KR20150078680A - Apparatus and method for transmitting and receiving reference signal on small cells environment - Google Patents

Abstract

Disclosed are a method and an apparatus for transmitting and receiving reference signals in a small cell environment. The method for transmission of reference signals by a terminal in a wireless communication system comprises the following steps. The terminal determines whether an uplink transmission based on reduction DM-RS is possible, based on overhead reduction activation field received from a base station. When the uplink transmission based on reduction DM-RS is possible, the terminal determines whether to perform the uplink transmission based on reduction DM-RS, based on an uplink-related DCI received from the base station. The overhead reduction activation field is a field indicating whether a terminal can perform a uplink transmission based on reduction DM-RS and the reduction DM-RS can be assigned to a symbol of orthogonal frequency division multiplexing (OFDM) per sub-frame.

Description

TECHNICAL FIELD [0001] The present invention relates to a reference signal transmitting / receiving method and apparatus in a small cell environment,

The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting and receiving a reference signal in a wireless communication system supporting a small cell.

In a next generation communication system such as LTE-A (Advanced), a small cell based on a low-power node as well as a macro cell based on a high-power node (F2 Research is underway to provide wireless communication services indoors and outdoors through the Internet.

The small cell can be considered both in the frequency band that is the coverage of the macrocell and in the frequency band other than the coverage of the macrocell, and can be provided both in the indoor environment (in the cube) and in the outdoor environment (outside the cube). Also, an ideal or non-ideal backhaul network may be supported between macrocells and small cells, and / or between small cells. And the small cell can be provided both in a low density sparse deployment environment and / or a dense deployment environment.

SUMMARY OF THE INVENTION The present invention provides a method of transmitting a reference signal in a wireless communication system supporting a small cell.

It is another object of the present invention to provide an apparatus for transmitting a reference signal in a wireless communication system supporting a small cell.

According to another aspect of the present invention, there is provided a method for transmitting a reference signal of a UE in a wireless communication system, the method comprising: a decrease uplink DM demodulation based on an overhead reduction enable field received from a base station; Determining whether uplink transmission based on a reference signal (RS) is possible; and if uplink transmission based on the reduced uplink DM-RS is possible, And determining whether to perform uplink transmission based on the reduced uplink DM-RS based on a related uplink related downlink control information (DCI). The overhead reduction enable field is a field for indicating whether the UE can perform uplink transmission based on the reduced uplink DM-RS, and the reduced uplink DM-RS may be allocated to one symbol per subframe. have. Also, the step of determining whether to perform uplink transmission based on the reduced uplink DM-RS may include determining whether to perform uplink transmission based on the reduced uplink DM-RS, when the format of the uplink- Determining whether the number of layers allocated for uplink transmission of the UE is equal to or less than a threshold number of layers when the format of the uplink-related DCI is DCI format 4, And the UE may perform uplink transmission based on the reduced uplink DM-RS. Here, the number of the threshold layers is a number of layers serving as a reference for determining whether uplink transmission is performed based on the reduced uplink DM-RS. If the format of the uplink-related DCI is DCI format 0, the step of determining whether to perform uplink transmission based on the reduced uplink DM-RS may include determining whether to perform uplink transmission based on the decrease uplink DM- And if the format of the uplink-related DCI is DCI format 4, the UE performs the uplink transmission based on the overhead reduction field included in the DCI format 4, And determining whether to perform uplink transmission based on the uplink transmission. The overhead decrease field may be a field indicating whether the UE uses the decrease uplink DM-RS. Also, the step of determining whether to perform uplink transmission based on the reduced uplink DM-RS may include determining whether uplink transmission resources allocated based on the uplink-related DCI are available for the downlink DM- And performing uplink transmission based on the reduced uplink DM-RS when the uplink transmission resource is associated with the reduced uplink DM-RS transmission available resource, . The information on the resource for the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the UE can receive from the BS or be predefined between the UE and the BS. Wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-RS comprises: if the format of the uplink-related DCI is DCI format 0, determining whether to perform uplink transmission based on the reduced uplink DM- If the format of the uplink-related DCI is DCI format 4, whether the uplink transmission resource allocated based on the DCI format 4 is associated with the reduced uplink DM-RS transmission available resource And performing uplink transmission based on the reduced uplink DM-RS when the uplink transmission resource is associated with the reduced uplink DM-RS transmission available resource, The information on resources for transmission of the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the terminal receives from the base station, Can be defined. And determining whether to perform uplink transmission based on the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink related DCI, And determining whether to perform uplink transmission using the DM-RS. If the format of the uplink-related DCI is DCI format 0, the step of determining whether to perform uplink transmission based on the reduced uplink DM-RS may include determining whether to perform uplink transmission based on the decrease uplink DM- Based on information on a cyclic shift field included in the uplink-related DCI when the format of the uplink-related DCI is DCI format 4, the uplink- And determining whether to perform uplink transmission using the link DM-RS.

According to another aspect of the present invention, there is provided a terminal for transmitting a reference signal in a wireless communication system, the terminal including: a radio frequency (RF) unit for transmitting and receiving a radio signal; And the processor determines whether uplink transmission based on a reduced demodulation (RS) -RS (reference signal) is possible based on the overhead reduction enable field received from the base station Based on the uplink related downlink control information (DCI) received from the base station when uplink transmission based on the reduced uplink DM-RS is possible, Wherein the overhead reduction enable field is configured to determine whether to perform link transmission, A field indicating an uplink transmission is possible based on the size DM-RS, the reduced uplink DM-RS may be allocated to one symbol per sub-frame. Here, the processor performs uplink transmission based on the reduced uplink DM-RS when the format of the uplink-related DCI is DCI format 0, and when the format of the uplink-related DCI is DCI format 4 , And determines whether the number of layers allocated for uplink transmission of the UE is less than or equal to a threshold number of layers, and performs uplink transmission based on the reduced uplink DM-RS, And may be the number of layers serving as a reference for determining whether uplink transmission is performed based on the uplink DM-RS. The processor performs uplink transmission based on the reduced uplink DM-RS when the format of the uplink-related DCI is DCI format 0, and when the format of the uplink-related DCI is DCI format 4, Based on an overhead reduction field included in the DCI format 4, the overhead reduction field is configured to determine whether to perform uplink transmission based on the reduced uplink DM-RS, And may be a field indicating whether to use -RS. The processor determines whether or not the uplink transmission resource allocated based on the uplink related DCI is associated with the reduced uplink DM-RS transmission available resource, and the uplink transmission resource is allocated to the reduced uplink DM- RS transmission resources, the information on resources for the reduced uplink DM-RS transmission is implemented in the overhead reduction enable field, and the downlink DM-RS transmission available resources are configured to perform uplink transmission based on the reduced uplink DM- And the terminal may be received from the base station or may be predefined between the terminal and the base station. The processor performs uplink transmission based on the reduced uplink DM-RS when the format of the uplink-related DCI is DCI format 0, and when the format of the uplink-related DCI is DCI format 4, The UE determines whether the uplink transmission resource allocated based on the DCI format 4 is a reduced uplink DM-RS transmission available resource, and when the uplink transmission resource is the reduced uplink DM-RS transmission available resource, Information on a resource of the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the UE receives from the base station, And may be predefined between the terminal and the base station. Meanwhile, the processor may be configured to determine whether to perform uplink transmission using the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink-related DCI have. Also, the processor performs uplink transmission based on the reduced uplink DM-RS when the format of the uplink-related DCI is DCI format 0, and when the format of the uplink-related DCI is DCI format 4 , And determine whether to perform uplink transmission using the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink related DCI.

In the small cell environment, the UE can newly define resources allocated for transmitting a reference signal and perform uplink transmission. By controlling the resources allocated to the uplink DM (demodulation) -RS (reference signal) considering the channel environment of the small cells, the overhead of the uplink DM-RS can be reduced to increase the data transmission efficiency of the UE in the small cell have.

1 is a block diagram illustrating a wireless communication system to which the present invention is applied.
2 and 3 schematically show the structure of a radio frame to which the present invention is applied.
4 is a conceptual diagram illustrating transmission of an uplink DM-RS when a PUSCH is transmitted.
5 is a conceptual diagram showing that one basic reference signal sequence is generated as a plurality of reference sequences according to a cyclic shift.
6 shows an uplink DM-RS generated using an orthogonal cover code.
7 is a conceptual diagram showing a small cell environment.
FIG. 8 is a conceptual diagram illustrating that an uplink DM-RS is allocated in an existing resource block.
9 is a conceptual diagram illustrating resource allocation of an uplink DM-RS according to an embodiment of the present invention
10 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
11 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
12 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
13 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
14 illustrates a method for defining a reduced uplink DM-RS transmission available resource according to an embodiment of the present invention.
15 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
16 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
17 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.
18 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

The present invention will be described with reference to a communication network. The work performed in the communication network may be performed in a process of controlling the network and transmitting data by a system (e.g., a base station) that manages the communication network, The work can be done.

1 is a block diagram illustrating a wireless communication system to which the present invention is applied.

Referring to FIG. 1, a wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides communication services for a particular geographical area or frequency domain and may be referred to as a site. A site may be divided into a plurality of areas 15a, 15b, and 15c, which may be referred to as sectors, and the sectors may have different cell IDs.

