Terminal, base station, transmission method and reception method

Abstract

The present invention relates to a terminal, a base station, a transmission method, and a reception method. The base station includes: a transmission unit that transmits information on a transmission candidate subframe of a sounding reference signal (SRS) indicating a measurement of reception quality for an uplink; and a reception unit that receives a repeated signal generated by repeating a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) over a plurality of subframes. For the transmission unit, in the transmission candidate subframe of the SRS, the repeated signal of the PUCCH is generated using a shortened PUCCH format, and the repeated signal of the PUSCH configured in the last single-carrier frequency-division multiple access (SC-FDMA) symbol in the transmission candidate subframe of the SRS is truncated.

Description

[0001] This application is a divisional application of the invention patent application with the application date of March 9, 2016, the application number of 201680003604.9, and the invention name of "Terminal, Base Station, Transmission Method and Reception Method". Technical Field

[0002] The present invention relates to a terminal, a base station, a transmission method and a reception method. Background Art

[0003] In 3GPP LTE (3rd Generation Partnership Project Long Term Evolution), as a downlink communication method from a base station (sometimes also referred to as an eNB) to a terminal (sometimes also referred to as a UE (User Equipment)), OFDMA (Orthogonal Frequency Division Multiple Access) is adopted. In addition, as an uplink communication method from a terminal to a base station, SC-FDMA (Single Carrier-Frequency Division Multiple Access) is adopted (for example, refer to Non-Patent Documents 1-3).

[0004] In LTE, the base station communicates by allocating resource blocks (RBs: Resource Blocks) within the system bandwidth to the terminal for each time unit called a subframe. Figure 1 An example of the subframe structure in the LTE physical uplink shared channel (PUSCH: Physical Uplink Shared Channel) is shown. As Figure 1 shown, 1 subframe is composed of 2 time slots. In each time slot, multiple SC-FDMA data symbols and demodulation reference signals (DMRS: Demodulation Reference Signal) are time-division multiplexed. When the base station receives the PUSCH, it uses the DMRS for channel estimation. After that, the base station uses the channel estimation result to demodulate and decode the SC-FDMA data symbols.

[0005] In addition, in the uplink of LTE, in order to measure the reception quality between the base station and the terminal, SRS (Sounding Reference Signal) is used (for example, refer to Non-Patent Document 1). From the terminal to the base station, SRS is mapped to the SRS resource and sent. Here, the base station sets an SRS resource candidate group that includes all SRS resource candidates common to all terminals existing in the target cell through cell-specific upper-layer notification. Then, through upper-layer notification on a per-terminal basis, the SRS resources to be allocated to the target terminals for SRS resource allocation are respectively allocated as subsets of the SRS resource candidate group. The terminal maps SRS to the allocated SRS resource and sends it to the base station. Furthermore, each SRS resource candidate is the last SC-FDMA symbol in a subframe (SRS transmission candidate subframe) that is a candidate for SRS transmission. In addition, in the symbols that are SRS resource candidates, data transmission is not performed by all terminals in the cell where the SRS resource candidate group is set, preventing conflicts between SRS and data signals (PUSCH signals).

[0006] In LTE, as the cell-specific upper-layer notification for setting the SRS resource candidate group, srs-SubframeConfig etc. are defined (for example, refer to Non-Patent Document 1). Figure 2 Shows an example of the definition of srs-SubframeConfig. By sending from the base station to the terminal Figure 2 the srs-SubframeConfig number (0 to 15) shown, the base station indicates to the terminal the transmission interval (T SFC ) of SRS transmission and the offset (Δ SFC ) of the subframe used to indicate the start of SRS transmission. For example, in Figure 2 , when the srs-SubframeConfig number is 4 (Binary = 0100), since the transmission interval T SFC = 5 and the offset Δ SFC = 1, the 2nd (= 1 + Δ SFC ), 7th (= 1 + Δ SFC +(T SFC ×1)), 12th (= 1 + Δ SFC +(T SFC ×2)),..., (1 + Δ SFC +(T SFC ×n)) subframes become SRS transmission candidate subframes (for example, refer to Figure 3 ).

[0007] However, in recent years, as a mechanism to support the future information society, Machine-to-Machine (M2M) communication that realizes services through autonomous communication between devices without the judgment of users is expected. A specific application example of the M2M system is the smart grid. The smart grid is an infrastructure system that efficiently supplies lifelines such as electricity and natural gas, and M2M communication is implemented between smart meters and central servers installed in each home or building to autonomously and efficiently adjust the supply-demand balance of resources. As other application examples of the M2M communication system, surveillance systems for item management, environmental remote sensing, or telemedicine, and remote management of vending machine inventory or charging can be cited.

[0008] In the M2M communication system, the use of cellular systems with a wide communication area is particularly remarkable. In 3GPP, in the standardization of LTE and LTE-Advanced (LTE-A), advanced standardization of the cellular network for M2M, called Machine Type Communication (MTC), is underway (for example, Non-Patent Document 4), and specification research with requirements of low cost, power consumption reduction, and coverage enhancement is being promoted. In particular, different from many mobile phone terminals used by users while moving, in terminals such as smart meters that hardly move, ensuring coverage is a necessary condition for service provision. Therefore, in order to cope with the situation where MTC terminals (MTC terminals) corresponding to MTC are configured in places where they cannot be used in the existing LTE and LTE-A communication areas such as underground in buildings, "coverage enhancement (MTC coverage enhancement)" to further expand the communication area is an issue.

[0009] In order to further expand the communication area, in MTC coverage enhancement, research is being conducted on the "repetition" technique of repeatedly transmitting the same signal multiple times. In repetition, by synthesizing the signals repeatedly transmitted on the transmission side, the received signal power is increased, and the coverage range (communication area) is expanded.

[0010] Moreover, focusing on the environment where MTC terminals that are assumed to require coverage enhancement hardly move and there is no time variation of the channel, a technique for improving the channel estimation accuracy can be used.

[0011] As one of the techniques for improving the channel estimation accuracy, there is "cross-subframe channel estimation and symbol-level synthesis" (for example, refer to Non-Patent Document 5). In cross-subframe channel estimation and symbol-level synthesis, as Figure 4 shown, for the entire multiple subframes (N RepThe signals that are repeatedly transmitted within a subframe, the base station performs in-phase synthesis on a symbol-by-symbol basis within the entire subframe (X subframes) that is the same as or less than the number of repetitions. After that, the base station uses the in-phase synthesized DMRS for channel estimation, and uses the obtained channel estimation result to demodulate and decode the SC-FDMA data symbols.

[0012] When the number of subframes (X), which is the unit for performing channel estimation and symbol-level synthesis for multiple subframes, is less than the number of repetitions (N Rep ), the base station synthesizes the demodulated and decoded (N Rep / X) symbols.

[0013] By using channel estimation and symbol-level synthesis for multiple subframes, compared with the simple repetition of performing channel estimation and demodulating and decoding SC-FDMA data symbols on a subframe basis, it is obvious that the transmission quality of PUSCH can be improved (for example, refer to Non-Patent Document 5).

[0014] Prior Art Documents

[0015] Non-Patent Documents

[0016] Non-Patent Document 1: 3GPP TS 36.211 V12.5.0, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation (Release 12)," March 2015.

[0017] Non-Patent Document 2: 3GPP TS 36.212 V12.4.0, "Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding (Release 12)," March 2015.

