KR102504027B1 - Method and apparatus for precoding signal in mobile communication system - Google Patents

Abstract

The present disclosure relates to a 5G or pre-5G communication system for supporting a higher data rate after a 4G communication system such as LTE. A method for processing a signal in a base station included in a communication system according to an embodiment of the present disclosure includes performing layer mapping on an input signal and preprocessing of mapping the layer mapped layer signal to an antenna port. and performing a phase shift on the preprocessed antenna port signal.

Description

Signal processing method and apparatus in communication system {METHOD AND APPARATUS FOR PRECODING SIGNAL IN MOBILE COMMUNICATION SYSTEM}

The present disclosure relates to a method and apparatus for processing signals in a communication system, and more particularly, to a method and apparatus for processing signals in a full dimension multi-input multi-output (FD-MIMO) system. .

Efforts are being made to develop an improved 5 ^th -generation (5G) communication system or pre-5G communication system in order to meet the growing demand for wireless data traffic after the commercialization of 4G (4 ^th -generation) communication systems. . For this reason, the 5G communication system or the pre-5G communication system is called a beyond 4G network communication system or a long term evolution (LTE) system and a post LTE system.

In order to achieve a high data rate, the 5G communication system is being considered for implementation in a mmWave band (eg, a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, beamforming, massive multi-input multi-output (massive MIMO), FD-MIMO, Array antenna, analog beam-forming, and large scale antenna technologies are being discussed.

In addition, to improve the network of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network , device to device communication (D2D), wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMP), and reception interference cancellation cancellation) is being developed.

In addition, in the 5G system, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM), which is an advanced coding modulation (ACM) method, and sliding window overlapping coding (sliding window superposition coding: SWSC), advanced access technologies such as filter bank multi carrier (FBMC), non orthogonal multiple access (NOMA), and sparse code multiple access access: SCMA), etc. are being developed.

Among the 5G communication systems, the Massive MIMO system can satisfy a high data rate even if a simple linear precoding is performed by a precoder by installing multiple antennas in a base station. In addition, the Massive MIMO system can theoretically completely remove factors that limit system performance, such as noise, fast fading, and inter-user interference, when infinite antennas are used. has been studied as a core technology for next-generation communication systems. In the Massive MIMO system, it is important for the base station to have channel information with the terminal in order to obtain these advantages. Existing studies related to the massive MIMO system use channel reciprocity from the uplink channel to downlink A lot of things have been done in a time-division duplex (TDD) environment where downlink channel information can be obtained.

However, the TDD method has a disadvantage in that efficiency is lower than that of the frequency-division duplex (FDD) method when the distance between the base station and the terminal is long or when the uplink and downlink traffic requirements are similar. For this reason, many communication systems support the FDD scheme. Therefore, it is very essential to implement a massive MIMO system in an environment that supports the FDD method.

Recently, FD-MIMO systems that use 16 or more antenna ports in a two-dimensional array structure to implement such massive MIMO are being studied as a core technology of 5G technology. In the FD-MIMO system, elevation beamforming is possible because the base station uses a planar array structure, and accordingly, high system performance is achieved through technologies such as user-specific beamforming. There are advantages to being able to benefit from it. In order to maximize the advantages of the FD-MIMO system, a preprocessing method with improved performance is required in the FD-MIMO system.

An embodiment of the present disclosure provides a method and apparatus for processing a signal based on an open loop preprocessing method in an FD-MIMO system.

In addition, an embodiment of the present disclosure provides a method and apparatus for processing a signal based on cyclic delay diversity in an FD-MIMO system.

In addition, an embodiment of the present disclosure provides a method and apparatus for demodulating a signal processed based on an open loop preprocessing method in an FD-MIMO system.

In addition, an embodiment of the present disclosure provides a method and apparatus for demodulating a signal processed based on cyclic delay diversity in an FD-MIMO system.

A method proposed in an embodiment of the present disclosure; In a method for processing a signal in a base station included in a communication system, the process of performing layer mapping on an input signal, the process of performing preprocessing of mapping the layer mapped layer signal to an antenna port, and the preprocessed antenna and performing a phase shift on the port signal.

In addition, the method proposed in one embodiment of the present disclosure; A method for processing a signal in a base station included in a communication system, comprising: performing layer mapping on an input signal; performing preprocessing of mapping the layer mapped layer signal to an antenna port; and performing a phase shift on the antenna port signal.

In addition, the device proposed in one embodiment of the present disclosure; In a base station processing signals in a communication system, layer mapping is performed on an input signal, preprocessing is performed to map the layer mapped layer signal to an antenna port, and phase shift is performed on the preprocessed antenna port signal. and a transmission unit for transmitting the signal processed by the control unit to a terminal.

In addition, the device proposed in one embodiment of the present disclosure; A terminal processing a signal in a communication system, comprising a receiver for receiving a signal from a base station and a control unit for controlling demodulation of the received signal, wherein the received signal is pre-processed for mapping to an antenna port in the base station. After performing phase shift on the preprocessed antenna port signal, it is characterized in that it is a signal.

Other aspects, benefits and essential features of the present disclosure will become apparent to those skilled in the art from the following detailed description, taken in conjunction with the accompanying drawings, and disclosing preferred embodiments of the present disclosure.

Before addressing the Detailed Description portion of this disclosure below, it may be useful to establish definitions for certain words and phrases used throughout this patent document: the terms "include" and " "comprise" and its derivatives mean inclusive, without limitation; The term “or” is inclusive and means “and/or”; The phrases "associated with" and "associated therewith" and their derivatives include, be included within, and interconnected with ( interconnect with, contain, be contained within, connect to or connect to or with, connect to or couple to or with ), be communicable with, cooperate with, interleave, juxtapose, be proximate to, and likely to be It means content such as is large or likely to be bound to or with, have, have a property of, etc.; The term "controller" means any device, system, or portion thereof that controls at least one operation, such a device being hardware, firmware, or software, or some combination of at least two of the hardware, firmware, or software. can be implemented in It should be noted that functionality associated with any particular controller may be centralized or distributed, localized or remote. Definitions for certain words and phrases are provided throughout this patent document, and those skilled in the art will know that in many, if not most, cases such definitions are conventional as well as the words and phrases so defined. It should be understood that this also applies to future uses of the constructs.