A user equipment (UE) 12 may be fixed or mobile and may be a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, (personal digital assistant), a wireless modem, a handheld device, and the like. The base station 11 generally refers to a station that communicates with the terminal 12 and includes an evolved-NodeB (eNodeB), a base transceiver system (BTS), an access point, a femto base station (Femto eNodeB) (ENodeB), a relay, a remote radio head (RRH), and the like. The cells 15a, 15b and 15c should be interpreted in a comprehensive sense to indicate a partial area covered by the base station 11 and include all coverage areas such as megacell, macrocell, microcell, picocell, femtocell to be.

Hereinafter, a downlink refers to a communication or communication path from the base station 11 to the terminal 12, and an uplink refers to a communication or communication path from the terminal 12 to the base station 11 . In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11. There is no limit to the multiple access scheme applied to the wireless communication system 10. [ (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. These modulation techniques increase the capacity of the communication system by demodulating signals received from multiple users of the communication system. The uplink transmission and the downlink transmission may be performed using a time division duplex (TDD) scheme transmitted at different times or a frequency division duplex (FDD) scheme using different frequencies.

The layers of the radio interface protocol between the terminal and the base station are divided into a first layer (L1), a second layer (L1), and a second layer (L2) based on the lower three layers of an Open System Interconnection A second layer (L2), and a third layer (L3). Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel.

There are several physical channels used in the physical layer. The physical downlink control channel (PDCCH) includes a resource allocation and transmission format of a downlink shared channel (DL-SCH), a resource of an uplink shared channel (UL-SCH) Resource allocation of an upper layer control message such as allocation information, a random access response transmitted on a physical downlink shared channel (PDSCH), transmission power control for individual terminals in an arbitrary terminal group : TPC) commands, and so on. A plurality of PDCCHs can be transmitted in the control domain, and the UE can monitor a plurality of PDCCHs.

The control information of the physical layer mapped to the PDCCH is referred to as downlink control information (DCI). That is, the DCI is transmitted on the PDCCH. The DCI may include an uplink or downlink resource allocation field, an uplink transmission power control command field, a control field for paging, a control field for indicating a random access response (RA response), and the like.

2 and 3 schematically show the structure of a radio frame to which the present invention is applied.

Referring to FIGS. 2 and 3, a radio frame includes 10 subframes. One subframe includes two slots. The time (length) for transmitting one subframe is called a transmission time interval (TTI). Referring to FIG. 2, for example, the length of one subframe (1 subframe) may be 1 ms and the length of one slot may be 0.5 ms.

A slot may contain a plurality of symbols in the time domain. For example, in the case of a radio system using OFDMA (Orthogonal Frequency Division Multiple Access) in a downlink (DL), the symbol may be an OFDM (Orthogonal Frequency Division Multiplexing) In the case of a radio system using Single Carrier-Frequency Division Multiple Access (FDMA), the symbol may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol. On the other hand, the representation of the symbol period of the time domain is not limited by the multiple access scheme or the name.

The number of symbols included in one slot may vary according to the length of a CP (Cyclic Prefix). For example, one slot may include seven symbols in the case of a normal CP, and one slot may include six symbols in the case of an extended CP.

A resource block (RB) is a resource allocation unit, which includes time-frequency resources corresponding to 180 kHz on the frequency axis and 1 slot on the time axis. A resource element (RE) represents a smallest time-frequency unit to which a modulation symbol of a data channel or a modulation symbol of a control channel is mapped.

In a wireless communication system, it is necessary to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like. A process of compensating for a distortion of a signal caused by a sudden change in channel environment and restoring a transmission signal is called channel estimation. It is also necessary to measure the channel state of the cell or other cell to which the terminal belongs. In general, a reference signal (RS) known between a UE and a transmission / reception point is used for channel estimation or channel state measurement.

)를 추정할 수 있다.In the case of the downlink channel estimation, since the UE knows the information of the reference signal, the UE estimates the channel based on the received reference signal and compensates the channel value so that the data transmitted from the base station can be accurately obtained. If the reference signal sent from the base station is p, the channel information experienced by the reference signal during transmission is h, the thermal noise generated by the terminal is n, and the signal received by the terminal is y, y = h p + n . Since the reference signal p is already known by the UE, if the LS (Least Square) scheme is used, the channel information

) Can be estimated.

&Quot; (1) "

는

값에 의존하게 되므로, 정확한 h값의 추정을 위해서는

이 0에 수렴시킬 필요가 있다. Here, the channel estimation value estimated using the reference signal p

The

Value, so for accurate estimation of the h value

It is necessary to converge to zero.

In the case of the uplink channel estimation, similar to the downlink channel estimation described above, except that the transmitting entity of the reference signal is the terminal and the receiving entity is the base station.

The reference signal is typically generated by generating a signal from a sequence of reference signals. The reference signal sequence may be one or more of several sequences having superior correlation characteristics. For example, a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence such as a Zadoff-Chu (ZC) sequence or a PN (pseudo-noise) sequence such as an m-sequence, a Gold sequence or a Kasami sequence May be used as a sequence of reference signals, and various other sequences having superior correlation characteristics may be used depending on system conditions. The reference signal sequence may be cyclic extension or truncation to adjust the length of the sequence or may be used in various forms such as binary phase shift keying (BPSK) or quadrature phase shift keying (QPSK) And may be mapped to RE (Resource element).

The downlink reference signal includes a cell-specific RS, a MBSFN reference signal, a UE-specific RS, a position reference signal PRS, RS and a channel state information (CSI) reference signal (CSI-RS).

The UE-specific reference signal is a reference signal received by a specific UE or a specific UE group in a cell and can be called a Demodulation RS (DM-RS) since it is mainly used for data demodulation of a specific UE or a specific UE group. have.

Similar to the downlink, the reference signal is also transmitted in the LTE uplink. In the LTE uplink, the uplink DM-RS and SRS can be used. The uplink DM-RS can be used by the base station for channel estimation for coherent demodulation of uplink physical channels (PUSCHs) and physical uplink control channels (PUCCHs) . Therefore, the uplink DM-RS is always transmitted as PUSCH or PUCCH and can be transmitted with the same bandwidth as the corresponding physical channels.

The uplink SRS can be used for channel estimation for channel dependent scheduling and link adaptation according to the uplink channel. The SRS can also be used for estimating the channel condition of the downlink when there is sufficient reciprocity between the uplink and downlink, that is, when the uplink and downlink channels exhibit sufficiently similar characteristics.

Hereinafter, the embodiment of the present invention further discloses the uplink DM-RS.

The uplink DM-RS is used for channel estimation for coherent demodulation of the PUSCH to which the UL-SCH transport channel is mapped, and is also required for coherent demodulation of the PUCCH that carries various types of L1 / L2 control signaling. Do. Although there are some differences, the basic uplink DM-RS structure can be the same for PUSCH and PUCCH. The difference is that the OFDM symbols transmitting the reference signal may be different.

4 is a conceptual diagram illustrating transmission of an uplink DM-RS when a PUSCH is transmitted.

Referring to FIG. 4, certain symbols may be used solely to transmit the uplink DM-RS. Therefore, the uplink reference signal is time multiplexed with other uplink transmissions from the same terminal. More specifically, in case of PUSCH transmission, the uplink DM-RS can be transmitted in the fourth symbol from the back of each uplink slot. That is, in the case of a normal CP, it can be transmitted in the fourth symbol (l = 3) from the beginning of each uplink slot. In case of an extended CP, a third symbol (l = 2). ≪ / RTI >

Thus, within each subframe, there may be a total of two transmissions of the reference signal once per slot.

In the case of PUCCH transmission, the number of symbols used for reference signal transmission and the exact positions of symbols used for transmission of reference signals in a slot may vary according to the PUCCH format. The basic structure of each reference signal transmission may be a frequency domain reference signal mapped to a continuous input (continuous subcarrier) of the signal generator, irrespective of whether the type of uplink transmission is PUCCH or PUSCH. The bandwidth of the reference signal corresponding to the sequence length of the reference signal may be the same as the transmission bandwidth of the PUSCH / PUCCH measured by the number of subcarriers. This means that in the case of PUSCH transmission, it is necessary to be able to generate reference signal sequences of different lengths corresponding to possible PUSCH transmission bandwidths. Since the uplink resource allocation for the PUCSH transmission is always performed in units of resource blocks having 12 subcarriers, the number of reference signals can always be a multiple of 12.

Hereinafter, a method for generating a reference signal sequence of an uplink DM-RS (demodulation reference signal for PUSCH) for PUCSH will be described in detail. That is, the uplink DM-RS disclosed in the embodiment of the present invention can indicate the uplink DM-RS for the PUSCH.

로서 레이어

에 따라 아래의 수학식 2와 같이 정의될 수 있다. The sequence of the uplink DM-RS for the PUSCH is

As a layer

Can be defined as shown in Equation (2) below.

&Quot; (2) "

는 참조 신호 시퀀스의 길이를 나타낸다.

로 정의될 수 있고,

는 하나의 자원 블록에 포함되는 부반송파(subcarrier)의 개수이다. m은

의 범위의 값으로 정의될 수 있다. 전술한 바와 같이 참조 신호 시퀀스의 길이는 하나의 자원 블록에 포함되는 부반송파 개수의 배수로 정의될 수 있다.

로써 참조 신호 시퀀스의 길이와 PUSCH에 할당된 부반송파의 개수가 동일함을 알 수 있다. Referring to Equation 2,

Represents the length of the reference signal sequence.

, ≪ / RTI >

Is the number of subcarriers included in one resource block. m is

Lt; / RTI > As described above, the length of the reference signal sequence can be defined as a multiple of the number of subcarriers included in one resource block.

