KR20190047410A - Apparatus and method for transmitting or receiving signal by reducing papr in wireless environment system - Google Patents

Abstract

Disclosed is a transmission device in an orthogonal frequency division multiplexing (OFDM) system, which is capable of further lowering a peak-to-average-power ratio (PAPR). According to one embodiment of the present invention, the device comprises: an input unit inputting M data symbol vectors related to a transmission signal (M is a natural number); an offset symbol generator dividing the M data symbol vectors into a real number part and an imaginary number part to perform a plurality of linear phase shifts so as to generate a symbol vector with mixed phases; an inverse discrete Fourier transform (IDFT) execution unit executing N-point inverse Fourier transform with respect to the symbol vector generated in the offset symbol vector (N is a natural number); and a cyclic prefix addition unit adding a cyclic prefix to a symbol Fourier-transformed in the IDFT execution unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for transmitting / receiving signals by lowering the PAPR in a wireless environment,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless environment system, and more particularly, to a method and structure for transmitting and receiving signals in a wireless communication system.

In 4G mobile communication, DFT-s-OFDM (DFT (Descrete Fourier Transform), which is a type of localized single-carrier frequency domain multiple access (SC-FDMA), is used to lower the peak- Tramsform spread Orthogonal Frequency Division Multiplexing (OFDM)) technology.

In order to solve the problem of PAPR in the uplink of the 5G mobile communication, the PAPR is reduced by using the pi / 2-BPSK symbol in addition to the conventional DFT-s-OFDM.

In uplink and mobile environments, where power is limited, PAPR is associated with all communication performance including battery run time, communication quality, and data transmission speed.

In particular, in 5G, which considers communication over 40GHz band, efficiency of PA (power amp) is lowered and bandwidth used is much wider than that of existing, so applying PAPR lowering technology is essential. It is a reality.

According to an aspect of the present invention, there is provided a method of reducing a PAPR in a wireless environment in which a PAPR can be further reduced while maintaining advantages of a DFT-s-OFDM technique used in a 4G uplink, And an apparatus and method for transmitting and receiving data.

Particularly, the present invention provides a signal transmitting and receiving apparatus and method that can reduce the PAPR by using a slight additional transmission / reception complexity while maintaining the transmission rate and reception performance intact.

According to an aspect of the present invention, there is provided a transmitter in an OFDM (Orthogonal Frequency Division Multiplexing) system, comprising: an input unit (M is a natural number) for inputting M data symbol vectors of blocks related to a transmission signal; An offset symbol generator for dividing the M data symbol vectors into a real part and an imaginary part and performing a plurality of linear phase shifts to generate a staggered symbol vector, An inverse discrete Fourier transform (IDFT) performing unit (where N is a natural number) for performing N-point inverse Fourier transform on the vector and a cyclic prefix to the inverse Fourier transformed symbol in the IDFT performing unit And may include a cyclic prefix appendage.

The offset symbol generator divides the M data symbol vectors into a real part of a data symbol vector including a QAM signal and an imaginary part of a data symbol vector including a QAM signal, An imaginary part processor for performing a linear phase shift on the real part of the data symbol vector including the QAM signal, an imaginary part processor for performing two linear phase shifts on the imaginary part of the data symbol vector including the QAM signal, And a summer for summing the symbol vector generated by the real part processor and the symbol vector generated by the imaginary part processor.

The real part processor may perform a first linear phase shift and then perform an M-point discrete Fourier transform (DFT) on the phase-shifted vector.

The imaginary part processor performs a second linear phase shift on the imaginary part of the data symbol vector including the QAM signal and then performs an M-point DFT and performs a third linear phase < RTI ID = 0.0 > Shift can be performed.

The QAM signal may include at least one of a Quadrature Phase Shift Keying (QPSK) signal, a 16QAM signal, and a 64QAM signal.