1 is a diagram showing signal flow between a base station and a terminal when a closed loop preprocessing method is used and an open loop preprocessing method is used in a communication system;
2 is a diagram showing an example of a case where a base station applies a CDD preprocessing method in a communication system;
3 and 4 are diagrams briefly illustrating a communication system to which an embodiment of the present disclosure is applied;
5 is a diagram illustrating a method of processing a signal based on a port level LD-CDD scheme in a base station 300 according to a first embodiment of the present disclosure;
6 is a diagram showing cyclic delay characteristics when a cyclic delay scaling scheme according to a second embodiment of the present disclosure is applied to a CDD scheme;
7 is a diagram showing an example of applying a circular area scaling method to a port level LD-CDD method according to a second embodiment of the present disclosure;
8 is a diagram illustrating a method of processing a signal by applying a cyclic delay scaling method to an LD-CDD method in a base station 300 according to a second embodiment of the present disclosure;
9 is a diagram showing an example of a first effective channel configuration method in which the terminal 400 configures an effective channel for demodulating a preprocessed signal according to an embodiment of the present disclosure;
10 is a diagram showing an example of a second effective channel configuration method in which the terminal 400 configures an effective channel for demodulating a preprocessed signal according to an embodiment of the present disclosure;
11 is a diagram showing an example of a process 1011 of reconfiguring an effective channel by a terminal 400 in a second effective channel configuration method according to an embodiment of the present disclosure;
12 is a diagram briefly illustrating an internal configuration of a base station 300 for processing signals in a communication system according to an embodiment of the present disclosure;
13 is a diagram briefly showing the internal configuration of a terminal 400 for processing signals in a communication system according to an embodiment of the present disclosure;
14 is a diagram showing performance according to the number of antenna ports when a conventional layer level CDD scheme is applied in a base station and when a port level CDD scheme according to the first embodiment of the present disclosure is applied;
15 is a diagram showing bit error rate (BER) performance when a conventional layer level CDD method is applied in a base station and when a port level CDD method according to the first embodiment of the present disclosure is applied;
16 is a diagram illustrating BER performance according to channel conditions when a conventional layer level CDD method is applied in a base station and when a port level CDD method according to the first embodiment of the present disclosure is applied.
It should be noted that throughout the drawings, like reference numbers are used to show the same or similar elements, features and structures.

The following detailed description with reference to the accompanying drawings will aid in a comprehensive understanding of various embodiments of the present disclosure, which is defined by the claims and their equivalents. The detailed description that follows includes numerous specific details for an understanding thereof, which are to be regarded merely as examples. Accordingly, those skilled in the art will recognize that various changes and modifications of the various embodiments described herein may be made without departing from the scope and spirit of the present disclosure. Also, descriptions of well-known functions and configurations may be omitted for clarity and conciseness.

The terms and words used in the following detailed description and claims are not limited in their literal sense, but are simply used to enable a clear and consistent understanding of the present disclosure by the inventors. Accordingly, to those skilled in the art, the following detailed description of various embodiments of the present disclosure is provided for illustrative purposes only, and is not intended to limit the present disclosure as defined by the appended claims and their equivalents. It should be clear that it is not provided for.

In addition, it will be understood that singular expressions such as “a” and “above” include plural expressions in this specification unless clearly indicated otherwise. Thus, in one example, a "component surface" includes one or more component representations.

In addition, terms including ordinal numbers, such as first and second, may be used to describe various components, but the components are not limited by the terms. These terms are only used for the purpose of distinguishing one component from another. For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present disclosure. The terms and/or include any combination of a plurality of related recited items or any of a plurality of related recited items.

In addition, terms used in this specification are only used to describe specific embodiments, and are not intended to limit the present disclosure. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "include" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other features It should be understood that the presence or addition of numbers, steps, operations, components, parts, or combinations thereof is not precluded.

In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure belongs. Terms such as those defined in commonly used dictionaries should be understood to have meanings consistent with meanings in the context of related art.

In a communication system, a pre-processing unit included in a base station performs pre-processing on an input signal using one of a predetermined method among open-loop precoding and closed-loop precoding.

1 shows a signal flow between a base station and a terminal when a closed loop preprocessing method is used and an open loop preprocessing method is used in a communication system.

Referring to FIG. 1, when the base station 110 performs pre-processing using the closed-loop pre-processing method (a), the base station 110 transmits a reference signal for channel transmission to the terminal 130. do (151). Here, the reference signal includes a channel reference signal (CRS) and a channel state indicator-reference signal (CSI-RS).

When receiving the reference signal from the base station 110, the terminal 130 estimates a channel between the base station 110 and the terminal 130 and feeds back information on the estimated channel to the base station 153. (153). Here, the information on the estimated channel basically includes a channel quality indicator (CQI) and a rank indicator (RI) for a modulation and coding scheme (MCS). In addition, when the terminal 130 receives a signal from the base station 110 using the closed loop preprocessing method, the base station 110 receives a precoding matrix indicator (PMI) as information about a channel matrix in addition to the CQI and RI ) feedback.

Thereafter, the base station 110 performs closed-loop pre-processing on the input signal based on the feedback received PMI, CQI, and RI (155). Then, the base station 110 transmits the closed-loop preprocessing signal to the terminal 130 (157). Then, the terminal 130 demodulates the signal received from the base station 110 (159).

On the other hand, when the base station 110 performs preprocessing using the open loop preprocessing method (b), the base station 110 transmits the CRS to the terminal 130 (171), and the estimated channel from the terminal 130 Information on (ie, CQI and RI) is fed back (173). However, the base station 110 does not perform preprocessing based on the information fed back from the terminal 130, but processes the signal using an open loop preprocessing method agreed in advance with the terminal 130 in the time and frequency domain ( 175). Then, the base station 110 transmits the open-loop preprocessing signal to the terminal 130 (177). Then, the mobile station 130 demodulates the signal received from the base station 110 using a prearranged open-loop pre-processing method (179).

For example, when the base station 110 intends to support the terminal 130 by using transmission mode 3 for performing open-loop pre-processing among the transmission modes used in the LTE system, the base station 110 Preprocessing is performed for each subcarrier. The terminal 130 may demodulate the received signal by performing pre-processing based on the subcarrier index.

This open-loop pre-processing method has a performance loss compared to the closed-loop pre-processing method based on channel information fed back from the terminal in the base station. However, the open-loop preprocessing method is suitable for supporting highly mobile terminals or rapidly changing channels over time. In particular, when the open-loop preprocessing method is applied to an FD-MIMO system capable of flexible antenna virtualization, the advantage of the FD-MIMO system can be maximized in that it can support terminals in various states. In addition, in an FD-MIMO system that assumes a large number of antennas, it can be very difficult for a terminal to feed back channel information to a base station in a limited feedback environment, so the open-loop preprocessing method is a closed-loop method requiring feedback of channel information. Compared to the preprocessing method, there is an advantage in terms of performance versus required feedback overhead.