It can be seen that the length of the reference signal sequence is equal to the number of subcarriers allocated to the PUSCH.

는

로 정의될 수 있다. ≪ RTI ID = 0.0 >

The

. ≪ / RTI >

는 순환 쉬프트(cyclic shift)

및 기본 시퀀스

에 의해 정의될 수 있다. 아래의 수학식 3은

을 나타낸다.

Is a cyclic shift,

And basic sequence

Lt; / RTI > The following equation (3)

.

&Quot; (3) "

는 참조 신호 시퀀스의 길이이다. 순환 쉬프트

에 따라 하나의 기본 시퀀스

가 복수의 참조 신호 시퀀스로 정의될 수 있다. As described above

Is the length of the reference signal sequence. Cyclic shift

According to one basic sequence

May be defined as a plurality of reference signal sequences.

는 자드오프-추(Zadoff-Chu) 시퀀스에 의해 정의될 수 있다. 이러한 기본 시퀀스의 정의에 대해서는 2013년 9월에 개시된 ‘3GPP TS36.211 V11.4.0, 3rd Generation Partnership Project Technical Specification Group Radio Access Network Evolved Universal Terrestrial Radio Access (E-UTRA) Physical Channels and Modulation(Release 11)’(이하, 3GPP TS36.211)의 5.5.1 절에 개시되어 있다.
Basic sequence

Can be defined by the Zadoff-Chu sequence. The definition of such a basic sequence is described in 3GPP TS36.211 V11.4.0, 3rd Generation Partnership Project Technical Specification Group Radio Access Network Evolved Universal Terrestrial Radio Access (E-UTRA) Physical Channels and Modulation (Release 11) ≪ / RTI > (hereinafter 3GPP TS36.211).

5 is a conceptual diagram showing that one basic reference signal sequence is generated as a plurality of reference sequences according to a cyclic shift.

의 값이

과 같은 값을 같게 되면 하나의 기본 시퀀스를 기반으로 순환 쉬프트의 변화에 따라 서로 직교하는 참조 신호 시퀀스를 생성할 수 있다. 즉, 하나의 기본 시퀀스로부터 최대 12개까지의 직교 참조 신호를 정의할 수 잇다. The uplink DM-RSs defined from different reference signal sequences generally have a relatively low but non-zero mutual correlation. On the other hand, the reference signals defined by different phase rotations of the same basic reference signal sequence are completely orthogonal to one another and do not interfere with each other. For example, when m varies from 0 to 11,

The value of

The reference signal sequence orthogonal to each other can be generated according to the change of the cyclic shift based on one basic sequence. That is, up to twelve orthogonal reference signals can be defined from one basic sequence.

는 직교 시퀀스(orthogonal sequence)(또는 직교 커버 코드(OCC, orthogonal cover code))를 나타낸다. 직교 시퀀스는 상향링크 다중 안테나 전송, 구체적으로는 공간 다중화를 포함한 다중 안테나 프리코딩 방식에서 사용될 수 있다. 공간 다중화를 수행하는 경우 레이어(layer) 당 별도의 상향링크 DM-RS가 필요하다. 예를 들어, 4개의 공간적으로 다중화되는 레이어를 동시에 전송하는 것을 지원해야 하는 경우, 하나의 단말은 4개의 서로 다른 상향링크 DM-RS를 전송할 수 있어야 한다. 이러한 서로 다른 상향링크 DM-RS를 생성하기 위해서는 전술한 바와 같이 서로 다른 순환 시퀀스를 사용하여 복수개의 상호 직교하는 참조 신호를 생성하거나 또는 서브프레임 내의 2개의 참조 신호 전송에 대하여 직교 커버 코드(orthogonal cover code)와 같은 상호 직교 패턴을 적용함으로써 2개의 서로 다른 참조 신호를 생성할 수 있다. Referring again to Equation (2)

Denotes an orthogonal sequence (or orthogonal cover code (OCC)). The orthogonal sequence can be used in a multiple antenna precoding scheme including uplink multiple antenna transmission, specifically spatial multiplexing. When spatial multiplexing is performed, a separate uplink DM-RS is required per layer. For example, if it is necessary to support simultaneous transmission of four spatially multiplexed layers, one terminal must be able to transmit four different uplink DM-RSs. In order to generate such different uplink DM-RSs, a plurality of mutually orthogonal reference signals are generated using different cyclic sequences as described above, or an orthogonal cover code is generated for two reference signal transmissions in a subframe code to generate two different reference signals.

6 shows an uplink DM-RS generated using an orthogonal cover code.

6 is the uplink DM-RS generated when the orthogonal cover code is [+1, +1] and the lower end of FIG. 6 is the uplink DM generated when the orthogonal cover code is [+1, -1] -RS. The plurality of orthogonal reference signals generated in this manner may be used, for example, in performing a multiple input multiple output (MIMO) -multiple input multiple output (MIMO).

는 DCI(downlink control information) 포맷(format)이 0에 대해,

로 정의될 수 있다. If the upper layer parameter Activate-DMRS-with-OCC is not set or the temporary uplink-related DCI for the transport block associated with the corresponding PUSCH transmission is transmitted, When a temporary cell radio network identifier (RNTI) is used, the orthogonal sequence < RTI ID = 0.0 >

For the downlink control information (DCI) format 0,

. ≪ / RTI >

는 상응하는(corresponding) PUSCH 전송과 관련된 전송 블록에 대한 가장 최근의 상향링크 관련 DCI의 순환 쉬프트 필드를 사용하여 아래의 표 1에 의해 주어질 수 있다. Otherwise, the orthogonal sequence

May be given by Table 1 below using the cyclic shift field of the most recent uplink-related DCI for the transport block associated with the corresponding PUSCH transmission.

<Table 1>

를 결정하기 위한 순환 쉬프트(cyclic shift)

는 슬롯

에서

로 정의될 수 있고

는 아래의 수학식 4와 같이 정의될 수 있다.In Equation 2,

(Cyclic shift)

Slot

in

Can be defined as

Can be defined as Equation (4) below.

&Quot; (4) &quot;

는 아래의 표 2와 같이 순환 쉬프트의 값에 따라 결정될 수 있다. In Equation 4,

Can be determined according to the value of the cyclic shift as shown in Table 2 below.

<Table 2>

는 전술한 표 1에서와 같이 상향링크 관련 DCI 포맷에서 순환 쉬프트 필드에 의해 결정될 수 있다.

Can be determined by the cyclic shift field in the uplink-related DCI format as shown in Table 1 above.

는 아래의 수학식 5에 의해 결정될 수 있다.

Can be determined by the following equation (5).

&Quot; (5) &quot;

In Equation (5), a pseudo-random sequence c (i) is defined by a Gold sequence of length 31 as follows.

&Quot; (6) &quot;

을 기반으로 초기화될 수 있다. 만약, 상위 계층에서

에 대한 값이 설정되지 않는 경우, 또는 랜덤 액세스 승인(grant) 또는 경쟁 기반의 랜덤 액세스 절차의 일부로써 동일한 전송 블록의 재전송이 PUSCH 전송과 관련된 경우

는

로 초기화될 수 있다.

는 셀의 PCI(physical cell identifier)이다. 그 외의 경우에는

로 초기화될 수 있다. Here, N _c = 1600, the first m-sequence is initialized to x ₁ (0) = 1, x ₁ (n) = 0, n = 1, 2, ..., The second m-sequence is transmitted at the beginning of each radio frame

Lt; / RTI &gt; If the upper layer

Or a retransmission of the same transport block as part of a random access grant or a contention based random access procedure is associated with a PUSCH transmission

The

Lt; / RTI &gt;

Is the physical cell identifier (PCI) of the cell. Otherwise

Lt; / RTI &gt;

Hereinafter, an uplink-related DCI format will be described in the embodiment of the present invention.

DCI format 0 or DCI format 4 may be used for the scheduling of the PUSCH in one uplink cell. DCI format 4 was added in release 10 to support UL spatial multiplexing. The basis of the uplink resource allocation scheme is a single cluster scheme in which resource blocks are all continuous in the frequency domain. In Release 10, the uplink resource allocation scheme supports transmission to a maximum of two clusters per component carrier A multi-cluster approach has been added.

DCI format 0 can be used to schedule uplink transmissions when spatial multiplexing on a component carrier is not used and has the same size as a control signaling message of compact downlink allocation (DCI Format 1A). The flag on the message may inform the UE about whether it is an uplink scheduling grant (DCI format 0) or a downlink scheduling assignment (DCI format 1A).

The information included in DCI format 0 and DCI format 4 is' 3GPP TS36.212 V11.3.0, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); 5.3.3.1.1 FORMAT 0, 5.3.3.1.8 FORMAT 4 of Multiplexing and channel coding (Release 11) '(hereinafter 3GPP TS36.212). The information contained in each DCI format is shown below.

The DCI format 0 includes a carrier indicator, a DCI format differentiation flag, a frequency hopping flag, a resource block allocation and hopping resource a TPC command for a scheduled PUSCH, a cyclic shift and a cyclic shift for a DM-RS and an RNC, OCC index, UL index, downlink assignment index, CSI request, SRS request, resource allocation type, etc. . &Lt; / RTI &gt;

DCI format 4 can be used in the case of uplink transmission using spatial multiplexing on one component carrier.

DCI format 4 includes a carrier indicator, a resource block assignment, a PUSCH power for information (TPC command for PUSCH), cyclic shift and orthogonal code information (cyclic shift for DM-RS and OCC index) A UL index, a downlink assignment index, CSI request, SRS request, resource allocation type, and the like.