[0018] Non-Patent Document 3: 3GPP TS 36.213 V12.5.0, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 12)," March 2015.

[0019] Non-Patent Document 4: RP-141660, Ericsson, Nokia Networks, "New WI proposal: Further LTE Physical Layer Enhancements for MTC," September 2014

[0020] Non-Patent Document 5: R1-150312, Panasonic, "Discussion and performance evaluation on PUSCH coverage enhancement"

[0021] Non-Patent Document 6: R1-152528, RAN4, "LS Out on Additional Aspects for MTC," May 2015

[0022] Non-Patent Document 7: R1-151454, MCC Support, "Final Report of 3GPP TSG RAN WG1#80 v1.0.0," February 2015 Summary of the Invention

[0023] In a cell supporting MTC terminals, it is necessary to enable coexistence of MTC terminals and existing LTE terminals, and preferably support MTC terminals so as to minimize the impact on the existing LTE system. For this purpose, for example, in the uplink transmission (e.g., PUSCH transmission) of an MTC terminal (MTC coverage extension terminal) that requires retransmission, in order to prevent a conflict with the SRS of the existing LTE system, as described above, data transmission is not performed in the SRS resource candidates. Thereby, a conflict between the SRS and the data signal of the MTC coverage extension terminal is prevented.

[0024] However, the technology for improving the above-mentioned channel estimation accuracy assumes that the received signals of a plurality of entire subframes (X subframes) can be synthesized in phase, and in retransmission, it is premised that there will be no phase discontinuity of the transmission signal at least in the X subframe period. There is also research that as long as the transmission power and the center frequency of RF (Radio Frequency) do not change, there will be no phase discontinuity of the transmission signal in retransmission (for example, refer to Non-Patent Document 6).

[0025] However, in the case where a part of the subframe for retransmission is a candidate subframe for SRS transmission, data is not transmitted in the last SC-FDMA symbol of the candidate subframe for SRS transmission. In this case, since the transmission power of the last SC-FDMA symbol of the candidate subframe for SRS transmission is 0, a change in transmission power occurs in the retransmission period. Therefore, it may not be possible to satisfy the condition that the phase discontinuity of the above-described transmission signal does not occur, and a phase discontinuity may occur in the repeated signal. Thus, if a phase discontinuity of the transmission signal occurs, in-phase synthesis of the received signals within the entire X subframe cannot be performed at the base station, and the effect of improving the channel estimation accuracy cannot be obtained sufficiently.

[0026] One aspect of the present invention provides a base station, a terminal, a transmission method, and a reception method capable of improving channel estimation accuracy through channel estimation and symbol-level synthesis of a plurality of subframes.

[0027] The structure adopted by the terminal according to one aspect of the present invention includes: a repetition unit that repeats an uplink signal within a plurality of subframes to generate a repeated signal; a control unit that sets the timing for transmitting the repeated signal based on information on a candidate subframe for transmitting a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; and a transmission unit that transmits the repeated signal at the set timing.

[0028] The structure adopted by the base station according to one aspect of the present invention includes: a transmission unit that transmits information on a candidate subframe for transmitting a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; and a reception unit that receives a repeated signal generated by repeating a PUSCH and a PUCCH over a plurality of subframes; for the transmission unit, in the candidate subframe for SRS transmission, the repeated signal of the PUCCH is generated using a shortened PUCCH format, and the repeated signal of the PUSCH configured in the last SC-FDMA symbol of the candidate subframe for SRS transmission is truncated.

[0029] The communication method of the base station according to one aspect of the present invention includes: a transmission step of transmitting information on a candidate subframe for transmitting a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; and a reception step of receiving a repeated signal generated by repeating a PUSCH and a PUCCH over a plurality of subframes, in the transmission step, in the candidate subframe for SRS transmission, the repeated signal of the PUCCH is generated using a shortened PUCCH format, and the repeated signal of the PUSCH configured in the last SC-FDMA symbol of the candidate subframe for SRS transmission is truncated.

[0030] Base Station-Facing Integrated Circuit Processing in One Embodiment of the Present Invention: A transmission step of transmitting information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; and a reception step of receiving a repeated signal, which is generated by repeating a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH) over a plurality of subframes. In the transmission step, in the transmission candidate subframe of the SRS, the repeated signal of the PUCCH is generated using a shortened PUCCH format, and the repeated signal of the PUSCH configured in the last single-carrier frequency-division multiple access (SC-FDMA) symbol of the SRS transmission candidate subframe is truncated.

[0031] Furthermore, these general or specific embodiments can be implemented in the form of a system, method, integrated circuit, computer program, or recording medium, or can also be implemented by any combination of a system, apparatus, method, integrated circuit, computer program, and recording medium.

[0032] According to one embodiment of the present invention, channel estimation accuracy can be improved through channel estimation over multiple subframes and symbol-level synthesis.

[0033] More advantages and effects in one embodiment of the present invention will be clear from the description and the drawings. These advantages and / or effects can be provided separately by several embodiments and the features described in the description and the drawings, and it is not necessary to provide all the features in order to obtain one or more of the same features. Description of the Drawings

[0034] Figure 1 A diagram showing an example of the subframe structure of the PUSCH.

[0035] Figure 2 A diagram showing an example of the definition of srs-SubframeConfig.

[0036] Figure 3 A diagram showing an example of the setting of the SRS transmission candidate subframe and the SRS resource.

[0037] Figure 4 A diagram showing an example of the operation of channel estimation over multiple subframes and symbol-level synthesis.

[0038] Figure 5 A diagram showing an example of the configuration of the machine type communication (MTC) narrowband.

[0039] Figure 6 A block diagram showing the main part structure of the base station in Embodiment 1.

[0040] Figure 7 A block diagram showing the main part structure of the terminal in Embodiment 1.

[0041] Figure 8Block diagram showing the structure of the base station according to Embodiment 1.

[0042] Figure 9 Block diagram showing the structure of the terminal according to Embodiment 1.

[0043] Figure 10 Diagram showing a configuration example of the MTC narrowband according to Embodiment 1.

[0044] Figure 11 Diagram showing a configuration example of the MTC narrowband.

[0045] Figure 12 Diagram showing a configuration example of the MTC narrowband according to Embodiment 2.

[0046] Figure 13 Diagram showing a configuration example of the MTC narrowband according to Embodiment 3.

[0047] Figure 14 Diagram showing a configuration example of the MTC narrowband according to Embodiment 3.

[0048] Figure 15 Diagram showing a configuration example of the MTC narrowband according to Embodiment 4. Detailed implementation manners

[0049] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0050] [Outline of the communication system]

[0051] The communication system according to each embodiment of the present invention includes, for example, a base station 100 and a terminal 200 corresponding to an advanced LTE (LTE-Advanced) system.

[0052] In addition, it is assumed that there is a case where a terminal 200 (MTC coverage extension terminal) to which the MTC coverage extension mode is applied exists within the cell of the base station 100. For example, in the case where the MTC coverage extension mode is applied, the terminal 200 applies a technique for improving the above-described channel estimation accuracy.

[0053] In addition, in MTC for which standardization research is being promoted in LTE-Advanced Release 13, in order to achieve low cost of the terminal, the MTC terminal only supports a bandwidth of 1.4 MHz (sometimes also referred to as the MTC narrowband). In addition, frequency hopping is introduced in which the 1.4 MHz frequency band of the transmission signal assigned to the MTC terminal hops within the system bandwidth every certain subframe (for example, refer to Non-Patent Document 7).

