KR101710952B1 - Method of transmitting uplink demodulation reference signal multiplexed with data in uplink multi-input multi-output transmission - Google Patents

Abstract

A multi-layer transmission method in which data of an uplink DFT-s-OFDM transmission scheme to which MIMO is applied and a DM-RS sequence are multiplexed and transmitted is disclosed. One DM-RS sequence is allocated for the uplink transmission and is allocated to the DM-RS signal sequence of the first transmission layer, and a cyclic shift value of the same sequence as the DM-RS signal sequence of the first transmission layer is allocated The DM-RS signal sequence, which is differently configured, is allocated to the DM-RS signal sequence of the second transmission layer, and the data for each layer and the DM-RS sequence for each layer for each of the first transmission layer and the second transmission layer are multiplexed Thereby constituting a multi-layer transmission method in which data and a DM-RS sequence are multiplexed and transmitted. Therefore, it is possible to transmit a reference signal in more OFDM symbols in a slot or a sub-frame without increasing the overhead, and it is possible to cope with LTE-Advanced which requires support of a high frequency band and a moving speed, It is possible to transmit and receive data with orthogonality maintained.

Description

[0001] The present invention relates to a method of transmitting uplink DM-RS multiplexed with data in uplink MIMO transmission,

The present invention relates to demodulation reference signal transmission in an uplink, and more particularly, to a method and apparatus for maintaining a low CM (Cubic Metric) in a DFT-spread-OFDM scheme, which is an uplink access scheme of 3GPP LTE- And multiplexing the data and the DM-RS signal into one OFDM symbol, and transmitting the multiplexed data.

The DFT spread Orthogonal Frequency Division Multiplexing (OFDM) scheme is a promising alternative to the conventional power amplifier because of its superior characteristics of low Cubic Metric (CM) or equivalent low peak to average power ratio (PAPR) Can be efficiently used. This is a great advantage when the cost of coverage and power amplifier is a problem.

That is, the DFT-s-OFDM has a similar structure to the OFDM, thereby obtaining robustness against the multipath channel, and solving the disadvantage that the existing OFDM increases the PAPR through the IFFT operation, By reducing the power consumption by 3 dB, it is possible to use PA (Power Amplifier) more efficiently. The advantage of SC-FDMA is that the structure itself has minimized the burden on the mobile terminal, but has shifted the burden to the base station.

Because of this advantage, the DFT spread OFDM scheme is adopted as the uplink transmission scheme of the 3GPP LTE system, and the DFT spread OFDM scheme is equivalently referred to as a single carrier frequency division multiple access scheme (SC-FDMA) Also.

Also, the 3GPP LTE-Advanced is considered to be an uplink transmission scheme, and is adapted to the clustered DFT-s-OFDM scheme that allows non-contiguous resource allocation in response to carrier aggregation considered in LTE-Advanced It was decided in early 2009.

The reference or pilot signal is transmitted to the receiving end according to a certain rule at the transmitting end of most communication systems for channel estimation of the receiving end. In 3GPP LTE, one OFDM symbol per slot is used to transmit a reference signal . This is because the characteristics of the DFT spread OFDM signal generally cause CM and PAPR to increase when data and reference signals are mixed in one OFDM symbol (which means DFT spread OFDM symbol for the sake of convenience, herein referred to as OFDM symbol) This is to prevent this.

On the other hand, in LTE-Advanced, basic communication services should be performed even in a frequency spectrum higher than LTE and a high mobile speed. For example, according to the requirements of LTE-advanced, it is required to support high travel speeds of 350 Km / s (even 500 Km / s) per hour, which corresponds to the speed of high-speed trains.

Therefore, a higher Doppler spread environment occurs in the LTE-Advanced than in the LTE system, so it is difficult to expect a satisfactory performance with the reference signal structure of the LTE system. That is, the length of each OFDM symbol in LTE is 66.67 us, which is sufficiently shorter than the coherence time in a typical environment. However, in LTE-Advanced, If the Doppler frequency is high, the fading channel may change drastically even within one slot period (0.5 ms). In addition, the current LTE standard does not suggest a transmission method for multi-layer (Spatial Mutiplexing) transmission in uplink, which is introduced in LTE-advanced, only in DM-RS transmission in uplink single layer transmission / reception .

It is an object of the present invention to solve the above problems and to provide a method of transmitting uplink DM-RS multiplexed with data in uplink MIMO transmission, supporting a high mobile speed corresponding to requirements of LTE- And an uplink DM-RS transmission method capable of supporting multi-layer transmission of uplink MIMO.