Considering the advantage of the open-loop pre-processing method as described above, embodiments of the present disclosure propose a method for further enhancing the advantage of the open-loop pre-processing method suitable for the FD-MIMO system. In particular, an embodiment of the present disclosure proposes an open loop preprocessing method (hereinafter referred to as a CDD preprocessing method) based on a cyclic delay diversity (CDD) scheme. The CDD preprocessing method is a method capable of obtaining a performance gain in terms of link reliability without separate feedback, and will be described in detail based on FIG. 2 .

2 shows an example of a case in which a base station applies a CDD preprocessing method in a communication system. In FIG. 2, a case in which the communication system is an orthogonal frequency division multiplexing (OFDM) system is shown as an example, but the CDD preprocessing method described based on FIG. 2 is applicable to other communication systems. Of course, it is possible.

Referring to FIG. 2 , units related to preprocessing in the OFDM system include a preprocessor 230 and an inverse fast fourier transform (IFFT) unit 250 .

The preprocessor 230 performs a phase shift proportional to the subcarrier index on the transmission signal 210 carried on each subcarrier, and transmits the phase shift to the IFFT unit 250. Then, the IFFT unit 250 may output a signal having a cyclic delay in the time domain as shown in Equation 1 below.

<Equation 1>

는 순환 지연 값(cyclic delay value), N _FFT는 IFFT의 FFT 사이즈(size), k는 부반송파 인덱스, X(k)는 부반송파 k에 실리는 주파수 영역의 송신 신호, l은 시간 인덱스(time index), x[l]은 시간 인덱스 l에 해당하는 시간 영역의 송신 신호이다.here

is a cyclic delay value, N _FFT is the FFT size of the IFFT, k is a subcarrier index, X ( k ) is a transmission signal in the frequency domain carried on subcarrier k , l is a time index , x [ l ] is a transmission signal in the time domain corresponding to the time index l .

As described above, when a base station using multiple antennas uses a plurality of cyclic delay values (ie, using the CDD preprocessing method), frequency selectivity in the frequency domain of the effective channel after the preprocessing process can increase In addition, since frequency selectivity can be increased in the base station, channel coding gain can also be increased through this.

A communication system to which the CDD preprocessing method of FIG. 2 is applied may be configured as shown in FIGS. 3 and 4 . 3 and 4 briefly illustrate a communication system to which an embodiment of the present disclosure is applied, in particular, FIG. 3 shows a configuration of a base station in a communication system, and FIG. 4 shows a configuration of a terminal in a communication system. A general description of the CDD preprocessing method described below and a description of embodiments of the present disclosure will refer to FIGS. 3 and 4 .

Referring to FIG. 3 , in a communication system, a base station 300 may transmit one or more codewords (code work: CW) through downlink. That is, each of one or more CWs is processed as a complex symbol through corresponding scramblers 301-1 to 301-n and modulation mappers 303-1 to 303-n. Thereafter, the complex symbols are mapped to a plurality of layers by a layer mapper 305, and preprocessing of the symbols mapped to each layer is mapped to each transmit antenna port by a preprocessor 307.

The transmission signals for each antenna port processed in this way are mapped to time-frequency resource elements to be used for transmission by the resource element mappers 309-1 to 309-n, respectively, and the OFDM signal generators 311-1 to 311-n ) through which each OFDM signal is processed. Each of the OFDM signals may be transmitted through each antenna port via IFFT units 315-1 to 315-n and cyclic prefix (CP) inserters 315-1 to 315-7.

In particular, the pre-processing unit 307 performs CDD pre-processing based on Equation 2 below.

<Equation 2>

는 주파수 영역에서 안테나 포트 신호(antenna port signal) 를 나타낸 것이다. 여기서 i는 레이어 인덱스(layer index), s는 안테나 포트 신호, x는 레이어 신호(layer signal), U는 레이어 다중화 행렬(layer multiplexing matrix), D는 위상 천이(phase shift)를 위한 대각 행렬(diagonal matrix), W는 전처리 행렬을 나타낸다. In the above <Equation 2>

represents an antenna port signal in the frequency domain. where i is a layer index, s is an antenna port signal, x is a layer signal, U is a layer multiplexing matrix, and D is a diagonal matrix for phase shift matrix), W denotes a preprocessing matrix.

That is, the pre-processor 307 of FIG. 3 may perform pre-processing by mapping layer signals to antenna port signals, and perform phase shift by applying a diagonal matrix for phase shift to the pre-processed antenna port signals. Here, an operation of applying a diagonal matrix for phase shift to the preprocessed antenna port signal may be processed in a separate unit subsequent to the preprocessor 307 .

Next, referring to FIG. 4 , the base station 300 transmits a signal to the terminal 400 based on a physical downlink shared channel (PDSCH). At this time, the signal transmitted from the base station 300 is received by the terminal 400 after experiencing the MIMO channel environment. The signal received by the terminal 400 is converted into a signal in the frequency domain through CP cancelers 401-1 to 401-n and FFT units 403-1 to 403-n. At this time, the signal converted to the signal in the frequency domain can be expressed as in Equation 3 below.

<Equation 3>

Here, s ( i ) is the antenna port signal of the base station 300 shown in Equation 3 above, y ( i ) is the received signal of the terminal 400 corresponding to the layer index i , and H ( i ) is It is a MIMO channel, and n ( i ) means a noise signal in the reception process. All signals shown in Equation 3 above are signals in the frequency domain.

Thereafter, the signal in the frequency domain is demodulated through the MIMO detector 405 and demodulators 407-1 to 407-n.

The CDD preprocessing method performed by the preprocessing unit 307 of the communication system as shown in FIGS. 3 and 4 is a preprocessing method based on a large delay CDD (hereinafter referred to as LD-CDD) method according to the degree of cyclic delay and It can be classified as a preprocessing method based on a small delay CDD (hereinafter referred to as SD-CDD) method. For convenience of description, the following description will be made on the assumption that the CDD preprocessing method is the LD-CDD method, but is not limited thereto, and the embodiments of the present disclosure can be applied to the LD-CDD method as well.

Hereinafter, it is assumed that the LD-CDD method is applied in the preprocessing method according to the embodiment of the present disclosure. In the LD-CDD scheme applied in the embodiment of the present disclosure, it is assumed that signals transmitted from each antenna have a cyclic delay difference of N _FFT / D. where D is the row/column size of matrix D. At this time, if D is equal to the number of layers, it is defined as layer level CDD, and if it is equal to the number of antenna ports, it is defined as port level CDD. The current standard uses a layer level LD-CDD scheme that supports up to four layers. To this end, the diagonal matrix for phase shift represented by D ( i ) in <Equation 2> and <Equation 3> is It can be expressed as D _layer ( i ) in <Equation 4> below.

