JP5567688B2 - Method and apparatus for generating reference signal sequence in wireless communication system - Google Patents

Description

  The present invention relates to wireless communication, and more particularly to a reference signal sequence generation method and apparatus in a wireless communication system.

  Multiple-input multiple-output (MIMO) technology uses multiple transmit antennas and multiple receive antennas to improve data transmission and reception efficiency. A scheme for implementing diversity by a MIMO system includes a space frequency block code (SFBC), a space time block code (STBC), a cyclic delay diversity (CDD), a frequency switching transmission diversity (FSTD), and a time switching transmission diversity (TSTD). ), Precoding vector switching (PVS), spatial multiplexing (SM), and the like. A MIMO channel matrix corresponding to the number of reception antennas and the number of transmission antennas can be decomposed into a plurality of independent channels. Each independent channel is called a hierarchy or a stream. The number of layers is called rank.

  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. In a wireless communication system environment, fading occurs due to multipath time delay. The process of reconstructing a transmission signal by compensating for signal distortion caused by a rapid environmental change due to fading is called channel estimation. In addition, it is necessary to measure the channel state for the cell to which the terminal belongs or for other cells. For channel estimation or channel state measurement, channel estimation is typically performed using reference signals (RS) that are known to each other by the transceiver.

  A subcarrier used for reference signal transmission is called a reference signal subcarrier, and a resource element used for data transmission is called a data subcarrier. In an orthogonal frequency division multiplexing (OFDM) system, there are a method of assigning a reference signal to all subcarriers and a method of assigning between data subcarriers. A method of assigning a reference signal to all subcarriers uses a signal consisting only of a reference signal such as a preamble signal in order to obtain a gain of channel estimation performance. When this is used, since the density of the reference signal is generally high, the channel estimation performance can be improved as compared with the method of assigning the reference signal between the data subcarriers. However, since the amount of data transmission decreases, a method of allocating a reference signal between data subcarriers is used to increase the amount of data transmission. When such a method is used, since the density of the reference signal decreases, the channel estimation performance deteriorates, and an appropriate arrangement that can minimize this is required.

受信器は、参照信号の情報を知っているため、受信された信号から参照信号の情報を分離してチャネルを推定することができ、推定されたチャネル値を補償して送信端で送ったデータを正確に推定することができる。送信器が送る参照信号をｐ、参照信号が伝送中に経験するチャネル情報をｈ、受信器で発生する熱雑音をｎ、受信器で受信された信号をｙとすると、ｙ＝ｈ・ｐ＋ｎのように表すことができる。この場合、参照信号ｐは、受信器が既に知っているため、最小二乗（ＬＳ）方式を用いるとき、式１のようにチャネル情報（ｈａｔ−ｈ）を推定することができる。

Since the receiver knows the information of the reference signal, it can estimate the channel by separating the information of the reference signal from the received signal, and compensates the estimated channel value and transmits the data transmitted at the transmission end. Can be estimated accurately. If the reference signal sent by the transmitter is p, the channel information experienced by the reference signal during transmission is h, the thermal noise generated by the receiver is n, and the signal received by the receiver is y, y = h · p + n. Can be expressed as: In this case, since the receiver already knows the reference signal p, the channel information (hat-h) can be estimated as shown in Equation 1 when the least square (LS) method is used.

(Formula 1)

  At this time, the accuracy of the channel estimation value hat-h estimated using the reference signal p is determined by the hat-n value. Therefore, in order to accurately estimate the h value, hat-n must converge to 0. For this purpose, the channel is estimated using a large number of reference signals, and the influence of hat-n is affected. Must be minimized. There are various algorithms to obtain excellent channel estimation performance.

  In order to minimize inter-cell interference (ICI) in reference signal transmission, a sequence group hop (SGH) or a sequence hop (SH) or the like can be applied to the reference signal sequence. By applying SGH, the sequence group index of the reference signal sequence transmitted in each slot changes.

  In a multi-user MIMO (MU-MIMO) environment, an orthogonal covering code (OCC) can be applied to guarantee orthogonality between reference signals transmitted by a plurality of terminals. By applying OCC, it is possible to guarantee improvement in orthogonality and throughput. On the other hand, in a MU-MIMO environment, multiple terminals can use different bandwidths. When OCC is applied together while performing SGH on a reference signal transmitted by a plurality of terminals having different bandwidths, the complexity of cell planning increases. That is, it is difficult to guarantee orthogonality between reference signals transmitted by a plurality of terminals.

  For this reason, another method of instructing whether or not SGH or SH can be executed for the reference signal sequence is required.

  The technical problem of the present invention is to provide a reference signal sequence generation method and apparatus in a wireless communication system.

  In one aspect, a method for generating a reference signal sequence by a terminal (UE) in a wireless communication system is provided. The method for generating a reference signal sequence includes receiving a terminal specific sequence group hop (SGH) parameter specific to the terminal, and generating a reference signal sequence based on a basic sequence for each slot, The basic sequence is classified according to a sequence group number and a basic sequence number determined for each slot according to the terminal specific SGH parameter instructing whether or not SGH can be executed.

  The terminal specific SGH parameter is transmitted via an upper layer.

  The reference signal sequence is a demodulated reference signal (DMRS) sequence for demodulating a signal using physical uplink shared channel (PUSCH) resources.

  When the terminal specific SGH parameter indicates that SGH is not performed, the sequence group number of the slot in one subframe and the basic sequence number in the sequence group are the same.

  When the terminal specific SGH parameter indicates that the sequence hop (SH) is not executed, the sequence group number of the slot in one subframe and the basic sequence number in the sequence group are the same.

  When the terminal specific SGH parameter indicates that SGH is not performed, the sequence group numbers of all slots in the frame are the same.

  The reference signal sequence generation method further includes a step of receiving a cell-specific SGH parameter indicating whether or not SGH can be performed or a cell-specific SH parameter indicating whether or not SH can be performed. When the cell-specific GH parameter indicates that SGH is to be executed, the terminal-specific SGH parameter has priority over the cell-specific SGH parameter in instructing whether or not to perform SGH. When the cell-specific SH parameter indicates that SH is to be executed, the terminal-specific SGH parameter has priority over the cell-specific SH parameter in instructing whether or not SH can be executed.

  The reference signal sequence generation method further includes mapping the reference signal sequence to a subcarrier and transmitting it.

  The reference signal sequence is generated further based on a cyclic shift.

  The basic sequence is based on a Zadoff-Chu (ZC) sequence.

  OCC is applied to the reference signal sequence. The applicability of the OCC is indicated by an OCC index transmitted via an upper layer.

  In another aspect, a terminal is provided. The terminal is connected to a radio frequency (RF) unit configured to receive a terminal specific SGH parameter and the RF unit, and configured to generate a reference signal sequence based on a basic sequence for each slot. The basic sequence is classified according to a sequence group number and a basic sequence number determined for each slot according to the terminal specific SGH parameter that indicates whether or not SGH can be executed. .

  In a MU-MIMO environment, orthogonality between multiple terminals using separate bandwidths can be guaranteed.