Also, the DCI format 4 may include precoding information, and the precoding information may include information on the number of transmitted precoding matrix indicators (TPMI) and layers.

Table 3 below shows the number of bits allocated to the precoding information according to the number of antenna ports of the UE.

<Table 3>

The information included in the precoding information may be defined differently depending on the number of the antenna ports of the UE, and the number of the precoding matrix indicator and the layer transmitted.

Table 4 below shows the number of precoding matrix indicators and layers included in the precoding information when there are two antenna ports.

<Table 4>

Table 5 below shows the number of precoding matrix indicators and layers included in the precoding information when there are four antenna ports.

<Table 5>

Referring to Table 4 and Table 5, the precoding matrix indicator and the number of layers can be determined according to the value of the bits mapped to the precoding information.

7 is a conceptual diagram showing a small cell environment.

7, in 3GPP, a feasibility study for improving a technology for a small base station (Small eNodeB) that can be used to cover a small area compared to existing macro base stations among various technical standard items (work items) have.

Referring to FIG. 7, the base station can be classified into a macro, a pico, a femto base station, or the like depending on the size of a coverage area. The macro base station may be a base station which is generally used and which covers a wider area than a pico base station. Therefore, the macro base station can use a relatively stronger power in transmission than the pico base station. A pico base station covers a small area for a hotspot or a coverage hole. Also, in general, the pico base station can use relatively less power than the macro base station. Therefore, the connection reliability of the pico base station may be lower than that of the macro base station. In 3GPP, a cell provided by a small base station, such as a pico base station, is called a small cell 750 in comparison with a macro base station. Research is underway on various schemes that can more efficiently use the network in a situation where the macro cell 700 by the macro base station and the small cell 750 by the small base station are mixed together, The load on the network can be controlled by offloading the traffic to the small cell 750 according to the load condition of the network 700, thereby increasing the efficiency. In addition, different types of QoS traffic processing can be handled using differences in the connection status of the macro cell 700 and the small cell 750. [ Research on dual connectivity is under way so that traffic can be transmitted and received by simultaneously connecting to the macro cell 700 and the small cell 750 on the side of the terminal.

In the embodiment of the present invention, a resource allocated for transmitting a reference signal by a mobile station in such a small cell environment can be newly defined. According to an embodiment of the present invention, a UE can perform uplink transmission using a newly defined reference signal according to a transmission environment of a cell. For example, if the channel environment of the small cells 750 has low frequency-selective and low-time-selective fading, the overhead of the uplink DM-RS can be reduced So that the data transfer efficiency can be increased in the small cell 750.

FIG. 8 is a conceptual diagram illustrating that an uplink DM-RS is allocated in an existing resource block.

Referring to FIG. 8, the uplink DM-RS associated with the current PUSCH is a fourth symbol of each slot and an extended CP for a normal CP, and a PUSCH is transmitted from a third symbol for each slot. Can be mapped and transmitted for each subcarrier.

That is, the uplink DM-RS can be mapped and transmitted for each subcarrier in the resource block allocated in two symbols of one subframe.

According to the embodiment of the present invention, if a specific condition is satisfied, the UE can reduce resources allocated to the uplink DM-RS in the small cell by using the uplink DM-RS of the new format for uplink transmission. The resources allocated to the uplink DM-RS can be used for transmission of the PUSCH, thereby increasing the data transmission efficiency of the UE.

The downlink overhead reduction of the uplink DM-RS can be accomplished in two main ways in time and / or frequency domain. In the time domain, the number of symbols allocated for the uplink DM-RS per subframe can be reduced. For example, in one subframe, the uplink DM-RS can be allocated to only one symbol, not to two symbols. In the frequency domain, the number of subcarriers for transmitting a reference signal can be reduced. For example, the reference signal is not mapped and transmitted for each sub-carrier on which the PUSCH is transmitted, but the uplink DM-RS may be mapped to some of the sub-carriers on which the PUSCH is transmitted.

In the embodiment of the present invention, when a specific condition is satisfied for convenience of description, a method for transmitting a reduced downlink overhead of an uplink DM-RS in a time domain is disclosed.

9 is a conceptual diagram illustrating resource allocation of an uplink DM-RS according to an embodiment of the present invention.

In FIG. 9, a resource allocation method for reducing the overhead of the uplink DM-RS will be described.

Referring to FIG. 9, uplink DM-RSs may be allocated and transmitted in only one symbol of an even-numbered slot. The uplink DM-RS may be allocated only to one symbol of the odd-numbered slot other than the even-numbered slot. That is, the uplink DM-RS is not allocated to two symbols for one subframe at present but the uplink DM-RS can be allocated for only one symbol and transmitted.

When the uplink DM-RS transmission method is used, the orthogonal code used to generate the uplink DM-RS may be changed or not used.

를 사용할 수 있다. As described above, in the uplink DM-RS, uplink DM-RSs generated based on different cyclic shifts are used to ensure orthogonality between layers and terminals. In addition, the uplink DM-RS may further use orthogonal cover codes (OCC) to ensure orthogonality. As described above, the uplink DM-RS is an orthogonal sequence of length 2 OCC

Can be used.

For the uplink DM-RS as shown in Table 1, one of [1 1] and [1 -1], which is a 2-length OCC, can be used. The current cyclic shift value and OCC can be indicated by a 3-bit value in a cyclic shift field of uplink-related Downlink Control Information (DCI) as shown in Table 1. [

의 값으로 ‘+1’이 적용되고, 상기 하나의 서브프레임에서 상향링크 DM-RS가 매핑된 두 번째 심볼에서도 ‘+1’이 적용된다. OCC가 [1 -1]인 경우 도 8에서 보는 것과 같은 하나의 서브프레임에서 상향링크 DM-RS가 매핑된 첫 번째 심볼에

의 값으로 ‘+1’이 적용되고, 상기 하나의 서브프레임에서 상향링크 DM-RS가 매핑된 두 번째 심볼는 ‘-1’이 적용된다. The OCC defined in Table 1 is a 2-length OCC mapped to two symbols in consideration of transmission of an existing uplink DM-RS. When OCC is [1 1], in the same subframe as shown in FIG. 8, the uplink DM-RS is mapped to the first symbol

'+1' is applied as the value of the uplink DM-RS, and '+1' is also applied to the second symbol to which the uplink DM-RS is mapped in the one subframe. When the OCC is [1 -1], in one subframe as shown in FIG. 8, the uplink DM-RS is mapped to the first symbol

'-1' is applied to the second symbol to which the uplink DM-RS is mapped in the one subframe.

The OCC can play a role in ensuring orthogonality according to the transmission method. The OCC may not be necessary to ensure orthogonality between the uplink DM-RS depending on the transmission method and the number of all layers used

For example, in the case of a single user (SU) -MIMO, when the total number of layers is three or more, the OCC assists the cyclic shift, thereby further ensuring orthogonality between the layers. When the number of layers is two or less in SU-MIMO, the OCC is applied to the two layers in the same manner, and therefore there is no effect of orthogonality due to OCC. In addition, the OCC can guarantee the orthogonality between layers even when the number of layers in the SU-MIMO is three or more, even with different cyclic shift values. In this case, the OCC can assist the cyclic shift to further ensure orthogonality between the layers.

In the case of MU-MIMO, OCC can be used not only for orthogonality between layers but also for ensuring orthogonality between terminals. When there are four or less total layers (total number of layers used for each UE) in the MU-MIMO, orthogonality between the layer and the UE can be guaranteed to some extent by using different cyclic shift values even if there is no OCC. In this case, the OCC can also assist the cyclic shift to further guarantee the orthogonality between the layer and the terminal. Even when the number of total layers (the sum of layers used for each terminal) in SU-MIMO is five or more, there is a limit to guarantee orthogonality between layers with different cyclic shift values alone. Therefore, it may be necessary to apply different OCCs between layers and / or terminals.

를 의미할 수 있다. 여기서, 레이어 및/또는 단말 간에 순환 쉬프트의 값은 최소한 2 이상 차이가 나는 경우를 고려할 수 있다 왜냐하면, 그 이상 차이가 나지 않을 경우 순환 쉬프트를 적용한 경우에도 시스템 상황에 따라 직교성의 보장이 힘들 수도 있다.Here, the value of the cyclic shift is calculated based on the 3-bit cyclic shift field described in Table 1

. &Lt; / RTI &gt; Here, it is possible to consider a case in which the value of the cyclic shift between the layer and / or the terminal is at least two or more, because if the cyclic shift is applied, it may be difficult to guarantee orthogonality depending on the system condition .

The OCC can distinguish whether it is essential to guarantee orthogonality according to the transmission method and the number of layers, and the necessity of OCC can be divided into three types as follows.

In the first case, the orthogonality between the uplink DM-RSs can be guaranteed based on the cyclic shift without OCC. This case can be satisfied when the total number of layers is one or two. For example, when performing transmission of rank 1 or performing rank-2 SU-MIMO transmission, the total number of layers may be one or two.

In the second case, even if there is no OCC, a certain degree of orthogonality can be maintained due to the cyclic shift. However, in the case of OCC, the orthogonality can be further improved as an auxiliary means of the cyclic shift. This case can be satisfied when the total number of layers is three or four. For example, in the case of performing SU-MIMO with rank 3, when performing SU-MIMO with rank 4, the total number of layers may be three or four.