According to an aspect of the present invention, there is provided a transmission method in an OFDM (Orthogonal Frequency Division Multiplexing) system, comprising: inputting M data symbol vectors of a block related to a transmission signal (where M is a natural number) Dividing the M data symbol vectors into a real part and an imaginary part and performing a plurality of linear phase shifts to generate a phase-shifted symbol vector; performing N-point inverse Fourier transform on the staggered symbol vector; (Where N is a natural number), and adding a cyclic prefix to the inverse Fourier transformed symbol in the IDFT performing unit.

According to an aspect of the present invention, there is provided a receiving apparatus in an OFDM (Orthogonal Frequency Division Multiplexing) system, which includes a cyclic prefix removing unit that removes a cyclic prefix from a received signal generated based on a staggered vector, (N is a natural number) for performing an N-point discrete Fourier transform (DFT) on a signal from which the cyclic prefix is removed, equalization for performing equalization on a signal on which the DFT is performed, And an offset symbol receiver for dividing the signal passed through the equalizer into an imaginary part and a real part and performing a plurality of linear phase shifts to generate an aligned symbol vector.

The offset symbol generator includes a demultiplexer (M is a natural number) for dividing the M data symbol vectors of the received signal into two portions, performs a linear phase shift on the first portion of the symbol vector An imaginary receiver configured to perform a second linear phase shift on a second portion of the symbol vector and to generate an imaginary number; and a receiver configured to receive a symbol vector generated at the real receiver and a symbol vector generated at the imaginary receiver And a summer that sums the symbol vectors.

The real receiver may perform an M-point inverse discrete Fourier transform (IDFT) on the first part of the symbol vector, perform a first linear phase shift on the inverse Fourier transformed symbol vector, and take a real part .

The imaginary receiver performs a second linear phase shift on the second portion of the symbol vector and then performs an M-point IDFT and performs a third linear phase shift on the M-point inverse Fourier transformed symbol vector , Then imaginary parts can be taken and then the imaginary number can be multiplied by the imaginary number 1j.

According to an aspect of the present invention, there is provided a receiving method in an OFDM (Orthogonal Frequency Division Multiplexing) system, comprising: removing a cyclic prefix from a received signal generated based on a staggered vector; Performing an N-point discrete Fourier transform (DFT) on the signal from which the cyclic prefix has been removed (where N is a natural number), performing equalization on the signal on which the DFT is performed, And performing a plurality of linear phase shifts by separating the imaginary part and the real part with respect to one signal to generate an aligned symbol vector.

According to the apparatus and method for transmitting and receiving signals by lowering the PAPR in the wireless environment of the present invention, the transmission signal generated by the apparatus has the same transmission rate and reception performance as conventional DFT-s-OFDM, and the PAPR is reduced by 0.7 to 1 dB .

1 is a block diagram illustrating a general DFT-s-OFDM transmitter structure,
2 is a block diagram illustrating a modified DFT-s-OFDM overall transmitter structure for lowering PAPR according to an embodiment of the present invention;
FIG. 3 is a detailed block diagram showing the detailed structure of the offset symbol generator of FIG. 2,
FIG. 4 is a diagram showing the function of a linear phase shift block used in the blocks (a), (a *), (b), (b *), (c) Fig.
FIG. 5 is a detailed block diagram showing the detailed operation of the block operation of FIG. 3 (a)
FIG. 6 is a detailed block diagram showing the detailed operation of the block operation of FIG. 3 (b)
FIG. 7 is a detailed block diagram showing the detailed operation of the block operation of FIG. 3 (c)
8 is a block diagram illustrating a general DFT-s-OFDM receiver structure,
9 is a block diagram illustrating a receiver structure according to an embodiment of the present invention.
FIG. 10 is a detailed block diagram illustrating the offset symbol receiver detailed structure of FIG. 9;
11 is a graph illustrating a performance improvement effect of QPSK in a transmitter according to an embodiment of the present invention,
12 is a graph illustrating a performance improvement effect of 16-QAM in a transmitter according to an embodiment of the present invention,
13 is a graph illustrating the performance improvement effect of 64-QAM in a transmitter according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

In this specification, OFDM and SC-FDMA systems may include base stations and / or terminals. Also, OFDM and SC-FDMA systems can be used for uplink and / or downlink signal transmission.