According to an aspect of the present invention, there is provided a multi-layer transmission method for multiplexing data of an uplink DFT-s-OFDM transmission scheme and a DM-RS sequence applied with MIMO, RS signal sequence of a first transmission layer and a DM-RS signal sequence having a cyclic shift value of a same sequence as the DM-RS signal sequence of the first transmission layer, To the DM-RS signal sequence of the second transmission layer, and multiplexing the data for each layer and the DM-RS sequence for each layer for each of the first transmission layer and the second transmission layer, -RS transmission method.

Here, the step of multiplexing the data for each layer and the DM-RS sequence for each layer may be configured to multiplex the data for each layer and the DM-RS sequence for each layer in the time domain before DFT application.

Here, the step of multiplexing the data for each layer and the DM-RS sequence for each layer may be configured to multiplex the data for each layer and the DM-RS sequence for each layer using IFDM (Interleaved FDM) method.

Herein, the uplink DM-RS transmission method is configured to transmit at least two OFDM symbols, each of which includes data for each layer and a DM-RS sequence for each layer, The OFDM symbol in which the data and the DM-RS sequence for each layer are multiplexed can be configured to be transmitted twice per slot, as a second OFDM symbol and a sixth OFDM symbol of the slot.

Here, the cyclic shift value of the first transmission layer DM-RS signal sequence and the cyclic shift value of the second transmission layer DM-RS signal sequence may be configured to separate the maximum possible value.

In the case of using the uplink DM-RS transmission method according to the present invention, in the 3GPP LTE system, the reference signal is configured for one OFDM symbol for transmission of the reference signal, while the reference signal The reference signal can be transmitted in more OFDM symbols in a slot or a subframe without increasing the overhead due to the reference signal, thereby providing a higher frequency spectrum and higher mobile velocity than LTE It is possible to support the required LTE-Advanced.

Also, in the uplink multi-layer transmission, it is possible to transmit and receive the DM-RS multiplexed with the data while maintaining the orthogonality, and it is possible to separate the DM-RS for each antenna.

1 is a frame diagram for explaining an uplink DM-RS transmission structure of 3GPP LTE.
2 is a flowchart illustrating a multi-layer transmission method for multiplexing data and a DM-RS sequence in an uplink DFT-s-OFDM transmission scheme to which MIMO is applied according to the present invention.
3 is a frame diagram illustrating an example of a configuration of an OFDM symbol per slot in which data and a reference signal are multiplexed according to the present invention.
4 is a block diagram of an uplink transmission function for explaining another embodiment in which data and a reference signal are multiplexed according to the present invention.
5 is a detailed view for explaining the block functions of the functional blocks 430 to 470 in the case where the reference signal generates an OFDM symbol that is IFDM with the data / control information.
6 is a block diagram for explaining major functional blocks of an LTE-Advaced uplink communication system (including transmission and reception).

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 is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements 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 are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a frame diagram for explaining an uplink DM-RS transmission structure of 3GPP LTE.

Referring to FIG. 1, one subframe 110 is composed of two slots 121 and 122, and one slot 121 is composed of OFDM symbols 131 to 137. The number of OFDM symbols in one slot may vary depending on whether a normal cyclic prefix (CP) and an extended cyclic prefix (CP) are used, whether or not a sounding reference signal (SRS) is present, and the like. Here, it can be seen that the DM-RS symbol is located in the central OFDM symbol (fourth OFDM symbol) every slot.

In FIG. 1, for convenience of description, a regular CP is used and a slot structure composed of seven OFDM symbols is shown as an example where there is no sounding reference signal. In the case of using an extended CP, one slot is divided into six OFDM symbols And a third OFDM symbol per slot is composed of DM-RS symbols.

On the other hand, in LTE-Advanced, basic communication services should be performed even in a frequency spectrum higher than LTE and a high mobile speed. For example, according to the requirements of LTE-advanced, it is required to support high travel speeds of 350 Km / s (even 500 Km / s) per hour, which corresponds to the speed of high-speed trains. Therefore, a higher Doppler spread environment occurs in the LTE-Advanced than in the LTE system, so it is difficult to expect a satisfactory performance in the reference signal structure of the LTE system illustrated in FIG. That is, the length of each OFDM symbol in LTE is 66.67 us, which is sufficiently shorter than the coherence time in a typical environment. However, in LTE-Advanced, If the Doppler frequency is high, the fading channel may change drastically even within one slot period (0.5 ms).