In the third case, it is difficult to ensure orthogonality by only cyclic shift, and OCC is necessary. This case can be satisfied when the total number of layers is 5 or more. For example, when performing MU-MIMO with a rank of 5 or more, the total number of layers may be five or more.

As described above, in the first case, the number of layers is one or two for one terminal. In the second case, in the case of SU-MIMO, the number of layers is three or four for one terminal, but in the case of MU-MIMO, the number of layers is one or two for each terminal . In the third case, it is general that the number of layers of each terminal is 3 or more as MU-MIMO. Of course, even in the third case, MU-MIMO may be configured when the number of layers is one or two for each terminal, but in this case, MU-MIMO among a large number of terminals is not general.

That is, when the number of layers is one or two for each terminal (especially in the case of Rel-8/9 in which only one layer is supported), the first or second case corresponds to the case where there is no OCC, Only a certain degree of orthogonality can be obtained with respect to the uplink DM-RS.

When the overhead of the uplink DM-RS decreases as shown in FIG. 9, since the uplink DM-RS is allocated to one symbol in one subframe, the OCC can not be applied as in the conventional art. Therefore, new approaches such as not applying OCC or applying OCC in other ways may be necessary.

In the present invention, the following two types of uplink DM-RS configurations can be considered in a small cell environment.

In the first case, the overhead reduction of the uplink DM-RS is not used. In the embodiment of the present invention, a case where the overhead reduction of the uplink DM-RS is not used is referred to as a 'default uplink DM-RS'. As shown in FIG. 8, the uplink DM-RS can be mapped and transmitted in two symbols in one subframe.

이 새롭게 정의될 수 있다. 표 1에서 OCC와 관련된 표의 오른쪽의

과 관련된 열들은 OCC가 적용되지 않을 수 있다. 따라서, 수학식 7과 같이 그 값이 항상 1인

부분만 사용되거나 수학식 8과 같이 아예 사용되지 않을 수 있다. The second case is to apply the downlink DM-RS overhead reduction. Hereinafter, the case where the overhead reduction of the uplink DM-RS is applied will be referred to as a &quot; reduced uplink DM-RS &quot;. As shown in FIG. 9, the uplink DM-RS can be mapped and transmitted in only one symbol in one subframe. When the downlink DM-RS overhead reduction is applied, the existing OCC may not be applied. In this case, in relation to the sequence of the uplink DM-RS with respect to the PUSCH described above in Equation (2)

Can be newly defined. In Table 1, to the right of the table related to OCC

May not be subject to OCC. Therefore, as shown in Equation (7), when the value is always 1

Portion or may not be used at all as in Equation (8).

&Quot; (7) &quot;

&Quot; (8) &quot;

According to the embodiment of the present invention, the case where the default uplink DM-RS is used and the case where the decrease uplink DM-RS is used can be selectively determined. For example, it is possible to selectively determine whether to use the default uplink DM-RS or the decrease uplink DM-RS in the uplink sub-frame considering the number of layers used for uplink transmission in each UE .

For example, in the case where the number of layers of each terminal is one or two, as described above, orthogonality can be obtained to some extent by only cyclic shift without OCC. In this case, the UE can use the reduced uplink DM-RS as the uplink DM-RS in the uplink transmission. On the contrary, if orthogonality can be obtained between the uplink DM-RS due to the presence of the OCC, the UE can use the default uplink DM-RS as the uplink DM-RS in the uplink transmission.

Hereinafter, a specific method for selecting whether to use the default uplink DM-RS or the decrease uplink DM-RS in the uplink sub-frame will be described.

10 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

FIG. 10 shows a method for selecting an uplink DM-RS of a UE. FIG. 10 discloses a method for determining whether the UE uses the default uplink DM-RS or the reduced uplink DM-RS based on the DCI format and the number of layers.

Referring to FIG. 10, the UE can determine whether overhead reduction is possible (step S1000).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted based on, for example, an overhead reduction enabling field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1010).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1010.

Conversely, when it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal, the UE determines whether to use the reduced uplink DM-RS based on the uplink-related DCI format allocated from the base station .

Or when an upper layer signal (e.g., an overhead reduction active field) associated with an overhead reduction is configured (and thus a terminal receives an upper layer signal associated with overhead reduction) Based on the DCI format, you can decide whether to use the reduced uplink DM-RS.

It is determined whether the DCI format is 0 (step S1020).

The terminal can determine the DCI format for transmitting the control signal. For convenience of explanation, it is determined in step S1020 that the DCI format is 0, but it may be determined in step S1020 whether the DCI format is 4 or not.

As a result of the determination based on step S1020, if the DCI format is 0, the reduced uplink DM-RS can be applied (step S1030).

According to the embodiment of the present invention, it is possible to determine whether to use the reduced uplink DM-RS preferentially based on the DCI format. As described above, in the DCI format 0, the number of transport layers for the uplink DM-RS associated with the PUSCH and PUSCH of the UE may be one. That is, in DCI format 0, orthogonality can be guaranteed to some extent only by circular shift without applying OCC. Therefore, when the UE receives the uplink control signal of DCI format 0 from the base station, the UE can perform the uplink transmission using the reduced uplink DM-RS which can reduce the overhead of the uplink DM-RS without applying the OCC have.

As a result of the determination based on step S1020, in the case of DCI format 4, it can be determined whether or not the number of layers is equal to or less than the threshold number (step S1040).

As a result of the determination based on step S1020, it can be further determined whether the number of layers is equal to or less than a threshold number (for example, 1) in case of DCI format 4, and it is determined whether to use the reduced uplink DM-RS .

For example, if uplink-related control information is transmitted in DCI format 4 and the number of layers is 1, uplink transmission may be performed by applying a reduced uplink DM-RS (step S1030). On the contrary, if the number of layers is larger than one, uplink transmission can be performed using the default uplink DM-RS without applying the reduced uplink DM-RS (step S1010).

That is, when the number of layers is larger than a certain number, OCC should be used to secure orthogonality. In this case, uplink transmission can be performed using a default uplink DM-RS using OCC without using a reduced uplink DM-RS that can not use OCC.

Information on the number of layers can be obtained based on information on the number of layers and the precoding information defined in Table 4 and Table 5. [ As shown in Table 3, when the bits included in the precoding information field transmitted based on the DCI format 4 are 3 bits, it is for 2 antenna ports, and when the bits included in the precoding information field are 6 bits May be for four antenna ports.

Referring to Tables 4 and 5, in the precoding information field for two antenna ports, all cases where one codeword is used is one in which the number of layers is one. In the case of using one codeword in the precoding information field for four antenna ports, the case where the bit value of 6 bits is 0 to 23 may be the case where the number of layers is one.

That is, when the uplink-related control information is transmitted through the DCI format 4, the UE updates the default uplink data transmission based on the information on the number of layers acquired based on the precoding information field included in the DCI format 4 You can decide whether to use link DM-RS or decrease uplink DM-RS.

11 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

11, a method for selecting an uplink DM-RS of a UE will be described. 11, it is determined whether the UE uses the default uplink DM-RS or the reduced uplink DM-RS based on the DCI format and the number of layers, The number of threshold layers for determining whether or not to use them may be set differently.

Referring to FIG. 11, the UE can determine whether overhead reduction is possible (step S1100).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted based on, for example, an overhead reduction enabling field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1110).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1110 (step S1110).

Conversely, when it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal, the UE determines whether to use the reduced uplink DM-RS based on the uplink-related DCI format allocated from the base station .

Or when an upper layer signal (e.g., an overhead reduction active field) associated with an overhead reduction is configured (and thus a terminal receives an upper layer signal associated with overhead reduction) Based on the DCI format, you can decide whether to use the reduced uplink DM-RS.

It is determined whether the DCI format is 0 (step S1120).

The terminal can determine the DCI format for transmitting the control signal. For convenience of explanation, the step of determining whether the DCI format is 0 is started in step S1120, but it may be determined whether the DCI format is 4 in step S1120.

As a result of the determination based on step S1120, if the DCI format is 0, the reduced uplink DM-RS can be applied (step S1130).

According to the embodiment of the present invention, it is possible to determine whether to use the reduced uplink DM-RS preferentially based on the DCI format. As described above, in the DCI format 0, the number of transport layers for the uplink DM-RS associated with the PUSCH and PUSCH of the UE may be one. That is, in DCI format 0, orthogonality can be guaranteed to some extent only by circular shift without applying OCC. Therefore, the UE can perform uplink transmission based on the reduced uplink DM-RS, which can reduce the overhead of the uplink DM-RS without applying the OCC.

As a result of the determination based on step S1120, in the case of DCI format 4, it can be determined whether or not the number of layers is equal to or less than the threshold number (step S1140).

As a result of the determination based on the step S1120, in the case of the DCI format 4, it can be additionally determined whether the number of layers is equal to or less than a threshold number (for example, two) to decide whether to use the reduced uplink DM-RS .

For example, if uplink-related control information is transmitted in DCI format 4 and the number of layers is two or less, uplink transmission may be performed by applying a reduced uplink DM-RS (step S1130). On the other hand, if the number of layers is larger than two, uplink transmission can be performed using the default uplink DM-RS without applying the reduced uplink DM-RS (step S1110).

In other words, when the number of layers is larger than a certain number, OCC should be used in order to secure orthogonality. In this case, using a default uplink DM-RS without using a reduced uplink DM- Uplink transmission can be performed.