[0054] When applying frequency hopping, in order to also apply the above-mentioned technique for improving channel estimation accuracy simultaneously, the MTC terminal needs to transmit signals using the same resources in the X subframe. In addition, when performing frequency hopping, considering the time required for switching the carrier frequency (Retuning time), it is necessary to ensure approximately 1 subframe (1 ms).

[0055] Particularly in the uplink transmission of MTC coverage extension terminals with a large number of repetitions, as Figure 5 shown, assuming that the MTC coverage extension terminal transmits repeated signals in a continuous X subframe manner using the same resources, then changes (frequency hops) the MTC narrowband (1.4 MHz band), and transmits repeated signals in a continuous X subframe manner using the same resources after the change.

[0056] Furthermore, hereinafter, the parameter X representing the number of consecutive subframes for transmitting repeated signals ( Figure 5 which is 4 subframes in Figure 5 ) and the retuning time ( Figure 5 which is 1 subframe in

[0057] ) are sometimes added together (number of subframes) and represented as the parameter "Y" representing the frequency hopping period ( Figure 5 which is 5 subframes in

[0057] ). Furthermore, the retuning time is not limited to 1 subframe.

[0057] In addition, the communication system also includes terminals corresponding to the existing LTE system (not shown). As described above, in LTE, as an example of the cell-specific upper layer notification for setting the SRS resource candidate group, it is set as the case of defining Figure 2 such as srs-SubframeConfig shown

[0058] . Here, in order to perform multi-subframe channel estimation and symbol-level synthesis in the base station 100, the X subframe needs to be a continuous subframe that is not set as a candidate subframe for SRS transmission. That is, the value of X needs to be set to be the same as or smaller than the number of consecutive subframes that are not set as candidate subframes for SRS transmission. The number of consecutive subframes that are not set as candidate subframes for SRS transmission, for example, is 4 subframes in the case of srs-SubframeConfig = 3 (T SFC = 5, Δ SFC = {0}), and is 3 subframes in the case of srs-SubframeConfig = 7 (T SFC = 5, Δ SFC = {0, 1}). The same applies to other srs-SubframeConfigs. For example, for multi-subframe channel estimation and symbol-level synthesis in the entire X = 4 subframes, it can be said that it has a function when the number of consecutive subframes that are not set as candidate subframes for SRS transmission is 4 or more, that is, in the cases of srs-SubframeConfig = 3, 4, 5, 6, 9, 10, 11, 12.

[0059] Therefore, in various embodiments of the present invention, the base station 100 and the terminal 200 set the position of the X subframe for performing channel estimation and symbol-level synthesis of multiple subframes based on the srs-SubframeConfig indicating the SRS transmission candidate subframes. Thereby, the influence of the conflict between the uplink transmission of the MTC coverage extension terminal that needs to repeat transmission and the SRS of the existing LTE system is minimized, and the base station 100 can use a sufficient number of subframes to perform channel estimation and symbol-level synthesis of multiple subframes, improving the channel estimation accuracy.

[0060] Hereinafter, a method for avoiding the conflict between the repeated transmission of the MTC coverage extension terminal and the SRS of the existing system and improving the channel estimation accuracy through channel estimation and symbol-level synthesis of multiple subframes will be described.

[0061] Figure 6 It is a block diagram showing the main part structure of the base station 100 according to an embodiment of the present invention. In Figure 6 In the shown base station 100, the control unit 101 sets the timing for the terminal 200 to transmit a repeated signal generated by repeating the uplink signal within a plurality of subframes based on information (e.g., srs-SubframeConfig) indicating the transmission candidate subframes of the sounding reference signal (SRS) for measuring the reception quality for the uplink. The receiving unit 110 receives the repeated signal, and the synthesizing unit 113 in-phase synthesizes the repeated signals of multiple subframes based on the set timing.

[0062] In addition, Figure 7 It is a block diagram showing the main part structure of the terminal 200 according to various embodiments of the present invention. In Figure 7 In the shown terminal 200, the repeating unit 212 generates a repeated signal by repeating the uplink signal within a plurality of subframes. The control unit 206 sets the timing for transmitting the repeated signal based on information (e.g., srs-SubframeConfig) indicating the transmission candidate subframes of the sounding reference signal (SRS) for measuring the reception quality for the uplink, and the transmitting unit 216 transmits the repeated signal at the set timing.

[0063] (Embodiment 1)

[0064] [Structure of the base station]

[0065] Figure 8 It is a block diagram showing the structure of the base station 100 according to Embodiment 1 of the present invention. In Figure 8In this, base station 100 has: a control unit 101; a control signal generation unit 102; an encoding unit 103; a modulation unit 104; a signal distribution unit 105; an IFFT (Inverse Fast Fourier Transform) unit 106; a CP (Cyclic Prefix) addition unit 107; a transmission unit 108; an antenna 109; a reception unit 110; a CP removal unit 111; an FFT (Fast Fourier Transform) unit 112; a synthesis unit 113; a demapping unit 114; a channel estimation unit 115; an equalization unit 116; a demodulation unit 117; a decoding unit 118; and a determination unit 119.

[0066] The control unit 101 determines a candidate group of SRS resources in the cell, considering the amounts of SRS resources required by each of the multiple existing LTE terminals present in the cell covered by the base station 100, and outputs information indicating the determined candidate group of SRS resources to the control signal generation unit 102. The candidate group of SRS resources is selected, for example, from the Figure 2 table shown.

[0067] In addition, the control unit 101 determines, from the candidate group of SRS resources, the subframes in which the terminal 200 performs PUSCH retransmission, and outputs information indicating the determined subframes to the synthesis unit 113.

[0068] In addition, the control unit 101 determines the allocation of PUSCH for the MTC coverage extension terminal. At this time, the control unit 101 determines the frequency allocation resources, modulation, and coding methods, etc. indicated for the MTC coverage extension terminal, and outputs information related to the determined parameters to the control signal generation unit 102.

[0069] In addition, the control unit 101 determines the encoding level of the control signal, and outputs the determined encoding level to the encoding unit 103. In addition, the control unit 101 determines the radio resources (downlink resources) for mapping the control signal, and outputs information related to the determined radio resources to the signal distribution unit 105.

[0070] In addition, the control unit 101 determines the coverage extension level of the MTC coverage extension terminal, and outputs information related to the determined coverage extension level, or the number of repetitions required for PUSCH transmission at the determined coverage extension level, to the control signal generation unit 102. In addition, the control unit 101 generates information related to the value of parameter X or parameter Y used by the MTC coverage extension terminal in PUSCH repetition, based on the information related to the coverage extension level or the number of repetitions required for PUSCH transmission. The generated information is output to the control signal generation unit 102.

[0071] Furthermore, the control unit 101 can independently determine the value of X regardless of the information of the SRS resource candidate group, or can use the information of the SRS resource candidate group to determine the value of X, so as to have the functions of multi-subframe channel estimation and symbol-level synthesis.

[0072] The control signal generation unit 102 generates a control signal for the MTC coverage extension terminal. In the control signal, it includes a cell-specific upper-layer signal, a terminal-specific upper-layer signal, or an uplink grant (UL grant) indicating the allocation of PUSCH.

