WO2017034105A1

WO2017034105A1 - Method for transmitting dmrs and device therefor

Info

Publication number: WO2017034105A1
Application number: PCT/KR2016/000815
Authority: WO
Inventors: 이상림; 고현수; 노광석; 김동규; 이호재
Original assignee: 엘지전자 주식회사
Priority date: 2015-08-24
Filing date: 2016-01-26
Publication date: 2017-03-02

Abstract

A method for a terminal transmitting a demodulation reference signal (DMRS) may comprise the steps of: for a DMRS sequence generated per each subcarrier of a first resource block (RB) allocated to the terminal, pre-compensating, per each of the subcarriers, a phase per corresponding filter coefficient and the reciprocal of the size of the corresponding filter coefficient; and transmitting, to a base station, the DMRS having the pre-compensation applied thereto.

Description

Method for transmitting DMRS and apparatus therefor

The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting DMRS.

Conventional Orthogonal Frequency Division Multiplexing (OFDM) strongly demands time-frequency synchronization constraints, whereas New waveform, one of the core technologies of 5G communication technologies, relaxes these constraints. It is being developed to compensate for weaknesses and accommodate a wider range of services.

The new waveform technology, which is being considered as the core technology of the next generation 5G system, significantly reduces out-of-band emission (OOBE) compared to OFDM, and effectively utilizes fragmented spectrum in time depleted and time asynchronous performance. You can expect a benefit.

The technical problem to be achieved in the present invention is to provide a method for a terminal to transmit a DeModulation Referenece Signal (DMRS).

Another object of the present invention is to provide a terminal for transmitting a DMRS (DeModulation Referenece Signal).

Technical problems to be achieved in the present invention are not limited to the above technical problems, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, a method for transmitting a DMRS (DeModulation Referenece Signal) by the terminal, for each DMRS sequence generated for each subcarrier of the first resource block (RB) allocated to the terminal Presenting an inverse of a phase of a corresponding filter coefficient and a magnitude of the corresponding filter coefficient for each subcarrier; And transmitting the DMRS to which the presentation is applied to a base station.

The method may further include performing the presentation in RB units for each of the RBs allocated by the terminal in addition to the first RB; And transmitting, to the base station, a DMRS to which an award is applied for each of the RBs allocated by the terminal, in addition to the first RB. In the presenting step, the phase for each filter coefficient is different for each subcarrier.

And the inverse of the magnitude of the corresponding filter coefficient for each subcarrier is 1 / | f1 |, 1 / | f2 |,. , 1 / | f12 |, respectively, in the DMRS sequence generated for each subcarrier

Multiplying by 1, 2, ..., 12 denotes the indices of the respective subcarriers. The filter is characterized in that the filtering is applied to a plurality of subcarriers.

In order to achieve the above another technical problem, a terminal transmitting a DMRS (DeModulation Referenece Signal) includes a subcarrier for each DMRS sequence generated for each subcarrier of a first resource block (RB) allocated to the terminal. A processor configured to present a reciprocal of a phase of each filter coefficient and a magnitude of the magnitude of the corresponding filter coefficient for each; And a transmitter configured to transmit the DMRS to which the announcement is applied to a base station. The processor is configured to present the prizes in RB units for each of the RBs allocated by the terminal in addition to the first RB, and the transmitter is configured to apply the prize for each of the RBs allocated by the terminal in addition to the first RB. And may transmit a DMRS to the base station. The processor may be configured to phase out corresponding filter coefficients for each subcarrier.

It is configured to perform the presentation by multiplying, where 1, 2, ..., 12 may represent the index of each subcarrier. The filter is characterized in that the filtering is applied to a plurality of subcarriers.

According to the inventive technique according to the present invention, all channels of RB-wise filtered OFDM or Filtered Multicarrier system as well as FCP-OFDM can maintain and receive DMRS sequence characteristics, thereby enabling accurate channel estimation.

Effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.

1 is a block diagram showing the configuration of a base station 105 and a terminal 110 in a wireless communication system 100.