Information on the number of layers can be obtained based on information on the number of layers and the precoding information defined in Table 4 and Table 5. [ As shown in Table 3, when the bits included in the precoding information field transmitted based on the DCI format 4 are 3 bits, it is for 2 antenna ports, and when the bits included in the precoding information field are 6 bits May be for four antenna ports.

Referring to Tables 4 and 5, in the precoding information field for two antenna ports, all cases in which one codeword is used have one or two layers. In the precoding information field for four antenna ports, when all codewords are used and when two codewords are used, the bit number of 6 bits is from 0 to 15, and the number of layers is one or 2 &lt; / RTI &gt;

That is, when the uplink-related control information is transmitted through the DCI format 4, the UE updates the default uplink data transmission based on the information on the number of layers acquired based on the precoding field information included in the DCI format 4 You can decide whether to use link DM-RS or decrease uplink DM-RS.

12 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

12, a method for selecting an uplink DM-RS of a UE will be described. In FIG. 12, it is possible to decide whether to use the default uplink DM-RS or the decrease uplink DM-RS based on the field defined in the DCI format 4.

Referring to FIG. 12, the UE can determine whether overhead reduction is possible (step S1200).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted based on, for example, an overhead reduction enabling field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1210).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1210 (step &lt; RTI ID = 0.0 &gt; S1210). &Lt; / RTI &gt;

Conversely, when it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal, the UE determines whether to use the reduced uplink DM-RS based on the uplink-related DCI format allocated from the base station .

Or when an upper layer signal (e.g., an overhead reduction active field) associated with an overhead reduction is configured (and thus a terminal receives an upper layer signal associated with overhead reduction) Based on the DCI format, you can decide whether to use the reduced uplink DM-RS.

It is determined whether the DCI format is 0 (step S1220).

The terminal can determine the DCI format for transmitting the control signal. In step S1220, it is determined whether the DCI format is 0 or not. However, in step S1220, it may be determined whether the DCI format is 4 or not.

As a result of the determination based on step S1220, if the DCI format is 0, the reduced uplink DM-RS can be applied (step S1230).

According to the embodiment of the present invention, it is possible to determine whether to use the reduced uplink DM-RS preferentially based on the DCI format. As described above, in the DCI format 0, the number of transport layers for the uplink DM-RS associated with the PUSCH and PUSCH of the UE may be one. That is, in DCI format 0, orthogonality can be guaranteed to some extent only by circular shift without applying OCC. Therefore, a reduced uplink DM-RS that can reduce the overhead of the uplink DM-RS without applying the OCC can be used.

As a result of the determination based on step S1220, in case of DCI format 4, it may be determined whether the overhead reduction field indicates the use of the reduced uplink DM-RS (step S1240).

As a result of the determination based on step S1220, in the case of the DCI format 4, the value of the overhead reduction field transmitted through the DCI format 4 can be determined. The overhead reduction field may include information indicating whether to apply the reduced uplink DM-RS. For example, if the value of the Overhead Reduction field is 0, the reduced uplink DM-RS is used and if the value of the Overhead Reduction field is 1, the reduced uplink DM-RS is not used and the default uplink DM- Can be used. On the contrary, when the value of the overhead reduction field is 1, the reduced uplink DM-RS is used, and when the value of the overhead reduction field is 0, the reduced uplink DM-RS is not used and the default uplink DM- have.

In case of DCI format 4, since there is no strict restriction to have the same payload size as other DCI formats, a new 1-bit field such as an overhead reduction field can additionally be set. However, in DCI format 0 used for uplink grant (UL grant) in addition to DCI format 4, there is a constraint condition that the payload size must be the same as that of DCI format 1A used for DL assignment. Thus, in the case of DCI format 0, additional settings for fields of a new 1-bit size may be difficult. As described above, if the overhead reduction is activated based on the overhead reduction enable field and the UE is uplinked in the DCI format 0, the UE performs uplink transmission based on the reduced uplink DM-RS without further determination can do.

In addition, according to the embodiment of the present invention, it is possible to indicate whether the reduced uplink DM-RS is used based on the existing field information of the DCI format. For example, it may indicate whether a decrease uplink DM-RS is used based on information on a circular shift field included in the RB allocation field of the DCI format or the uplink-related DCI format. Hereinafter, a method for indicating whether a reduced uplink DM-RS is used based on existing field information in DCI format will be described in the embodiment of the present invention.

13 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

FIG. 13 illustrates a method for a UE to select an uplink DM-RS based on information on an overhead reduction enabling field and a resource for a reduced uplink DM-RS transmission availability. When the information on the resource for the reduced uplink DM-RS transmission is pre-defined in the specification, the overhead reduction active field is used for the overhead reduction mentioned in the embodiments according to FIGS. 10 to 12 Reduction activation field. If the information on the resources for the reduced uplink DM-RS transmission is included in the overhead reduction enable field and signaled from the upper layer, the overhead decrease enable field is a resource based overhead enable field reduction enabling field.

In FIG. 13, when the uplink resource allocated to the UE is scheduled to transmit the uplink data and the uplink DM-RS and is associated with the reduced uplink DM-RS transmission available resource, Can be performed. For example, if a resource block corresponding to the lowest resource block index among the UL resource blocks allocated to the UE and scheduled to transmit the uplink data and the uplink DM-RS belongs to the resource for the decrease uplink DM-RS transmission , The UE can perform uplink transmission based on the reduced uplink DM-RS.

Referring to FIG. 13, the UE can determine whether overhead reduction is possible (step S1300).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted, for example, via an overhead reduction enabling field. The overhead reduction enable field may be the same as the overhead reduction enable field mentioned in the embodiments according to FIGS. 10 to 12 as mentioned above, and may include resources for information on available resources for reduced uplink DM-RS transmission Based overhead reduction activation field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1310).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1310 (step &lt; RTI ID = 0.0 &gt; S1310). &Lt; / RTI &gt;

On the contrary, when it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal (for example, the overhead reduction enable field), the UE allocates the allocated uplink DCI format The UE determines whether the uplink DM-RS is transmitted or not by determining whether the uplink resource is associated with the reduced uplink DM-RS transmission available resource.

Or when an upper layer signal (e.g., an overhead reduction active field) associated with an overhead reduction is configured (and thus a terminal receives an upper layer signal associated with overhead reduction) It can be determined whether or not the uplink DM-RS allocated to the UE through the DCI format is connected to the reduced uplink DM-RS transmission available resource.

It is determined whether the uplink allocated resources allocated to the UE through the uplink related DCI format are associated with the downlink DM-RS available resources (step S1320).

The UE can determine whether to transmit the reduced uplink DM-RS by determining whether the allocated uplink resource is associated with the reduced uplink DM-RS transmission available resource.

The resource blocks allocated to the UE based on the resource block allocation information allocated for transmitting uplink data and the uplink DM-RS in the uplink-related DCI format (DCI format 0 or DCI format 4) It is possible to judge whether or not it is associated with a transmission available resource. For example, it is determined whether a resource block having the lowest resource block index among the resource blocks allocated to the UE belongs to a resource of the reduced uplink DM-RS transmission, and the resource block allocated to the UE is transmitted to the downlink DM- It can be judged whether or not it is associated with available resources.

When the uplink resource allocated to the UE is associated with the reduced uplink DM-RS transmission available resource, for example, the downlink resource block corresponding to the lowest resource block index among the uplink resource blocks allocated to the UE through the uplink- If the resource block belongs to the reduced uplink DM-RS transmission available resource, the UE can perform uplink transmission based on the reduced uplink DM-RS (step S1330).

On the contrary, when the uplink resource allocated to the UE is not associated with the reduced uplink DM-RS transmission available resource, for example, the uplink resource block is allocated to the lowest resource block index among the uplink resource blocks allocated to the UE through the uplink- If the corresponding resource block does not belong to the resource for the reduced uplink DM-RS transmission, the UE can perform uplink transmission based on the default uplink DM-RS (step S1310).

That is, in the embodiment of the present invention, the uplink DM-RS can be determined by using the uplink resources and allocating the corresponding resources to the UE. The UE can receive information on which of the uplink resources is the reduced uplink DM-RS transmission available resource from the base station. Or reduced uplink DM-RS transmission available resources may be defined in advance between the UE and the BS.

14 illustrates a method for defining a reduced uplink DM-RS transmission available resource according to an embodiment of the present invention.

Referring to FIG. 14, the first uplink resource 1400 of the uplink resource is used as a resource for a decrease uplink DM-RS transmission, the second uplink resource 1450 is used as a resource for a decrease uplink DM- Can be used. In FIG. 14, it is assumed that a resource for a reduced uplink DM-RS transmission is allocated over a plurality of subframes. However, a resource for a reduced uplink DM-RS transmission may be defined for each subframe.

)를 기반으로 감소 상향링크 DM-RS 전송 가용 자원을 정의할 수 있다. 감소 상향링크 DM-RS 전송 가용 자원은 아래의 수학식 9와 같이 자원 지시 값(resource indication value)으로 정의될 수 있다.For example, to transmit information on available resources of the uplink DM-RS transmission, information on the starting resource block from which the resource for decreasing uplink DM-RS transmission is started and the number of consecutive resource blocks from the starting resource block May be used. Specifically, information on a starting resource block (RB _start ), information on consecutive resource blocks from the starting resource block (

), It is possible to define resources for transmission of reduced uplink DM-RS transmission. The reduced uplink DM-RS transmission available resource can be defined as a resource indication value as shown in Equation (9) below.

&Quot; (9) &quot;

는 상향링크에서 설정된 자원 블록의 개수에 대한 정보를 나타낸다.

