KR101539533B1 - Method and apparatus for amplify-and-forward mimo-ofdm relay systems - Google Patents

Abstract

Disclosed are an amplify-and-forward relay method for multi-antenna / carrier systems and an apparatus thereof. The present invention provides a method for designing a hybrid beamformer in a relay network which comprises the steps of: setting up an optimal beamformer matrix which assumes full complexity RF chains as many as the number of antennas within a relay network environment in which an amplify-and-forward (AF) relay is placed between a transmitter and a receiver; and designing a transmission RF beam, a reception RF beam, and a baseband signal processing matrix using the optimal beamformer matrix.

Description

≪ Desc / Clms Page number 1 > METHOD AND APPARATUS FOR AMPLIFY-AND-FORWARD MIMO-OFDM RELAY SYSTEMS <

BACKGROUND OF THE INVENTION Field of the Invention [0001] The present invention relates to a relay operation in a multi-antenna / carrier system, and more particularly, to a multi-antenna / carrier system in which, in a situation where a relay has more antennas than an RF chain, To techniques for designing processing operations.

In recent years, a millimeter wave (WDM) wireless communication system has received much attention as a candidate technology for next generation mobile communication. Millimeter-wave systems have a powerful advantage that not only provides a wide bandwidth available to support the rapidly increasing demanded data transmission capacity, but also enables integration of many antennas into a small space. Because of these advantages, it has begun to be used as indoor and short-range communication methods such as wireless LAN and PAN.

However, as it experiences considerably higher attenuation than the conventional mobile communication band, a beamforming technique using a plurality of antenna arrays must be used to overcome this. In order to maximize the gain of the beamforming, an RF chain must be formed for each antenna, which is a considerable burden to a relay and a terminal featuring a low power. The RF chain consists of an amplifier, a mixer, an analog-to-digital converter (ADC), and a digital-to-analog converter (DAC). Therefore, the transceiver architecture of millimeter wave radio communication is composed of a large number of antennas and much less RF chain, and this structure is generally defined as a hybrid beamformer.

For example, Korean Patent Laid-Open Publication No. 10-2013-0127376 (published November 22, 2013) entitled " Communication Method and Apparatus via Analog and Digital Hybrid Beam Forming " The contents of a hybrid beamforming structure through combination of digital beamforming are disclosed.

In addition to the new transceiver structure required for millimeter-wave communication in a mobile communication system, relay technology with beamforming is essential to maintain or extend the coverage of the base station in comparison with microwave radio communication in a severe radio attenuation environment. The relay is also configured with a hybrid beamformer, and the RF and baseband signal processing operations must be designed. An amplify-and-forward (AF) relay in a relay network operating in a half-duplex protocol receives a signal from the transmitter in the first interval. After that, the signal is amplified and transmitted to the receiver in the second interval. Therefore, unlike signal processing operation designs of hybrid beamformers of existing transceivers, relays are required to design the signal processing of the receiving RF stage, the baseband stage, and the transmitting RF stage.

The hybrid beamformer design replaces the problem of designing the baseband stage by selecting the number of RF beams from the set of possible RF beams when the RF stage is composed of a phased array beamformer that is useful in design and operation. do. Therefore, the hybrid beamformer design in the relay is defined as the problem of designing the baseband signal processing while selecting the transmitting and receiving RF beams. The basic approach to this problem is to allow the RF beams, which are capable of increasing the beam gain (RF beam with high correlation to the channel) among the possible RF beams when the relay knows the receiving channel of the first section and the transmitting channel of the second section, There is a way to design the optimal baseband after selecting the number of RF chains at once, but it is difficult to guarantee the good performance because it is designed by ignoring the mutual influences between the selected reception RF beam, transmission RF beam and baseband. Also, the constraint that the signal processing of the transmitting and receiving RF stages should be the same for all subcarriers due to the multi-carrier system should be considered. In order to solve this problem, the present invention relates to a hybrid beamformer design of an after-amplification transmission relay designed for all subcarriers simultaneously considering selection of transmission and reception RF beams and operation of a baseband signal processing.

The present invention relates to a relay hybrid beamformer design in a multi-carrier system, and aims at the following two purposes.