2 is a diagram illustrating a transmitting and receiving end of an apparatus using an FCP-OFDM scheme that applies a filter in units of a subcarrier bundle.

3 is a diagram illustrating an example of a power spectrum comparison between FCP-OFDM and OFDM.

4 shows the characteristics in the time domain and frequency domain of a Dolph-Chebyshev filter.

5 is a diagram illustrating a frequency response of an actual chebyshev filter applied to one RB.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. For example, the following detailed description will be described in detail on the assumption that the mobile communication system is a 3GPP LTE, LTE-A system, but is also applied to any other mobile communication system except for the specific matters of 3GPP LTE, LTE-A. Applicable

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

In addition, in the following description, it is assumed that a terminal collectively refers to a mobile or fixed user terminal device such as a user equipment (UE), a mobile station (MS), an advanced mobile station (AMS), and the like. In addition, it is assumed that the base station collectively refers to any node of the network side that communicates with the terminal such as a Node B, an eNode B, a Base Station, and an Access Point (AP). Although described herein based on the IEEE 802.16 system, the contents of the present invention can be applied to various other communication systems.

In a mobile communication system, a terminal or a user equipment may receive information from a base station through downlink, and the terminal may also transmit information through uplink. The information transmitted or received by the terminal includes data and various control information, and various physical channels exist according to the type and purpose of the information transmitted or received by the terminal.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) employs OFDMA in downlink and SC-FDMA in uplink as part of Evolved UMTS (E-UMTS) using E-UTRA. LTE-A (Advanced) is an evolution of 3GPP LTE.

In addition, specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

Although one base station 105 and one terminal 110 are shown to simplify the wireless communication system 100, the wireless communication system 100 may include one or more base stations and / or one or more terminals. .

Referring to FIG. 1, the base station 105 includes a transmit (Tx) data processor 115, a symbol modulator 120, a transmitter 125, a transmit / receive antenna 130, a processor 180, a memory 185, and a receiver ( 190, a symbol demodulator 195, and a receive data processor 197. The terminal 110 transmits (Tx) the data processor 165, the symbol modulator 170, the transmitter 175, the transmit / receive antenna 135, the processor 155, the memory 160, the receiver 140, and the symbol. It may include a demodulator 155 and a receive data processor 150. Although the transmit and receive

antennas

130 and 135 are shown as one in the base station 105 and the terminal 110, respectively, the base station 105 and the terminal 110 are provided with a plurality of transmit and receive antennas. Accordingly, the base station 105 and the terminal 110 according to the present invention support a multiple input multiple output (MIMO) system. In addition, the base station 105 according to the present invention may support both a single user-MIMO (SU-MIMO) and a multi-user-MIMO (MU-MIMO) scheme.

On the downlink, the transmit data processor 115 receives the traffic data, formats the received traffic data, codes it, interleaves and modulates (or symbol maps) the coded traffic data, and modulates the symbols ("data"). Symbols "). The symbol modulator 120 receives and processes these data symbols and pilot symbols to provide a stream of symbols.

The symbol modulator 120 multiplexes the data and pilot symbols and sends it to the transmitter 125. In this case, each transmission symbol may be a data symbol, a pilot symbol, or a signal value of zero. In each symbol period, pilot symbols may be sent continuously. The pilot symbols may be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), or code division multiplexed (CDM) symbols.

Transmitter 125 receives the stream of symbols and converts it into one or more analog signals, and further adjusts (eg, amplifies, filters, and frequency upconverts) the analog signals to provide a wireless channel. Generates a downlink signal suitable for transmission via the transmission antenna 130, the transmission antenna 130 transmits the generated downlink signal to the terminal.

In the configuration of the terminal 110, the receiving antenna 135 receives the downlink signal from the base station and provides the received signal to the receiver 140. Receiver 140 adjusts the received signal (eg, filtering, amplifying, and frequency downconverting), and digitizes the adjusted signal to obtain samples. The symbol demodulator 145 demodulates the received pilot symbols and provides them to the processor 155 for channel estimation.