<Equation 4>

where v is the number of layers.

The effect of the preprocessing method based on the LD-CDD scheme according to D (hereinafter referred to as the LD-CDD preprocessing method) is that the phase shift applied to each subcarrier increases in proportion to the subcarrier index. That is, in the case of the LD-CDD preprocessing method, it can be confirmed that the same phase shift is applied to the transmission signal for every D subcarriers as shown in Equation 5 below.

<Equation 5>

As in Equation 5 above, the fact that the same phase shift is applied to the transmission signal means that the frequency selectivity of the two effective channels has the same change pattern. Accordingly, it can be said that a change in correlation of an effective channel due to the CDD preprocessing method occurs with respect to an effective channel corresponding to adjacent 2D -2 subcarriers. Based on the characteristics of these CDD preprocessing methods, an embodiment of the present disclosure proposes CDD preprocessing methods suitable for the following two FD-MIMO systems.

First, the first embodiment of the present invention is to perform a signal processing method based on the port level LD-CDD method in the base station 300.

The CDD preprocessing method currently used in the 3GPP LTE standard obtains a CDD gain by applying a phase shift to each layer. However, in the FD-MIMO system in which the base station 300 uses a very large number of antennas, the gain cannot be sufficiently obtained. And since the LD-CDD preprocessing method reduces the correlation between effective channels of adjacent 2D -2 subcarriers, the larger the size of the diagonal matrix for phase shift, the greater the number of subcarriers that can reduce the correlation. Since this means a decrease in average effective channel correlation, an increase in channel coding gain can be expected. In this respect, in a situation where the number of antenna ports is greater than the number of layers, the preprocessing method based on the port level LD-CDD method that applies a phase shift to the antenna port signal is more effective than the preprocessing method based on the layer level LD-CDD method. High performance gains can be expected. In addition, the preprocessing method based on the port level LD-CDD method is expected to be more suitable for an FD-MIMO system capable of using a very large number of antenna ports.

Referring to FIG. 3, the port level LD-CDD scheme means a case where the size of a diagonal matrix for phase shift is equal to the number of antenna ports. Therefore, the base station 300 according to the first embodiment of the present disclosure applies a diagonal matrix for phase shift to the preprocessed signal after performing preprocessing by mapping the layer signal to the antenna port signal.

For example, the base station 300 according to the first embodiment of the present disclosure performs preprocessing of mapping an input layer signal to an antenna port signal based on Equation 6 below, and performs a phase shift on the preprocessed antenna port signal. can be performed.

<Equation 6>

Here, matrix D _port is an antenna port signal. Accordingly, the base station 300 performs a phase shift by applying a diagonal matrix for phase shift to the matrix D _port of Equation 6 based on Equation 7 below. Meanwhile, <Equation 6> is an example of a preprocessing method based on the port level LD-CDD method in the preprocessor 307, and can be changed to a structure such as adding a matrix for multiplexing to an antenna port signal do.

<Equation 7>

Here, the size D of the matrix D _port is equal to the number P of antenna ports.

In the signal processing method based on the port level LD-CDD method according to the first embodiment of the present disclosure, when the number of antenna ports is greater than the number of layers, the number of cyclic delays is increased compared to the layer level LD-CDD method to obtain intra-band An average decrease in correlation between effective channels of subcarriers can be obtained.

Hereinafter, referring to FIG. 5, a signal processing method in which the base station 300 and the terminal 400 pre-promise in the time frequency domain are based on the port level LD-CDD method according to the first embodiment of the present disclosure. In this case, the operation of the base station 300 will be described.

5 shows a method of performing signal processing based on a port level LD-CDD scheme in the base station 300 according to the first embodiment of the present disclosure.

Referring to FIG. 5 , a base station 300 performs layer mapping on an input signal (501). The base station 300 performs preprocessing of mapping the layer-mapped layer signal to an antenna port (503).

Thereafter, the base station 300 performs phase shift by applying a diagonal matrix for phase shift to the preprocessed antenna port signal (505).

For example, the base station 300 performs preprocessing by mapping an antenna port signal to at least one layer signal based on Equation 6 and Equation 7, and then performs a phase shift on the preprocessed antenna port signal. A diagonal matrix for can be applied.

Therefore, when the base station 300 and the terminal 400 promise to use the signal processing method based on the portlevel LD-CDD method according to the first embodiment of the present disclosure as a pre-processing method, the base station 300 Processing is performed based on the port level LD-CDD method previously agreed with the terminal 400 and the processed signal is transmitted to the terminal 400 . Here, the processed signal means a signal that is phase-shifted after preprocessing has been performed. Then, since the terminal 400 also knows the preprocessing method processed by the base station 300 in advance, it does not transmit/receive additional information with the base station 300, and demodulates the received signal based on the port level LD-CDD method promised in advance can do.

The signal processing method based on the port level LD-CDD scheme according to the first embodiment of the present disclosure has been described above, and the signal processing method according to the second embodiment of the present disclosure will be described below.

A second embodiment of the present disclosure is to apply a cyclic delay scaling method to the CDD method when the preprocessing unit 307 performs preprocessing. The second embodiment of the present disclosure is applied after the signal processing method according to the first embodiment of the present disclosure is performed, or the conventional preprocessing is performed without performing the signal processing method according to the first embodiment of the present disclosure. method can be applied.

The cyclic delay scaling method applied to the CDD method in the second embodiment of the present disclosure is a method of generating irregular cyclic delay values by using the fact that the cyclic delay value is a cyclic value having N _FFT -1 as a maximum value. In detail, the cyclic delay scaling method applied to the CDD method according to the second embodiment of the present disclosure may be performed by the base station 300 as shown in Equation 10 below, for example.

That is, the conventional layer level CDD method outputs a signal such as <Equation 8> below for each layer, and the Port level CDD method according to the first embodiment of the present disclosure outputs a signal such as <Equation 9> for each antenna port. outputs

<Equation 8>

Here, v is the number of layers.

<Equation 9>

Here, N _T is the number of transmit antennas.

For example, when the cyclic delay scaling method according to the second embodiment of the present disclosure is applied to the port level CDD method according to the first embodiment of the present disclosure, the base station 300 generates a signal as shown in Equation 10 below. can be printed out.

<Equation 10>

는 순환 지연 스케일링 팩터로, 0<

<N_T로 정의되고,

는 N_FFT보다 큰 값을 가진다.here,

is the cyclic delay scaling factor, 0<

<N is defined as _T ,

has a value greater than N _FFT .