First, we propose a design method for simultaneous or sequential design considering the mutual influences of transmission RF beam, reception RF beam, and baseband signal processing operations in the hybrid design of relays.

Second, we propose a scheme for designing a common transmit RF beam and a receive RF beam for all subcarriers and a scheme for designing baseband signal processing operations for each subcarrier.

Setting an optimal beamformer matrix assuming an RF chain (full complexity RF chain) as many as the number of antennas in a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver; And designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix. The present invention also provides a method of designing a hybrid beamformer in a relay network.

According to an aspect, the designing step includes designing the transmit RF beam, the receive RF beam, and the baseband signal processing matrix in consideration of the mutual influence between the transmit RF beam, the receive RF beam, and the baseband signal processing matrix. Can be designed simultaneously.

According to another aspect, the designing step may include designing the transmit RF beam, the receive RF beam, and the baseband signal processing matrix in consideration of mutual influences between the transmit RF beam, the receive RF beam, and the baseband signal processing matrix Or sequentially design the transmission RF beam, the reception RF beam, and the baseband signal processing matrix in the order of the reception RF beam, the transmission RF beam, and the baseband signal processing matrix.

According to another aspect, the designing step may select a transmitting RF beam and a receiving RF beam from a set of RF beams reflecting the constraint structure of the RF beam former.

According to another aspect, the designing step may select a transmitting RF beam and a receiving RF beam by at least one or more than the actual number of RF chains.

According to another aspect, in the designing step, the baseband signal processing matrix having the smallest error from the optimum beamformer matrix may be designed using the transmission RF beam and the reception RF beam.

According to another aspect, the designing step may design a common transmission RF beam and a reception RF beam for all subcarriers, and design a baseband signal processing matrix corresponding to each subcarrier.

According to another aspect, the designing step may design a common transmit RF beam and a receive RF beam for the entire subcarrier.

According to another aspect, the designing step may design a common transmitting RF beam and a receiving RF beam for selected subcarriers in all subcarriers.

According to another aspect, the designing step may design an individual baseband signal processing matrix for all subcarriers using the transmitted RF beam and the received RF beam.

According to another aspect, the designing step may include designing an individual baseband signal processing matrix for a selected subcarrier using all of the subcarriers using the transmitted RF beam and the received RF beam, An individual baseband signal processing matrix can be designed.

And an amplify-and-forward (AF) relay located between the transmitter and the receiver for amplifying a signal received from the transmitter and transmitting the amplified signal to the receiver, wherein the RF amplifier includes a full complexity RF chain, The relay hybrid beamformer is constructed by designing a transmission RF beam, a reception RF beam, and a baseband signal processing matrix using an optimal beamformer matrix.

Relay hybrid beamformer design in a multicarrier system designed simultaneously or sequentially considering the mutual influences of transmission RF beam, reception RF beam, and baseband signal processing operations in the hybrid design of relays.

We propose a relay hybrid beamformer design technique for a multicarrier system designing common transmission RF beam and receiving RF beam for all subcarriers and baseband signal processing operations for each subcarrier.

1 is a diagram illustrating a multi-antenna / carrier-after-amplification (AF) relay network in an embodiment of the present invention.
FIG. 2 is a flow chart for designing transmission and reception RF beam selection and baseband signal processing of a relay according to an exemplary embodiment of the present invention. Referring to FIG.
3 is a diagram for explaining an average throughput performance through a relay hybrid beamformer design in a multi-carrier system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention proposes a hybrid hybrid beamformer design in a multi-antenna / carrier system. In the hybrid beamformer design of the relay, the design method considering the mutual influence of the transmitting and receiving RF beamformer and the baseband beam former, and the design method of the whole or a part of the beamformer to design a common RF beamformer for each subcarrier and a separate beamformer for each subcarrier in the multi- We propose a design method considering the influence of subcarriers.

The method of designing a relay hybrid beamformer in a multi-antenna / carrier system according to the present invention can be applied to all base stations and terminals using multiple antennas in a wireless communication system.

The relay has a large number of antennas to obtain sufficient beamforming gain in a channel environment where propagation attenuation is severe. And because it features low-power operation, it has fewer RF chains than the number of antennas. This structure is defined as a hybrid beamformer and the signal processing operation of the RF stage and baseband stage must be designed for beamforming. The hybrid beamformer design of existing transceivers consists of a design for the transmit or receive RF beam and baseband signal processing.