[0073] The uplink grant is composed of multiple bits and includes information indicating frequency allocation resources, modulation and coding methods, etc. In addition, in the uplink grant, information related to the coverage extension level or the number of repetitions required for PUSCH transmission, as well as the values of parameters X or Y used for PUSCH repetition, may also be included.

[0074] The control signal generation unit 102 uses the control information input from the control unit 101 to generate a control information bit sequence and outputs the generated control information bit sequence (control signal) to the encoding unit 103. Furthermore, since the control information is sometimes sent to multiple terminals 200, the control signal generation unit 102 includes a terminal ID generation bit sequence for each terminal 200 in the control information for each terminal 200. For example, in the control information, CRC (Cyclic Redundancy Check) bits masked by the terminal ID of the destination terminal are appended.

[0075] In addition, the information of the SRS resource candidate group is notified to the MTC coverage extension terminal (the control unit 206 described later) through the cell-specific upper-layer signal. Information related to the coverage extension level or the number of repetitions required for PUSCH transmission can be notified to the MTC coverage extension terminal through the terminal-specific upper-layer signaling, or as described above, using the uplink grant indicating the allocation of PUSCH. In addition, information related to the values of parameters X and Y used for PUSCH repetition can similarly be notified to the MTC coverage extension terminal through the terminal-specific upper-layer signaling, or using the uplink grant indicating the allocation of PUSCH. Moreover, when the information related to the values of parameters X and Y used for PUSCH repetition is a parameter determined based on a predefined standard, it may not be notified from the base station 100 to the terminal.

[0076] The encoding unit 103 encodes the control signal (control information bit sequence) received from the control signal generation unit 102 according to the encoding level indicated by the control unit 101 and outputs the encoded control signal to the modulation unit 104.

[0077] The modulation unit 104 modulates the control signal received from the encoding unit 103 and outputs the modulated control signal (symbol sequence) to the signal distribution unit 105.

[0078] The signal distribution unit 105 maps the control signal (symbol sequence) received from the modulation unit 104 to the radio resources indicated by the control unit 101. Furthermore, the control channel that is the object of the mapped control signal can be the PDCCH for MTC (Physical Downlink Control Channel (PDCCH)) or the EPDCCH (Enhanced PDCCH). The signal distribution unit 105 outputs the signal of the downlink subframe including the PDCCH for MTC or EPDCCH to which the control signal is mapped to the IFFT unit 106.

[0079] The IFFT unit 106 converts the frequency-domain signal into a time-domain signal by performing IFFT processing on the signal received from the signal distribution unit 105. The IFFT unit 106 outputs the time-domain signal to the CP addition unit 107.

[0080] The CP addition unit 107 adds CP to the signal received from the IFFT unit 106 and outputs the signal after CP addition (OFDM signal) to the transmission unit 108.

[0081] The transmission unit 108 performs RF processing such as D / A (Digital-to-Analog) conversion and upconversion on the OFDM signal received from the CP addition unit 107 and transmits a radio signal to the terminal 200 through the antenna 109.

[0082] The receiving unit 110 performs RF processing such as downconversion or A / D (Analog-to-Digital) conversion on the uplink signal (PUSCH) received from the terminal 200 through the antenna 109 and outputs the obtained received signal to the CP removal unit 111. In the uplink signal (PUSCH) transmitted from the terminal 200, there is a signal that is repeatedly processed within a plurality of subframes.

[0083] The CP removal unit 111 removes the CP added to the received signal received from the receiving unit 110 and outputs the signal after CP removal to the FFT unit 112.

[0084] The FFT unit 112 decomposes the signal received from the CP removal unit 111 into a signal sequence in the frequency domain, extracts the signal corresponding to the subframe of the PUSCH, and outputs the extracted signal to the synthesis unit 113.

[0085] The combining unit 113 uses the information input from the control unit 101 and related to the subframes for PUSCH repeated transmission by the MTC coverage extension terminal. For the PUSCH within the entire multiple repeated subframes, at the symbol level combining, the data signal and the signal corresponding to the DMRS part are combined in phase. The combining unit 113 outputs the combined signal to the demapping unit 114.

[0086] From the signal received by the demapping unit 114 from the combining unit 113, the demapping unit 114 extracts the subframe part of the PUSCH allocated to the terminal 200. In addition, the demapping unit 114 decomposes the extracted subframe part of the PUSCH of the terminal 200 into DMRS and data symbols (SC-FDMA data symbols), outputs the DMRS to the channel estimation unit 115, and outputs the data symbols to the equalization unit 116.

[0087] The channel estimation unit 115 performs channel estimation using the DMRS input from the demapping unit 114. The channel estimation unit 115 outputs the obtained channel estimation value to the equalization unit 116.

[0088] The equalization unit 116 performs equalization of the data symbols input from the demapping unit 114 using the channel estimation value input from the channel estimation unit 115. The equalization unit 116 outputs the equalized data symbols to the demodulation unit 117.

[0089] The demodulation unit 117 applies IDFT (Inverse Discrete Fourier Transform) processing to the frequency-domain SC-FDMA data symbols input from the equalization unit 116. After converting to a time-domain signal, data demodulation is performed. Specifically, the demodulation unit 117 converts the symbol sequence to a bit sequence based on the modulation method indicated for the terminal 200, and outputs the obtained bit sequence to the decoding unit 118.

[0090] The decoding unit 118 performs error correction decoding on the bit sequence input from the demodulation unit 117, and outputs the decoded bit sequence to the determination unit 119.

[0091] The determination unit 119 performs error detection on the bit sequence input from the decoding unit 118. The error detection is performed using the CRC bits appended to the bit sequence. When the determination result of the CRC bits is error-free, the determination unit 119 extracts the received data and outputs ACK. On the other hand, when the determination result of the CRC bits has an error, the determination unit 119 outputs NACK. The ACK and NACK output from the determination unit 119 are used for retransmission control processing in a processing unit (not shown).

[0092] [Structure of the terminal]

[0093] Figure 9 This is a block diagram showing the structure of the terminal 200 according to Embodiment 1 of the present invention. In Figure 9 this, the terminal 200 includes an antenna 201, a receiving unit 202, a CP removal unit 203, an FFT unit 204, an extraction unit 205, a control unit 206, a DMRS generation unit 207, an encoding unit 208, a modulation unit 209, a multiplexing unit 210, a DFT unit 211, a repetition unit 212, a signal distribution unit 213, an IFFT unit 214, a CP addition unit 215, and a transmission unit 216.

[0094] The receiving unit 202 performs RF processing such as downconversion or AD conversion on the wireless signal (PDCCH or EPDCCH for MTC) received from the base station 100 through the antenna 201 to obtain a baseband OFDM signal. The receiving unit 202 outputs the OFDM signal to the CP removal unit 203.

[0095] The CP removal unit 203 removes the CP added to the OFDM signal received from the receiving unit 202 and outputs the signal after CP removal to the FFT unit 204.

[0096] The FFT unit 204 converts the time-domain signal into a frequency-domain signal by performing FFT processing on the signal received from the CP removal unit 203. The FFT unit 204 outputs the frequency-domain signal to the extraction unit 205.