It is a figure which shows a radio | wireless communications system. It is a figure which shows the structure of the radio | wireless frame in 3GPP LTE. It is a figure which shows an example of the resource grid with respect to one downlink slot. It is a figure which shows the structure of a downlink sub-frame. It is a figure which shows the structure of an uplink sub-frame. It is a figure which shows an example of the transmitter structure in SC-FDMA system. It is a figure which shows an example of the system in which a subcarrier mapper maps a complex number symbol to each subcarrier of a frequency domain. It is a figure which shows an example of the reference signal transmitter structure for a demodulation. It is a figure which shows an example of the structure of the sub-frame by which a reference signal is transmitted. It is a figure which shows an example of the transmitter to which the clustered DFT-s OFDM transmission system is applied. It is a figure which shows the other example of the transmitter to which the clustered DFT-s OFDM transmission system is applied. It is a figure which shows the other example of the transmitter to which the clustered DFT-s OFDM transmission system is applied. It is a figure which shows an example in which OCC is applied to a reference signal. It is a figure which shows an example in case a some terminal performs MU-MIMO transmission using a separate bandwidth. It is a figure which shows an example when SGH is not performed by the proposed terminal specific SGH parameter. It is a figure which shows one Example of the proposed reference signal sequence production | generation method. It is a block diagram of a base station and a terminal in which an embodiment of the present invention is implemented.

  The following techniques are code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), and single carrier frequency division multiple access (SC-FDMA). It can be used for various wireless communication systems such as. CDMA may be implemented by a radio technology such as General Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented by a radio technology such as Global System for Mobile Communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rate for Evolution (EDGE). OFDMA can be implemented by a wireless technology such as IEEE802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802.20, E-UTRA (Evolved UTRA) and the like. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of a general purpose mobile communication system (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution System (LTE) is part of Evolved UMTS (E-UMTS) using Evolved UTRA (E-UTRA), adopts OFDMA in the downlink and uplink Adopts SC-FDMA. Advanced LTE (LTE-A) is an evolution of 3GPP LTE.

  For clarity of explanation, LTE-A is mainly described, but the technical idea of the present invention is not limited to this.

  FIG. 1 shows a wireless communication system.

  The wireless communication system 10 includes at least one base station (BS) 11. Each base station 11 provides a communication service to a specific geographical area (generally called a cell) 15a, 15b, 15c. The cell can be divided into a plurality of areas (referred to as sectors). The terminal (UE) 12 may be fixed or mobile, and may be a mobile device (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), wireless It may also be called by other terms such as a device, a PDA (Personal Digital Assistant), a wireless modem, or a portable device. The base station 11 generally means a fixed station that communicates with the terminal 12, and may be referred to by other terms such as an evolution Node B (eNB), a base station apparatus (BTS), an access point, and the like.

  A terminal usually belongs to one cell, and a cell to which the terminal belongs is called a serving cell. A base station that provides a communication service to a service providing cell is referred to as a service providing base station (serving BS). Since the wireless communication system is a cellular system, there are other cells adjacent to the serving cell. Another cell adjacent to the service providing cell is referred to as an adjacent cell. A base station that provides a communication service to an adjacent cell is called an adjacent base station). The service providing cell and the neighboring cell are determined relative to the terminal.

  This technique can be used for the downlink or uplink. In general, the downlink means communication from the base station 11 to the terminal 12, and the uplink means communication from the terminal 12 to the base station 11. In the downlink, the transmitter is part of the base station 11 and the receiver is part of the terminal 12. In the uplink, the transmitter is part of the terminal 12 and the receiver is part of the base station 11.

  The wireless communication system is any one of a multiple-input multiple-output (MIMO) system, a multiple-input single-output (MISO) system, a single-input single-output (SISO) system, and a single-input multiple-output (SIMO) system. The MIMO system uses a plurality of transmission antennas and a plurality of reception antennas). The MISO system uses multiple transmit antennas and one receive antenna. The SISO system uses one transmit antenna and one receive antenna. A SIMO system uses one transmit antenna and multiple receive antennas. Hereinafter, a transmit antenna refers to a physical or logical antenna used to transmit a single signal or stream, and a receive antenna refers to a physical or logical antenna used to receive a single signal or stream. Means.

  FIG. 2 shows a structure of a radio frame in 3GPP LTE.

  This is 3GPP TS 36.211 V8.2.0, “Technical Specification Group Radio Access Network, Evolved Universal Terrestrial Relative 8 (E-UTRA); Can be referred to. Referring to FIG. 2, a radio frame is composed of 10 subframes, and one subframe is composed of 2 slots. Slot numbers in the radio frame are assigned slot numbers from # 0 to # 19. The time taken to transmit one subframe is called a transmission time interval (TTI). TTI means a schedule unit for data transmission. For example, the length of one radio frame is 10 ms, the length of one subframe is 1 ms, and the length of one slot is 0.5 ms.

  One slot includes a plurality of OFDM symbols in the time domain, and includes a plurality of subcarriers in the frequency domain. Since 3GPP LTE uses OFDMA in the downlink, OFDM symbols are used to represent one symbol period. An OFDM symbol may be referred to by another name depending on the multiple access scheme. For example, when SC-FDMA is used for the uplink multiple access scheme, it may be called an SC-FDMA symbol. A resource block (RB) is a resource allocation unit and includes a plurality of continuous subcarriers in one slot. The structure of the radio frame is only an example. Therefore, the number of subframes included in the radio frame, the number of slots included in the subframe, or the number of OFDM symbols included in the slots can be variously changed.

  In 3GPP LTE, one slot includes 7 OFDM symbols in the case of normal cyclic prefix (CP), and one slot includes 6 OFDM symbols in the case of extended CP. doing.

  Wireless communication systems are broadly divided into frequency division duplex communication (FDD) and time division duplex communication (TDD). According to the FDD scheme, uplink transmission and downlink transmission occupy separate frequency bands. According to the TDD scheme, uplink transmission and downlink transmission occupy the same frequency band and are performed at different times. The channel response of the TDD scheme is substantially reciprocal. This means that the downlink channel response and the uplink channel response are almost the same in a given frequency domain. Thus, the downlink channel response in a wireless communication system based on TDD can be obtained from the uplink channel response. In the TDD scheme, since uplink transmission and downlink transmission are time-divided in the entire frequency band, downlink transmission by the base station and uplink transmission by the terminal cannot be performed simultaneously. In TDD systems where uplink transmission and downlink transmission are distinguished on a subframe basis, uplink transmission and downlink transmission are performed in separate subframes.

  FIG. 3 shows an example of a resource grid for one downlink slot.

The downlink slot includes a plurality of OFDM symbols in the time domain, and includes N _RB resource blocks in the frequency domain. The number N _{RB of} resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the cell. For example, N _RB in the LTE system is any one of 60 to 110. One resource block includes a plurality of subcarriers in the frequency domain. The structure of the uplink slot is the same as the structure of the downlink slot.

Each element on the resource grid is called a resource element. Resource elements on the resource grid can be identified by the index pair (k, l) in the slot. Here, k (k = 0,..., N _RB × 12-1) is a subcarrier index in the frequency domain, and l (l = 0,..., 6) is an OFDM symbol in the time domain. It is an index.