The symbol demodulator 145 also receives a frequency response estimate for the downlink from the processor 155 and performs data demodulation on the received data symbols to obtain a data symbol estimate (which is an estimate of the transmitted data symbols). Obtain and provide data symbol estimates to a receive (Rx) data processor 150. Receive data processor 150 demodulates (ie, symbol de-maps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data.

The processing by symbol demodulator 145 and receiving data processor 150 is complementary to the processing by symbol modulator 120 and transmitting data processor 115 at base station 105, respectively.

The terminal 110 is on the uplink, and the transmit data processor 165 processes the traffic data to provide data symbols. The symbol modulator 170 may receive and multiplex data symbols, perform modulation, and provide a stream of symbols to the transmitter 175. The transmitter 175 receives and processes a stream of symbols to generate an uplink signal. The transmit antenna 135 transmits the generated uplink signal to the base station 105.

In the base station 105, an uplink signal is received from the terminal 110 through the reception antenna 130, and the receiver 190 processes the received uplink signal to obtain samples. The symbol demodulator 195 then processes these samples to provide received pilot symbols and data symbol estimates for the uplink. The received data processor 197 processes the data symbol estimates to recover the traffic data transmitted from the terminal 110.

Processors

155 and 180 of the terminal 110 and the base station 105 respectively instruct (eg, control, coordinate, manage, etc.) operations at the terminal 110 and the base station 105, respectively.

Respective processors

155 and 180 may be connected to memory units 160 and 185 that store program codes and data. The memory 160, 185 is coupled to the processor 180 to store the operating system, applications, and general files.

The

processors

155 and 180 may also be referred to as controllers, microcontrollers, microprocessors, microcomputers, or the like. The

processors

155 and 180 may be implemented by hardware or firmware, software, or a combination thereof. When implementing embodiments of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the

processors

155 and 180.

Meanwhile, when implementing embodiments of the present invention using firmware or software, the firmware or software may be configured to include a module, a procedure, or a function for performing the functions or operations of the present invention, and to perform the present invention. The firmware or software configured to be may be provided in the

processors

155 and 180 or stored in the memory 160 and 185 to be driven by the

processors

155 and 180.

The layers of the air interface protocol between the terminal and the base station between the wireless communication system (network) are based on the lower three layers of the open system interconnection (OSI) model, which is well known in the communication system. ), And the third layer L3. The physical layer belongs to the first layer and provides an information transmission service through a physical channel. A Radio Resource Control (RRC) layer belongs to the third layer and provides control radio resources between the UE and the network. The terminal and the base station may exchange RRC messages through the wireless communication network and the RRC layer.

In the present specification, the processor 155 of the terminal and the processor 180 of the base station process the signals and data, except for the function of receiving or transmitting the signal and the storage function of the terminal 110 and the base station 105, respectively. For convenience of description, the following description does not specifically refer to the

processors

155 and 180. Although not specifically mentioned by the

processors

155 and 180, it may be said that a series of operations such as a function of receiving or transmitting a signal and a data processing other than a storage function are performed.

The present invention relates to a new waveform, called Filtered CP-OFDM (FCP-OFDM), which is a new waveform for future communication. Specifically, unlike the existing CP-OFDM, the present invention proposes a sequence when a filter is applied in RB units.

As shown in FIG. 2, unlike the conventional OFDM, the transmitter applies a filter in units of a bundle of several subcarriers. By applying filters in subband units as described above, the influence of signals on other adjacent bands can be greatly reduced as compared to the conventional OFDM scheme. The application of subband filters has great gains in terms of the utilization of the fragmented spectrum in a situation where the frequency resources are currently depleted, and also serves as a foundation for future technology communication.

As shown in FIG. 3, the power of the signal affecting the other bands of the existing OFDM gradually drops, whereas in the case of UF-OFDM, it drops quickly. Based on this characteristic, it is regarded as one candidate of the new waveform.

