A first signal (x _{S1 ) received from a first source node (S 1} ) in a first time slot through the transceiver, a second signal (x _S2 ) received from a second source node (S ₂ ) and the relay ( _{storing the received signal (r ∈} ) including the self-interference signal of R) in the memory;
detecting the first signal by applying a first reception beamforming vector to the signal stored in the memory to cancel the influence of the self-interference signal of the relay and the second signal;
removing the detected first signal to the signal stored in the memory and then detecting the second signal by applying a second reception beamforming vector;
_{configured to transmit a signal (x R} ) obtained by combining the detected first signal and the detected second signal to the first source node and the second source node in a second time slot through the transceiver,
relay device.

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