  Here, it is exemplarily described that one resource block includes 7 × 12 resource elements composed of 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain, and the number of OFDM symbols in the resource block and The number of subcarriers is not limited to this. The number of OFDM symbols and the number of subcarriers can be variously changed according to the length of the CP, the frequency interval, and the like. For example, in the case of regular CP, the number of OFDM symbols is 7, and in the case of extended CP, the number of OFDM symbols is 6. The number of subcarriers in one OFDM symbol can be selected and used from among 128, 256, 512, 1024, 1536, and 2048.

  FIG. 4 shows a structure of the downlink subframe.

  The downlink subframe includes 2 slots in the time domain, and each slot includes 7 OFDM symbols in the regular CP. Up to 3 OFDM symbols (up to 4 OFDM symbols for the 1.4 MHz bandwidth) in the front part of the first slot in the subframe is a control region to which a control channel is allocated, and the remaining OFDM symbols are physical downlinks. This is a data area to which a shared channel (PDSCH) is allocated.

  The physical downlink control channel (PDCCH) includes downlink shared channel (DL-SCH) resource allocation and transmission format, uplink shared channel (UL-SCH) resource allocation information, call information on a call channel (PCH), System information on DL-SCH, resource allocation of higher layer control messages such as random access response transmitted on PDSCH, set of transmission power control commands for individual UEs in an arbitrary UE group, IP phone (VoIP) Can carry activation, etc. Multiple PDCCHs can be transmitted in the control region, and the terminal can monitor multiple PDCCHs. The PDCCH is transmitted on one or more consecutive control channel element (CCE) aggregations. The CCE is a logical allocation unit used to provide the PDCCH with a coding rate according to the state of the radio channel. The CCE corresponds to a plurality of resource element groups. The relationship between the number of CCEs and the coding rate provided by the CCEs determines the PDCCH format and the number of possible PDCCH bits.

  The base station determines the PDCCH format based on DCI to be transmitted to the terminal, and adds a cyclic redundancy check bit (CRC) to the control information. A unique identifier (Radio Network Temporary Identifier, RNTI) is masked in the CRC depending on the owner or use of the PDCCH. In the case of PDCCH for a specific terminal, a unique identifier of the terminal, for example, a cell RNTI (C-RNTI) can mask the CRC. Or, in the case of PDCCH for a paging message, a paging indication identifier, eg, paging RNTI (P-RNTI) may mask the CRC. In the case of the PDCCH for the system information block (SIB), the system information RNTI (SI-RNTI) can mask the CRC. The random access RNTI (RA-RNTI) can mask the CRC to indicate a random access response that is a response to the terminal's transmission of the random access preamble.

  FIG. 5 shows a structure of the uplink subframe.

  The uplink subframe can be divided into a control region and a data region in the frequency domain. A physical uplink control channel (PUCCH) for transmitting uplink control information is allocated to the control region. A physical uplink shared channel (PUSCH) for transmitting data is allocated to the data area. When instructed by an upper layer, the terminal can perform simultaneous transmission of PUSCH and PUCCH.

  The PUCCH for one terminal is allocated as a resource block (RB) pair in the subframe. Resource blocks belonging to a resource block pair occupy separate subcarriers in each of the first slot and the second slot. The frequency occupied by the resource block belonging to the resource block pair assigned to the PUCCH is changed based on the slot boundary. This is because the frequency of the RB pair assigned to the PUCCH is hopped at the slot boundary. Frequency diversity gain can be obtained by the UE transmitting uplink control information through separate subcarriers according to time. m is a position index indicating the logical frequency domain position of the resource block pair assigned to the PUCCH in the subframe.

  The uplink control information transmitted on the PUCCH includes a hybrid automatic repeat request (HARQ) acknowledgment (ACK) / negative acknowledgment (NACK), a channel quality indicator (CQI) indicating a downlink channel state, and uplink radio resources. There is a schedule request (SR) which is an allocation request.

  PUSCH is mapped to UL-SCH which is a transport channel. The uplink data transmitted on the PUSCH is a transport block that is a data block for the UL-SCH transmitted during TTI. The transport block is user information. Alternatively, the uplink data is multiplexed data. The multiplexed data is obtained by multiplexing a transport block for UL-SCH and control information. For example, control information multiplexed with data includes CQI, precoding matrix indicator (PMI), HARQ, rank indicator (RI), and the like. Alternatively, the uplink data can be configured only with control information.

  FIG. 6 shows an example of a transmitter structure in an SC-FDMA system.

  Referring to FIG. 6, the transmitter 50 includes a discrete Fourier transform (DFT) unit 51, a subcarrier mapper 52, an inverse fast Fourier transform (IFFT) unit 53, and a CP insertion unit 54. The transmitter 50 may include a scramble unit (not shown), a modulation mapper (not shown), a hierarchical mapper (not shown), and a hierarchical permutator (not shown). Can be arranged.

The DFT unit 51 performs DFT on the input symbols and outputs complex symbols. For example, when N _tx symbols (where N _tx is a natural number) are input, the DFT size is N _tx . The DFT unit 51 may be called a conversion precoder. The subcarrier mapper 52 maps the complex symbol to each subcarrier in the frequency domain. The complex symbols can be mapped to resource elements corresponding to resource blocks allocated for data transmission. The subcarrier mapper 52 may be called a resource mapper. IFFT section 53 performs IFFT on the input symbol and outputs a baseband signal for data that is a time domain signal. The CP insertion unit 54 copies a part of the rear part of the baseband signal for data and inserts it in the front part of the baseband signal for data. Since intersymbol interference (ISI) and intercarrier interference (ICI) are prevented through CP insertion, orthogonality can be maintained even in a multipath channel.

  FIG. 7 shows an example of a scheme in which the subcarrier mapper maps a complex symbol to each subcarrier in the frequency domain. Referring to (a) of FIG. 7, the subcarrier mapper maps the complex symbols output from the DFT unit to consecutive subcarriers in the frequency domain. '0' is inserted in a subcarrier to which no complex symbol is mapped. This is called a localized map. In the 3GPP LTE system, a centralized map method is used. Referring to (b) of FIG. 7, the subcarrier mapper inserts L−1 ‘0’ between two consecutive complex symbols output from the DFT unit (L is a natural number). That is, the complex symbols output from the DFT unit are mapped to subcarriers distributed at equal intervals in the frequency domain. This is called a distributed map. When the subcarrier mapper uses a centralized mapping scheme as shown in FIG. 7A or a distributed mapping scheme as shown in FIG. 7B, the single carrier characteristics are maintained.

  FIG. 8 shows an example of a reference signal transmitter structure for demodulation.

  Referring to FIG. 8, the reference signal transmitter 60 includes a subcarrier mapper 61, an IFFT unit 62, and a CP insertion unit 63. Unlike the transmitter 50 of FIG. 6, the reference signal transmitter 60 is generated in the frequency domain without passing through the DFT unit 51, and is mapped to the subcarrier via the subcarrier mapper 61. At this time, the subcarrier mapper can map the reference signal to the subcarrier using the centralized mapping method of FIG.