As a filter for reducing out-of-emission radiation in FCP-OFDM, a filter as shown in FIG. 4 is generally applied. Application of the filter shown in FIG. 4 reduces out-of-band emissions of the FCP-OFDM shown in FIG. This new waveform enables a variety of services using the fragmented spectrum. For example, it can provide machine type communication and low latency services. In addition, it can be regarded as one waveform that satisfies heterogeneous service requirements in the future.

In the case of CP-OFDM in the existing LTE system, when the same amount of power is applied to the subcarriers, the power per subcarrier in the transmission signal is the same. On the other hand, in the case of the FCP-OFDM to which the filter is applied, the characteristics of the reference signal are different from those of the conventional one, and a new sequence design technique is required to overcome this.

Accordingly, the present invention proposes a new reference signal design for a new waveform to which a filter is applied in RB units. More specifically, the position pattern of the new reference signal according to the characteristics of the filter is proposed.

As described above, in the case of using the filter in units of RB, as shown in FIG. 5, the signal-to-noise ratio of each subcarrier differs according to the frequency response of the filter.

Looking at the portion in bold box in Figure 5 it can be seen that the frequency response of the portion is not flat. That is, the magnitude and phase of the corresponding frequency response are different from the conventional one. Therefore, in the case of the existing uplink demodual reference reference singling (DMRS), the characteristics of the existing Zad-off sequence are changed by the influence of the filter, and the pre-selection is performed in advance according to the applied filter in order to maintain this property. Compensation is possible to operate the same in the existing receiver.

Table 1 below shows a method of generating an uplink DMRS sequence in an LTE / LTE-A system. The uplink DMRS sequence shown in Table 1 is generated for each subcarrier. In Table 1, n represents a subcarrier index.

A method of creating an uplink DMRS sequence in an existing LTE / LTE-A system will be described. In the existing LTE system, in order to estimate a channel between layers in a multi-antenna situation, it is designed to maintain orthogonality with each other. However, due to the change of the magnitude and phase of the sequence due to the filter, the orthogonality at the receiver or the receiver is broken, resulting in degradation of channel estimation.

First, the filtering coefficients in the frequency domain in units of one RB are denoted by F = [f1, f2,... , f12]. Here, f1 to f12 have complex values. Therefore, in order to maintain the orthogonality of the DMRS sequence at the receiving end or the receiving side, the transmission end or the transmitting side may preliminarily present the subcarrier unit to multiply the inverse of the filter coefficient magnitude by the inverse of the phase to maintain the orthogonality of the sequence. This will affect performance.

Table 1

Embodiment 1: Phase Presentation Technique for Uplink DMRS Reception

It is a method of presenting phase first of magnitude and phase. For example, the sequence is S1, S2,... In each subcarrier of one RB among the N resource blocks (RBs) allocated by the terminal. Assume that S12 is applied. And, the phase for each coefficient of the filter F

Suppose that the DMRS sequence generated for each subcarrier

Multiply by to compensate for the phase of the original data through the filter at the transmitting end of the terminal, the receiving end of the base station can receive the DMRS while maintaining the characteristics of the original sequence.

The receiving end of the base station receives a value multiplied by the size of the filter coefficient for each RB unit. Therefore, after receiving the DMRS, the base station receives 1 / | f1 |, 1 / | f2 |, which are inverses of the magnitude of the filter coefficient in the subcarrier unit in the DMRS sequence block generated for each subcarrier. By multiplying 1 / | f12 |, the characteristics of the DMRS sequence can be maintained and channel estimation can be performed.

Embodiment 2: A Size and Phase Representation Technique for Uplink DMRS Reception

It is a method of presenting both magnitude and phase at the transmitting end of the terminal. In this case, the reciprocal of the magnitude and the phase are simultaneously applied to the sequence of subcarriers of one RB among the N RBs allocated by the UE as follows.

Equation 1

Therefore, the receiving end of the base station can estimate a better channel using the characteristics of the existing DMRS sequence without further processing.

