KR20150090586A - Apparatus and method for mapping uplink demodulation-reference signal sequence - Google Patents

Abstract

Disclosed are a method and an apparatus for mapping an uplink demodulation-reference signal (SM-RS) sequence. The method for mapping an uplink DM-RS sequence includes: a step in which a terminal receives information about the number of resource block(s) assigned for an uplink DM-RS sequence through a resource block assignment field in an uplink-related DCI; and a step where the terminal maps the uplink DM-RS sequence for the resource block(s) assigned in an uplink sub-frame based on the information about the number of the assigned resource block(s). If the number of the assigned resource block(s) is an even number, the uplink DM-RS sequence is mapped in a part of subcarriers forming all of the assigned resource block(s) individually. And if the number of the assigned resource block(s) is an odd number, the uplink DM-RS sequence can be mapped in all subcarriers forming a resource block among the assigned resource block(s) and a part of the subcarriers constituting each of the rest resource block(s) except for one resource block among the assigned resource block(s).

Description

[0001] APPARATUS AND METHOD FOR MAPPING UPLINK DEMODULATION-REFERENCE SIGNAL SEQUENCE [0002]

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

In a next generation communication system such as LTE-A (Advanced), a small cell (F2) based on a low-power node as well as a macro cell (F1) based on a high- 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 mapping an uplink DM-RS sequence.

Another object of the present invention is to provide an apparatus for performing a method of mapping an uplink DM-RS sequence.

According to an aspect of the present invention, there is provided a method of mapping an uplink DM (demodulation) -RS (reference signal) sequence according to an aspect of the present invention, Receiving information on the number of resource blocks (s) allocated for the uplink DM-RS sequence through a block allocation field, determining whether the number of allocated resource blocks (s) And mapping the uplink DM-RS sequence to the allocated resource block (s) in the uplink subframe based on the information of the allocated resource block (s), wherein when the number of allocated resource blocks is an even number , The uplink DM-RS sequence is mapped to a part of subcarriers constituting each allocated resource block (s), and the number of allocated resource blocks (s) is an odd number The uplink DM-RS sequence includes all the sub-carriers constituting one resource block of the allocated resource block (s) and the remaining resource blocks excluding the one resource block among the allocated resource blocks (s) May be mapped to some subcarriers constituting each of the subcarriers.

According to another aspect of the present invention, there is provided a method for mapping an uplink DM (demodulation) -RS (reference signal) sequence to an RF and a processor selectively connected to the RF unit, wherein the processor is allocated for the uplink DM-RS sequence through a resource block allocation field in uplink-related downlink control information (DCI) The method comprising: receiving information on the number of resource blocks in the uplink subframe based on information on the number of allocated resource blocks; RS, the uplink DM-RS sequence may be configured to map the uplink DM-RS sequence, if the number of allocated resource blocks is an even number, And the uplink DM-RS sequence is mapped to a part of the sub-carriers constituting each resource block (s), and when the number of allocated resource blocks is an odd number, All the subcarriers constituting one resource block and a part of subcarriers constituting each resource block (s) excluding the one resource block among the allocated resource block (s).

In the small cell environment, the UE can newly define resources allocated for transmitting a reference signal and perform uplink transmission. The mapping method of the uplink DM-RS sequence to be transmitted to the base station can be determined based on the information transmitted from the upper layer and the number of the resource block (s) allocated to map the uplink DM-RS sequence. By using this method, the resource allocated to the uplink DM-RS sequence can be adjusted to reduce the overhead of the uplink DM-RS, thereby increasing the data transmission efficiency of the UE in the small cell.

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.
8 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.
9 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.
10 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.
11 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.
12 is a flowchart illustrating a method of determining an uplink DM-RS sequence according to an embodiment of the present invention.
13 is a conceptual diagram illustrating a resource block (s) according to an embodiment of the present invention.
FIG. 14 is a flowchart illustrating a method of determining an uplink DM-RS sequence according to an embodiment of the present invention.
15 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.

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 in a downlink (DL), the symbol may be an Orthogonal Frequency Division Multiplexing (OFDM) 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.

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) "

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 a 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, in the embodiment of the present invention, the uplink DM-RS is additionally posted.

The uplink DM-RS is used for channel estimation for the coherent demodulation of the PUSCH to which the UL-SCH transport channel is mapped and for the coherent demodulation of the PUCCH that carries various types of L1 / L2 control signaling need. Although there are some differences, the basic uplink DM-RS structure can be the same for PUSCH and PUCCH. The difference is that the number and position of the SC-FDMA symbols transmitting the reference signal in one subframe may be different from each other.

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. Regardless of whether the type of uplink transmission is PUCCH or PUSCH, the basic structure of each reference signal transmission may be a reference signal in the frequency domain mapped to successive inputs (continuous subcarriers) of the signal generator . The bandwidth of the reference signal corresponding to the sequence length of the reference signal may be equal to 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 length of the sequence of the reference signal can always be a multiple of 12.

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

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) "

Referring to Equation 2,

Denotes the length of the reference signal sequence as the number of subcarriers allocated for the reference signal sequence.

, ≪ / RTI >

Is the number of subcarriers included in one resource block. m is the number of the resource block (s) allocated for the PUSCH and the uplink DM-RS associated therewith

(Where m in Equation 2 is an index of an orthogonal sequence having a value of 0 or 1, and m (m) corresponding to the number of allocated resource block (s) It is a different parameter from. As described above, the length of the reference signal sequence may be defined as a multiple of the number of subcarriers included in one resource block.

It can be seen that the number of subcarriers allocated for the reference signal sequence corresponding to the length of the reference signal sequence is the same as the number of subcarriers allocated to the PUSCH.

≪ RTI ID = 0.0 > The

. ≪ / RTI >

Is a cyclic shift,

And basic sequence

Lt; / RTI > The following equation (3)

.

&Quot; (3) "

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.

Basic sequence

Can be defined by the Zadoff-Chu sequence. The definition of this 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 ) (Hereinafter referred to as 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.

The uplink DM-RSs defined from different reference signal sequences generally have a non-zero cross-correlation, albeit relatively low. 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. E.g

Changes from 0 to 11, the cyclic shift

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.

Referring again to Equation (2)

Represents an orthogonal sequence such as an orthogonal cover code (OCC). Hereinafter, in an embodiment of the present invention, an orthogonal sequence may be defined and used in terms of an orthogonal cover code or 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).

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 >

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>

In Equation 2,

(Cyclic shift)

Slot

in

Can be defined as

Can be defined as Equation (4) below.