Herein, the terminal includes a mobile station (MS), a user equipment (UE), a user terminal (UT), a wireless terminal, an access terminal (AT), a terminal, a fixed or mobile subscriber unit, A cellular phone, a wireless device, a wireless communication device, a wireless transmit / receive unit (WTRU), a mobile node, a mobile station, a mobile station, a personal digital assistant ; PDAs), smart phones, laptops, netbooks, personal computers, wireless sensors, consumer electronics (CE) or other terms. Various embodiments of the terminal may be used in various applications such as cellular telephones, smart phones with wireless communication capabilities, personal digital assistants (PDAs) with wireless communication capabilities, wireless modems, portable computers with wireless communication capabilities, Devices, gaming devices with wireless communication capabilities, music storage and playback appliances with wireless communication capabilities, Internet appliances capable of wireless Internet access and browsing, as well as portable units or terminals incorporating combinations of such functions However, the present invention is not limited thereto.

A base station generally refers to a fixed point in communication with a terminal and includes a base station, a Node-B, an eNode-B, an advanced base station (ABS) But is not limited to, an HR-BS, a site controller, a base transceiver system (BTS), an access point (AP), or any other type of interfacing device capable of operating in a wireless environment.

A base station may be part of a RAN, which may also include other base stations and / or network elements such as a base station controller (BSC), a radio network controller (RNC), relay nodes,

A base station may be configured to transmit and / or receive wireless signals within a particular geographic area that may be referred to as a cell.

A cell may also be divided into cell sectors. For example, a cell associated with a base station may be divided into three sectors. Thus, in one embodiment, the base station may include three transceivers, one transceiver for each sector of the cell. In another embodiment, the base station may utilize a multiple-input multiple-output (MIMO) technique and therefore utilize multiple transceivers for each sector of the cell.

Transmitter structure

1 is a block diagram illustrating a general DFT-s-OFDM transmitter structure.

1, the DFT-s-0FDM transmitter includes an M-point DFT (Descrete Fourier Tramsform) performing unit 110, an N-point IDFT performing unit 120 and a CP adding unit 130. [ . ≪ / RTI > This general transmitter operates on the basis of the following mathematical operation. Here, M and N represent natural numbers.

Where y is the received signal, x is the transmitted signal, n is the noise, and H is the multipath channel toeplitz matrix.

를 전송할 때, M-포인트 DFT 수행기(110)는 M X 1의 벡터

를 M-포인트 DFT 시킨다. First, the M data symbol vectors of the k-th block

The M-point DFT performer 110 receives the vector of MX 1

Point DFT.

Then, the N-point IDFT performing unit 120 performs an N-point inverse Fourier transform after subcarrier mapping the N-point vector.

The CP adding unit 130 adds the CP to the inverse Fourier transformed symbol vector and transmits it to the receiver.

2 is a block diagram illustrating a modified DFT-s-OFDM overall transmitter structure that lowers PAPR according to an embodiment of the present invention. 2, the transmitter according to an exemplary embodiment of the present invention may include an offset symbol generator 210, an N-point IDFT performing unit 220, and a CP adding unit 230. Referring to FIG.

Referring to FIG. 2, if the input data to be transmitted is , This is allocated to a plurality of M x 1 matrices in the form of allocating subcarriers. According to an embodiment of the present invention, to reduce the PAPR, an offset symbol generator 210 is utilized without using a general M-point DFT.

The offset symbol generator 210 divides the M data symbol vectors into a real part and an imaginary part, and performs a plurality of linear phase shifts to generate a phase-staggered symbol vector.