The above <Equation 10> may be used as shown in FIG. 6 .

)가 3/2인 경우를 가정한다.6 shows cyclic delay characteristics when the cyclic delay scaling scheme according to the second embodiment of the present disclosure is applied to the CDD scheme. In FIG. 6, the signal processing method based on the port level LD-CDD method according to the first embodiment of the present disclosure is used in the preprocessor 307, the number of antenna ports is 4, and the cyclic delay scaling factor scaling factor,

) is 3/2.

Referring to FIG. 6, when the base station 300 performs preprocessing based on the port level LD-CDD method, as in (a), it can be confirmed that there is a cyclic delay difference of N _FFT /4 for each antenna port. can Additionally, after the base station 300 performs preprocessing, if the cyclic delay scaling factor is applied to the port level LD-CDD method according to the second embodiment of the present disclosure, the cyclic delay difference for each antenna port as in (b) It can be increased to 3 N _FFT /8. From this, when the base station 300 applies the cyclic delay scaling factor to the port level LD-CDD method according to the second embodiment of the present disclosure, compared to the case where the cyclic delay scaling factor is not applied, the cyclic delay characteristic becomes irregular In particular, it can be seen that the maximum value of the cyclic delay difference for each antenna port increases to 7 N _FFT /8. In addition, the phenomenon in which the maximum value of the cyclic delay difference for each antenna port increases increases the frequency selectivity of an effective channel and can be expected to increase the channel coding gain.

For example, when the base station 300 performing the preprocessing method according to the second embodiment of the present disclosure applies the assumption of FIG. 6 to <Equation 7> described in the first embodiment of the present disclosure, You can print a matrix.

7 shows an example of applying a circular area scaling method to a port level LD-CDD method according to a second embodiment of the present disclosure. 7 shows the phenomenon in which the maximum value of the cyclic delay difference for each antenna port increases in terms of correlation between two effective channels in the frequency domain when the cyclic delay scaling method is not applied (a) and when the cyclic delay scaling method is applied The difference in case (b) is shown.

)를 적용하면,(b)와 같은 행렬 D를 출력할 수 있다. 따라서, 본 개시의 제2 실시 예에 따른 전처리 방법은(b)와 같이 유효 채널의 상관도가 줄어드는 인접한 부반송파의 수를 증가시켜 평균적인 유효 채널 간 상관도를 줄일 수 있다. 이때, 위상 천이를 위한 대각 행렬은, 상기 <수학식 5>와 같이 D개의 부반송파마다 반복됨을 확인할 수 있다.Referring to FIG. 7, according to the second embodiment of the present disclosure, the preprocessor 307 calculates a cyclic delay scaling factor for applying the cyclic delay scaling scheme to the port level LD-CDD scheme (a) (

), a matrix D such as (b) can be output. Therefore, in the preprocessing method according to the second embodiment of the present disclosure, the average effective channel correlation can be reduced by increasing the number of adjacent subcarriers in which the effective channel correlation decreases, as shown in (b). At this time, it can be confirmed that the diagonal matrix for the phase shift is repeated for every D subcarriers as shown in Equation 5 above.

Therefore, in the preprocessing method according to the second embodiment of the present disclosure, the cyclic delay scaling method is applied to the LD-CDD method, and performance gain through the preprocessing process can be increased. At this time, in the preprocessing method according to the second embodiment of the present disclosure, obtainable performance gains differ according to the cyclic delay scaling factor applied to the LD-CDD scheme. Accordingly, the base station 300 needs to determine a cyclic delay scaling factor based on at least one of the number of antenna ports and the current channel state. Also, since the cyclic delay scaling factor is not a parameter prearranged between the base station 300 and the terminal 400, the base station 300 must transmit the determined cyclic delay scaling factor to the terminal 400. In detail, an operation of the base station 300 performing the preprocessing method according to the second embodiment of the present disclosure will be described with reference to FIG. 8 .

FIG. 8 shows a method of performing preprocessing by applying a cyclic delay scaling method to an LD-CDD method in a base station 300 according to a second embodiment of the present disclosure.

First, since channel selectivity of an effective channel has a significant effect on performance in the CDD preprocessing method, the base station 300 needs information about frequency selectivity of a physical channel in the process of determining a cyclic delay scaling factor. However, the base station 300 using the current CDD preprocessing method does not have a feedback signal capable of obtaining information for estimating frequency selectivity of a channel. Accordingly, the base station 300 uses an uplink sounding reference signal (SRS) transmitted from the terminal 400 to obtain information for estimating frequency selectivity of a channel.

That is, referring to FIG. 8, the base station 300 receives an uplink SRS from the terminal 400 (801). In addition, the base station 300 estimates the frequency selectivity of the uplink channel from the received uplink SRS using the characteristic that the frequency selectivity of the uplink channel and the downlink channel are similar to each other, and estimates the frequency selectivity of the estimated uplink channel is determined as a downlink channel state (ie, frequency selectivity) (803).

Thereafter, the base station 300 determines a cyclic delay scaling factor based on the downlink channel state and the number of antenna ports (805), and transmits the determined cyclic delay scaling factor to the terminal 400 (807). In addition, the base station 300 performs preprocessing by applying the CDD method to the input layer signal according to the preprocessing method previously agreed with the terminal 400 (809). Next, the base station 300 transmits a phase-shifted signal based on the cyclic delay scaling factor to the terminal 400 for the preprocessed signal (811). Since the terminal 400 receives the cyclic delay scaling factor from the base station 300, the terminal 400 demodulates the signal received from the base station 300 by using the cyclic delay scaling factor based on a pre-promised preprocessing method in the demodulation process. can do.

In this case, the pre-processing method pre-arranged between the base station 300 and the terminal 400 may be the method according to the second embodiment of the present disclosure, the signal processing method according to the first embodiment of the present disclosure, or the conventional pre-processing method. When the pre-processing method previously agreed between the base station 300 and the terminal 400 is the signal processing method according to the first embodiment of the present disclosure or the conventional pre-processing method, the base station 300 determines a cyclic delay scaling factor. , a cyclic delay scaling factor may be additionally applied to the signal processing method according to the first embodiment of the present disclosure or the conventional preprocessing method.

In the above, a method of processing a signal in the base station 300 and receiving the processed signal from the base station 300 in the terminal 400 according to the first and second embodiments of the present disclosure has been described. Hereinafter, the terminal 400 In, a method of configuring an effective channel for demodulating a signal received from the base station 300 will be described.