&Quot; (4) &quot;

In Equation 4,

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

<Table 2>

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

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;

Here, Nc = 1600, the first m-sequence is initialized to x1 (0) = 1, x1 (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, in the embodiment of the present invention, an uplink-related DCI format is posted.

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 all of the resource block (s) are continuous in the frequency domain, but in release 10, transmission to a maximum of two clusters per component carrier And a multi-cluster scheme supporting the same.

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 &quot; 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, a CSI request, an SRS request, a resource allocation type, a transport block, Modulation and coding scheme (MCS) and new data indicator (NDI) information for each of the transport blocks 1 and / or 2.

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 the technology of a small base station (eNodeB), which can be used to cover a small area compared with existing macro base stations, is performed among various technical standard items .

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 an embodiment of the present invention, a method of selectively mapping a reduced uplink DM-RS sequence and / or a default uplink DM-RS sequence to a resource allocated for a UE to map an uplink DM-RS sequence in a small cell environment .

The default DM-RS sequence may be a sequence generated based on the method published in FIGS. 4 to 6 and mapped to the resource block (s).

A reduced uplink DM-RS sequence according to an embodiment of the present invention may include a first reduced uplink DM-RS sequence and a second reduced uplink DM-RS sequence. The first reduced uplink DM-RS sequence may be mapped to even-numbered sub-carriers or odd-numbered sub-carriers in one symbol constituting the resource block (s) of an even slot (first slot in one sub-frame) . The second reduced uplink DM-RS sequence includes a first reduced uplink DM-RS sequence mapped to one symbol constituting the resource block (s) of an odd slot (second slot in one subframe) May be mapped to subcarriers having the same subcarrier index as the carriers.

The first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence may be a sequence generated by applying OCC to the first reduced reference signal sequence and the second reduced reference signal sequence. Hereinafter, in an embodiment of the present invention, the reference signal sequence indicates a sequence of a DM-RS for an uplink before OCC is applied, and an uplink DM-RS sequence indicates a sequence of an uplink after OCC is applied to a reference signal sequence. It is used as a term to indicate the sequence of DM-RS.

By using the mapping method for the uplink DM-RS sequence according to the embodiment of the present invention, the amount of radio resources used for the UE to transmit the uplink DM-RS can be reduced. Also, in the case of using the mapping method for the uplink DM-RS sequence according to the embodiment of the present invention, although the amount of resources used for transmitting the uplink DM-RS is reduced, By applying OCC, orthogonality between sequences can be guaranteed.

Hereinafter, in the embodiment of the present invention, the uplink DM-RS mapping method is specifically described.

Hereinafter, a method for generating a reduced uplink DM-RS sequence will be described in an embodiment of the present invention.

A reduced uplink DM-RS sequence according to an embodiment of the present invention may include a first reduced uplink DM-RS sequence and a second reduced uplink DM-RS sequence.

For example, the first reduced uplink DM-RS sequence of the reduced uplink DM-RS sequence to be disclosed in FIG. 8 and FIG. 9 may be a resource block (s) of an even slot (first slot in one subframe) May be mapped to even-numbered subcarriers or odd-numbered subcarriers in one symbol. Also, the second reduced uplink DM-RS sequence may be mapped to a first reduced uplink DM-RS sequence in one symbol constituting the resource block (s) of the odd slot (second slot in one subframe) And may be mapped to subcarriers having the same subcarrier index as the subcarriers. The default DM-RS sequence may be a sequence generated based on the method published in FIGS. 4 to 6 and mapped to the resource block (s).

The first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence may be orthogonal sequences (e.g., orthogonal sequences) for the first reduced reference signal sequence and the second reduced reference signal sequence, OCC) (hereinafter referred to as &quot; OCC &quot;). Hereinafter, in an embodiment of the present invention, the reference signal sequence indicates a sequence of a DM-RS for an uplink before OCC is applied, and an uplink DM-RS sequence indicates a sequence of an uplink after OCC is applied to a reference signal sequence. It is used as a term to indicate the sequence of DM-RS.

In the method for generating a reduced uplink DM-RS sequence according to an embodiment of the present invention, regardless of whether the number of resource blocks (s) allocated for the uplink DM-RS sequence is an even number or an odd number, It is possible to guarantee the orthogonality of the reduced uplink DM-RS transmitted between the layers when the uplink DM-RS is transmitted to a plurality of layers.

Hereinafter, a reduced uplink DM-RS mapping method and a reduced uplink DM-RS generating method according to an embodiment of the present invention will be specifically described with reference to FIGS. 8 to 11. FIG. The reduced uplink DM-RS mapping method and generation method disclosed in FIGS. 8 to 11 is one example of the other various reduced uplink DM-RS mapping methods that are compared with the default DM-RS sequence and mapped to few resources Can be used.

8 is a conceptual diagram illustrating a method of mapping a reduced uplink DM-RS sequence according to an embodiment of the present invention.

8 illustrates a method for mapping a first reduced uplink DM-RS sequence 810 and a second reduced uplink DM-RS 820 in a resource block (s) for each slot included in a subframe Post. The reference signal sequence for generating the first reduced uplink DM-RS sequence 810 and the second reduced uplink DM-RS sequence 820 may be defined as a reduced reference signal sequence and used. A method for generating a reduced reference signal sequence for generating a first reduced uplink DM-RS sequence 810 and a second reduced uplink DM-RS sequence 820 will be described later.

8 shows a normal CP subframe defined by a single carrier-frequency division multiple access (SC-FDMA) symbol including a normal cyclic prefix (CP). One resource block (RB) of the normal CP subframe includes seven consecutive SC-FDMA symbols (l = 0 to 6) in the time domain and 12 subcarriers (k '= 0 ~ 11) (for a subcarrier index k defined for the overall system bandwidth

. here

Is a physical resource block index. For example, if the number of resource blocks corresponding to the total system bandwidth is 50,

= 4) and the sixth (

= 5), if the first uplink DM-RS sequence and the second uplink DM-RS sequence are mapped,

= 4 and

= 5 For each resource block, the indexes of subcarriers in one resource block are k '= 0 to k' = 11, but the subcarrier indexes defined for the total system bandwidth are k = 4 * 12 + 0 = 48 to k = 5 * 12 + 11 = 71. The index of the SC-FDMA symbol may increase sequentially as the time increases. The index of the subcarriers constituting the resource block (s) may increase sequentially in the direction of increasing frequency. Referring to the upper part of FIG. 8, the location to which the first reduced uplink DM-RS sequence 810 is mapped in the time domain may be preceded in time in an even slot (first slot in one subframe) (L = 3), which is the fourth SC-FDMA symbol. That is, the first reduced uplink DM-RS sequence 810 in the time domain is allocated to a position where the index of the SC-FDMA symbol is l = 3 in the even slot (first slot in one subframe) of the normal CP subframe Lt; / RTI &gt;

The first reduced uplink DM-RS sequence 810 in the frequency domain may be mapped to some subcarriers of 12 subcarriers (subcarriers # 0 to # 12, k '= 0 to 11) have. For example, the first reduced uplink DM-RS sequence 810 may be mapped to subcarriers corresponding to even indexes (k '= 0, 2, 4, 6, 8, 10).