The N-point IDFT performing unit 220 and the CP adding unit 230 perform the same functions as the N-point IDFT performing unit 120 and the CP adding unit 130 of FIG.

The operation of the offset symbol generator 210 will now be described in more detail.

3 is a detailed block diagram showing the detailed structure of the offset symbol generator of FIG.

(M개의 데이터 심볼 벡터)에 대해 2개의 스트림으로 데이터를 구분한 후에 구분된 데이터에 별도의 연산 처리를 수행한 후, 합산하여 전송한다.Referring to FIG. 3, the offset symbol generator

(M data symbol vectors) are divided into two streams, and then the divided data are subjected to separate arithmetic processing, and are summed and transmitted.

The two streams are divided into a real part Re of a data symbol vector including a QAM (Quadrature Amplitude Modulation) signal and an imaginary part Im of a data symbol vector including a QAM signal. Thus, the real part is subjected to the arithmetic processing at the upper end in the drawing according to the embodiment of Fig. 3 and the imaginary part at the lower end in the drawing.

In particular, the processing for the real part includes one linear phase shift related block ((a) block), and after (a) linear phase shift associated with the block, it undergoes an M-point DFT process.

The processing for the imaginary part includes two phase shift related blocks ((b) block and (c) block), and an M-point DFT process between the (b) block and the (c) block.

Thus, by generating a phase-shifted symbol vector by performing one linear phase shift for the real part and two linear phase shifts for the imaginary part, it is possible to obtain a PAPR Can be reduced.

FIG. 4 is a diagram showing the function of a linear phase shift block used in the blocks (a), (a *), (b), (b *), (c) Fig.

Referring to FIG. 4, with respect to the linear phase shift, the equations relating to R (?) And? ₀ are shown, which represent the following operations.

라는 M x 1의 데이터 심볼 벡터가 들어갔을 경우, 이라는 연산 결과가 도출된다. 이를 도 3의 (a), (b) 및 (c) 블록에 각각 적용하는 것을 도 5 내지 도 7을 통해 설명한다. Through the above operation

If an M x 1 data symbol vector is entered, Is obtained. The application of this to each of the blocks (a), (b) and (c) of FIG. 3 will be described with reference to FIGS. 5 to 7.

FIG. 5 is a detailed block diagram showing the detailed operation of the block operation of FIG. 3 (a).

의 실수부인 Re(

)를 입력으로 받아, R(φ₀)의 선형 위상 쉬프트 연산을 수행한다. 이에 따라, R(φ₀)Re(

)를 출력으로 내보내고, 이렇게 출력된 위상 쉬프트된 벡터, R(φ₀)Re(

)는 다시 M-포인트 DFT를 거쳐 허수부와 합산된다.Referring to Figure 5, (a) the block

Re's mistake, Re (

) As an input, and performs a linear phase shift operation of R ( ₀ ). Accordingly, R (? ₀ ) Re (

) To the output, and outputs the phase-shifted vector R ( ₀ ) Re (

) Is again added to the imaginary part through the M-point DFT.

FIG. 6 is a detailed block diagram showing the detailed operation of the block operation of FIG. 3 (b).

의 허수부인 IM(

)를 입력으로 받아,

의 선형 위상 쉬프트 연산을 수행한다. 상기 연산에 따라 출력된 심볼 벡터는 M-포인트 DFT 연산으로 들어가고, DFT 연산 이후 (c) 블록에서 다시 한번 선형 위상 쉬프트가 된다.Referring to FIG. 6, the (b) block processes the second stream. This is the imaginary part of the data symbol vector containing the QAM signal. In other words,

Imaginary wife of IM (

) As an input,

To perform a linear phase shift operation. The symbol vector output according to the above operation enters the M-point DFT operation and becomes linear phase shift once again in the block after the DFT operation (c).