  FIG. 9 is an example of a subframe structure in which a reference signal is transmitted. The structure of the subframe in FIG. 9A shows the case of a regular CP. The subframe includes a first slot and a second slot. Each of the first slot and the second slot includes 7SC-FDMA symbols. Symbol indexes from 0 to 13 are attached to 14SC-FDMA symbols in the subframe. The reference signal can be transmitted through SC-FDMA symbols having symbol indexes of 3 and 10. The reference signal can be transmitted using a sequence. A ZC sequence can be used as the reference signal sequence, and various ZC sequences can be generated according to the root index and the cyclic shift value. The base station can assign separate cyclic shift values to the terminals and estimate the channels of multiple terminals via orthogonal sequences or quasi-orthogonal sequences. The position of the frequency domain occupied by the reference signal in the two slots in the subframe may be the same or different. The same reference signal sequence is used in the two slots. Data can be transmitted through the remaining SC-FDMA symbols excluding the SC-FDMA symbol to which the reference signal is transmitted. The structure of the subframe in (b) of FIG. 9 shows the case of extended CP. The subframe includes a first slot and a second slot. Each of the first slot and the second slot includes 6SC-FDMA symbols. Symbol indexes from 0 to 11 are attached to 12SC-FDMA symbols in the subframe. The reference signal is transmitted via SC-FDMA symbols with symbol indexes 2 and 8. Data is transmitted through the remaining SC-FDMA symbols excluding the SC-FDMA symbol to which the reference signal is transmitted.

  Although not shown in FIG. 9, a measurement reference signal (SRS) can also be transmitted via an SC-FDMA symbol in a subframe. The measurement reference signal is a reference signal that the terminal transmits to the base station for the uplink schedule. The base station estimates the uplink channel via the received measurement reference signal and uses the estimated uplink channel for the uplink schedule.

  The clustered DFT-s OFDM transmission scheme is a modification of the existing SC-FDMA transmission scheme, and a data symbol that has passed through a precoder is divided into a plurality of subblocks, and the subblocks are separated and mapped to the frequency domain. Is the method.

  FIG. 10 is an example of a transmitter to which a clustered DFT-s OFDM transmission scheme is applied. Referring to FIG. 10, the transmitter 70 includes a DFT unit 71, a subcarrier mapper 72, an IFFT unit 73, and a CP insertion unit 74. The transmitter 70 may further include a scramble unit (not shown), a modulation mapper (not shown), a hierarchical mapper (not shown), and a hierarchical permutator (not shown). Can be placed in front.

  The complex symbol output from the DFT unit 71 is divided into N sub-blocks (N is a natural number). The N subblocks are subblock # 1, subblock # 2,. . . , Sub-block #N. The subcarrier mapper 72 maps the N subblocks to the subcarriers by dispersing them in the frequency domain. A NULL can be inserted between every two consecutive sub-blocks. Complex symbols within one sub-block can be mapped to consecutive sub-carriers in the frequency domain. That is, the centralized map method can be used in one sub-block.

  The transmitter 70 of FIG. 10 can be used for either a single carrier transmitter or a multi-carrier transmitter. When used in a single carrier transmitter, all N sub-blocks correspond to one carrier. When used in a multi-carrier transmitter, each of the N sub-blocks can correspond to one carrier. Alternatively, when used in a multi-carrier transmitter, a plurality of sub-blocks among N sub-blocks can correspond to one carrier. On the other hand, a time domain signal is generated via one IFFT unit 73 in the transmitter 70 of FIG. Therefore, in order to use the transmitter 70 of FIG. 10 as a multi-carrier transmitter, the subcarrier spacing between adjacent carriers must be aligned in a continuous carrier allocation situation.

  FIG. 11 is another example of a transmitter to which a clustered DFT-s OFDM transmission scheme is applied. Referring to FIG. 11, the transmitter 80 includes a DFT unit 81, a subcarrier mapper 82, a plurality of IFFT units 83-1, 83-2,. . . , 83-N (N is a natural number), and CP insertion section 84. The transmitter 80 may further include a scramble unit (not shown), a modulation mapper (not shown), a hierarchical mapper (not shown), and a hierarchical permutator (not shown). Can be placed in front.

  IFFT is performed individually for each of the N sub-blocks. The n-th IFFT unit 83-n performs IFFT on the sub-block #n and outputs an n-th baseband signal (n = 1, 2,..., N). The nth radio signal is generated by multiplying the nth baseband signal and the nth carrier signal. The N radio signals generated from the N subblocks are added, and then the CP is inserted by the CP insertion unit 84. The transmitter 80 of FIG. 11 can be used in a non-contiguous carrier assignment situation where the carrier to which the transmitter has been assigned is not adjacent.

  FIG. 12 is another example of a transmitter to which a clustered DFT-s OFDM transmission scheme is applied. FIG. 12 illustrates a chunk specific DFT-s OFDM system that performs DFT precoding on a chunk basis. This can be referred to as Nx SC-FDMA. Referring to FIG. 12, the transmitter 90 includes a code block division unit 91, a chunk division unit 92, a plurality of channel coding units 93-1,. . . , 93-N, a plurality of modulators 94-1,. . . , 94-N, a plurality of DFT units 95-1,. . . , 95-N, a plurality of subcarrier mappers 96-1,. . . , 96-N, a plurality of IFFT units 97-1,. . . , 97-N, and a CP insertion part 98. Here, N is the number of multiple carriers used by the multiple carrier transmitter. Channel encoding units 93-1,. . . , 93-N can each include a scramble unit (not shown). Modulators 94-1,. . . , 94-N may be referred to as modulation mappers. The transmitter 90 may further include a hierarchical mapper (not shown) and a hierarchical permutator (not shown), which includes the DFT units 95-1,. . . , 95-N.

  The code block dividing unit 91 divides the transport block into a plurality of code blocks. The chunk division unit 92 divides the code block into a plurality of chunks. Here, the code block refers to data transmitted from a multi-carrier transmitter, and the chunk refers to a data fragment transmitted via one carrier among the multiple carriers. The transmitter 90 performs DFT for each chunk. The transmitter 90 can be used in a discontinuous carrier assignment situation or a continuous carrier assignment situation.

  Hereinafter, an uplink reference signal will be described.

  The reference signal is generally transmitted in the form of a sequence. An arbitrary sequence can be used as the reference signal sequence without any particular limitation. The reference signal sequence may be a sequence generated via a phase shift keying (PSK) based computer. Examples of PSK include two-phase phase shift keying (BPSK) and four-phase phase shift keying (QPSK). Alternatively, the reference signal sequence can use a constant amplitude zero autocorrelation (CAZAC) sequence. Examples of CAZAC sequences include ZC-based sequences, circularly extended ZC sequences, truncation ZC sequences, and the like. Alternatively, the reference signal sequence can use a pseudo-random (PN) sequence. Examples of the PN sequence include an m-sequence, a sequence generated via a computer, a Gold sequence, a Kasami sequence, and the like. Further, a cyclically shifted sequence can be used as the reference signal sequence.