The second reduced uplink DM-RS sequence 820 in the time domain is a 4 th SC-FDMA symbol (l = 1, 2, 3, 4, 3). &Lt; / RTI &gt; In other words, the second reduced uplink DM-RS sequence 820 in the time domain is located at the position where the index of the SC-FDMA symbol is l = 3 in the odd number slot (second slot in one subframe) of the normal CP subframe Lt; / RTI &gt;

The second reduced uplink DM-RS sequence 820 in the frequency domain includes a first reduced uplink DM-RS of the 12 subcarriers (subcarriers # 0 to # 12, k '= 0 to 11) The sequence 810 may be mapped to subcarriers of the same index as the mapped subcarriers. For example, the second reduced uplink DM-RS sequence 820 may be mapped to subcarriers corresponding to even indexes (k '= 0, 2, 4, 6, 8, 10).

That is, the first reduced uplink DM-RS sequence 810 is located at l = 3 in the even slot (the first slot in one subframe) of the normal CP subframe in the time domain, It can be mapped to the position of the index. Also, the second reduced uplink DM-RS sequence 820 is located at a position of l = 3 in an odd slot (the second slot in one subframe) of the normal CP subframe in the time domain, an even subcarrier It can be mapped to the position of the index.

In other words, the first reduced uplink DM-RS sequence 810 is a sequence of subcarriers sequentially increasing in the SC-FDMA symbols of l = 3 in an even slot (first slot in one subframe) The index of the subcarrier may be even. The second reduced uplink DM-RS sequence 820 is mapped in the order of decreasing indexes of subcarriers sequentially in SC-FDMA symbols with l = 3 of odd slots (second slot in one subframe) , And the index of the subcarrier may be an even number.

A subcarrier having an even index can be represented by a subcarrier having a subcarrier index satisfying mod2 = 0 in another expression (subcarrier index). By using the reduced uplink DM-RS sequence mapping method according to the embodiment of the present invention, compared to the case of transmitting the existing default uplink DM-RS, it is possible to use different uplink DM-RS resources, The applied reduced uplink DM-RS sequence may be mapped.

8 shows an extended CP subframe defined by an SC-FDMA symbol including an extended cyclic prefix (CP). One resource block of the extended CP subframe is defined as six consecutive SC-FDMA symbols (l = 0 to 5) in the time domain and 12 subcarriers (k '= 0 to 11) continuous in the frequency domain .

Referring to the lower part of FIG. 8, the position to which the first reduced uplink DM-RS sequence 810 is mapped in the time domain is pre-coded in an even time slot (first slot in one subframe) (L = 2), which is the third SC-FDMA symbol. That is, the first reduced uplink DM-RS sequence 810 in the time domain is located at the position where the index of the SC-FDMA symbol is l = 2 in an even slot (first slot in one subframe) of the extended CP subframe Lt; / RTI &gt;

The first reduced uplink DM-RS sequence 810 in the frequency domain may be mapped to some subcarriers of 12 subcarriers (subcarriers # 0 to # 12, k '= 0 to 11) have. For example, the first reduced uplink DM-RS sequence 810 may be mapped to subcarriers corresponding to even indexes (k '= 0, 2, 4, 6, 8, 10).

Also, the second reduced uplink DM-RS sequence 820 in the time domain is a third SC-FDMA symbol (l = 1, 2, ..., 2). &Lt; / RTI &gt; That is, the second reduced uplink DM-RS sequence 820 in the time domain is located at the position where the index of the SC-FDMA symbol is l = 2 in the odd slot (second slot in one subframe) of the extended CP subframe Lt; / RTI &gt;

The second reduced uplink DM-RS sequence 820 in the frequency domain includes a first reduced uplink DM-RS of the 12 subcarriers (subcarriers # 0 to # 12, k '= 0 to 11) The sequence 810 may be mapped to subcarriers of the same index as the mapped subcarriers. For example, the second reduced uplink DM-RS sequence 820 may be mapped to subcarriers corresponding to even indexes (k '= 0, 2, 4, 6, 8, 10).

That is, the first reduced uplink DM-RS sequence 810 is located at l = 2 in an even slot (the first slot in one subframe) of the extended CP subframe in the time domain, an even subcarrier It can be mapped to the position of the index. Also, the second reduced uplink DM-RS sequence 820 is located at l = 2 in the odd-numbered slot (the second slot in one subframe) of the extended CP subframe in the time domain, It can be mapped to the position of the index.

In other words, the first reduced uplink DM-RS sequence 810 is a sequence of subcarriers sequentially increasing in the SC-FDMA symbol with l = 2 in an even slot (first slot in one subframe) The index of the subcarrier may be even. The second reduced uplink DM-RS sequence 820 is mapped in the order of increasing subcarrier indices sequentially in SC-FDMA symbols of l = 2 in an even slot (first slot in one subframe) , And the index of the subcarrier may be an even number.

The first reduced uplink DM-RS sequence 810 and the second reduced uplink DM-RS sequence 820 are mapped to even-numbered subcarriers as an example. The first reduced uplink DM-RS sequence 810 and the second reduced uplink DM- And the second reduced uplink DM-RS sequence may be mapped to odd-numbered subcarriers.

9 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.

9, a method for mapping the first reduced uplink DM-RS sequence 910 and the second reduced uplink DM-RS sequence 920 to odd-numbered subcarriers, as in FIG. 8, is posted.

The upper part of FIG. 9 posts about how the first reduced uplink DM-RS sequence 910 and the second reduced uplink DM-RS sequence 920 are mapped in the normal CP sub-frame.

9, the first reduced uplink DM-RS sequence 910 is a sequence of subcarriers sequentially in an SC-FDMA symbol with l = 3 in an even slot (first slot in one subframe) The index of the subcarrier may be an odd number. Also, the second reduced uplink DM-RS sequence 920 is mapped in order of sequentially increasing indexes of subcarriers in an SC-FDMA symbol of l = 3 in an odd slot (a second slot in one subframe) , And the index of the subcarrier may be an odd number.