Represents information on the number of resource blocks set in the uplink.

Alternatively, existing uplink resource allocation 0, existing uplink resource allocation 1 and existing downlink resource allocation 0, existing downlink resource allocation 1 or existing downlink resource allocation 2, The allocation scheme used to allocate resources may be used to send information about reduced uplink DM-RS transmission available resources. The information on such reduced uplink DM-RS transmission available resources can be transmitted through an upper layer (e.g., RRC). For example, as mentioned above, information on available resources for reduced uplink DM-RS transmission may be included in the overhead reduction active field and signaled from the upper layer and transmitted.

On the other hand, as mentioned above, the information on the resource of the reduced uplink DM-RS transmission may be pre-defined in the specification. For example, information on pre-defined reduced uplink DM-RS transmission available resources may be allocated to RBs whose RB index is an odd number or RBs that are even numbered by a resource of a reduced uplink DM-RS transmission (RB index) mod N = 0 (where N is an integer of 2 or more) can be used as a resource for the reduced uplink DM-RS transmission.

15 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

15, in addition to the information on the overhead reduction enabling field and the resources for the downlink DM-RS transmission mentioned in the embodiment of FIG. 13, information on the DCI format is additionally considered, A method of selecting the link DM-RS will be described.

Referring to FIG. 15, it can be determined whether overhead reduction is possible (step S1500).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted, for example, via an overhead reduction enabling field. The overhead reduction enable field may be the same as the overhead reduction enable field mentioned in the embodiments according to FIGS. 10 to 12 as mentioned above, and may include resources for information on available resources for reduced uplink DM-RS transmission Based overhead reduction activation field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1510).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1510.

On the contrary, when it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal, the UE determines whether to use the reduced uplink DM-RS based on the information on the DCI format and the uplink resource allocated to the UE You can decide whether or not.

(E.g., an overhead reduction enable field) associated with overhead reduction (e.g., when the terminal receives an upper layer signal associated with overhead reduction), information on the DCI format and information on assignment to the terminal Based on the uplink resources, the UE can determine whether to use the reduced uplink DM-RS.

It is determined whether the DCI format is 0 (step S1520).

If the UE can use the reduced uplink DM-RS, it can further determine whether the DCI format is 0 or 4 to determine whether to use the reduced uplink DM-RS.

According to the embodiment of the present invention, when the DCI format is 0, the reduced uplink DM-RS can be used (step S1540).

In contrast, when the DCI format is not 0, that is, when the DCI format is 4, it is determined whether the resources allocated by the UE are associated with the resources of the reduced uplink DM-RS transmission, and whether to use the reduced uplink DM- As shown in FIG.

It is determined whether the uplink allocated resources are associated with the reduced uplink DM-RS available resources (step S1530).

When the UE is scheduled for uplink based on the DCI format 4, the UE determines whether the allocated uplink resource is associated with the reduced uplink DM-RS transmission available resource and decides whether to transmit the reduced uplink DM-RS .

In the DCI format 4, it is possible to determine whether a resource block allocated to the UE based on the resource block allocation information allocated for transmitting the uplink data and the uplink DM-RS is associated with the resource for the reduced uplink DM-RS transmission have. For example, it is determined whether a resource block having the lowest resource block index among the resource blocks allocated to the UE belongs to a resource of the reduced uplink DM-RS transmission, and the resource block allocated to the UE is transmitted to the downlink DM- It can be judged whether or not it is associated with available resources.

When the UE is associated with the downlink DM-RS transmission available resource allocated to the UE based on the DCI format 4, for example, the downlink resource block allocated to the UE through the DCI format 4 If the resource block corresponding to the resource block index belongs to the resource for the reduced uplink DM-RS transmission, the UE can perform uplink transmission based on the reduced uplink DM-RS (step S1540).

On the other hand, if the UE does not have uplink resources allocated to the UE based on the DCI format 4 and is not associated with the reduced uplink DM-RS transmission available resource, for example, among the uplink resource blocks allocated to the UE through the DCI format 4 If the resource block corresponding to the lowest resource block index does not belong to the resource for the reduced uplink DM-RS transmission, the UE can perform uplink transmission based on the default uplink DM-RS (step S1510 ).

That is, in the embodiment of the present invention, information on the DCI format used for transmitting uplink-related control information and uplink resources can be distinguished and the uplink DM-RS to be used by the UE allocated with the corresponding resource can be determined. The UE can receive information on which of the uplink resources is the reduced uplink DM-RS transmission available resource from the base station. Or reduced uplink DM-RS transmission available resources may be defined in advance between the UE and the BS.

16 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

16, a method for selecting an uplink DM-RS by a UE considering information on an overhead decrease enable field and a cyclic shift field will be described.

Referring to FIG. 16, it can be determined whether overhead reduction is possible (step S1600).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted based on, for example, an overhead reduction enabling field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1610).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1610 (step S1610).

Conversely, if it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal, it may be determined whether to use the reduced uplink DM-RS based on the cyclic-shift field information included in the DCI format .

Or when an upper layer signal (e.g., an overhead reduction enable field) related to overhead reduction is configured (thus, the terminal has received an upper layer signal associated with overhead reduction), the cyclic shift field information included in the DCI format Based on whether or not to use the reduced uplink DM-RS.

It is determined whether the cyclic shift field belongs to the first cyclic shift group (step S1620).

It is determined whether the uplink DM-RS overhead reduction is applied through the cyclic shift field in the uplink-related DCI format (DCI format 0 or DCI format 4).

As shown in Table 1, the eight 3-bit values indicated by the cyclic shift field are divided into two groups (a first cyclic shift group and a second cyclic shift group), and a 3-bit value of the cyclic shift field is divided into a first cyclic group It is possible to apply overhead reduction when belonging to a shift group and not to apply overhead reduction when belonging to a second cyclic shift group.

For example, the 3-bit field value corresponding to the cyclic shift field belonging to the first cyclic shift group and the 3-bit field value corresponding to the cyclic shift field belonging to the second cyclic shift group can be set variously. Hereinafter, in the embodiment of the present invention, it is assumed that four of the eight cyclic shift field values are included in the first cyclic shift group and the remaining four are included in the second cyclic shift group for convenience of explanation. The first cyclic shift group and the second cyclic shift group can be distinguished.

Referring to Table 1, a cyclic shift field having the same OCC mapping value for each layer can be paired into two field values as shown below.

The first set can have an OCC value of (0001, 111) ([1 1], [1 1], [1 -1], [1 -1]). The second set can have 00, 010 as OCC values ([1 -1], [1 -1], [1 1], [1 1]). The third set can have 011, 100 as OCC values ([1 1], [1 1], [1 1], [1 1]). The fourth set is 101, 110 and can have OCC values ([1 -1], [1 -1], [1 -1], [1 -1]).

One cyclic shift field value of one of two cyclic shift field values included in each set of the first set to the fourth set may be divided into a first cyclic shift group and the remaining one into a second cyclic shift group. For example, '111, 010, 100, and 110' may be classified into a first cyclic shift group and '000, 001, 011, and 101' may be classified into a second cyclic shift group. As another example, '001, 100, 101, and 111' may be classified into a first cyclic shift group and '000, 010, 011, and 110' may be classified into a second cyclic shift group.

In addition, various methods may be used to divide the cyclic shift field value of one of the two cyclic shift field values included in the first to fourth sets into a first cyclic shift group and the remaining one into a second cyclic shift group.

If the value of the cyclic shift is the first cyclic shift group based on the cyclic shift field included in the DCI format, transmission is performed using the reduced uplink DM-RS. If the value of the cyclic shift is the second cyclic shift group, Can be used to perform the transmission. That is, in the case of the first cyclic shift group, since the reduced uplink DM-RS is not used, the OCC may not be defined separately. Tables 6 and 7 below are tables defining the first cyclic shift and the second cyclic shift separately. Table 6 or Table 7 may be used instead of Table 1 if overhead reduction is enabled based on the overhead reduction enable field.

<Table 6>

<Table 7>

As a result of the determination in step S1620, in the case of the first cyclic shift group, uplink transmission may be performed using the reduced uplink DM-RS (step S1630).

As a result of the determination in step S1620, in the case of the second cyclic shift group, uplink transmission may be performed using the default uplink DM-RS (step S1610).

17 is a flowchart illustrating an uplink DM-RS selection method according to an embodiment of the present invention.

In FIG. 17, a method for selecting an uplink DM-RS by a UE considering information on an overhead reduction enable field, a DCI format, and a cyclic shift field will be described.

Referring to FIG. 17, the UE can determine whether overhead reduction is possible (step S1700).

The UE can acquire information on whether it can use the reduced uplink DM-RS based on an upper layer signal transmitted from an upper layer (for example, radio resource control (RRC)). Information on whether the reduced uplink DM-RS can be used based on the upper layer signal can be transmitted based on, for example, an overhead reduction enabling field. The overhead reduction enable field can be transmitted semi-static in consideration of a small cell layout environment and the like. The overhead reduction enable field may serve to indicate a mode where a kind of overhead reduction is possible.

If it is not possible to use the reduced uplink DM-RS in the UE as a result of receiving an upper layer signal (e.g., an overhead reduction enable field), the UE transmits an uplink transmission based on the default uplink DM- (Step S1710).