In the case of the conventional CDD preprocessing method, when the base station 300 transmits a physical channel to the terminal 400 using the CRS, the terminal 400 interpolates the physical channel in a resource block (RE) and then An effective channel was configured by adding information on a pre-promised preprocessing method. However, since the CRS can support only up to 4 antenna ports, a new channel transmission method between the base station 300 and the terminal 400 is required in the case of an FD-MIMO system assuming 16 or more antenna ports.

To this end, methods for configuring an effective channel for demodulating a signal received by the terminal 400 in an embodiment of the present disclosure will be described based on FIGS. 9 and 10 . Methods for configuring the effective channel of the terminal 400 may be configured in the following two configuration methods.

- In the first effective channel configuration method, the base station 300 transmits information on a physical channel to the terminal 400 using CSI-RS. Then, the terminal 400 transmits the physical transmission based on a pre-promised pre-processing method (that is, at least one of the signal processing method according to the first embodiment and the signal processing method according to the second embodiment of the present invention). A channel can be configured as an effective channel.

- In the second effective channel configuration method, when the base station 300 directly transmits information on the effective channel to the terminal 400 using the DMRS, the terminal 400 constructs the effective channel.

FIG. 9 shows an example of a first effective channel configuration method in which the terminal 400 configures an effective channel for demodulating a preprocessed signal according to an embodiment of the present disclosure.

First, it is assumed that the terminal 400 knows the CDD preprocessing method used by the base station 300, the preprocessing matrix W used in each subcarrier, the diagonal matrix D for phase shift, and the layer multiplexing matrix U. However, in the case of the FD-MIMO system, since channel transmission using CRS used for channel transmission in the conventional technique is difficult, the base station 300 uses CSI-RS supporting 8 or more antenna ports to transmit physical channels. Information about is transmitted (901). Then, the terminal 400 interpolates the physical channel received from the base station 300 (903). The terminal 400 configures the interpolated physical channel as an effective channel based on preprocessing information known in advance (905).

Thereafter, when the terminal 400 receives the processed signal from the base station 300 (907), it demodulates the received signal based on the effective channel (909).

10 illustrates an example of a second effective channel configuration method in which the terminal 400 configures an effective channel for demodulating a preprocessed signal according to an embodiment of the present disclosure. Here, the second effective channel configuration method is a method in which the base station 300 directly transmits information on an effective channel to the terminal 400 . In particular, referring to FIG. 10, the base station 300 determines an RE for transmitting information on an effective channel to the terminal 400, and the terminal 400 determines an effective channel based on the effective channel received from the base station 300. A method of reconstructing will be described.

Referring to FIG. 10 , a base station 300 receives an SRS from a terminal 400 (100). The base station 300 estimates frequency selectivity of an uplink channel based on the received SRS (1003). The base station 300 determines an RE for transmitting RS overhead and information on an effective channel based on the frequency selectivity of the estimated uplink channel (1005). The base station 300 transmits information on the determined RE to the terminal 400 (1007) and directly transmits information on an effective channel using the determined RE (1009). When the number of antenna ports of the base station 300 is very large, RS overhead for effective channel transmission increases in proportion to the number of antenna ports. In order to solve this problem, when the base station 300 directly transmits information on an effective channel to the terminal 400 as in the embodiment of the present disclosure, RS overhead is mitigated when the number of layers is small compared to the number of antenna ports. can make it However, when the CDD preprocessing method is used in the base station 300 according to the first and second embodiments of the present disclosure, frequency selectivity of an effective channel is very high. For this reason, the base station 300 cannot directly interpolate the effective channels after estimating the effective channels in some REs. Accordingly, after receiving an effective channel from the base station 300, the terminal 400 configures an effective channel for the remaining REs using the received effective channel (1011). In this case, a method for configuring the effective channel by the terminal 400 will be described in detail with reference to FIG. 11 below.

Thereafter, when the terminal 400 receives the processed signal from the base station 300 (1013), it demodulates the received signal based on the reconstructed effective channel (1015).

11 shows an example of a process 1011 of reconfiguring an effective channel by the terminal 400 in the second effective channel configuration method according to an embodiment of the present disclosure.

Referring to FIG. 11 , a process 1011 of reconfiguring an effective channel by a terminal 400 includes an operation 1101 of estimating a physical channel and an operation 1103 of configuring an effective channel.

The operation 1101 of estimating the physical channel is an operation of inversely calculating the physical channel. That is, since the physical channel has low frequency selectivity compared to the effective channel, the terminal 400 may inversely calculate the physical channel from the effective channel received from the base station 300 and interpolate the physical channel corresponding to the remaining REs. At this time, if the number of layers is less than the number of antenna ports in the terminal 400, since information on all physical channels cannot be known from the effective channel corresponding to the RE transmitted by the base station 300, effective channels corresponding to a plurality of REs A physical channel is estimated using (1011). For example, in a system in which the number of antenna ports is 4 and the number of layers is 2, if an RE for transmitting information about an effective channel is used at intervals of C subcarriers, the terminal 400 does not change the channel within the C subcarriers. Under the assumption, a physical channel corresponding to subcarrier k + i ( i = 0, 1, ..., C ) can be estimated.

Next, the terminal 400 reconfigures the estimated physical channel into an effective channel based on the preprocessing information used by the base station 300 (1103). In this case, the terminal 400 may configure an effective channel for subcarrier k + i as shown in Equation 11 by considering the physical channel estimated in the physical channel estimation operation 1101.

<Equation 11>

와

는 각각 부반송파 k에 해당하는 유효 채널과 기지국(300)에서 사용된 전처리 정보이다. 유효 채널에 대한 정보를 기지국(300)이 직접 전송하는 방식은 안테나 포트의 수보다 레이어의 수가 적을 경우 RS 오버헤드를 줄일 수 있다는 장점이 있다. 그러나 기지국(300)이 CDD 전처리 방법을 이용하는 경우 유효 채널의 주파수 선택성이 높기 때문에 물리 채널의 선택성에 따라 RS 오버헤드에 해당하는 C 값을 결정하여 단말(400)로 전송해야 한다.here,

and

is an effective channel corresponding to subcarrier k and preprocessing information used by the base station 300, respectively. The method in which the base station 300 directly transmits information on an effective channel has an advantage in that RS overhead can be reduced when the number of layers is smaller than the number of antenna ports. However, when the base station 300 uses the CDD preprocessing method, since the frequency selectivity of the effective channel is high, a C value corresponding to the RS overhead must be determined according to the selectivity of the physical channel and transmitted to the terminal 400.

In the above, methods for configuring an effective channel for the terminal 400 to demodulate a signal processed by the base station 300 according to an embodiment of the present disclosure have been described, and hereinafter, based on FIGS. 12 and 13, the present disclosure Internal configurations of the base station 300 and terminal 400 performing examples will be briefly described.