A subcarrier having an odd index can be represented by a subcarrier having a subcarrier index satisfying mod2 = 1 in another expression (subcarrier index).

The lower part of FIG. 9 posts about how the first reduced uplink DM-RS sequence 910 and the second reduced uplink DM-RS sequence 920 are mapped in the extended CP subframe.

9, the first reduced uplink DM-RS sequence 910 is a sequence of subcarriers sequentially in an SC-FDMA symbol with l = 2 in an even slot (first slot in one subframe) The index of the subcarrier may be an odd number. Also, the second reduced uplink DM-RS sequence 820 is mapped in order of increasing index of subcarriers sequentially in SC-FDMA symbols of l = 2 in an odd slot (second slot in one subframe) , And the index of the subcarrier may be an odd number.

Hereinafter, in an embodiment of the present invention, a method for generating the reduced uplink DM-RS (the first reduced uplink DM-RS sequence and the second reduced DM-RS sequence) disclosed in FIGS. 8 and 9 do. The first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence may be generated based on Equation (7) below.

&Quot; (7) &quot;

Referring to Equation (7), unlike Equation (2)

May be determined differently depending on the number of subcarriers allocated for the physical uplink shared channel (PUSCH). The PUSCH is a channel for transmitting uplink traffic data of a mobile station to a channel allocated to the mobile station by the base station.

In Equation (7)

Referring to FIG.

If this is an even number,

The number of subcarriers used for the uplink DM-RS reduced to one-half of the number of subcarriers used for the PUSCH.

Also,

If this is an odd number,

The number of subcarriers used for the uplink DM-RS decreased by one half of the number of subcarriers used for the PUSCH

/ 2. &Lt; / RTI &gt;

Generally, the number of subcarriers constituting one resource block is 12 (

)Because of,

The

Lt; / RTI &gt;

In the case of this odd number

The

. &Lt; / RTI &gt;

In another expression, when the number of allocated resource block (s) to transmit the reduced uplink DM-RS is an even number, the number of subcarriers used for the reduced uplink DM-RS is used for PUSCH Lt; / RTI &gt; of the number of subcarriers. On the other hand, if the number of allocated resource block (s) to transmit the reduced uplink DM-RS is an odd number, the number of subcarriers used for the reduced uplink DM-RS is used for the PUSCH At half the number of subcarriers

/ 2. &Lt; / RTI &gt;

That is, in the reduced uplink DM-RS sequence mapping method according to the embodiment of the present invention, based on the first reduced reference signal sequence having a length shorter than the length of the existing reference signal sequence and the second reduced reference signal sequence Thereby generating a first reduced uplink DM-RS sequence and a second reduced uplink DM-RS sequence, respectively. The first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence are assigned to the first reduced reference signal sequence and the second reduced reference signal sequence as OCC

Can be determined. For example, if the first reduced sequence of reference signals is the first sequence value of the OCC

To determine a first reduced uplink DM-RS sequence, and in a second reduced reference signal sequence, a second sequence value of the OCC

May be applied to determine the second reduced uplink DM-RS sequence.

The first reduced reference signal sequence and the second reduced reference signal sequence may be generated based on Equation (8) below.

&Quot; (8) &quot;

Referring to Equation (8), the number of subcarriers used for the reduced reference signal sequence (the first reduced reference signal sequence and the second reduced reference signal sequence), i.e., the reduced reference signal The length of the sequence is

Lt; / RTI &gt;

If m is even, the number of subcarriers used for the reduced reference signal sequence is

. That is, if m is an even number, the number of subcarriers used for the reduced reference signal sequence is one half of the number of allocated resource block (s) multiplied by the number of subcarriers in one resource block Lt; / RTI &gt;

When m is odd, the number of subcarriers used for the reduced reference signal sequence is

. That is, when m is an odd number, the number of subcarriers used for the reduced reference signal sequence is one half of the number of allocated resource block (s) multiplied by the number of subcarriers in one resource block in

/ 2. &Lt; / RTI &gt;

Generally, the number of subcarriers constituting one resource block is 12 (

)Because of,

The

. This formula can be summarized as follows: If m is an even number, it is used for a reduced reference signal sequence and, consequently, the number of subcarriers to which the reduced uplink DM-RS sequence is mapped

The

And if m is an odd number, it is used for the reduced reference signal sequence and is the number of subcarriers to which the reduced uplink DM-RS sequence is mapped

The

.

Basic sequence (

(Physical cell ID or virtual cell ID) in the case of u and v, which are parameters required for generation of the virtual cell ID, may have different values. That is, if the slot or cell ID is different, the basic sequence may be different. A first reduced uplink DM-RS sequence and a second reduced uplink DM-RS sequence according to an embodiment of the present invention may be mapped in one symbol of different slots. That is, the first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence may be generated based on different first reduced reference signal sequences and second reduced reference signal sequences. Also, according to an embodiment of the present invention, a cyclic shift (cs) value per layer multiplied by a reference signal sequence

Can be determined as Equation (9) below.

&Quot; (9) &quot;

The resource block (s) allocated to map the reduced uplink DM-RS sequence (e.g., the first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence) The sequence generation method and the CS / OCC generation / mapping method, which have been previously defined with a length of the sequence being a multiple of 12, can be used as they are. However, the number of resource block (s) allocated to map the reduced uplink DM-RS sequence (e.g., the first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence) When m is an odd number, the number of subcarriers to which a reduced uplink DM-RS sequence is mapped is mapped to only the even-numbered subcarriers or odd-numbered subcarriers for all allocated resource block (s) It may not be a multiple of 12. That is, the length of the reduced uplink DM-RS sequence may not be a multiple of 12. Therefore, when applying the cyclic shift and / or OCC that was previously used to determine the default uplink DM-RS sequence, the orthogonality between the sequences may be compromised.

In order to solve the problem of orthogonality between sequences, in the embodiment of the present invention, the number of resource block (s) allocated for the reduced uplink DM-RS sequence is even or odd, The uplink DM-RS sequence can be determined differently. This will be described later in detail.

8 and 9 illustrate an example of a reduced uplink DM-RS. In addition, the reduced uplink DM-RS may be mapped to the resource block (s) in the same manner as in FIGS. 10 and 11. FIG.