  The uplink reference signal can be distinguished into a demodulation reference signal (DMRS) and a measurement reference signal (SRS). DMRS is a reference signal used for channel estimation for demodulation of a received signal. DMRS may be combined with PUSCH or PUCCH transmission. The SRS is a reference signal that the terminal transmits to the base station for the uplink schedule. The base station estimates the uplink channel via the received measurement reference signal and uses the estimated uplink channel for the uplink schedule. SRS is not combined with PUSCH or PUCCH transmission. The same kind of basic sequence can be used for DMRS and SRS. On the other hand, precoding applied to DMRS in uplink multiple antenna transmission is the same as precoding applied to PUSCH. Cyclic shift separation is a basic method for multiplexing DMRS. The SRS in the 3GPP LTE-A system may not be precoded and may be an antenna-specific reference signal.

The reference signal sequence r _{u, v} ^(α) (n) can be defined based on the basic sequence b _{u, v} ^(α) and the cyclic shift α according to Equation 2.

(Formula 2)

In Equation 2, M _sc ^RS (1 ≦ m ≦ N _RB ^{max, UL} ) is the length of the reference signal sequence, and M _sc ^RS = m * N _sc ^RB . N _sc ^RB indicates the size of the resource block expressed by the number of subcarriers in the frequency domain, and N _RB ^{max, UL} indicates the maximum value of the uplink bandwidth expressed by a multiple of N _sc ^RB . A plurality of reference signal sequences can be defined by applying different cyclic shift values α to one basic sequence.

The basic sequence b _{u, v} ⁽ⁿ⁾ is divided into a plurality of groups, where u∈ {0, 1,..., 29} indicates a group index, and v indicates a basic sequence index within the group. The basic sequence depends on the length of the basic sequence (M _sc ^RS ). Each group includes one basic sequence (v = 0) of length M _sc ^RS for m where 1 ≦ m ≦ 5, and for m where 6 ≦ m ≦ n _RB ^{max, UL} _Contains two basic sequences (v = 0, 1) of length M _sc ^RS . The sequence group index u and the basic sequence index v in the group may change with time like a group hop or a sequence hop described later.

If the length of the reference signal sequence is 3N _sc ^RB or more, the basic sequence can be defined by Equation 3.

(Formula 3)

In Equation 3, q indicates the root index of the ZC sequence. N _ZC ^RS is the length of the ZC sequence and can be given as the largest prime number less than M _sc ^RS . The ZC sequence that is the root index q can be defined by Equation 4.

(Formula 4)

  q can be given by Equation 5.

(Formula 5)

If the length of the reference signal sequence is 3N _sc ^RB or less, the basic sequence can be defined by Equation 6.

(Formula 6)

Table 1 is an example in which φ (n) is defined when M _sc ^RS = N _sc ^RB .

(Table 1)

Table 2 is an example in which φ (n) is defined when M _sc ^RS = 2 * N _sc ^RB .

(Table 2)

  The reference signal hop can be applied as follows.

The sequence group index u of the slot index n _s can be defined based on the group hop pattern f _gh (n _s ) and the sequence shift pattern f _ss according to Equation 7.

(Formula 7)

  There can be 17 distinct group hop patterns and 30 distinct sequence shift patterns. Applicability of the group hop can be instructed by an upper layer.

PUCCH and PUSCH may have the same group hop pattern. The group hop pattern f _gh (n _s ) can be defined by Equation 8.

(Formula 8)

  In Equation 8, c (i) is a pseudo-random sequence that is a PN sequence and can be defined by a Gold sequence of length 31. Equation 9 shows an example of the Gold sequence c (n).

(Formula 9)

として初期化することができる。 Here, Nc = 1600, x ₁ (i) is the first m-sequence, and x ₂ (i) is the second m-sequence. For example, the first m-sequence or the second m-sequence is initialized depending on the cell ID, the slot number in one radio frame, the SC-FDMA symbol index in the slot, the CP type, etc. for each SC-FDMA symbol. Can be The pseudo-random sequence generator is at the beginning of each radio frame.

Can be initialized as

PUCCH and PUSCH may have the same sequence shift pattern. The sequence shift pattern of ^PUCCH can be given as f _ss ^PUCCH = N _ID ^cell mod 30. The sequence shift pattern of ^PUSCH can be given as f _ss ^PUSCH = (f _ss ^PUCCH + Δ _ss ) mod 30, and Δ _ss ε {0, 1,..., 29} can be configured by an upper layer.

Sequence hops can only be applied to reference signal sequences that are longer than 6N _sc ^RB . At this time, the basic sequence index v in the basic sequence group of the slot index n _s can be defined by Equation 10.

(Formula 10)

として初期化することができる。 c (i) can be expressed by an example of Expression 9, and whether or not a sequence hop can be applied can be indicated by an upper layer. The pseudo-random sequence generator is at the beginning of each radio frame.

Can be initialized as

  The DMRS sequence for PUSCH can be defined by Equation 11.

(Formula 11)

In Equation 11, m = 0, 1,..., N = 0,..., M _sc ^RS −1. M _sc ^RS = M _sc ^PUSCH .

The cyclic shift value α = 2πn _cs / 12 is given in the slot, and n _cs can be defined by Equation 12.

(Formula 12)

In Equation 12, n _DMRS ⁽¹⁾ is indicated by a parameter transmitted in the upper layer, and Table 3 shows an example of a correspondence relationship between the parameter and n _DMRS ⁽¹⁾ .

(Table 3)

Also, in Equation 12, n _DMRS ⁽²⁾ can be defined by a cyclic shift field in DCI format 0 for the transport block corresponding to PUSCH transmission. The DCI format is transmitted on the PDCCH. The cyclic shift field may have a length of 3 bits.

Table 4 is an example of a correspondence relationship between the cyclic shift field and n _DMRS ⁽²⁾ .

(Table 4)

When PDCCH including DCI format 0 is not transmitted in the same transport block, when the first PUSCH is semi-permanently scheduled in the same transport block, or when the first PUSCH is random access response grant in the same transport block ( n _DMRS ⁽²⁾ is 0 if scheduled by grant).

n _PRS (n _s ) can be defined by Equation 13.

(Formula 13)

として初期化することができる。 c (i) can be expressed by the example of Expression 9, and can be applied to the cell specification indicated by c (i). The pseudo-random sequence generator is at the beginning of each radio frame.

Can be initialized as

The DMRS sequence r ^PUSCH is multiplied by the amplitude scaling coefficient β _PUSCH and mapped from the r ^PUSCH (0) at the beginning of the sequence to the physical transport block used for the corresponding PUSCH transmission. The DMRS sequence is the fourth SC-FDMA symbol (SC-FDMA symbol index 3) when it is a regular CP in one slot, and the third SC-FDMA symbol (SC-FDMA) when it is an extended CP. Maps to symbol index 2).

The SRS sequence r _SRS (n) = r _{u, v} ^(α) (n) is defined. u indicates a PUCCH sequence group index, and v indicates a basic sequence index. The cyclic shift value α is defined by Equation 14.

(Formula 14)

n _SRS ^cs is a value configured by an upper layer for each terminal, and is any one of integers from 0 to 7.