[0097] The extraction unit 205 performs blind decoding on the frequency-domain signal (PDCCH or EPDCCH for MTC) received from the FFT unit 204 and attempts to decode the control signal sent to the local device. In the control signal sent to the terminal 200, a CRC masked by the terminal ID of the terminal is added. Therefore, if the CRC determination in the result of blind decoding is OK, the extraction unit 205 extracts the control information and outputs it to the control unit 206.

[0098] The control unit 206 controls the PUSCH transmission based on the control signal input from the extraction unit 205. Specifically, the control unit 206 indicates the resource allocation at the time of PUSCH transmission to the signal distribution unit 213 based on the resource allocation information of the PUSCH included in the control signal. In addition, the control unit 206 indicates the encoding method and modulation method at the time of PUSCH transmission to the encoding unit 208 and the modulation unit 209, respectively, based on the information on the encoding and modulation methods included in the control signal.

[0099] In addition, in the case where information on the coverage extension level or information on the number of repetitions necessary for PUSCH transmission is included in the control signal, the control unit 206 determines the number of repetitions during PUSCH retransmission based on this information. The information indicating the determined number of repetitions is indicated to the repetition unit 212. In addition, in the case where information on the value of parameter X or Y used for PUSCH repetition is included in the control signal, the control unit 206 indicates resource allocation during PUSCH retransmission to the signal allocation unit 213 based on this information.

[0100] In addition, in the case where the upper layer is notified by the base station 100 of information related to the coverage extension level or information related to the number of repetitions necessary for PUSCH transmission, the control unit 206 determines the number of repetitions during PUSCH retransmission based on the notified information. The determined information is indicated to the repetition unit 212. Similarly, in the case where the upper layer is notified by the base station 100 of information related to the value of parameter X or Y used for PUSCH repetition, the control unit 206 indicates resource allocation during PUSCH retransmission to the signal allocation unit 213 based on the notified information.

[0101] In addition, the control unit 206 determines the subframe in which PUSCH is retransmitted from the SRS resource candidate group notified by the base station 100 in the cell-specific upper layer, and outputs the determined information to the signal allocation unit 213.

[0102] The DMRS generation unit 207 generates DMRS and outputs the generated DMRS to the multiplexing unit 210.

[0103] The encoding unit 208 appends CRC bits masked by the terminal ID of the terminal 200 to the input transmission data (uplink data), performs error correction encoding, and outputs the encoded bit sequence to the modulation unit 209.

[0104] The modulation unit 209 modulates the bit sequence received from the encoding unit 208 and outputs the modulated signal (data symbol sequence) to the multiplexing unit 210.

[0105] The multiplexing unit 210 time-division multiplexes the data symbol sequence input from the modulation unit 209 and the DMRS input from the DMRS generation unit 207, and outputs the multiplexed signal to the DFT unit 211.

[0106] The DFT unit 211 applies DFT to the signal input from the multiplexing unit 210, generates a frequency-domain signal, and outputs the generated frequency-domain signal to the repetition unit 212.

[0107] When the present terminal is in the MTC coverage extension mode, the repeating unit 212 repeats the signal input from the DFT unit 211 within a plurality of subframes based on the number of repetitions indicated by the control unit 206, and generates a repeated signal. The repeating unit 212 outputs the repeated signal to the signal allocation unit 213.

[0108] The signal allocation unit 213 maps the signal received from the repeating unit 212 to the time and frequency resources of the PUSCH indicated by the control unit 206. The signal allocation unit 213 outputs the signal of the PUSCH to which the signal is mapped to the IFFT unit 214.

[0109] The IFFT unit 214 generates a time-domain signal by performing IFFT processing on the frequency-domain PUSCH signal input from the signal allocation unit 213. The IFFT unit 214 outputs the generated signal to the CP addition unit 215.

[0110] The CP addition unit 215 adds CP to the time-domain signal received from the IFFT unit 214, and outputs the signal after CP addition to the transmission unit 216.

[0111] The transmission unit 216 performs RF processing such as D / A conversion and up-conversion on the signal received from the CP addition unit 215, and transmits a radio signal to the base station 100 through the antenna 201.

[0112] [Operations of the Base Station 100 and the Terminal 200]

[0113] The operations in the base station 100 and the terminal 200 having the above structure will be described in detail.

[0114] Hereinafter, the case where the transmission interval (T SFC ) for transmitting the SRS is 5 or 10, and there is only one SRS transmission candidate subframe among the transmission intervals (T SFC ) for transmitting the SRS (the case where Δ SFC has only one value) will be described. That is, the case where srs-SubframeConfig shown in Figure 2 is 3, 4, 5, 6, 9, 10, 11, 12 will be described.

[0115] The base station 100 notifies the terminal 200 of srs-SubframeConfig as a cell-specific upper-layer notification for setting the SRS resource candidate group.

[0116] In addition, before transmitting and receiving the PUSCH, the base station 100 notifies the terminal 200 of the number of repetitions (N Rep ) in advance. The number of repetitions (N Rep)It can be notified from the base station 100 to the terminal 200 through the upper layer inherent to the terminal, or it can also be notified using the PDCCH for MTC.

[0117] In addition, before transmitting and receiving the PUSCH, the base station 100 notifies the terminal 200 in advance of the value of parameter X.

[0118] The terminal 200 repeatedly transmits the PUSCH by the number of repetitions (N Rep ) notified from the base station 100. When the number of repetitions (N Rep ) is greater than X, as Figure 5 shown, after the terminal 200 transmits repeated signals in a continuous manner of X subframes using the same resource, it changes the frequency band of 1.4 MHz (MTC narrowband) by frequency hopping, and then uses the same resource again to continuously transmit repeated signals in X subframes. That is, for the repeated signals, frequency hopping is performed for each of the consecutive X subframes among the N Rep subframes. Furthermore, as Figure 5 shown, a return time (for example, equivalent to 1 subframe) is ensured during frequency hopping.

[0119] At this time, the terminal 200 sets the timing for transmitting the repeated signals based on the srs-SubframeConfig (information indicating the SRS transmission candidate subframes) notified by the base station 100. Specifically, in the repeated transmission of the PUSCH, the terminal 200 maps the repeated signals (MTC narrowband) transmitted continuously in X subframes so that they do not overlap with the SRS transmission candidate subframes notified by srs-SubframeConfig.

[0120] Figure 10 An example of the mapping of the MTC narrowband signal in the case where srs-SubframeConfig = 3 and X = 4 is shown. In addition, in Figure 10 , it is assumed that the number of repetitions N Rep = 12.

[0121] In the case where srs-SubframeConfig = 3, the transmission interval (T SFC ) for transmitting the SRS = 5, and Δ SFC = 0 (refer to Figure 2 ), so in Figure 10 , the 1st subframe, the 6th subframe, the 11th subframe, and the 16th subframe become the SRS transmission candidate subframes. That is, in Figure 10 , the number of consecutive subframes not set as the SRS transmission candidate subframes is 5 subframes.

[0122] In Figure 10Among them, the terminal 200 transmits repeated signals in four consecutive subframes from the second subframe to the fifth subframe, four consecutive subframes from the seventh subframe to the tenth subframe, and four consecutive subframes from the twelfth subframe to the fifteenth subframe. That is, each of the X = 4 subframes to which the repeated signals are mapped is a consecutive subframe not set as an SRS transmission candidate subframe. Thus, the repeated signals (MTC narrowband) transmitted continuously in X subframes are mapped into subframes such that they do not overlap with the SRS transmission candidate subframes notified by srs-SubframeConfig.