Hereinafter, the reduced uplink DM-RS sequence disclosed in FIGS. 10 and 11 is mapped to a first reduced uplink DM-RS sequence mapped to even-numbered subcarriers in one symbol and odd-numbered subcarriers And a second reduced uplink DM-RS sequence. The first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence may be a sequence generated by applying OCC to the first reduced reference signal sequence and the second reduced reference signal sequence. Hereinafter, in an embodiment of the present invention, the reference signal sequence indicates a sequence of a DM-RS for an uplink before OCC is applied, and an uplink DM-RS sequence indicates a sequence of an uplink after OCC is applied to a reference signal sequence. It is used as a term to indicate the sequence of DM-RS.

8 and 9, a first reduced reference signal sequence for generating a first reduced uplink DM-RS sequence and a second reduced uplink DM-RS sequence disclosed in FIGS. 10 and 11, and a second reduced reference signal sequence for generating a second reduced uplink DM- 2 The reduced candidate signal sequence may be the same sequence.

8 and 9, the amount of resources used for transmitting the uplink DM-RS can be reduced by using the reduced uplink DM-RS sequence mapping method as shown in FIG. 10 and FIG. In addition, although the amount of resources used to transmit the uplink DM-RS is reduced, orthogonality between sequences can be guaranteed by applying OCC to each reference signal sequence.

In addition, when using the reduced uplink DM-RS sequence mapping method disclosed in FIGS. 10 and 11, a first reduced uplink DM-RS sequence mapping method, in which OCC is applied on the same symbol in one slot unlike FIGS. 8 and 9, By using the RS and the second reduced uplink DM-RS, a reduced uplink DM-RS with OCC can be used without disabling group hopping and sequence hopping.

Hereinafter, the embodiment of the present invention specifically posts the reduced uplink DM-RS sequence.

10 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.

FIG. 10 illustrates a method for mapping a first reduced uplink DM-RS sequence 1010 and a second reduced uplink DM-RS 1020 in a subframe. As described above, the reference signal sequence for generating the first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 may be the same sequence. A method for generating a reference signal sequence for generating the first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 will be described later.

The upper part of FIG. 10 shows a normal CP subframe defined by an SC-FDMA symbol including a normal CP. One resource block of the normal CP subframe is defined as 7 consecutive SC-FDMA symbols (l = 0 to 6) in the time domain and 12 subcarriers (k '= 0 to 11) continuous in the frequency domain . The index of the SC-FDMA symbol may increase sequentially as the time increases. The index of the subcarrier can be sequentially increased in the direction of increasing frequency.

10, the locations to which the first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 are mapped in the time domain are the even-numbered slots of the normal CP sub- (L = 3) preceding a time in the first slot (one slot in one subframe). That is, the first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 in the time domain are even slots (the first slot in one subframe) of the normal CP subframe, The index of the SC-FDMA symbol may be mapped to a position of l = 3.

The first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 in the frequency domain are divided into 12 subcarriers (subcarriers # 0 through # 11, k ' 0 to 11) and the remaining subcarriers, respectively. For example, a first reduced uplink DM-RS sequence 1010 is mapped to specific subcarriers and a second reduced uplink DM-RS sequence 1020 is mapped to specific subcarriers of the twelve subcarriers And may be mapped to the remaining subcarriers.

More specifically, for example, the first reduced uplink DM-RS sequence 1010 is mapped to subcarriers of an even index (k '= 0, 2, 4, 6, 8, 10) The uplink DM-RS sequence 1020 may be mapped to subcarriers of an odd index (k '= 1, 3, 5, 7, 9, 11). That is, the first reduced uplink DM-RS sequence 1010 is located at l = 3 in the even slot (the first slot in one subframe) of the normal CP subframe in the time domain, It can be mapped to the position of the index. Also, the second uplink DM-RS sequence 1020 is located at a position of l = 3 in the even slot (the first slot in one subframe) of the normal CP subframe in the time domain, the position of the odd subcarrier index Location. &Lt; / RTI &gt;

In other words, the first reduced uplink DM-RS sequence 1010 is mapped in order of decreasing subcarrier index sequentially in the SC-FDMA symbol with l = 3, and the index of the subcarrier may be even. Also, the second reduced uplink DM-RS sequence 1020 is mapped in order of sequentially increasing indexes of subcarriers in the SC-FDMA symbol with l = 3, and the index of the subcarriers may be odd.

A subcarrier having an even index can be represented by a subcarrier having a subcarrier index satisfying mod2 = 0 in another expression (subcarrier index). Similarly, a subcarrier having an odd index can be represented by a subcarrier having a subcarrier index satisfying mod2 = 1 in another expression (subcarrier index).

By using the reduced uplink DM-RS sequence mapping method as shown in FIGS. 10 and 11, a reduced uplink DM-RS sequence applying different OCCs in one symbol can be mapped. The reduced uplink DM-RS sequence applying different OCCs in one symbol is more effective for UEs moving with high mobility in a frequency-selective fading channel of a small cell Lt; / RTI &gt; For a UE with high mobility, a reduced uplink DM-RS sequence applying OCC between adjacent subcarriers rather than an uplink DM-RS sequence applying OCC between slots can have higher reliability in terms of orthogonality.

The lower part of FIG. 10 shows an extended CP subframe defined by an SC-FDMA symbol including an extended CP. One resource block of the extended CP subframe is defined as six consecutive SC-FDMA symbols (l = 0 to 5) in the time domain and 12 subcarriers (k '= 0 to 11) continuous in the frequency domain .

10, the positions where the first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 are mapped in the time domain are the even slots of the extended CP subframe (L = 2) preceding a time in the first slot (one slot in one subframe). That is, the first reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 in the time domain are allocated to even slots (first slot in one subframe) Lt; RTI ID = 0.0 &gt; l = 2 &lt; / RTI &gt;

On the frequency domain, the extended CP subframe may be mapped to the first reduced uplink DM-RS 1010 and the second reduced uplink DM-RS 1020, similar to the normal CP subframe. That is, in the extended CP subframe, the first reduced uplink DM-RS sequence 1010 is mapped in order of increasing index of subcarriers sequentially in SC-FDMA symbols of l = 2, and the index of subcarriers is mapped to even Lt; / RTI &gt; Also, the second reduced uplink DM-RS sequence 1020 is mapped in order of sequentially increasing indexes of subcarriers in the SC-FDMA symbol with l = 2, and the index of the subcarriers may be an odd number. That the index of the subcarrier is an even number can indicate a subcarrier index satisfying (subcarrier index) mod2 = 0. In addition, when the index of the subcarrier is an odd number, it can indicate a subcarrier index satisfying (subcarrier index) mod2 = 1.