  On the other hand, OCC can be applied to the reference signal sequence. OCC means a code that is orthogonal to each other and can be applied to a sequence. In general, separate sequences can be used to distinguish between multiple channels, but OCC can be used to distinguish between multiple channels.

  The OCC can be used for the following applications.

  1) OCC can be applied to increase the amount of radio resources allocated to uplink reference signals.

  For example, when the cyclic shift value of the reference signal transmitted in the first slot and the second slot is assigned to a, a (−) code can be assigned to the reference signal transmitted in the second slot. That is, the first user transmits a reference signal having a cyclic shift value a and a sign (+) in the second slot, and the second user has a cyclic shift value in the second slot. A reference signal which is a and has a sign (−) can be transmitted. The base station can estimate the channel of the first user by adding the reference signal transmitted in the first slot and the reference signal transmitted in the second slot. Also, the base station can estimate the channel of the second user by subtracting the reference signal transmitted in the second slot from the reference signal transmitted in the first slot. That is, by applying OCC, the base station can distinguish the reference signal transmitted by the first user from the reference signal transmitted by the second user. This can double the amount of available radio resources by using separate OCCs while at least two users use the same reference signal sequence.

  2) OCC can be applied to increase the interval of cyclic shift values assigned to multiple antennas or multiple layers of a single user. Hereinafter, cyclic shift values assigned to a plurality of hierarchies will be described, but the present invention can also be applied to cyclic shift values assigned to a plurality of antennas.

  The uplink reference signal distinguishes channels based on the cyclic shift value. In a multi-antenna system, a separate cyclic shift value can be assigned to the reference signal for each layer to distinguish the multiple layers. As the number of hierarchies increases, the cyclic shift value to be assigned must be increased, and therefore the interval between the cyclic shift values decreases. Therefore, it becomes difficult to distinguish between a plurality of channels, so that channel estimation performance is reduced. In order to overcome this, OCC can be applied to each layer. For example, it is assumed that the cyclic shift offset of the reference signal for each layer is assigned to 0, 6, 3, and 9 for four layers, respectively. The interval of the cyclic shift value between the reference signals for each layer is 3. At this time, the OCC of the (−) code is applied to the third layer and the fourth layer, and the interval of the cyclic shift value between the reference signals of each antenna can be increased to 6. This can increase the performance of channel estimation.

  3) OCC can be applied to increase the interval of cyclic shift values assigned to a single user.

  In a multi-user MIMO (MU-MIMO) system including a large number of users with multiple antennas, OCC can be applied to cyclic shift values. For example, from the viewpoint of a single user performing MIMO transmission, a cyclic shift value with a long interval between each antenna or each hierarchy can be assigned to distinguish between a plurality of antennas or a plurality of hierarchies. Then, the cyclic shift interval between the users may be narrow. To overcome this, OCC can be applied. When OCC is applied, the same cyclic shift value can be applied among multiple users according to the type of OCC.

  FIG. 13 shows an example in which OCC is applied to a reference signal.

  Within one subframe, both the reference signal sequence for layer 0 and the reference signal sequence for layer 1 are the fourth OFDM symbol of the first slot and the fourth OFDM symbol of the second slot. Mapped. The same sequence is mapped to two OFDM symbols in each layer. At this time, the reference signal sequence for layer 0 is multiplied by an [+ 1 + 1] orthogonal sequence and mapped to an OFDM symbol. The reference signal sequence for layer 1 is mapped to an OFDM symbol by multiplying [+1 −1] orthogonal sequences. That is, when the reference signal sequence for layer 1 is mapped to the second slot in one subframe, it is multiplied and mapped by -1.

  When OCC is applied as described above, the base station that receives the reference signal adds the reference signal sequence transmitted in the first slot and the reference signal sequence transmitted in the second slot, and Zero channels can be estimated. Further, the base station can estimate the layer 1 channel by subtracting the reference signal sequence transmitted in the second slot from the reference signal sequence transmitted in the first slot. That is, by applying OCC, the base station can distinguish the reference signal transmitted in each layer. Therefore, a plurality of reference signals can be transmitted using the same resource. When the number of possible cyclic shifts is 6, the number of layers or users that can be multiplexed by applying the OCC can be increased to 12.

  In this example, it is assumed that a binary format of [+1 +1] or [+1 or 1] is used as the OCC. However, the present invention is not limited to this, and various kinds of orthogonal sequences can be used as the OCC. . For example, orthogonal sequences such as Walsh codes, DFT coefficients, and CAZAC sequences can be applied to the OCC. Also, by applying OCC, reference signals can be more easily multiplexed between users having different bandwidths.

  The proposed reference signal sequence generation method will be described below.

  As described above, whether or not the sequence group hop (SGH) can be performed with respect to the reference signal sequence in LTE rel-8 can be instructed by a signal transmitted as cell specific. Hereinafter, the cell identification signal that indicates whether or not SGH can be performed for the reference signal sequence is referred to as a cell identification GH parameter. Although an LTE rel-8 terminal and an LTE-A terminal can exist simultaneously in the cell, whether the LTE Rel-8 terminal and the LTE-A terminal can perform SGH on the reference signal sequence is the same. Currently defined SGH or sequence hop (SH) can be performed on a slot basis. The cell specific GH parameter is a Group-hopping-enabled parameter provided by an upper layer. When the value of Group-hopping-enabled is true, SGH for the reference signal sequence is executed, and at this time, SH is not executed. When the value of Group-hopping-enabled is false, SGH for the reference signal sequence is not executed, and whether or not SH can be executed is determined by the cell specific SH parameter provided by the upper layer and instructing whether or not SH can be executed. The cell specific SH parameter is a Sequence-hopping-enabled parameter provided by an upper layer.

  On the other hand, in LTE-A, the LTE rel-8 terminal and the LTE-A terminal can execute MU-MIMO transmission, or the LTE-A terminal can execute MU-MIMO transmission. At this time, OCC can be applied to support MU-MIMO of a terminal having a separate bandwidth. By applying the OCC, it is possible to improve orthogonality between terminals that perform MU-MIMO transmission and to improve throughput. However, when the bandwidth between terminals is different and whether or not SGH or SH can be performed for the reference signal sequence is determined by the cell specific GH or SH parameter defined in LTE rel-8, the reference signal transmitted by each terminal The orthogonality between them cannot be sufficiently guaranteed.

  FIG. 14 is an example when a plurality of terminals perform MU-MIMO transmission using separate bandwidths. In FIG. 14A, the first terminal (UE1) and the second terminal (UE2) use the same bandwidth. In this case, whether or not to perform SGH or SH for the basic sequence of the reference signal can be determined according to the cell specific GH or SH parameter defined in LTE rel-8. In FIG. 14B, the first terminal (UE1) uses a bandwidth that is the sum of the bandwidths used by the second terminal (UE2) and the third terminal (UE3). That is, the first terminal, the second terminal, and the third terminal each use separate bandwidths. In this case, it is necessary to determine whether to perform SGH or SH for the basic sequence of the reference signal transmitted by each terminal by a new method.