Example 3 Selective Size and Phase Representation Techniques for Uplink DMRS Reception

In general, as the pulse shape is compressed in the frequency domain, the peak-to-average power ratio (PAPR) is increased, and conversely, as the pulse shape is spread in the frequency domain, the PAPR is lowered. Therefore, as shown in the first embodiment, when only a phase is presented at the transmitting end of the terminal, the out-of-band (OOB) is kept low by the filter, but the PAPR is deteriorated due to the compression effect in the frequency domain. However, as in the second embodiment, the technique of presenting both the phase and the magnitude at the transmitting end of the terminal flattens the frequency response in the in-band region, thereby improving the PAPR. However, the subcarrier located at the edge of the RB Increasing power results in worsening OOB. Therefore, which of the first and second embodiments is to be used, it is necessary to adaptively use both techniques according to the power situation of the terminal.

The UE located at the cell edge is in a power-limited environment and the issue of PAPR becomes an important issue. Accordingly, the terminal located at the cell edge can mitigate the PAPR problem through the technique of presenting both magnitude and phase as in the first embodiment.

On the contrary, in the case of the UE located in the center of the cell, the effect of reducing OOB can be maximized by only showing the phase as in the second embodiment.

For this adaptive technique, the base station may instruct the terminal whether to use any of the first and second techniques as a physical layer signal or a higher layer signal. On the contrary, the terminal may indicate to the base station which technique to use for the base station as a physical layer signal (for example, PUCCH, PUSCH). In this case, it may be indicated by a size of 1 bit indicating whether to use which technique.

The method proposed in the present invention can be applied not only to FCP-OFDM but also to all RB-wise filtered OFDM schemes or to a filtered multicarrier system.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

The method of transmitting a DMRS by the terminal can be used in various industries in various wireless communication systems such as 3GPP LTE / LTE-A system.

Claims

In a method for transmitting a DMRS (DeModulation Referenece Signal),

Presenting an inverse of the phase of each filter coefficient and the magnitude of the corresponding filter coefficient for each subcarrier with respect to a DMRS sequence generated for each subcarrier of a first resource block (RB) allocated to the terminal; And

And transmitting the DMRS to which the presentation is applied to a base station.
The method of claim 1,

Performing the award in RB units for each of the RBs allocated by the UE in addition to the first RB; And

And transmitting the DMRS to which the presentation is applied for each of the RBs allocated by the terminal in addition to the first RB, to the base station.
The method of claim 1,

In the presenting step, the phase for each filter coefficient is different for each subcarrier.
And the inverse of the magnitude of the corresponding filter coefficient for each subcarrier is 1 / | f1 |, 1 / | f2 |,. , When 1 / | f12 |

In the DMRS sequence generated for each subcarrier, respectively
And multiplying by 1, 2, ..., 12, indicative of the indices of the respective subcarriers.
The method of claim 1,

The filter, DMRS transmission method, characterized in that for applying a plurality of sub-carrier filtering.
In a terminal for transmitting a DMRS (DeModulation Referenece Signal),

A processor configured to present a reciprocal of a phase of each filter coefficient and an inverse of the magnitude of the filter coefficient for each subcarrier with respect to a DMRS sequence generated for each subcarrier of a first resource block (RB) allocated to the terminal; And

And a transmitter configured to transmit the DMRS to which the announcement is applied to a base station.
The method of claim 5,

The processor is configured to present the prize in RB units for each of the RBs allocated by the terminal in addition to the first RB.

The transmitter is configured to transmit to the base station a DMRS to which an award is applied for each of the RBs allocated by the terminal in addition to the first RB.
The method of claim 5,

The processor,

Phase for each filter coefficient is different for each subcarrier
And the inverse of the magnitude of the corresponding filter coefficient for each subcarrier is 1 / | f1 |, 1 / | f2 |,. , 1 / | f12 |, respectively, in the DMRS sequence generated for each subcarrier
And presenting the presentation by multiplying, wherein 1, 2,..., 12 represent an index of each subcarrier.
The method of claim 5,

The filter is characterized in that to apply filtering in a plurality of subcarriers.