In FIG. 10, a first reduced uplink DM-RS (first slot in one subframe) mapped to an even slot (first slot in one subframe) and an even slot Sequence 1010 and the second reduced uplink DM-RS sequence 1020. [0064] According to an embodiment of the present invention, an odd-numbered slot (a second slot in one subframe) and an odd-numbered slot (a second slot in one subframe) of a normal CP subframe other than an even- The reduced uplink DM-RS sequence 1010 and the second reduced uplink DM-RS sequence 1020 may be mapped.

11 is a conceptual diagram illustrating a method of mapping an uplink DM-RS sequence according to an embodiment of the present invention.

In FIG. 11, the first reduced uplink DM-RS sequence (the first one in one subframe) and the second reduced uplink DM-RS sequence (the second one in one subframe) in the normal CP subframe 1110 and the second reduced uplink DM-RS 1120 are mapped.

The upper part of FIG. 11 shows a first reduced uplink DM-RS sequence 1110 and a second reduced uplink DM-RS 1120 in an odd slot (a second slot in one subframe) of the normal CP subframe Is mapped.

In the frequency domain, mapping can be performed in the same manner as described above with reference to FIG. The positions at which the first reduced uplink DM-RS sequence 1110 and the second reduced uplink DM-RS sequence 1120 are mapped in the time domain are odd-numbered slots of the normal CP subframe (the second Slot) preceding a time slot in the first SC-FDMA symbol (l = 3).

The lower part of FIG. 11 shows a first reduced uplink DM-RS sequence 1110 and a second reduced uplink DM-RS 1120 in an odd number slot (a second slot in one subframe) of the extended CP subframe Is mapped.

In the frequency domain, mapping can be performed in the same manner as described above with reference to FIG. The location to which the first reduced uplink DM-RS sequence 1110 and the second reduced uplink DM-RS sequence 1120 are mapped in the time domain is an odd-numbered slot of the extended CP subframe (the second Slot) preceding the time slot in the first SC-FDMA symbol (l = 2).

The method for generating the first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence disclosed in FIGS. 10 and 11 will be described with reference to FIGS. 8 and 9, (A first reduced uplink DM-RS sequence and a second reduced DM-RS sequence). That is, the first reduced uplink DM-RS sequence and the second reduced uplink DM-RS sequence disclosed in FIGS. 10 and 11 may be generated based on Equations (7) to (10) as described above .

Therefore, as in the case of the reduced uplink DM-RS disclosed in FIGS. 8 and 9, when the number of the allocated resource block (s) allocated to the reduced uplink DM-RS disclosed in FIGS. 10 and 11 is odd The orthogonality of the reduced uplink DM-RS may be impaired.

Hereinafter, a method for solving the problem of degrading orthogonality between reduced uplink DM-RS sequences will be described in the embodiment of the present invention.

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

Referring to FIG. 12, it can be determined whether or not the overhead reduction enable field is activated (step S1200).

The overhead reduction-enabled field may be transmitted from the upper layer to the terminal, for example, radio resource control (RRC).

The overhead reduction enable field indicates whether the overhead is reduced for some resource blocks (or ones) among the uplink DM-RS or allocated resource block (s) with reduced overhead for all resource blocks (s) And may include information as to whether or not to transmit the uplink DM-RS. If overhead reduction is activated by the overhead reduction enable field, the UE can transmit the reduced uplink DM-RS by determining information on the resource block (s) allocated the uplink DM-RS. Conversely, if the overhead reduction is not activated by the overhead reduction enable field, the transmission of the reduced uplink DM-RS is not performed and no overhead reduction is applied to all allocated resource block (s) Only the transmission of the default uplink DM-RS is allowed.

The overhead reduction enable field may be transmitted to the terminal in a semi-static manner in consideration of a small cell layout environment and the like. The overhead reduction enable field may enable transmission of the reduced uplink DM-RS of the UE. The UE can transmit the reduced uplink DM-RS applying the overhead reduction substantially after the overhead reduction enable field is activated.

The overhead reduction enable field may be omitted. That is, according to the embodiment of the present invention, the reduced uplink DM-RS may be used basically regardless of whether or not the overhead reduction is activated. In this case, the UE may not determine the overhead reduction enable field. In this case, the UE performs only the determination of the number of the resource block (s) allocated to transmit the uplink DM-RS, and transmits an uplink DM-RS with reduced overhead to all allocated resource blocks RS to determine whether to transmit the uplink DM-RS with reduced overhead to some resource block (s) of the allocated resource block (s).

Hereinafter, for convenience of description, it is assumed that all the resource blocks (s) allocated based on whether the number of the resource block (s) allocated by the UE to transmit the uplink DM- RS determines whether to transmit the reduced uplink DM-RS or transmit the downlink DM-RS with reduced overhead for some resource block (s) of the allocated resource block (s). However, since the number of the resource block (s) allocated for transmitting the uplink DM-RS is eventually associated with the number of the resource block (s) allocated for transmitting the PUSCH, May be determined based on the number of allocated resource block (s) or the number of subcarriers allocated to transmit the PUSCH.

If the overhead reduction enable field indicates disabled overhead reduction, no overhead reduction is performed (step S1210).

If the overhead reduction enable field indicates that the overhead reduction is disabled, the UE transmits to the uplink DM-RS a default uplink DM for which overhead reduction is not applied to all resource blocks (s) allocated to the uplink DM- Only -RS can be used. That is, the number of subcarriers used for one uplink DM-RS sequence for the allocated resource block (s) may be 12 per resource block. That is, all the sub-carriers constituting the resource block (s) allocated for one uplink DM-RS sequence may be used.

If the overhead reduction enable field indicates enabling overhead reduction, it is determined whether the number of allocated resource block (s) is an even number (step S1220).

According to the embodiment of the present invention, depending on whether the number of the resource block (s) allocated to transmit the uplink DM-RS is an even number or an odd number, the UE decreases the overhead for all allocated resource blocks RS to transmit the uplink DM-RS with reduced overhead to some resource block (s) of the allocated resource block (s). The information on the resource block (s) allocated for transmitting the uplink DM-RS may be included in the DCI transmitted from the base station. The UE can acquire information on the resource blocks allocated for transmitting the uplink DM-RS based on the DCI having the DCI format 0 or the DCI format 4 information. The UE may include a DCI format 0 or DCI format 4 DCI having an RB assignment field for the UE. The uplink resource allocation field may include information on uplink resources allocated to the UE. The UE can determine whether the number of the resource blocks (s) allocated to transmit the uplink DM-RS based on the information of the uplink resource allocation field is an even number or an odd number. In step S1020, it is determined whether the number of the resource block (s) allocated to transmit the uplink DM-RS is an even number or not. It may be determined whether the number is an odd number.