The relay hybrid beamformer proposed in the present invention requires the design of a transmission RF beam, a reception RF beam, and baseband signal processing. Therefore, the proposed scheme is designed to simultaneously or sequentially design the transmission RF beam, the reception RF beam, and the baseband signal processing design considering the mutual influence of each other. The simultaneous design method is designed not to design the transmitting and receiving RF beams and the baseband signal processing independently but to consider the mutual influences simultaneously. Sequential design schemes include operations where the designed transmit RF beam is reflected in the receive RF beam design, while the receive RF beam designed is reflected in the transmit RF beam design. The designed transmit and receive RF beams include those reflected in the baseband signal processing design.

In a multi-carrier system, the relay hybrid beamformer design scheme requires the application of common transmit and receive RF beams for the entire subcarrier and the design of separate basedband signal processes for each subcarrier. The present invention proposes a scheme for designing a common transmission RF beam and a reception RF beam considering all subcarriers and a scheme for designing individual baseband signal processing operations for all subcarriers. In addition, a method of designing a common transmission RF beam and a reception RF beam considering only selected sub-carriers and a method of designing individual baseband signal processing operations for selected sub-carriers, and then performing individual baseband signal processing operations on individual sub- basedband signal processing operations.

The following embodiments relate to a hybrid hybrid beamformer scheme that considers the mutual influences of transmission and reception RF beams and baseband signal processing in a multi-carrier system. The sequential method is proposed based on orthogonal matching pursuit (DMP) algorithm.

1 is a diagram illustrating a multi-antenna / carrier-after-amplification (AF) relay network in an embodiment of the present invention.

The post-amplification relay is an example of a relay network as shown in Fig. 1, which is located between transmission and reception for the purpose of coverage expansion.

개의 RF 체인으로 구성된다.The relays and transceivers are characterized by having a hybrid beamformer structure. That is, a transmitter, an AF relay, and a receiver are composed of N antennas, and the number of antennas is much smaller than the number of antennas

RF chain.

Then, K multi-carrier systems are assumed. In a relay network that follows the half-duplex protocol, the transmitter transmits the signal to the relay in the first interval. The signal from the transmitter can be defined as in Equation (1).

[Equation 1]

크기의 행렬

는 송신기의 RF 신호처리를 정의하고,

크기의 행렬

는 k번째 부반송파에 대한 baseband 신호처리를 정의하고,

크기의 벡터

는 k번째 반송파를 이용해 보내게 될 N_S개의 데이터를 정의한다.

Matrix of size

Defines the RF signal processing of the transmitter,

Matrix of size

Defines the baseband signal processing for the k < th > subcarrier,

Vector of size

Defines N _S data to be sent using the k-th carrier.

In the second interval, the relay amplifies the signal received from the transmitter and transmits it to the receiver. The signal received by the receiver can be defined as Equation (2).

&Quot; (2) "

크기의 행렬

는 수신기의 RF단 신호처리를 정의하고,

크기의 행렬

는 k번째 부반송파에 대한 baseband 신호처리를 정의한다.

크기의 행렬

는 릴레이의 송신 RF단 신호처리를 정의하고,

크기의 행렬

는 k번째 부반송파에 대한 baseband 신호처리를 정의하고,

크기의 행렬

는 수신 RF단 신호처리를 정의한다.

크기의 행렬

와

는 송신기와 릴레이, 릴레이와 수신기 사이의 무선 채널을 정의하고,

크기의 벡터

와

는 각각 릴레이와 수신기에서의 잡음을 정의한다.

Matrix of size

Defines the RF-stage signal processing of the receiver,

Matrix of size

Defines the baseband signal processing for the kth subcarrier.

Matrix of size

Defines the transmit RF termination signaling of the relay,

Matrix of size

Defines the baseband signal processing for the k < th > subcarrier,

Matrix of size

Defines the receive RF termination signal processing.

Matrix of size

Wow

Defines a radio channel between a transmitter and a relay, a relay and a receiver,

Vector of size

Wow

Define the noise at the relay and receiver, respectively.