FIG. 7 is a detailed block diagram showing the detailed operation of the block operation of FIG. 3 (c).

를 입력으로 받아, R(-π/M))의 선형 위상 쉬프트 연산을 수행한다. 그리고는, 상기 연산에 따라 출력된 값을 실수부 연산을 통해 출력된 값과 합산할 수 있다. 합산된 값은 N-포인트 IDFT부로 제공된다. Referring to FIG. 7, (c) block is a symbol vector after DFT operation after linear phase shift of block (b)

And performs a linear phase shift operation of R (-π / M). Then, the output value according to the operation can be added to the value output through the real part operation. The summed value is provided to the N-point IDFT section.

Receiver structure

8 is a block diagram illustrating a general DFT-s-OFDM receiver structure. 8, the DFT-s-OFDM receiver may include a CP removal unit 820, an N-point DFT performing unit 830, an equalizer 840 and an M-point IDFT unit 850 have.

8, the CP removal unit 820 removes the cyclic prefix from the received signal, the N-point DFT performing unit 830 performs N-point Fourier transform on the received signal, The equalizer 840 performs an equalization operation, and the M-point IDFT unit 850 performs M-point inverse Fourier transform on the equalized signal.

9 is a block diagram illustrating a structure of a receiver according to an embodiment of the present invention. 9, a receiver according to an embodiment of the present invention includes a CP removing unit 920, an N-point DFT performing unit 930, an equalizer 940, and an offset symbol receiver 950 .

Referring to FIG. 9, the M-point inverse Fourier transform unit may be replaced with an offset symbol receiver. The detailed block of the offset symbol receiver is shown in FIG. The CP removing unit 920, the N-point DFT performing unit 930 and the equalizer 940 are the same as the CP removing unit 820 and the N- The point DFT performing unit 830, and the equalizer 840.

10 is a detailed block diagram illustrating the offset symbol receiver detailed structure of FIG.

Referring to FIG. 10, a (a *) block, a b * block and a c * block are included, Represents the inverse process.

에 대해 두 개의 스트림으로 나눠서 처리한다. That is, after removing the CP, an N-point DFT is performed, and an equalized input signal

Into two streams.

Here, in the calculation processing at the upper part divided into two parts, the linear phase shift calculation of the (a *) block and the real part are taken after the M-point IDFT. In the operation processing of the lower stage, the (c *) block operation is performed first, then the M-point IDFT operation is performed, and the (b *) operation is performed on the output value on which the M-point IDFT operation is performed. Then, the real part is taken from the result of the operation, and then the imaginary number 1j is multiplied.

Then, the result of the top operation and the bottom operation is added to restore the QAM signal. At this time, it may be applied to a case where an error correcting code or the like is used as a soft output.

The transceiver according to an exemplary embodiment of the present invention is applicable to a proper complex multiple QAM signal such as a Quadrature Phase Shift Keying (QPSK) signal, a 16QAM signal, and a 64QAM signal.

Simulation result

FIG. 11 is a graph illustrating a performance improvement effect in QPSK of a transmitter according to an embodiment of the present invention, FIG. 12 is a graph illustrating a performance improvement effect of 16-QAM in a transmitter according to an embodiment of the present invention, 13 is a graph illustrating the performance improvement effect of 64-QAM in a transmitter according to an embodiment of the present invention.

Referring to FIGS. 11 to 13, it can be seen that the performance of the transmitter according to an exemplary embodiment of the present invention is lower than that of the DFT-s-OFDM system for 16QAM and 64QAM signals as well as QPSK .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (11)