As a method for solving this problem, it is necessary to increase the frequency of the reference signal per slot on the time axis.

A method of increasing the reference signal in the time domain can be considered as a simple method of increasing the number of OFDM symbols transmitting reference signals per slot. For example, one DM-RS The DM-RS is arranged to transmit two OFDM symbols per slot. The performance improvement in the channel estimation is surely doubled, but the overhead due to the reference signal is doubled, resulting in a serious reduction in the data rate.

In order to solve this problem, a reference signal and data are multiplexed in one OFDM symbol and transmitted.

In this case, since the ratio of the reference signal occupied in one OFDM symbol is reduced, it is possible to avoid an increase in overhead due to the reference signal even if the reference signal is multiplexed with a plurality of OFDM symbols in one slot.

As a method of multiplexing the data and the reference signal in one OFDM symbol, methods such as CDM (Code Division Multiplexing), FDM (Frequency Division Multiplexing), and TDM (Time Division Multiplexing) may be considered.

First, the CDM method generally causes problems such as an increase in CM and interference between data and reference signals, which is hardly considered at present.

Next, an example of the FDM method is a method of constructing a reference signal and data / control information in an OFDM symbol in which a reference signal is multiplexed with data / control information by multiplexing the IFDM (Interleaved FDM) / Control information is sequentially input to one of the two subcarriers by the resource mapper, and the reference signal is inserted into the empty subcarriers between the subcarriers.

Finally, in the TDM method, a method of multiplexing the data and the reference signal in the time domain before the DFT can be considered during the process of generating the DFT spread OFDM signal.

That is, multiplexing the data and the repaper signal in the time domain before the DFT, the data and the reference signal are spread by the DFT together, which prevents the increase of the CM.

However, there is a disadvantage in that the overhead due to the cyclic prefix is increased because a transmission signal must be configured such that each cyclic prefix exists in the data region and the reference signal region multiplexed in one OFDM symbol. However, The overhead is reduced as compared with the overhead in which the entire DM-RS is transmitted using a plurality of OFDM symbols in the DM-RS.

Currently, in the above-described TDM method, a method of multiplexing data and a reference signal in the time domain before the DFT during the process of generating the DFT spread OFDM signal is described in the preceding article (3GPP TSG-RAN WG # 56bis R1-091472). However, in the above article, only the uplink DM-RS transmission in the single layer transmission / reception is assumed, and the transmission for the multi-layer (spatial multiplexing) transmission in the uplink introduced in LTE- It does not suggest a method.

DM-RS multiplex transmission method in multi-layer transmission according to the present invention

2 is a flowchart illustrating a multi-layer transmission method for multiplexing data and a DM-RS sequence in an uplink DFT-s-OFDM transmission scheme to which MIMO is applied according to the present invention.

Referring to FIG. 2, a multi-layer transmission method for multiplexing data and a DM-RS sequence in an uplink DFT-s-OFDM transmission scheme according to the present invention includes a DM-RS sequence for uplink transmission (S210) of assigning a DM-RS sequence of a first transmission layer to a DM-RS sequence of a first transmission layer, a DM-RS sequence of signals having different cyclic shift values of the same sequence as the DM- To a DM-RS signal sequence of a second transmission layer (S220); and multiplexing data for each layer and a DM-RS sequence for each layer for each of the first transmission layer and the second transmission layer (S230 ). ≪ / RTI >

Here, a multi-layer transmission method for multiplexing data and a DM-RS sequence in an uplink DFT-s-OFDM transmission method according to the present invention is a multi-layer transmission method in which a multi-layer transmission method comprising two layers (a first layer and a second layer) In addition to the layer transmission, multi-layer transmission considering up to four layers under consideration in uplink transmission of LTE-advanced can be considered, and can be applied to multi-layer transmission in four or more layers in the future.

At this time, the uplink DM-RS sequence allocation method of the conventional LTE can be used as it is in step S210 of allocating one DM-RS sequence for uplink transmission.

That is, the DM-RS sequence is generated from a CAZAC (Constant Amplitude Zero AutoCorrelation) sequence. The length of the generated DM-RS sequence is the number of sub-carriers corresponding to the number of RBs Is 12 subcarriers in frequency).

In this case, when the total length of the DM-RS to be generated is 3RB or more, a DM-RS sequence is generated from an extened Zadoff-Chu (ZC) sequence, which is a kind of CAZAC sequence. A DM-RS sequence can be generated using a computer-generated-CAZAC sequence.