If the number of allocated resource block (s) is even, the uplink DM-RS with reduced overhead is transmitted to all allocated resource block (s) (step S1230).

If the number of resource block (s) allocated to transmit the uplink DM-RS is an even number, it is possible to transmit the uplink DM-RS with reduced overhead to all allocated resource blocks (s). As described above, when the number of resource block (s) allocated to transmit the uplink DM-RS is even, even if overhead reduction is applied to all allocated resource block (s), the uplink DM- The length can be a multiple of twelve. Therefore, in this case, the uplink DM-RS with reduced overhead can be transmitted to all resource blocks (s) allocated to transmit the uplink DM-RS.

If the number of allocated resource block (s) is not even, the uplink DM-RS with reduced overhead is transmitted to some resource block (s) among the allocated resource block (s) (step S1240).

If the number of resource block (s) allocated to transmit the uplink DM-RS is not an even number, the UE does not apply overhead reduction in one resource block among the allocated resource block (s) The uplink DM-RS with reduced overhead can be transmitted. When the number of resource blocks allocated for transmitting the uplink DM-RS is an odd number as described above, if overhead reduction is applied to all allocated resource blocks, the uplink DM-RS sequence May be a multiple of six rather than a multiple of twelve. Therefore, in order to prevent the orthogonality of the sequence from being corrupted in this case, the overhead reduction may not be applied to one resource block of all the resource block (s) allocated to transmit the uplink DM-RS. That is, 12 subcarriers corresponding to all the subcarriers in one resource block among all resource blocks (s) allocated to transmit the uplink DM-RS can be used to map the uplink DM-RS sequence . , The overhead reduction is applied to the remaining resource block (s) among all the resource blocks (s) allocated to transmit the uplink DM-RS, so that six subcarriers per resource block are mapped to the uplink DM-RS sequence Lt; / RTI &gt;

If there is m allocated resource block (s) to transmit the uplink DM-RS, one resource block to which overhead reduction is not applied may be a resource block located in the middle among m allocated resource blocks (s) . The index of the resource block may be a resource block having an index of (m-1) / 2 when indexes of 0 to m-1 are sequentially allocated in the order of increasing frequency band. In addition, one resource block to which the uplink DM-RS to which overhead reduction is not applied may be a resource block having the lowest index or the highest index.

13 is a conceptual diagram illustrating a resource block (s) according to an embodiment of the present invention.

13, when the number of resource block (s) allocated to transmit the uplink DM-RS is odd, the resource block (s) to which the overhead reduction is applied and the resource block FIG.

If there are m allocated resource block (s) to transmit the DM-RS, one resource block to which overhead reduction is not applied may be a resource block located in the middle of m assigned resource block (s). It can be assumed that resource blocks of 0 to m-1 are allocated to a resource block allocated to a high frequency band from a resource block allocated to a low frequency band.

The left side of FIG. 13 shows that a resource block located in the middle of the resource block (s) allocated for transmitting the uplink DM-RS is one resource block in which overhead is not applied to the decrease. The resource block located at the middle among m allocated resource blocks may be a resource block having an index of (m-1) / 2. That is, overhead reduction is not applied to a resource block having an index of (m-1) / 2, and overhead reduction can be applied to m-1 blocks corresponding to the remaining indexes.

In the middle of FIG. 13, a resource block located at the bottom of the resource block (s) allocated to transmit the uplink DM-RS is one resource block to which overhead is not applied. A resource block located at the bottom of m allocated resource blocks may be a resource block having an index 0. That is, overhead reduction is not applied to a resource block having an index of 0, and overhead reduction can be applied to m-1 blocks corresponding to the remaining indexes.

The right side of FIG. 13 shows that the resource block located at the top of the resource block (s) allocated for transmitting the uplink DM-RS is one resource block to which overhead is not applied. A resource block located at the top of the allocated m resource blocks (s) may be a resource block having an index m-1. That is, overhead reduction is not applied to a resource block having an index of m-1, and overhead reduction can be applied to m-1 resource blocks (s) corresponding to the remaining indexes.

FIG. 14 is a flowchart illustrating a method of determining an uplink DM-RS sequence according to an embodiment of the present invention.

In FIG. 14, unlike FIG. 12, even when the number of resource block (s) allocated to transmit the uplink DM-RS is an odd number, a default uplink The DM-RS is mapped and transmitted.

Referring to FIG. 14, it is determined whether or not the overhead reduction enable field is activated (step S1400).

As described above, the overhead reduction enable field may be used to activate transmission of the UE's reduced uplink DM-RS. The UE can transmit the reduced uplink DM-RS applying the overhead reduction substantially after the overhead reduction enable field is activated. As described above, the overhead reduction enable field may be omitted.

If the overhead reduction enable field indicates disabled overhead reduction, then no overhead reduction is performed (step S1410). That is, for all allocated resource block (s), a default uplink DM-RS to which no overhead reduction is applied is mapped to all allocated resource block (s).

If the overhead reduction enable field indicates that the overhead reduction is disabled, the UE transmits to the uplink DM-RS a default uplink DM for which overhead reduction is not applied to all resource blocks (s) allocated to the uplink DM- Only -RS can be used. That is, the number of subcarriers used for one uplink DM-RS sequence for the allocated resource block (s) may be 12 per resource block. That is, all subcarriers in the resource block (s) may be used for one uplink DM-RS sequence.

If the overhead reduction enable field indicates enabling overhead reduction, it is determined whether the number of allocated resource block (s) is an even number (step S1420).

According to the embodiment of the present invention, it is possible to increase the overhead for all resource blocks (or resources) allocated according to whether the number of resource blocks (s) allocated to transmit the uplink DM-RS is even or odd It is possible to use a default uplink DM-RS with no overhead reduction applied to the link DM-RS or all allocated resource block (s). The information on the resource block (s) allocated to transmit the uplink DM-RS may include an uplink resource allocation field (RB assignment field) of the DCI transmitted from the base station. The uplink resource allocation field may include information on uplink resources allocated to the UE. The UE can determine whether the resource block (s) allocated to transmit the uplink DM-RS based on the information of the uplink resource allocation field is an even number or an odd number. Similarly, in step S1220, it is determined whether the resource block (s) allocated to transmit the uplink DM-RS is an even number, and the resource block (s) allocated for transmitting the uplink DM- Or not. Hereinafter, for convenience of description, it is assumed that all resource blocks (s) allocated on the basis of whether the number of resource block (s) allocated by the UE to transmit the uplink DM-RS is an even number RS determines whether to transmit a default uplink DM-RS for which overhead reduction is not applied for the uplink DM-RS with reduced overhead or all allocated resource block (s). However, since the number of the resource block (s) allocated for transmitting the uplink DM-RS is eventually associated with the number of the resource block (s) allocated for transmitting the PUSCH, May be determined based on the number of allocated resource block (s) or the number of subcarriers allocated to transmit the PUSCH.