12 shows an internal configuration of a base station 300 processing signals in a communication system according to an embodiment of the present disclosure. The main unit for performing the preprocessing method according to the embodiments of the present disclosure in the base station 300 is the preprocessor 307, but the operation of generating and transmitting information and signals necessary for performing the preprocessing may be performed by another unit. there is. Accordingly, the internal configuration shown in FIG. 12 is not limited to any one unit included in the base station 300, but simply shows the configuration of the entire base station 300.

Referring to FIG. 12 , a base station 300 includes a control unit 1201, a transmission unit 1203, a reception unit 1205, and a storage unit 1207.

The controller 1201 controls overall operations of the base station 300, and particularly controls operations related to signal processing according to embodiments of the present disclosure. Operations related to signal processing according to embodiments of the present disclosure are the same as those described with reference to FIGS. 3 to 11, and thus detailed description thereof will be omitted herein.

The transmission unit 1203 receives various signals and various messages from other entities included in the communication system under the control of the control unit 1201. Here, since various signals and various messages received by the transmission unit 1203 are the same as those described in FIGS. 3 to 11, a detailed description thereof will be omitted here.

In addition, the receiving unit 1205 receives various signals and various messages from other entities included in the communication system under the control of the control unit 1201. Here, since various signals and various messages received by the receiving unit 1205 are the same as those described in FIGS. 3 to 11, a detailed description thereof will be omitted here.

The storage unit 1207 stores programs and various data related to operations related to signal processing operations performed by the base station 300 according to an embodiment of the present disclosure under the control of the controller 1201 . In addition, the storage unit 1207 stores various signals and various messages received by the receiving unit 1205 from the other entities.

12 shows a case where the base station 300 is implemented as separate units such as the controller 1201, the transmitter 1203, the receiver 1205, and the storage unit 1207, but the base station ( 300) can be implemented in an integrated form of at least two of the control unit 1201, transmission unit 1203, reception unit 1205, and storage unit 1207. Also, of course, the base station 300 may be implemented with one processor.

13 shows an internal configuration of a terminal 400 that processes signals in a communication system according to an embodiment of the present disclosure. In the terminal 400, the main unit for configuring an effective channel and demodulating a signal according to embodiments of the present disclosure is a demodulation unit, but operations for generating and transmitting information and signals necessary for configuring an effective channel and demodulating a signal are It can be done in other units. Accordingly, the internal configuration shown in FIG. 13 is not limited to any one unit included in the terminal 400, but simply shows the configuration of the entire terminal 400.

Referring to FIG. 13 , a terminal 400 includes a controller 1301 , a transmitter 1303 , a receiver 1305 and a storage unit 1307 .

The controller 1301 controls overall operations of the terminal 400, and particularly controls operations related to signal processing according to embodiments of the present disclosure. Operations related to signal processing according to an embodiment of the present disclosure are the same as those described in FIGS. 4 and 9 to 11, so detailed description thereof will be omitted here.

The transmission unit 1303 receives various signals and various messages from other entities included in the communication system under the control of the control unit 1301. Here, since various signals and various messages received by the transmission unit 1303 are the same as those described in FIGS. 4 and 9 to 11, a detailed description thereof will be omitted here.

In addition, the receiving unit 1305 receives various signals and various messages from other entities included in the communication system under the control of the control unit 1301. Here, since various signals and various messages received by the receiving unit 1305 are the same as those described in FIGS. 4 and 9 to 11, a detailed description thereof will be omitted here.

The storage unit 1307 stores programs and various data related to operations related to signal processing operations performed by the terminal 400 according to an embodiment of the present disclosure under the control of the controller 1301 . In addition, the storage unit 1307 stores various signals and various messages received by the receiving unit 1305 from the other entities.

13 shows a case where the terminal 400 is implemented as separate units such as the control unit 1301, the transmission unit 1303, the reception unit 1305, and the storage unit 1307, but the terminal ( 400) can be implemented in an integrated form of at least two of the control unit 1301, transmission unit 1303, reception unit 1305, and storage unit 1307. Also, of course, the base station 300 may be implemented with one processor.

In the above, the internal configurations of the base station 300 and the terminal 400 performing the embodiments of the present disclosure have been described based on FIGS. 12 and 13, and below, the base station 300 and the terminal 400 ) will explain the effect when applied.

14 shows performance according to the number of antenna ports when the base station applies the conventional layer level CDD method and when the port level CDD method according to the first embodiment of the present disclosure is applied.

Referring to FIG. 14, when the base station preprocesses, when the conventional layer level CDD method is applied, performance change according to the number of antenna ports is insignificant, whereas when the port level CDD method is applied, out-age capacity according to the number of antenna ports ( It can be confirmed that outage capacity) increased by about 5%. In addition, when the base station applies the port level CDD scheme according to the first embodiment of the present disclosure, link reliability can be increased as the outage capacity can be increased.

15 shows bit error rate (BER) performance when a conventional layer level CDD method is applied in a base station and when a port level CDD method according to the first embodiment of the present disclosure is applied.

Referring to FIG. 15 , it can be confirmed that the case where the port level CDD method according to the first embodiment of the present disclosure is applied has a performance gain in terms of diversity compared to the case where the conventional layer level CDD method is applied in the base station. In addition, when the cyclic delay scaling method according to the second embodiment of the present disclosure is applied to the port lever CDD method according to the first embodiment of the present disclosure, it can be confirmed that the CDD precoding performance is improved.

16 shows BER performance according to channel conditions when the base station applies the conventional layer level CDD method and when the port level CDD method according to the first embodiment of the present disclosure is applied.

Referring to FIG. 16, when the port level CDD method according to the first embodiment of the present disclosure is applied to the base station, it can be seen that the gain for precoding performance increases in a high mobility environment with high channel selectivity. . In addition, when the cyclic delay scaling method according to the second embodiment of the present disclosure is applied to the base station, it can be confirmed that the performance gain significantly occurs in an environment with low mobility.

Meanwhile, in the detailed description of the present disclosure, specific embodiments have been described, but various modifications are possible without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure should not be limited to the described embodiments and should not be defined by the scope of the following claims as well as those equivalent to the scope of these claims.