There are 30 base sequence groups in the CAZAC sequence for DM-RS generation, and one or two base sequences are available for each DM-RS length in each group. If the DM-RS length is less than 5RB There is one base sequence per DM-RS length for each group, and if the DM-RS length is greater than 5RB, there are two base sequences per DM-RS length for each group. A base sequence used by terminals in one cell for DM-RS generation is a base sequence existing in one of these base sequence groups.

Next, in step S220, a sequence identical to the DM-RS signal sequence allocated to the first transmission layer in step S210 is configured to have a cyclic shift value different from that of the DM-RS signal sequence of the second transmission layer .

That is, the present invention is configured to have different CS (Cyclic Shift) between layers in order to maintain orthogonality for distinguishing DM-RS signals for respective antennas in multi-layer transmission of one UE.

At this time, it is preferable that the CS value of the DM-RS sequence for each layer is separated to the maximum possible value to increase the orthogonality of the DM-RS signal for each layer.

Next, in step S230, data for each layer and a DM-RS sequence for each layer are multiplexed for each of the first transmission layer and the second transmission layer.

As an embodiment of a method of generating an OFDM symbol by multiplexing the data of each layer and the DM-RS sequence for each layer, there is a method of multiplexing the data for each layer and the DM-RS sequence for each layer in the time domain before DFT And an interleaved FDM (IFDM) scheme in which data for each layer and DM-RS sequences for each layer are multiplexed in the frequency domain after passing through the DFT are described below.

Finally, the OFDM symbol multiplexed with the data for each layer and the DM-RS sequence for each layer may be transmitted by including at least two or more times per slot.

3 is a frame diagram illustrating an example of a configuration of an OFDM symbol per slot in which data and a reference signal are multiplexed according to the present invention.

A comparison between the frame for explaining the uplink DM-RS transmission structure of the conventional 3GPP LTE illustrated in FIG. 1 and the frame diagram according to the present invention illustrated in FIG. 3 shows that the weight of the reference signal in one OFDM symbol is remarkably It can be seen that the reference signal can be transmitted in more OFDM symbols within one slot or subframe without increasing the overhead due to the reference signal. For example, it can be seen that the data / control information and the RS signal can be multiplexed and transmitted in the second and sixth OFDM symbols 332 and 336 in one slot.

A method of multiplexing data and a DM-RS sequence in one OFDM symbol

1) Embodiment # 1 (IFDM system)

In the case of Embodiment # 2 to be described later, the data / control information and the DM-RS sequence are multiplexed before the M-point DFT and are spread together in the M-point DFT. On the other hand, when the data and the reference signal are mixed by the FDM A method of multiplexing data of an IFDM (Interleaved FDM) structure and a reference signal, which can increase the CM and increase the channel estimation performance at the same time, can be implemented as an embodiment.

A method of multiplexing the IFDM data and the reference signal is described in the contents of the applicant's patent application 2009-0052208.

4 is a block diagram of an uplink transmission function for explaining another embodiment in which data and a reference signal are multiplexed according to the present invention.

4, the uplink transmission unit includes a scrambling unit 410, a modulation mapper 420, a DFT 430, a Time / Interleaved Frequency Division Multiplexing unit 440, A reference signal generator 450, an RE (Resource Element) mapper 460, an N-point IFFT 470 and a Cyclic Prefix (CP) adder 480. [

First, the scrambling unit 410 scrambles an input bit stream encoded and interleaved by convolutional, turbo, LDPC, etc. using a scrambling bit string of the same length. The scrambling sequence generally includes identification information for each user have.

The modulation mapper 420 generates QPSK (Quadratic Phase Shif Modulation) or QAM (Quadratic Amplitude Modulation) complex symbol streams from the scrambled bit streams.

The DFT 430 is a component that sequentially receives input complex symbols corresponding to a predetermined DFT size and performs DFT. In this case, when the data / control information and the reference signal are to be spread by DFT, the M-point DFT is applied to the DFT 430. However, in this embodiment # 1, the reference signal and the data / It is possible to perform M / 2-pt DFT by receiving QPSK or QAM input complex symbols as much as M / 2. On the other hand, it is also possible to perform an M-point DFT after inserting 0 (zero) between input complex symbols of M / 2.