[0123] Here, in Figure 10 , the value of X (X = 4) is less than the SRS transmission interval (T SFC ) = 5. That is, the value of X (X = 4) is less than or equal to the number of consecutive subframes (4 subframes) not set as SRS transmission candidate subframes. In addition, for srs-SubframeConfig = 4, 5, 6 where the numbers of the transmission interval (T SFC ) and Δ SFC are the same as those in the case of srs-SubframeConfig = 3, the same applies. That is, in the cases of srs-SubframeConfig = 3, 4, 5, 6, multiple subframe channel estimation and symbol-level synthesis can be performed within the entire X = 2, 3, 4 subframes. Similarly, in the cases of srs-SubframeConfig = 9, 10, 11, 12, the number of consecutive subframes not set as SRS transmission candidate subframes is 9 subframes, so multiple subframe channel estimation and symbol-level synthesis can be performed within the entire X = 2, 3, 4, 5, 6, 7, 8, 9 subframes.

[0124] That is, as the parameter X which is the processing unit for multiple subframe channel estimation and symbol-level synthesis, one of the values less than or equal to the number of consecutive subframes not set as SRS transmission candidate subframes is set. In this way, when the value of X is less than or equal to (or less than) the number of consecutive subframes not set as SRS transmission candidate subframes (or less than the transmission interval T SFC ), the terminal 200 can map the repeated signals to subframes other than the SRS transmission candidate subframes. Thus, the terminal 200 can avoid the SRS transmission candidate subframes and map the repeated signals transmitted continuously in X subframes which are the objects of multiple subframe channel estimation and symbol-level synthesis.

[0125] In addition, in the example of Figure 10 , the first subframe of the X = 4 subframes (MTC narrowband) transmitting the repeated signals continuously is set as the next subframe of the SRS transmission candidate subframe, that is, the second subframe, the seventh subframe, and the twelfth subframe. In this way, the terminal 200 can make the most use of the consecutive subframes not set as SRS transmission candidate subframes to map the repeated signals.

[0126] Specifically, when the value of X is less than or equal to the number of consecutive subframes not set as SRS transmission candidate subframes, the terminal 200 can reliably avoid the SRS transmission candidate subframes and map the repeated signals by setting the start subframe of the X subframes as the next subframe of the SRS transmission candidate subframe.

[0127] In addition, similar to the terminal 200, the base station 100 sets (determines) the timing of the subframes for transmitting the repeated signals in the PUSCH repetition from the terminal 200 based on the srs-SubframeConfig set for the terminal 200. Then, the base station 100 in-phase synthesizes the repeated signals transmitted within the entire multiple subframes based on the set timing of the subframes.

[0128] In this way, in the present embodiment, the base station 100 and the terminal 200 set the timing for transmitting the PUSCH repeated signals based on the SRS transmission candidate subframes notified by the srs-SubframeConfig. By adjusting the transmission timing of the repeated signals continuously transmitted in the X subframes according to the SRS transmission candidate subframes, the base station 100 and the terminal 200 can avoid the conflict between the repeated transmission of the MTC coverage extension terminal and the SRS of the existing LTE system.

[0129] In addition, as the parameter X for continuously transmitting the repeated signals, a value not less than or equal to the number of consecutive subframes not set as SRS transmission candidate subframes is set. Therefore, in the X subframes, no SRS transmission candidate subframes are included, and no phase discontinuity occurs in the repeated transmission signals.

[0130] Thus, according to the present embodiment, by using the multiple subframe channel estimation and symbol-level synthesis of the X subframes in the base station 100, the channel estimation accuracy and the reception quality can be improved.

[0131] Furthermore, in Figure 10 it is described that the start subframe of the repeated signal (MTC narrowband) in the PUSCH repetition is set as the next subframe of the SRS transmission candidate subframe. However, the repeated signal (MTC narrowband) is not limited to being mapped to the case of including the next subframe of the SRS transmission candidate subframe, and can also be mapped to any one of the consecutive subframes not set as SRS transmission candidate subframes. That is, the X subframes can be mapped to the consecutive subframes not set as SRS transmission candidate subframes. For example, the last subframe of the repeated signal (MTC narrowband) can also be set as the subframe immediately before the SRS transmission candidate subframe.

[0132] (Embodiment 2)

[0133] As described above, the parameter Y is the hopping period (X ≤ Y) obtained by adding the round-trip time (here, 1 subframe) in the consecutive X subframes.

[0134] Figure 11 An example of mapping of the signal of the MTC narrowband indicating the case where srs-SubframeConfig = 9, X = 4, and the return time = 1 subframe (i.e., Y = 5).

[0135] In addition, Figure 11 in, the subframe at the start of the X = 4 subframes that continuously transmit the repeated signal is mapped with the repeated signal so as to be the next subframe of the SRS transmission candidate subframe. That is, in Figure 11 in, the next subframes of the SRS transmission candidate subframe, i.e., the second subframe and the twelfth subframe, become the subframes at the start of the X = 4 subframes.

[0136] Here, in the case where srs-SubframeConfig = 9, the transmission interval (T SFC ) of transmitting the SRS = 10, and Δ SFC = 0, so the transmission interval T SFC is twice the length of Y. In addition, in the case where srs-SubframeConfig = 9, the number of consecutive subframes not set as the SRS transmission candidate subframes is 9 subframes. That is, in Figure 11 in, among the 9 consecutive subframes not set as the SRS transmission candidate subframes, the remaining subframes other than the 4 subframes mapped with the repeated signal (MTC narrowband) and the 1 subframe set as the return time are 4 subframes. The number of the remaining subframes is the same as the parameter X.

[0137] Thus, in the case where T SFC ≥ nY (n is an integer of 2 or more), as Figure 11 shown, when the subframe at the start of the X subframes that continuously transmit the repeated signal is aligned with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig, there may be a decrease in transmission efficiency due to srs-SubframeConfig.

[0138] Therefore, in the present embodiment, a method of mapping the repeated signal without reducing the transmission efficiency according to srs-SubframeConfig, the parameter X, and the return time (i.e., the parameter Y) will be described.

[0139] Furthermore, the base station and the terminal of the present embodiment have the same basic structure as the base station 100 and the terminal 200 of the first embodiment, so Figure 8 and Figure 9 will be referred to for description.

[0140] Hereinafter, in the same manner as in the first embodiment, the case where the transmission interval (T SFC ) of transmitting the SRS = 5 or 10, and the transmission interval (T SFC) The case where there is only 1 SRS transmission candidate subframe in (Δ SFC The case of having only one value). That is, it shows Figure 2 the cases where srs-SubframeConfig = 3, 4, 5, 6, 9, 10, 11, 12 as shown.

[0141] The base station 100 notifies the terminal 200 of srs-SubframeConfig as an upper layer notification inherent to the cell for setting the SRS resource candidate group.

[0142] In addition, before transmitting and receiving the PUSCH, the base station 100 notifies the terminal 200 in advance of the repetition count (N Rep ). The repetition count (N Rep ) can be notified to the terminal 200 by the base station 100 through the upper layer inherent to the terminal, or can be notified using the PDCCH for MTC.

[0143] In addition, before transmitting and receiving the PUSCH, the base station 100 notifies the terminal 200 in advance of the values of parameter X and parameter Y.