  Thereby, a terminal specific SGH parameter can be newly defined in addition to the existing cell specific GH parameter and cell specific SH parameter. The terminal specific SGH parameter is information for a specific terminal and can be transmitted only to the specific terminal. The terminal specific SGH parameter can be applied to DMRS transmitted using a PUSCH resource assigned to a specific terminal. That is, the terminal specific SGH parameter can indicate whether or not SGH / SH can be performed on a DMRS basic sequence transmitted using a PUSCH resource. Hereinafter, for convenience of explanation, it is limited that only whether or not SGH and SH can be performed with respect to the basic sequence of the reference signal is determined by the terminal specific SGH parameter, but is not limited thereto. Whether or not SH can be applied to the basic sequence of the reference signal can be determined based on the terminal-specific SGH parameter and other terminal-specific SH parameters. Further, the present invention will be described with respect to a case where the present invention is applied to a DMRS basic sequence transmitted using PUSCH resources. However, the present invention is not limited to this, and DMRS and SRS transmitted using PUCCH resources are not limited thereto. It can be applied in various ways. Further, although a MU-MIMO environment in which a plurality of terminals have separate bandwidths is assumed, the present invention can also be applied to a MU-MIMO or SU-MIMO environment having the same bandwidth.

  When SGH or SH is performed on the basic sequence of the reference signal when the value of the cell specific GH parameter or the cell specific SH parameter is true, for DMRS using PUSCH resource, DMRS and SRS using PUCCH resource Slot level SGH or SH is commonly executed. That is, the sequence group index (or number) of the basic sequence of the reference signal changes per slot, or the basic sequence index (or number) changes within the sequence group. At this time, it is possible to instruct again whether or not to execute DMRS using the PUSCH resource by the terminal-specific SGH parameter. That is, the terminal specific SGH parameter has priority over the cell specific GH parameter or the cell specific SGH parameter. The terminal-specific SGH parameter is a Disable Sequence-group hopping parameter. That is, when the value of the terminal specific SGH parameter is true, SGH and SH are not executed regardless of the cell specific GH parameter or the cell specific SH parameter. More specifically, when the value of the terminal-specific SGH parameter is true, the cell-specific GH parameter or the cell-specific SH parameter instructs execution of SGH or SH with respect to the basic sequence of the reference signal. SGH and SH for the sequence are not executed. Since SGH is not executed, the sequence group index of the basic sequence of the reference signal does not change in slot units. Similarly to the case where SGH is executed by the cell specific GH parameter, since SH is not executed, the basic sequence index of the basic sequence of the reference signal does not change in slot units. At this time, SGH and SH are not executed only in one subframe, and two slots in the subframe transmit the basic sequence of the reference signal of the same sequence group index and the same basic sequence index, and between the subframes. SGH or SH can be applied. Alternatively, SGH and SH are not applied in the entire subframe, and all slots can transmit the basic sequence of the reference signal of the same basic sequence index as the same sequence group index. On the other hand, when the value of the terminal specific SGH parameter is false, SGH or SH for the basic sequence of the reference signal can be executed as instructed by the cell specific GH parameter or the cell specific SH parameter.

  FIG. 15 is an example when SGH and SH are not executed by the proposed terminal specific SGH parameter. Referring to FIG. 15, when SGH and SH are executed in LTE rel-8 or 9, the sequence group index or the basic sequence index of the basic sequence of the reference signal transmitted in each slot is different. Method 1 is a case where SGH and SH are not executed in the subframe by the terminal specific SGH parameter. Two slots in each subframe generate a reference signal basic sequence having the same sequence group index and the same basic sequence index, and the sequence group index or the basic sequence index changes between subframes. Method 2 is a case where SGH and SH are not performed in all subframes due to the terminal specific SGH parameter. As a result, all subframes generate a basic sequence of reference signals having the same sequence group index and the same basic sequence index.

  FIG. 16 shows an embodiment of the proposed reference signal sequence generation method.

  In step S100, the terminal receives terminal-specific SGH parameters. The terminal specific SGH parameter can be given by an upper layer. In step S110, the terminal generates a reference signal sequence based on the basic sequence for each slot. The basic sequence can be classified into a sequence group number and a basic sequence number determined for each slot according to the terminal-specific SGH parameter that indicates whether or not SGH and SH can be executed.

  Whether or not SGH and SH can be executed by the terminal-specific SGH parameter can be notified to the terminal by various methods described below.

  1) The frequency hop flag included in the DCI format for uplink transmission can serve as the terminal specific SGH parameter. For example, if a frequency hop is enabled by a frequency hop flag, slot level SGH or SH can be performed. Further, when the frequency hop is disabled by the frequency hop flag, SGH and SH for the DMRS basic sequence using the PUSCH resource are not executed. Alternatively, SGH or SH can be executed in units of subframes.

  2) Indication of whether or not SGH and SH can be performed by masking information indicating whether or not SGH and SH can be performed with respect to the basic sequence of the reference signal in a bit indicating UE ID included in the DCI format for uplink transmission it can.

  3) When the specific index of the cyclic shift indicator included in the DCI format for uplink transmission is designated, it is possible to instruct whether or not SGH and SH can be performed for the basic sequence of the reference signal.

  4) A DCI format for uplink transmission may include a terminal-specific SGH parameter that indicates whether or not SGH and SH can be performed in the basic sequence of the reference signal.

  5) The terminal specific SGH parameter can be transmitted to the terminal by higher layer signal notification for the specific terminal.

  6) When the clustered DFT-s OFDM transmission scheme is used, SGH and SH for the basic sequence of the reference signal are not performed.

  On the other hand, when SGH and SH for the basic sequence of the reference signal are not executed according to the terminal-specific SGH parameter, OCC can be applied to the corresponding reference signal. When SGH or SH for the basic sequence of reference signals is performed, OCC is not applied.

  Various methods may be used to indicate whether the OCC is applicable. First, when the cyclic shift index is indicated via the DCI format and the OCC index indicating whether the OCC is applicable is transmitted via the upper layer, if the SGH and SH for the basic sequence of the reference signal are not executed, the OCC Whether or not OCC can be applied by an index may be followed as it is. For example, when the OCC index is 0, the OCC is not applied, and when the OCC index is 1, the OCC can be applied. Or, conversely, when the OCC index is 1, the OCC is not applied, and when the OCC index is 0, the OCC can be applied. Further, when SGH or SH for the basic sequence of the reference signal is executed, it is possible to determine whether or not to apply OCC, contrary to the OCC index. For example, when the OCC index is 0, the OCC is applied as it is, and when the OCC index is 1, the OCC is not applied. Or, on the contrary, when the OCC index is 1, the OCC is applied as it is, and when the OCC index is 0, the OCC is not applied.

  Alternatively, the specific OCC is applied to the specific cyclic shift index by combining the 3-bit cyclic shift index and the OCC index in the DCI format without separately defining the OCC index indicating whether the OCC can be applied. Can be directed. At this time, the SGH for the basic sequence of the reference signal or, if temporarily executed, the OCC index indicated by the corresponding cyclic shift index is inverted once more, so that the OCC is not applied as a result. Further, when SGH and SH for the basic sequence of the reference signal are not executed by the terminal-specific SGH parameter, the OCC can be applied using the OCC index indicated by the corresponding cyclic shift index as it is. This can reduce interference between reference signals allocated to each layer.