The time / interleaved frequency division multiplexing unit 440 multiplexes an OFDM symbol (e.g., symbols 331, 333, 334, 335, and 337 in FIG. 3) and an OFDM symbol 3) is composed of TDM, and multiplexing between the reference signal and the data / control information in the OFDM symbol in which the reference signal is multiplexed with the data / control information is configured by IFDM (Interleaved Frequency Division Multiplexing) Element.

That is, the data / control information is sequentially input to the parallel input terminal of the RE mapper 460 one by one, and the reference signal is inserted into the empty parallel input terminal between the terminals and multiplexed.

The block function of functional blocks 430 to 470 when the reference signal generates an OFDM symbol that is IFDM with data / control information will be described later in FIG.

The reference signal generator 450 generates a reference signal, which is a signal sequence prearranged to be transmitted for channel estimation of a receiving end and is composed of a signal sequence that is suitable for channel estimation and has excellent CM characteristics, and outputs the reference signal to a time / interleaved frequency division multiplexer 440).

As described above, the RE mapper 460 receives the signal sequence output from the time / interleaved frequency division multiplexing unit 440 and maps the received sequence to a position of an allocated sub-carrier.

Finally, the N-point IFFT 470 performs an IFFT with a predetermined N size and the CP adding unit 480 adds a proper length CP (cyclic prefix) to the corresponding transmit antenna port Signal.

5 is a detailed view for explaining the block functions of the functional blocks 430 to 470 in the case where the reference signal generates an OFDM symbol that is IFDM with the data / control information.

4, the output complex symbol sequence of the DFT 510 (430 in FIG. 4) and the symbol sequence output from the reference signal generator 520 (450 in FIG. 4) are input to the RE mapper 530 And is mapped to M subcarrier positions allocated in advance and converted by the N-point IFFT 540 (470 in FIG. 4), and then CP is added to form an OFDM symbol .

At this time, the output symbol stream of the DFT precoder 510 may be mapped to the odd input terminal of the RE mapper 530, and the symbol stream of the reference signal 520 may be mapped to the even input terminal. , And the mapping order may be alternately changed for each OFDM symbol configured by IFDM, and may be changed to each slot level.

According to the multiplexing method of the embodiment # 1, the CM is somewhat increased as the reference signal is multiplexed with the data / control information in one OFDM symbol. However, due to the multiplexing method of the IFDM type, The reference becomes a form in which the signals are superimposed in the time domain, so that the CM does not increase significantly. That is, since the increase of the CM is not large, the density of the reference signal in the time domain within the slot or subframe increases, and the performance of the user channel having high mobility is higher than that of the 3GPP LTE uplink system .

2) Embodiment # 2 (TDM method)

A method of multiplexing data and a DM-RS sequence in one OFDM symbol for each layer can be explained by Embodiment # 2 according to the following derivation. The following data and the DM-RS sequence multiplexing scheme are based on the description in the article (R1-091472) published by Qualcomm at 3GPP LTE RAN TSG WG1 # 56bis conference.

6 is a block diagram for explaining major functional blocks of an LTE-Advaced uplink communication system (including transmission and reception).

6, a functional block of the uplink communication system of the LTE-Advanced includes an M-point DFT block 610, a tone-mapping method of allocating frequency-domain signals spread by an M-point DFT block, An N-point IFFT 630 for converting a frequency-domain signal tone-mapped into a time domain signal, and a CP adding unit 640 for inserting a Cyclic Prefix. (The power amplifier and the antenna on the transmission side are shown as being omitted).

The signal output to the transmitting unit is transmitted to the receiving unit via the equivalent channel 650.

The receiving unit includes a CP removing unit 660 for removing a cyclic prefix on the receiving side, an N-point FFT unit 670 for transforming a time domain signal into a frequency domain signal, a Tone reverse mapping unit for de- And a receiver processing unit (Receiver Processing) 690.

The main symbols represented in Fig. 6 are summarized as follows.

: M개의 변조 심볼(예컨대, QAM)들을 포함한 크기 M의 송신 벡터

: A transmit vector of size M containing M modulation symbols (e.g., QAMs)

:

에 대하여 M 포인트 DFT를 거쳐 주파수 영역으로 스프레딩된 신호

:

Lt; RTI ID = 0.0 > M-point DFT < / RTI >

: 송신 안테나와 수신 안테나간의 이산 시간 등가 채널 특성

: Discrete-time equivalent channel characteristics between transmit and receive antennas

: 주파수 영역으로 FFT된 수신 신호

: Received signal FFTed in the frequency domain

Assuming that M subcarriers are used from 0 to M-1, the received signal of the k-th subcarrier can be expressed as Equation 1 below.