Claims (24)

In the method of processing a signal using an open-loop preprocessing method in a base station included in a full dimension multi-input multi-output (FD-MIMO) communication system,
A process of performing layer mapping on an input signal;
Performing pre-processing of mapping the layer-mapped layer signal to an antenna port;
Performing a phase shift on the preprocessed antenna port signal using a diagonal matrix for phase shift to which a cyclic delay scaling factor is applied,
The cyclic delay scaling factor is determined by the base station based on information about frequency selectivity of a downlink channel and the number of antenna ports, and the frequency selectivity of the downlink channel is determined by the downlink channel from the terminal. It is estimated using the frequency selectivity of the uplink channel obtained based on the sounding reference signal (SRS) received through the uplink channel from the terminal without feedback information for estimating the frequency selectivity of ,
The cyclic delay scaling factor is transmitted to the terminal,
A signal output by performing phase shift to which the cyclic delay scaling factor is applied corresponds to Equation 1 below,
[Equation 1]

,
Here, N _T is the number of transmit antennas, N _FFT is the size of a fast fourier transform (FFT), α is a cyclic delay scaling factor, and is defined as 0 < α < 1,

is set to have a value greater than N _FFT .

delete delete According to claim 1,
Signal processing further comprising transmitting a channel state indicator-reference signal (CSI-RS) including information about a physical channel through which a signal output by performing the phase shift is transmitted to a terminal method.
According to claim 1,
determining a resource element for transmitting an effective channel for transmitting a signal output by performing the phase shift based on frequency selectivity of an uplink channel, and transmitting information about the resource element to a terminal;
and transmitting information on the effective channel through the resource element.
In a method for processing a signal using an open-loop preprocessing method in a terminal included in a full dimension multi-input multi-output (FD-MIMO) communication system,
receiving a signal from a base station;
demodulating the received signal;
The received signal is a signal obtained by performing a phase shift by using a diagonal matrix for phase shift to which a cyclic delay scaling factor is applied to the preprocessed antenna port signal after preprocessing of mapping to an antenna port in the base station. The cyclic delay scaling factor is determined by the base station based on information about the frequency selectivity of a downlink channel and the number of antenna ports, and the frequency selectivity of the downlink channel is determined by the frequency selectivity of the downlink channel from the terminal. Without feedback information for estimating frequency selectivity, it is estimated using the frequency selectivity of the uplink channel obtained based on a sounding reference signal (SRS) received through the uplink channel from the terminal, The cyclic delay scaling factor is transmitted to the terminal,
A signal output by performing phase shift to which the cyclic delay scaling factor is applied corresponds to Equation 1 below,
[Equation 1]

,
Here, N _T is the number of transmit antennas, N _FFT is the size of a fast fourier transform (FFT), α is a cyclic delay scaling factor, and is defined as 0 < α < 1,

is set to have a value greater than N _FFT .
delete delete According to claim 6,
Receiving a channel state indicator-reference signal (CSI-RS) including information about a physical channel through which a signal output by performing the phase shift is transmitted from the base station;
The signal processing method further comprising configuring an effective channel based on the information about the received physical channel.
According to claim 6,
Receiving information about a resource element determined to transmit an effective channel for transmitting a signal output by performing the phase shift based on frequency selectivity of an uplink channel from the base station;
receiving information on the effective channel from the base station;
and configuring an effective channel based on the information on the resource element and the information on the effective channel.
In a base station for processing a signal using an open-loop preprocessing method in a full dimension multi-input multi-output (FD-MIMO) communication system,
Perform layer mapping on the input signal, perform preprocessing of mapping the layer mapped layer signal to an antenna port, and use a diagonal matrix for phase shift to which a cyclic delay scaling factor is applied to the preprocessed antenna port signal A control unit for controlling performing phase shift;
A transmission unit for transmitting the signal processed by the control unit to a terminal,
The cyclic delay scaling factor is determined by the base station based on information about frequency selectivity of a downlink channel and the number of antenna ports, and the frequency selectivity of the downlink channel is determined by the downlink channel from the terminal. It is estimated using the frequency selectivity of the uplink channel obtained based on the sounding reference signal (SRS) received through the uplink channel from the terminal without feedback information for estimating the frequency selectivity of ,
The cyclic delay scaling factor is transmitted to the terminal,
A signal output by performing phase shift to which the cyclic delay scaling factor is applied corresponds to Equation 1 below,
[Equation 1]

,
Here, N _T is the number of transmit antennas, N _FFT is the size of a fast fourier transform (FFT), α is a cyclic delay scaling factor, and is defined as 0 < α < 1,

Is set to have a value greater than N _FFT , the base station.
delete delete The method of claim 11, wherein the transmitter,
A base station characterized by transmitting a channel state indicator-reference signal (CSI-RS) including information about a physical channel through which a signal output by performing the phase shift is transmitted to the terminal.
The method of claim 11, wherein the control unit,
Based on the frequency selectivity of the uplink channel, a resource element for transmitting an effective channel for transmitting a signal output by performing the phase shift is determined, information on the resource element is transmitted to the terminal, and through the resource element The base station characterized in that for controlling the transmission unit to transmit information on the effective channel to the terminal.
In a terminal for processing a signal using an open-loop preprocessing method in a full dimension multi-input multi-output (FD-MIMO) communication system,
a receiver for receiving a signal from a base station;
And a control unit for controlling the demodulation of the received signal,
The received signal is a signal obtained by performing a phase shift by using a diagonal matrix for phase shift to which a cyclic delay scaling factor is applied to the preprocessed antenna port signal after preprocessing of mapping to an antenna port in the base station. The cyclic delay scaling factor is determined by the base station based on information about the frequency selectivity of a downlink channel and the number of antenna ports, and the frequency selectivity of the downlink channel is determined by the frequency selectivity of the downlink channel from the terminal. Without feedback information for estimating frequency selectivity, it is estimated using the frequency selectivity of the uplink channel obtained based on a sounding reference signal (SRS) received through the uplink channel from the terminal, The cyclic delay scaling factor is transmitted to the terminal,
A signal output by performing phase shift to which the cyclic delay scaling factor is applied corresponds to Equation 1 below,
[Equation 1]

,
Here, N _T is the number of transmit antennas, N _FFT is the size of a fast fourier transform (FFT), α is a cyclic delay scaling factor, and is defined as 0 < α < 1,

Is set to have a value greater than N _FFT , the terminal.
delete delete The method of claim 16, wherein the control unit,
Control to receive a channel state indicator-reference signal (CSI-RS) including information about a physical channel through which a signal output by performing the phase shift is transmitted from the base station, and the received A terminal characterized in that an effective channel is configured based on information about a physical channel.
The method of claim 16, wherein the control unit,
Control to receive information on a resource element determined to transmit an effective channel for transmitting a signal output by performing the phase shift based on frequency selectivity of an uplink channel from the base station, and to receive information about the effective channel from the base station A terminal characterized in that it controls to receive information and configures an effective channel based on the information on the resource element and the information on the effective channel.
delete delete delete delete

Images