[0144] The terminal 200 repeats the transmission of the PUSCH by the repetition count (N Rep ) notified from the base station 100. When the repetition count (N Rep ) is greater than X, as Figure 5 shown, after the terminal 200 transmits repeated signals in a continuous manner of X subframes using the same resource, it changes the frequency band of 1.4 MHz (MTC narrowband) through frequency hopping and then uses the same resource to transmit repeated signals in a continuous manner of X subframes again. Furthermore, as Figure 5 shown, a return time (for example, equivalent to 1 subframe) is ensured during frequency hopping.

[0145] In this embodiment, during the repeated transmission of the PUSCH, the terminal 200 maps the repeated signals transmitted continuously in X subframes (i.e., MTC narrowband) in the subframes so that they do not overlap with the SRS transmission candidate subframes notified by srs-SubframeConfig.

[0146] In this embodiment, when T SFC ≥ nY (n is 2 or more), the subset of the subframes at the start of the X subframes for continuously transmitting repeated signals is aligned with the next subframe of the SRS transmission candidate subframes notified by srs-SubframeConfig. In addition, n - 1 times of frequency hopping are allowed within the transmission interval (T SFC ) for transmitting the SRS.

[0147] That is, the terminal 200 takes X subframes as a unit and within the transmission interval (T SFC) The repeated signal is sent in X subframes in n groups. At this time, for each n times, the terminal 200 aligns the subframe at the start of the X subframes that continuously send the repeated signal with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig. That is, the start subframe of the subset composed of n groups of X subframes is set as the next subframe of the SRS transmission candidate subframe.

[0148] Figure 12 An example of the mapping of the signal of the MTC narrowband indicating the case where srs-SubframeConfig = 9, X = 4, and the return time = 1 subframe (i.e., Y = 5). That is, in Figure 12 satisfies the relationship of T SFC ≥ 2 × Y (n = 2).

[0149] As Figure 12 shown, the repeated signal is mapped in the 2nd subframe to the 5th subframe, the 7th subframe to the 10th subframe, and the 12th subframe to the 15th subframe. Here, as Figure 12 shown, the start subframe of each of the 2nd subframe to the 5th subframe and the 12th subframe to the 15th subframe is the next subframe of the SRS transmission candidate subframe. That is, as Figure 12 shown, for each n = 2 times, the terminal 200 aligns the subframe at the start of the X subframes that continuously send the repeated signal with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig. Then, the terminal 200 performs (n - 1) times of frequency hopping within the transmission interval (T SFC = 10) of the SRS.

[0150] That is, the start subframe of the subset composed of n = 2 groups of X subframes is aligned with the next subframe of the SRS transmission candidate subframe. Thus, this subset is mapped to consecutive subframes ([[]] Figure 12 is 9 subframes) that are not set as SRS transmission candidate subframes. In addition, within this subset, (n - 1) = 1 time of frequency hopping is performed within the transmission interval (T SFC ) = 10 subframes of the SRS transmission.

[0151] In this way, in this embodiment, when the transmission interval T SFC of the SRS is equal to or greater than n times (n is an integer of 2 or more) of the sum value Y of the value of X and the return time, the start subframe of the subset composed of n groups of X subframes is set as the next subframe of the SRS transmission candidate subframe.

[0152] In this way, within the transmission interval of the SRS transmission, the repeated signal can be mapped to the subframes that are not set as SRS transmission candidate subframes to the maximum extent. Therefore, a decrease in transmission efficiency can be prevented.

[0153] In addition, similar to Embodiment 1, it is also possible to avoid the conflict between the repeated transmission of the MTC coverage extension terminal and the SRS transmission of the existing system. As a result, the phase discontinuity does not occur in the repeated transmission signal, so by using multiple subframe channel estimation and symbol-level synthesis of X subframes in the base station 100, the channel estimation accuracy and reception quality can be improved.

[0154] Furthermore, in the present embodiment, it is assumed that the value of nY is less than or equal to T SFC (T SFC ≥nY). That is, when srs-SubframeConfig = 3, 4, 5, 6 (T SFC = 5, Δ SFC is 1), it has the function of multiple subframe channel estimation and symbol-level synthesis within the entire X = 2 subframes (however, only in the case of X = Y), and when srs-SubframeConfig = 9, 10, 11, 12 (T SFC = 10, Δ SFC is 1), it has the function of multiple subframe channel estimation and symbol-level synthesis within the entire X = 2, 3, 4 subframes.

[0155] (Embodiment 3)

[0156] The base station and terminal of the present embodiment have the same basic structure as the base station 100 and terminal 200 of Embodiment 1, so references Figure 8 and Figure 9 are cited for description.

[0157] Hereinafter, the case where the transmission interval (T SFC ) of the SRS transmission is 2, 5 or 10, and there is only one SRS transmission candidate subframe among the transmission intervals (T SFC ) of the SRS transmission (Δ SFC has only one value) is described. That is, the cases of srs-SubframeConfig = 1, 2, 3, 4, 5, 6, 9, 10, 11, 12 shown in Figure 2 are described.

[0158] In addition, in the present embodiment, it is assumed that the value of X is greater than the number of consecutive subframes that are not set as SRS transmission candidate subframes (the case where the transmission interval T SFC is greater than or equal to). That is, when srs-SubframeConfig = 1, 2 (T SFC = 2), X≥2, when srs-SubframeConfig = 3, 4, 5, 6 (T SFC = 5), X≥5, when srs-SubframeConfig = 9, 10, 11, 12 (TSFC = 10), X ≥ 10.

[0159] As an upper layer notification inherent to the cell that sets the SRS resource candidate group, the base station 100 notifies the terminal 200 of srs-SubframeConfig.

[0160] In addition, before transmitting and receiving the PUSCH, the base station 100 notifies the terminal 200 in advance of the number of repetitions (N Rep ). The number of repetitions (N Rep ) can be notified from the base station 100 to the terminal 200 through the upper layer inherent to the terminal, or can be notified using the PDCCH for MTC.

[0161] In addition, before transmitting and receiving the PUSCH, the base station 100 notifies the terminal 200 in advance of the value of the parameter X.

[0162] The terminal 200 repeatedly transmits the PUSCH by the number of repetitions (N Rep ) notified from the base station 100. When the number of repetitions (N Rep ) is greater than X, as Figure 5 shown, after the terminal 200 transmits a repeated signal in a continuous manner of X subframes using the same resource, it changes the frequency band of 1.4 MHz (MTC narrowband) by frequency hopping, and then transmits a repeated signal again in a continuous manner of X subframes using the same resource. Furthermore, as Figure 5 shown, a return time (for example, equivalent to 1 subframe) is ensured during frequency hopping.

[0163] At this time, during the repeated transmission of the PUSCH, the terminal 200 aligns the start subframe of the X subframes that continuously transmit the repeated signal with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig. In addition, the terminal 200 truncates the symbol (here, the final SC-FDMA symbol within the subframe) that is a candidate for the SRS mapped in the SRS transmission candidate subframe among the subframes that transmit the repeated signal.

[0164] Figure 13 An example of the mapping of the signal in the MTC narrowband indicating the case where srs-SubframeConfig = 3 and X = 2. That is, in Figure 13 , T SFC = X.

[0165] As Figure 13 shown, the start subframe of each of the X = 2 subframes is set as the next subframe of the SRS transmission candidate subframe.