If the number of allocated resource block (s) is even, the uplink DM-RS with reduced overhead is transmitted to all allocated resource block (s) (step S1430).

If the number of resource block (s) allocated to transmit the uplink DM-RS is an even number, it is possible to transmit the uplink DM-RS with reduced overhead to all allocated resource blocks (s). As described above, when the number of resource block (s) allocated to transmit the uplink DM-RS is even, even if overhead reduction is applied to all allocated resource block (s), the uplink DM- The length can be a multiple of twelve. Therefore, in this case, the uplink DM-RS with reduced overhead can be transmitted to all resource blocks (s) allocated to transmit the uplink DM-RS.

If the number of allocated resource block (s) is not an even number, a default uplink DM-RS to which overhead reduction is not applied to all allocated resource block (s) is transmitted (step S1440).

If the resource block (s) allocated to transmit the uplink DM-RS is not an even number (odd number), a default uplink DM-RS Can be transmitted. When the resource block (s) allocated for transmitting the uplink DM-RS is an odd number as described above, when overhead reduction is applied to all allocated resource blocks (s), the length of the uplink DM-RS sequence May be a multiple of six rather than a multiple of twelve. Therefore, in order to prevent this, it is possible to map a default uplink DM-RS sequence to which no overhead reduction is applied to all resource block (s) allocated to transmit the uplink DM-RS.

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

Referring to FIG. 15, a base station 1300 includes a processor 1510, a memory 1520, and a RF unit (radio frequency) unit 1530. The memory 1520 is coupled to the processor 1510 and stores various information for driving the processor 1510. [ The RF unit 1520 is coupled to the processor 1510 to receive a wireless signal and / or a wireless signal (e.g., the uplink DM-RS published herein). The processor 1310 may receive the uplink DM-RS sequence published herein and demodulate the uplink data based on the received uplink DM-RS. The operation of the base station of the serving cell in the above-described embodiment may be implemented by the processor 1310. [

The wireless device (or terminal) 1550 includes a processor 1560, a memory 1570, and an RF section 1580. The memory 1570 is coupled to the processor 1560 to store various information for driving the processor 1560. RF section 1580 is coupled to processor 1560 to receive a radio signal or to transmit a radio signal (e.g., an uplink DM-RS sequence published herein). Processor 1560 implements the functions, processes and / or methods proposed in the embodiments of Figs. 8-14 of the present invention. The operation of the terminal in any of the embodiments disclosed herein may be implemented by the processor 1560. [

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 not intended to limit the scope of the present invention but to limit the scope of the technical idea of the present invention. 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 (8)

A method for mapping an uplink DM (demodulation) -RS (reference signal) sequence,
Receiving, by the UE, information on the number of resource blocks (s) allocated for the uplink DM-RS sequence through a resource block allocation field in uplink-related downlink control information (DCI); And
And mapping the uplink DM-RS sequence to the allocated resource block (s) in the uplink subframe based on information on the number of the allocated resource block (s) by the UE,
When the number of allocated resource blocks is an even number, the uplink DM-RS sequence is mapped to a part of subcarriers constituting each allocated resource block (s)
If the number of the allocated resource blocks is an odd number, the uplink DM-RS sequence includes all the sub-carriers constituting one resource block among the allocated resource blocks (s) ) To a part of the sub-carriers constituting each of the remaining resource blocks (except for the one resource block). The method according to claim 1,
Determining whether the terminal is enabled for overhead reduction; And
Determining whether the number of the allocated resource block (s) is even or odd if the overhead reduction is activated,
Wherein the uplink DM-RS sequence is mapped to all subcarriers constituting each allocated resource block (s) when the overhead reduction is not activated. The method according to claim 1,
If the number of allocated resource blocks (m) is m and the frequency bands of the resource block (s) included in the allocated resource block (s) increase, index 0 to index m-1 If granted,
Wherein the one resource block corresponds to an index (m-1) / 2, an index 0, or an index m-1. The method according to claim 1,
The uplink DM-RS sequence corresponds to subcarriers corresponding to even indexes or odd indexes among the subcarriers constituting each of the resource blocks (s) excluding the one resource block among the allocated resource blocks (s) And mapping the uplink sub-carriers to only the sub-carriers. In a UE performing an uplink DM (demodulation) -RS (reference signal) sequence mapping method,
A radio frequency (RF) unit configured to transmit and receive a wireless signal; And
And a processor selectively coupled to the RF unit,
The processor receives information on the number of resource blocks (s) allocated for the uplink DM-RS sequence through a resource block allocation field in uplink-related downlink control information (DCI)
And mapping the uplink DM-RS sequence to the allocated resource block (s) in an uplink subframe based on information on the number of the allocated resource block (s)
When the number of allocated resource blocks is an even number, the uplink DM-RS sequence is mapped to a part of subcarriers constituting each allocated resource block (s)
If the number of the allocated resource blocks is an odd number, the uplink DM-RS sequence includes all the sub-carriers constituting one resource block among the allocated resource blocks (s) ) Is mapped to a part of subcarriers constituting each of the resource blocks (s) except for the one resource block. 6. The method of claim 5,
The processor determines whether overhead reduction is activated,
When the decrease of the overhead is activated, the UE determines whether the number of the allocated resource block (s) is even or odd,
Wherein the uplink DM-RS sequence is mapped to all subcarriers constituting each allocated resource block (s) when the overhead reduction is not activated. The method according to claim 1,
If the number of allocated resource blocks (m) is m and the frequency bands of the resource block (s) included in the allocated resource block (s) increase, index 0 to index m-1 If granted,
Wherein the one resource block corresponds to an index (m-1) / 2, an index 0, or an index m-1. The method according to claim 1,
The uplink DM-RS sequence corresponds to subcarriers corresponding to even indexes or odd indexes among the subcarriers constituting each of the resource blocks (s) excluding the one resource block among the allocated resource blocks (s) Carriers are mapped to only the subcarriers.

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