The simultaneous design problem of the transmitting and receiving RF stages and the baseband signal processing for all subcarriers of the relay configured with the hybrid beamformer in the relay network of FIG. 1 can be defined as Equation (3).

&Quot; (3) "

크기의 행렬

는 k번째 부반송파에 대한 full complexity RF chain(모든 안테나에 대한 RF 체인)을 가정한 최적의 릴레이 빔포머 동작을 정의한다.

크기의 행렬

와

는 각 채널행렬의

(여기서, p=1,2, SVD(singular value decomposition)을 통해

개 만큼의 높은 특이 값(singular value)에 해당하는 열들을 선택하여 얻을 수 있다. 그리고,

크기의 행렬

는

개의 데이터에 대한 파워(power)를 할당하는 역할을 한다. 가능한 송수신 RF 빔들의 집합은 각각

와

으로 정의된다. 또한,

는 송신 RF 빔 행렬의 j번째 열을 정의하고 P는 릴레이 파워를 정의한다.

Matrix of size

Defines the optimal relay beamformer operation assuming a full complexity RF chain for the kth subcarrier (RF chain for all antennas).

Matrix of size

Wow

Lt; RTI ID = 0.0 >

(Where p = 1,2, through SVD (singular value decomposition)

Can be obtained by selecting the columns corresponding to a singular value as high as the number of rows. And,

Matrix of size

The

Quot; power " of the data. The set of possible transmit and receive RF beams is

Wow

. Also,

Defines the jth column of the transmit RF beam matrix and P defines the relay power.

The objective function of the relay hybrid beamformer design in the multi-carrier system (Equation (3)) is an optimal beamformer that assumes a full complexity RF chain for the entire subcarrier K and a transmission / reception RF The aim is to design beams and baseband. The first limitation of Equation (3) is that the transmitting and receiving RF beam should be selected from a set of possible RF beams. A possible RF beam set is a set of beams reflecting constraints of the RF beamformer, for example, a constraint structure capable of only quantized phase adjustment, and a constraint structure capable of adjusting quantized magnitudes and phases. The second limitation corresponds to the power constraint of the relay.

FIG. 2 is a flow chart for designing transmission and reception RF beam selection and baseband signal processing of a relay according to an exemplary embodiment of the present invention. Referring to FIG. The flowchart of the invention for finding the solution of Equation (3) is shown in Fig.

와 가능한 모든 송수신 RF빔들의 열들로 구성된 행렬

와

들이다. 초기화 작업으로 오차 행렬은 최적 빔포머 행렬과 같도록 설정하고,

, 송수신 RF 빔 행렬들은

로 설정한다. RF 빔 선택 시 송신 빔, 수신 빔의 순서는 변경이 가능하다. 그리고, 한번에 L개의 송수신 RF 빔들을 선택할 수 있지만, 아래의 알고리즘 예에서는 수신 RF 빔을 먼저 선택하는 경우와 한번에 하나의 송수신 RF 빔을 선택하는 경우를 고려한다.The input of the algorithm is an optimal beamformer matrix assuming a full complexity RF chain

And a matrix of columns of all possible transmit and receive RF beams

Wow

admit. In the initialization operation, the error matrix is set equal to the optimal beamformer matrix,

, The transmitting and receiving RF beam matrices

. When the RF beam is selected, the order of the transmission beam and the reception beam can be changed. Although it is possible to select L transmission / reception RF beams at a time, the following algorithm example considers the case of selecting the reception RF beam first and the case of selecting one transmission / reception RF beam at a time.

Step S1: The correlation between the error matrix and the possible reception RF beams can be measured to select the index of the reception RF beam having the greatest correlation in the set of possible reception RF beams (Equation 4) Equation 5).

&Quot; (4) "

&Quot; (5) "

Step S2: The selected RF beam from the set of possible RF beams can be reflected into the received RF beam (Equation 6).

&Quot; (6) "

Step S3: The correlation between the error matrix and the possible transmission RF beams is measured by reflecting the selected reception RF beam (Equation 7). The index of the transmission RF beam exhibiting the greatest correlation among the possible transmission RF beams ) Can be selected (Equation 8).