[Equation 1]

이며, 즉, H(k)는 h(n)를 DFT한 주파수 영역의 채널 특성을 의미하게 된다(이때, L은 채널의 탭수, W는 M by 1 노이즈 벡터).
At this time,

In other words, H (k) denotes a channel characteristic of a frequency domain in which h (n) is DFT (where L is the number of taps of the channel and W is M by 1 noise vector).

벡터로부터 시간 영역 수신신호는 하기 수학식 2와 같이 표현된다
Accordingly, in the receiver processing unit 690 of FIG. 6, when the M-point IDFT is performed, M by 1

The time-domain received signal from the vector is expressed as: < EMI ID =

&Quot; (2) "

는 M-point circular convolution을 의미한다.
At this time,

Denotes an M-point circular convolution.

를

To

를 가진 탭수(L)은

에 의해서 근사화될 수 있다.
If we define as Substantial energy

The tap number L with

. ≪ / RTI >

Therefore, if the transmission signal in the time domain before passing through the M point DFT to the transmitter is configured as shown in Equation 3,

&Quot; (3) "

임.
From here,

being.

The received signal in the time domain can be received as shown in Equation (4) below.

&Quot; (4) "

가 되도록 선택하면, 하기 수학식 5와 수학식 6을 얻을 수 있고,
That is, P ₁ defining the cyclic prefix length for the DM-RS sequence and P ₂ defining the length of the cyclic prefix for the data

, The following equations (5) and (6) can be obtained,

&Quot; (5) "

,

,

&Quot; (6) "

If DFT is applied to both sides of the equations (5) and (6), the following equations (7) and (8) can be obtained.

&Quot; (7) "

&Quot; (8) "

,

,

,

이다.
From here,

,

,

,

to be.

포인트 시퀀스

는 DM-RS 시퀀스가 되며,

포인트 시퀀스

는 데이터로서, 다중화됨을 알 수 있다. 즉, DFT 스프레딩 이전의 시간영역의 신호

에 단일 캐리어(Single Carrier) 특성을 해치지 않고 데이터와 DM-RS 시퀀스를 적절하게 다중화시킬 수 있음을 알 수 있다.
therefore,

Point sequence

Is a DM-RS sequence,

Point sequence

Are multiplexed as data. That is, the time domain signal before DFT spreading

The data and the DM-RS sequence can be properly multiplexed without sacrificing the single carrier characteristics.

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 present invention as defined by the following claims It can be understood that

Claims (6)

A multi-layer transmission method in which data of an uplink DFT-s-OFDM transmission scheme to which MIMO is applied and a DM-RS sequence are multiplexed and transmitted,
Assigning a first DM-RS sequence as a DM-RS signal sequence of a first transmission layer;
Assigning a second DM-RS sequence as a DM-RS signal sequence of a second transmission layer;
Generating a first layer OFDM symbol in which data of the first transmission layer and the first DM-RS sequence are multiplexed;
Generating a second layer OFDM symbol in which the data of the second transmission layer and the second DM-RS sequence are multiplexed; And
Transmitting the first layer OFDM symbol to the base station through the first transmission layer and transmitting the second layer OFDM symbol to the base station through the second transmission layer,
Wherein the first DM-RS sequence and the second DM-RS sequence have the same sequence and the cyclic shift value of the first DM-RS sequence is configured differently from the cyclic shift value of the second DM-RS sequence ,
Uplink DM-RS transmission method. The method according to claim 1,
The multiplexing of the data for each layer and the DM-RS sequence for each layer multiplexes the data for each layer and the DM-RS sequence for each layer in the time domain before the DFT application, . The method according to claim 1,
The multiplexing of the data for each layer and the DM-RS sequence for each layer multiplexes the data for each layer and the DM-RS sequence for each layer using an IFDM (Interleaved FDM) scheme. . The method according to claim 1,
Wherein the uplink DM-RS transmission method comprises transmitting at least two OFDM symbols, each layer-by-layer data and a DM-RS sequence for each layer being multiplexed, at least twice per slot. 5. The method of claim 4,
Wherein the OFDM symbol in which the data for each layer and the DM-RS sequence for each layer are multiplexed is transmitted twice a slot as a second OFDM symbol and a sixth OFDM symbol in the slot, . The method according to claim 1,
Wherein the cyclic shift value of the first transmission layer DM-RS signal sequence and the cyclic shift value of the second transmission layer DM-RS signal sequence are separated from the maximum possible value.

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