A transmitting apparatus in an OFDM (Orthogonal Frequency Division Multiplexing) system,
An input for inputting M data symbol vectors of a block associated with a transmitted signal, where M is a natural number;
An offset symbol generator for dividing the M data symbol vectors into a real part and an imaginary part and performing a plurality of linear phase shifts to generate a phase-staggered symbol vector;
An inverse discrete Fourier transform (IDFT) performing unit for performing N-point inverse Fourier transform on the symbol vector generated by the offset symbol generator, where N is a natural number; And
And a cyclic prefix appending section for adding a cyclic prefix to the IDFT performed by the IDFT performing section. 2. The apparatus of claim 1, wherein the offset symbol generator
Dividing the M data symbol vectors into a real part of a data symbol vector including a QAM (Quadrature Amplitude Modulation) signal and an imaginary part of a data symbol vector including a QAM signal;
A real part processor for performing a linear phase shift on a real part of a data symbol vector including the QAM signal;
An imaginary part processor for performing two linear phase shifts with respect to an imaginary part of a data symbol vector including the QAM signal; And
And a summer for summing the symbol vector generated by the real part processor and the symbol vector generated by the imaginary part processor. 3. The method of claim 2,
Wherein the real part processor performs a first linear phase shift and then performs an M-point discrete Fourier transform (DFT) on the phase-shifted vector. 3. The apparatus of claim 2, wherein the imaginary part processor
Performing an M-point DFT on the imaginary part of the data symbol vector including the QAM signal and then performing a third linear phase shift on the vector on which the M-point DFT is performed, A transmitting device in a system. 3. The method of claim 2,
Wherein the QAM signal comprises at least one of a Quadrature Phase Shift Keying (QPSK) signal, a 16QAM signal, and a 64QAM signal. A transmission method in an OFDM (Orthogonal Frequency Division Multiplexing) system,
Inputting M data symbol vectors of a block associated with a transmitted signal, where M is a natural number;
Dividing the M data symbol vectors into a real part and an imaginary part and performing a plurality of linear phase shifts to generate a phase-staggered symbol vector;
Performing an N-point inverse Fourier transform on the staggered symbol vector, where N is a natural number; And
And adding a cyclic prefix to an inverse Fourier transformed symbol in the IDFT performing unit. A receiving apparatus in an OFDM (Orthogonal Frequency Division Multiplexing) system,
A cyclic prefix removal unit that removes a cyclic prefix from a received signal generated based on a staggered thesis vector;
A DFT performing unit for performing an N-point discrete Fourier transform (DFT) on the signal from which the cyclic permutation is removed, wherein N is a natural number;
An equalizer for performing equalization on the DFT-performed signal; And
And an offset symbol receiver for dividing the signal passed through the equalizer into imaginary and real parts to perform a plurality of linear phase shifts to generate an aligned symbol vector. . 8. The apparatus of claim 7, wherein the offset symbol generator
A divider for dividing the M data symbol vectors of the received signal into two parts, where M is a natural number;
A real receiver that performs a linear phase shift on a first portion of the symbol vector and then takes a real part;
An imaginary receiver for generating an imaginary number after performing a second linear phase shift on a second portion of the symbol vector; And
And a summer for summing the symbol vector generated by the real receiver and the symbol vector generated by the imaginary receiver. 9. The method of claim 8,
The real receiver may perform an M-point inverse discrete Fourier transform (IDFT) on a first part of the symbol vector, perform a first linear phase shift on an inverse Fourier transformed symbol vector, . 9. The method of claim 8,
The imaginary receiver performs a second linear phase shift on the second portion of the symbol vector and then performs an M-point IDFT and performs a third linear phase shift on the M-point inverse Fourier transformed symbol vector And then taking the real part and then multiplying the imaginary number 1j to produce an imaginary number. A receiving method in an OFDM (Orthogonal Frequency Division Multiplexing) system,
Removing a cyclic prefix from a received signal generated based on a staggered thesis vector;
Performing an N-point discrete Fourier transform (DFT) on the signal from which the cyclic prefix has been removed, where N is a natural number;
Performing equalization on the DFT performed signal; And
And performing a plurality of linear phase shifts by dividing the signal passed through the equalizer into an imaginary part and a real part to generate an aligned symbol vector.

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