&Quot; (7) "

&Quot; (8) "

Step S4: The selected RF beam from the set of possible RF beams may be reflected into the transmitted RF beam (Equation 9).

&Quot; (9) "

Step S5: Baseband signal processing can be designed to reflect the selected transmit RF beam and receive RF beam (Equation 10).

&Quot; (10) "

The error matrix can be updated considering the transmission and reception RF beam and baseband signal processing (Equation 11).

&Quot; (11) "

,

들과 전체 부반송파에 대한 baseband 신호처리 행렬

들을 얻는다.When the number of the selected transmission RF beam and the reception RF beam reaches the number of RF chains (L) (S6), the transmission / reception RF beamformer matrix

,

And a baseband signal processing matrix for all subcarriers

.

The performance verification of the relay hybrid beamformer for the multi-carrier system according to the present invention is shown in FIG.

Referring to FIG. 3, it can be seen that the performance of the present invention is close to the beamformer performance of an optimal environment assuming a full complexity RF chain. In comparison with a beam steering system in which transmission and reception RF beams and baseband signal processing are independently designed, the present invention shows improved performance and also shows that the degree of performance degradation when the number of RF chains is reduced is significantly smaller than the comparison method .

As described above, the present invention can design a relay hybrid beam former of a multi-carrier system. Furthermore, it is possible to simultaneously or sequentially design the transmission RF beam, the reception RF beam, and baseband signal processing for each subcarrier, which are commonly applied to each subcarrier, taking into consideration mutual influences of each other.

According to the present invention, the performance of a hybrid beamformer in a multi-carrier system can approach the optimum beamformer performance assuming a full complexity RF chain as many as the number of antennas. Therefore, there is an advantage that the power consumption of the components of the relay, which is characterized by low-power operation, and the number of expensive RF chains can be reduced.

Conventional technologies only consider a single user environment or limit the hardware structure with high implementation complexity, so there is still a burden on commercial implementation. On the other hand, when the present invention having a low implementation complexity considering a multi-user environment is applied to a communication system utilizing a plurality of antennas, it is expected that the system can be highly competitive in terms of application range and implementation efficiency. Also, the transmission / reception RF beam designing method considered in the present invention has a high potential market in the field of systems using multiple antennas / carriers from commercial communication to mmWave communication to be next generation mobile communication.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA) , A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (12)

delete In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
And simultaneously designing the transmitted RF beam, the received RF beam, and the baseband signal processing matrix while considering mutual influences between the transmitted RF beam, the received RF beam, and the baseband signal processing matrix
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
The reception RF beam, the baseband signal processing matrix, or the reception RF beam, the transmission RF beam, and the baseband signal processing matrix in consideration of the mutual influence between the transmission RF beam, the reception RF beam, And sequentially designing the transmission RF beam, the reception RF beam, and the baseband signal processing matrix in the order of the baseband signal processing matrix
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Selecting the transmitted RF beam and the received RF beam from the set of RF beams reflecting the constraint structure of the RF beam former
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Selecting a transmitting RF beam and a receiving RF beam by at least one or more than the actual number of RF chains
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Designing a baseband signal processing matrix having the smallest error from the optimum beamformer matrix using the transmission RF beam and the reception RF beam
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Design a common transmit and receive RF beams for all subcarriers and design a baseband signal processing matrix for each subcarrier
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Designing common transmit and receive RF beams for all subcarriers
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Designing common transmit and receive RF beams for selected subcarriers in all subcarriers
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Designing separate baseband signal processing matrices for all subcarriers using the transmitted RF beam and the received RF beam
And a hybrid beamformer design method in a relay network. In a relay network environment in which an amplify-and-forward (AF) relay is located between a transmitter and a receiver,
Setting an optimal beamformer matrix assuming a full complexity RF chain as many as the number of antennas; And
Designing a transmit RF beam, a receive RF beam, and a baseband signal processing matrix using the optimal beamformer matrix;
Lt; / RTI >
Wherein the designing comprises:
Designing individual baseband signal processing matrices for selected subcarriers on all subcarriers using the transmitted RF beam and the received RF beam and then designing an individual baseband signal processing matrix for all subcarriers using interpolation
And a hybrid beamformer design method in a relay network. delete

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