(E.g., if the UE has not received an upper layer signal associated with overhead reduction), the UE will notify the UE of the default uplink DM &lt; RTI ID = 0.0 &gt; -RS in step S1710 (step &lt; RTI ID = 0.0 &gt; S1710). &Lt; / RTI &gt;

On the contrary, when it is possible to use the reduced uplink DM-RS in the UE as a result of receiving the upper layer signal, the base station determines the information on the DCI format used for transmitting the uplink related control information to the UE, It is possible to judge whether the RS is used or not.

(For example, an overhead reduction enable field) associated with the overhead reduction (i.e., when the terminal receives an upper layer signal related to overhead reduction), the uplink related control information The UE can determine whether to use the reduced uplink DM-RS by determining the information on the DCI format used for transmitting the uplink DM-RS.

It is determined whether the DCI format is 0 (step S1720).

If the UE can use the reduced uplink DM-RS, it can determine whether the DCI format is 0 or 4. If the DCI format is 0, uplink transmission can be performed based on the reduced uplink DM-RS (step S1740).

If the DCI format is 4, it can be determined whether to use the reduced uplink DM-RS based on the information on the cyclic shift field included in the DCI format 4.

It is determined whether or not it is included in the first cyclic shift group (step S1740).

When the UE is included in the first cyclic shift group, the UE can perform uplink transmission by applying the reduced uplink DM-RS.

If the UE is not included in the first cyclic shift group, i.e., included in the second cyclic shift group, the UE applies the default uplink DM-RS without performing the downlink DM-RS to perform the uplink transmission (Step S1710).

18 is a block diagram illustrating a wireless communication system according to an embodiment of the present invention.

18, a base station 1800 includes a processor 1810, a memory 1820, and a radio frequency (RF) unit 1830. The memory 1820 is coupled to the processor 1810 and stores various information for driving the processor 1810. RF section 1820 may be coupled to processor 1810 to provide a radio signal (e.g., an uplink signal associated with reduced overhead as disclosed herein, an uplink-related control signal by DCI format 0 or DCI format 4, etc.) And receives a transmit and / or wireless signal (e.g., uplink DM-RS, as disclosed herein). The processor 1810 configures the upper layer signal related to the overhead reduction disclosed herein and the setting related to the uplink related control signal by the DCI format 0 or the DCI format 4 and transmits the uplink signal from the uplink DM- Channel estimation is performed. The operation of the base station of the serving cell in the above-described embodiment may be implemented by processor 1810. [

The wireless device (or terminal) 1850 includes a processor 1860, a memory 1870, and an RF section 1880. Memory 1870 is coupled to processor 1860 to store various information for driving processor 1860. [ The RF section 1880 is coupled to the processor 1860 to provide a radio signal (e.g., an upper layer signal associated with reduced overhead as disclosed herein, an uplink-related control signal in DCI format 0 or DCI format 4, etc.) Or transmits a radio signal (e.g., the uplink DM-RS disclosed herein). Processor 1860 implements the functions, processes and / or methods proposed in the embodiments of Figs. 10-17 of the present invention. The operation of the terminal in all of the embodiments disclosed herein may be implemented by processor 1860. [

The processor may comprise an application-specific integrated circuit (ASIC), other chipset, logic circuitry and / or a data processing device. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory cards, storage media, and / or other storage devices. The RF unit may include a baseband circuit for processing the radio signal. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module is stored in memory and can be executed by the processor. The memory may be internal or external to the processor and may be coupled to the processor by any of a variety of well known means.

The foregoing description is merely illustrative of the technical idea of the present invention and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (14)

A method for transmitting a reference signal of a terminal in a wireless communication system,
Determining whether uplink transmission based on a downlink DM (demodulation) -RS (reference signal) is possible based on the overhead reduction enable field received from the base station; And
If uplink transmission based on the reduced uplink DM-RS is possible, based on the reduced uplink related downlink control information (DCI) based on the uplink related downlink control information (DCI) received from the base station Determining whether to perform one uplink transmission,
The overhead reduction enable field is a field for indicating whether the UE can perform uplink transmission based on the reduced uplink DM-RS,
Wherein the reduced uplink DM-RS is allocated to one symbol per subframe. 2. The method of claim 1, wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-
Performing uplink transmission based on the reduced uplink DM-RS if the format of the uplink related DCI is DCI format 0; And
Determining whether the number of layers allocated for uplink transmission of the UE is equal to or less than a threshold number of layers if the format of the uplink related DCI is DCI format 4, Performing uplink transmission,
Wherein the number of the threshold layers is a number of layers serving as a reference for determining whether to perform uplink transmission based on the reduced uplink DM-RS. 2. The method of claim 1, wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-
Performing uplink transmission based on the reduced uplink DM-RS if the format of the uplink related DCI is DCI format 0; And
If the format of the uplink related DCI is DCI format 4, the UE determines whether to perform uplink transmission based on the reduced uplink DM-RS based on the overhead reduction field included in the DCI format 4 , &Lt; / RTI &gt;
Wherein the overhead reduction field is a field indicating whether the UE uses the reduced uplink DM-RS. 2. The method of claim 1, wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-
Determining whether an uplink transmission resource allocated based on the uplink related DCI is associated with a reduced uplink DM-RS transmission available resource; And
And performing uplink transmission based on the reduced uplink DM-RS when the uplink transmission resource is associated with the reduced uplink DM-RS transmission available resource,
Wherein the information on the resources available for transmission of the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the terminal can receive from the base station or be predefined between the terminal and the base station. Reference signal transmission method. 2. The method of claim 1, wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-
Performing uplink transmission based on the reduced uplink DM-RS if the format of the uplink related DCI is DCI format 0;
Determining whether an uplink transmission resource allocated based on the DCI format 4 is associated with a reduced uplink DM-RS transmission available resource when the format of the uplink related DCI is DCI format 4; And
And performing uplink transmission based on the reduced uplink DM-RS when the uplink transmission resource is associated with the reduced uplink DM-RS transmission available resource,
Wherein the information on the resources available for transmission of the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the terminal can receive from the base station or be predefined between the terminal and the base station. Reference signal transmission method. 2. The method of claim 1, wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-
And determining whether to perform uplink transmission using the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink related DCI, Signal transmission method. 2. The method of claim 1, wherein the step of determining whether to perform uplink transmission based on the reduced uplink DM-
Performing uplink transmission based on the reduced uplink DM-RS if the format of the uplink related DCI is DCI format 0; And
If the format of the uplink-related DCI is DCI format 4, uplink transmission is performed using the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink-related DCI The method comprising the steps of: determining whether to transmit a reference signal to a terminal in a wireless communication system. A terminal for transmitting a reference signal in a wireless communication system,
A radio frequency (RF) unit for transmitting and receiving a radio signal; And
And a processor selectively coupled to the RF unit,
The processor determines whether uplink transmission based on a reduced DM (demodulation) -RS (reference signal) is possible based on the overhead reduction enable field received from the base station,
If uplink transmission based on the reduced uplink DM-RS is possible, based on the uplink related downlink control information (DCI) received from the base station, the downlink based on the downlink DM- To determine whether to perform the transmission,
The overhead reduction enable field is a field for indicating whether the UE can perform uplink transmission based on the reduced uplink DM-RS,
Wherein the reduced uplink DM-RS is allocated to one symbol per subframe. 9. The apparatus of claim 8,
If the format of the uplink-related DCI is DCI format 0, uplink transmission is performed based on the reduced uplink DM-RS,
If the format of the uplink-related DCI is DCI format 4, it is determined whether the number of layers allocated for uplink transmission of the UE is equal to or less than a threshold number of layers, , &Lt; / RTI &gt;
Wherein the number of the threshold layers is a number of layers serving as a reference for determining whether to perform uplink transmission based on the reduced uplink DM-RS. 9. The apparatus of claim 8,
If the format of the uplink-related DCI is DCI format 0, uplink transmission is performed based on the reduced uplink DM-RS,
If the format of the uplink-related DCI is DCI format 4, it is determined whether to perform uplink transmission based on the decrease uplink DM-RS based on the overhead reduction field included in the DCI format 4 ,
The overhead reduction field is a field for indicating whether the UE uses the reduced uplink DM-RS. 9. The apparatus of claim 8,
Determining whether an uplink transmission resource allocated based on the uplink-related DCI is associated with a reduced uplink DM-RS transmission available resource,
And performing uplink transmission based on the reduced uplink DM-RS when the uplink transmission resource is associated with the reduced uplink DM-RS transmission available resource,
Wherein the information on resources for the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the terminal can receive from the base station or be predefined between the terminal and the base station. . 9. The apparatus of claim 8,
If the format of the uplink-related DCI is DCI format 0, uplink transmission is performed based on the reduced uplink DM-RS,
Determining whether an uplink transmission resource allocated based on the DCI format 4 is a reduced uplink DM-RS transmission available resource when the format of the uplink related DCI is DCI format 4,
And performing uplink transmission based on the reduced uplink DM-RS when the uplink transmission resource is the reduced uplink DM-RS transmission available resource,
Wherein the information on resources for the reduced uplink DM-RS transmission is included in the overhead reduction enable field so that the terminal can receive from the base station or be predefined between the terminal and the base station. . 2. The apparatus of claim 1,
And determining whether to perform uplink transmission using the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink related DCI. 2. The apparatus of claim 1,
If the format of the uplink-related DCI is DCI format 0, uplink transmission is performed based on the reduced uplink DM-RS,
If the format of the uplink-related DCI is DCI format 4, uplink transmission is performed using the reduced uplink DM-RS based on information on a cyclic shift field included in the uplink-related DCI The terminal is implemented to determine whether to do so.

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