  As described above, it has been described that whether or not SGH and SH can be performed on the basic sequence of the reference signal is determined by the terminal-specific SGH parameter, but in order to further guarantee the orthogonality of the inter-terminal reference signal in the MU-MIMO environment, A parameter for instructing whether or not to execute SH can be newly defined. The new parameter for instructing whether or not to execute SH is a terminal-specific SH parameter. The terminal specific SH parameter can be applied to the same method as the terminal specific SGH parameter described above. That is, the terminal specific SH parameter can be applied with priority over the cell specific SH parameter. At this time, the terminal specific SGH parameter described above can determine only whether or not SGH can be executed. That is, when the value of the terminal specific SGH parameter is true, SGH for the basic sequence of the reference signal is not executed. Further, whether or not SH can be executed for the basic sequence of the reference signal is determined by the terminal-specific SH parameter. When the value of the terminal-specific SH parameter is true, SH for the basic sequence of the reference signal is not executed. When the value of the terminal-specific SH parameter is false, whether or not SH can be executed for the basic sequence of the reference signal depends on the cell-specific SH parameter. Can be determined. The terminal specific SH parameter may be dynamically signaled implicitly or explicitly using signaling via PDCCH, or may be implicitly or explicitly provided by an upper layer such as RRC signaling.

  On the other hand, in the above description, the terminal-specific SGH parameter, the terminal-specific GH parameter, or the terminal-specific SH parameter is applied with priority over the cell-specific GH parameter or the cell-specific SH parameter regardless of the uplink transmission mode. However, it can be changed depending on the transmission mode. In LTE rel-8 / 9, a single antenna transmission mode is basically provided, whereas in LTE-A, a multi-antenna transmission mode is provided for uplink transmission efficiency, and a transmission mode for providing non-contiguous allocation. Etc. can be defined. At this time, whether to execute the terminal-specific SGH parameter, the terminal-specific GH parameter, or the terminal-specific SH parameter can be determined according to the transmission mode. For example, in the single antenna transmission mode, the terminal-specific SGH parameter takes precedence over the cell-specific GH parameter or the cell-specific SH parameter, but this is ignored and the basic sequence of the reference signal is determined by the cell-specific GH parameter or the cell-specific SH parameter. Whether or not SGH or SH can be executed may be determined.

  FIG. 17 is a block diagram of a base station and a terminal in which an embodiment of the present invention is implemented.

  Base station 800 includes a processor 810, a memory 820, and a radio frequency (RF) unit 830. The processor 810 embodies the proposed functions, processes and / or methods. The hierarchy of the radio interface protocol can be implemented by the processor 810. The memory 820 is connected to the processor 810 and stores various information for driving the processor 810. The RF unit 830 is connected to the processor 810 and transmits a terminal-specific SGH parameter to the terminal.

  The terminal 900 includes a processor 910, a memory 920, and an RF unit 930. The RF unit 930 is connected to the processor 910 and receives the terminal specific SGH parameter. The processor 910 embodies the proposed functions, processes and / or methods. The hierarchy of the radio interface protocol can be implemented by the processor 910. The processor 910 is configured to generate a reference signal sequence based on the basic sequence for each slot unit. The basic sequence is classified according to a sequence group number and a basic sequence number determined for each slot by the terminal-specific SGH parameter that indicates whether or not SGH can be executed. The memory 920 is connected to the processor 910 and stores various information for driving the processor 910.

  The processors 810, 910 may include application specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memories 820, 920 may include ROM, RAM, flash memory, memory cards, storage media, and / or other storage devices. The RF units 830 and 930 may include a baseband circuit for processing a radio signal. When the embodiment is implemented by software, the above-described method can be implemented by modules (processes, functions, etc.) that perform the above-described functions. Modules are stored in memory 820, 920 and can be executed by processors 810, 910. The memories 820 and 920 are inside or outside the processors 810 and 910 and can be connected to the processors 810 and 910 by various well-known means.

  In the exemplary system described above, the method is described on the basis of a sequence diagram with a series of steps or blocks, but the present invention is not limited to the order of the steps, and certain steps differ from the foregoing. It can occur in a different order or simultaneously with the steps. Also, those skilled in the art are not exclusive of the steps shown in the sequence diagram and include other steps, and one or more steps of the sequence diagram can be deleted without affecting the scope of the present invention. You will understand that there is.

  The embodiments described above include illustrations of various aspects. Although not all possible combinations for describing various aspects can be described, those with ordinary knowledge in the relevant art will be able to recognize that other combinations are possible. Accordingly, the present invention includes all alterations, modifications, and variations that fall within the scope of the claims.

Claims (14)

A method for generating a reference signal sequence by a terminal (UE) in a wireless communication system, comprising:
Receiving from a base station cell specific SGH parameters used to enable sequence group hops (SGH) for multiple terminals in the cell;
Receiving, from the base station, a terminal specific SGH parameter used to invalidate the SGH enabled by the cell specific SGH parameter for the terminal;
Generating the reference signal sequence based on a base sequence and a sequence group number determined by the terminal specific SGH parameter;
Having a method.   The method of claim 1, wherein the terminal specific SGH parameter is received via an upper layer.   The method of claim 1, wherein the cell specific SGH parameter is received via an upper layer.   The method of claim 1, wherein the sequence group numbers in each slot are the same.   The method of claim 4, wherein the sequence group numbers in each slot are the same in one subframe.   The method of claim 4, wherein the sequence group numbers in each slot are the same in all subframes in a frame. The method of claim 1, wherein the sequence group number in each slot is determined by the following formula:

However, _{n s} is the slot number in the _{frame, f ss} represents a sequence shift pattern composed of a cell ID and an upper _layer, f gh _(n s) is 0. A terminal (UE) for generating a reference signal sequence in a wireless communication system,
A radio frequency (RF) unit for transmitting or receiving radio signals;
A processor connected to the RF unit,
The processor is
Receiving cell specific SGH parameters used to enable sequence group hop (SGH) for multiple terminals in a cell from a base station;
Receiving, from the base station, a terminal specific SGH parameter used to invalidate the SGH hop enabled by the cell specific SGH parameter for the terminal;
A terminal configured to generate the reference signal sequence based on a base sequence and a sequence group number determined by the terminal specific SGH parameter.   The terminal according to claim 8, wherein the terminal specific SGH parameter is received via an upper layer.   The terminal according to claim 8, wherein the cell specific SGH parameter is received via an upper layer.   The terminal according to claim 8, wherein the sequence group numbers in each slot are the same.   The terminal of claim 11, wherein the sequence group numbers in each slot are the same in one subframe.   The terminal according to claim 11, wherein the sequence group numbers in each slot are the same in all subframes in the frame. The terminal according to claim 8, wherein the sequence group number in each slot is determined by the following equation.

However, _{n s} is the slot number in the _{frame, f ss} represents a sequence shift pattern composed of a cell ID and an upper _layer, f gh _(n s) is 0.

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