[0166] However, in Figure 13 , the value of X (X = 2) and the transmission interval T of the SRS SFCis the same and greater than the number of consecutive subframes (1 subframe) not set as an SRS transmission candidate subframe. Therefore, one or more ( Figure 13 in this case, 1) of the subframes within the transmission interval of the X subframes become SRS transmission candidate subframes. That is, when the value of X is the transmission interval T SFC or more, there may be a conflict between the repeated signal (data signal) and the SRS in one or more subframes.

[0167] As described above, the terminal 200 prevents a conflict between the SRS and the data signal by transmitting data using the final SC-FDMA symbol (SRS resource candidate) of the SRS transmission candidate subframe. Therefore, in the present embodiment, as a format for transmitting data using the SRS transmission candidate subframe, similar to other subframes, the terminal 200 maps data to 12 SC-FDMA symbols other than the DMRS within the 1 subframe shown in Figure 1 and then truncates the final SC-FDMA symbol.

[0168] As described above, by allocating the first subframe of the X subframes that continuously transmit the repeated signal to the subframe next to the SRS transmission candidate subframe notified by srs-SubframeConfig, as Figure 13 shown, when X = T SFC the last subframe (the second subframe) of the X subframes overlaps with the SRS transmission candidate subframe. Therefore, the symbol (truncated symbol) for which the terminal 200 does not perform data transmission is only the final SC-FDMA symbol of the last subframe of the X subframes.

[0169] Thus, only the last 1 symbol has a phase discontinuity caused by truncation in the X subframes. In other words, in the X subframes, the phase continuity is maintained except for the last 1 symbol. Therefore, the influence on the channel estimation and symbol-level synthesis of multiple subframes within the entire X subframes caused by the phase discontinuity can be minimized.

[0170] In contrast, assume that in Figure 13 the first subframe of the X = 2 subframes that continuously transmit the repeated signal is moved one subframe earlier. In this case, the first subframe in the X = 2 subframes overlaps with the SRS transmission candidate subframe, and the final SC-FDMA symbol of this subframe is truncated. In this case, a phase discontinuity occurs between the first subframe and the second subframe, so in the base station, channel estimation and symbol-level synthesis cannot be performed for multiple subframes within the entire X = 2 subframes.

[0171] In this way, by Figure 13The subframe at the start of the X=2 subframe that continuously transmits a repeated signal as shown is aligned with the next subframe of the SRS transmission candidate subframe. The base station 100 can perform multi-subframe channel estimation and symbol-level synthesis within the entire X=2 subframe (except for the last symbol of the second subframe), which can improve the channel estimation accuracy and reception quality.

[0172] Next, Figure 14 An example of the mapping of the signal of the MTC narrowband indicating the case of srs-SubframeConfig = 3 and X = 4. That is, in Figure 14 T SFC <X.

[0173] When X>T SFC the data signal overlaps with the SRS transmission candidate subframe in the subframes in the middle of the X subframe. In Figure 14 in the X = 4 subframe, the data signal overlaps with the SRS transmission candidate subframe in two subframes, namely the second subframe and the fourth subframe. Therefore, in Figure 14 the terminal 200 truncates the last SC-FDMA symbols of the two subframes, namely the second subframe and the fourth subframe, among the X = 4 subframes.

[0174] Here, if it is assumed that Figure 14 as shown, the subframe at the start of the X = 4 subframe that continuously transmits a repeated signal is moved one subframe forward, then the last SC-FDMA symbols of the first subframe and the third subframe in the X = 4 subframe are truncated. In this case, a phase discontinuity of the transmitted signal occurs between the first subframe and the second subframe, and further a phase discontinuity of the transmitted signal also occurs between the third subframe and the fourth subframe. Therefore, for the multi-subframe channel estimation and symbol-level synthesis within the entire X = 2 subframe, only the second subframe and the third subframe are used.

[0175] In contrast, in the present embodiment, as Figure 14 shown, the subframe at the start of the X = 4 subframe is aligned with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig. As a result, the last SC-FDMA symbols of the second subframe and the fourth subframe in the X = 4 subframe are truncated. In this case, although the number of truncated SC-FDMA symbols in the above assumption is the same, a phase discontinuity occurs only between the second subframe and the third subframe.

[0176] Therefore, the base station 100 can use the group of the first subframe and the second subframe, and the group of the third subframe and the fourth subframe to perform multi-subframe channel estimation and symbol-level synthesis within the entire X = 2 subframe, so that the channel estimation accuracy and reception quality can be improved.

[0177] In this way, in the present embodiment, the subframe at the start of the X subframe that continuously transmits a repeated signal is set to be the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig. In this way, the influence on the channel estimation and symbol-level synthesis of multiple subframes within the entire X subframe caused by phase discontinuity can be minimized. In addition, the channel estimation accuracy and reception quality can be improved.

[0178] (Embodiment 4)

[0179] The base station and the terminal of the present embodiment have the same basic structure as the base station 100 and the terminal 200 of Embodiment 1, so references Figure 8 and Figure 9 are used for the description.

[0180] Hereinafter, the transmission interval (T SFC ) of transmitting the SRS is described, where T SFC = 5 or 10, and in the transmission interval (T SFC ) of transmitting the SRS, there are two or more SRS transmission candidate subframes (the case where Δ Figure 2 ) has two or more values). That is, the cases where srs-SubframeConfig = 7, 8, 13, 14 shown in

[0181] are described.

[0182] The base station 100 notifies the terminal 200 of srs-SubframeConfig as a cell-specific upper-layer notification for setting the SRS resource candidate group.

[0183] In addition, before the transmission and reception of the PUSCH, the base station 100 notifies the terminal 200 in advance of the number of repetitions (N Rep ). The number of repetitions (N Rep ) can be notified from the base station 100 to the terminal 200 through the terminal-specific upper layer, or can be notified using the PDCCH for MTC.

[0184] In addition, before the transmission and reception of the PUSCH, the base station 100 notifies the terminal 200 in advance of the value of the parameter X. Figure 5 Figure 5 The terminal 200 repeats the transmission of the PUSCH by the number of repetitions (N Rep ) notified from the base station 100. When the number of repetitions (N SFC ) is greater than X, as shown in Figure 5 , after the terminal 200 transmits the repeated signal in a continuous X-subframe manner using the same resource, it changes the 1.4 MHz band (MTC narrowband) by frequency hopping and then transmits the repeated signal again in a continuous X-subframe manner using the same resource. Furthermore, as shown in Figure 5 , a return time (for example, equivalent to 1 subframe) is ensured during frequency hopping.

[0185] At this time, the terminal 200 aligns the subframe at the start of the X subframes that continuously transmit repeated signals in the PUSCH repetition transmission with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig and the subframes that are not set as SRS transmission candidate subframes.

[0186] Figure 15 An example of the mapping of the signal of the MTC narrowband indicating the case where srs-SubframeConfig = 7 and X = 2.

[0187] As Figure 15 shown, in srs-SubframeConfig = 7, the transmission interval (T SFC ) for transmitting SRS = 5, and among the transmission intervals (T SFC ) for transmitting SRS, there are 2 SRS transmission candidate subframes (Δ SFC = {0, 1}). That is, the 1st subframe, the 2nd subframe, the 6th subframe, the 7th subframe,..., the (5n + 1)th subframe and the (5n + 2)th subframe are SRS transmission candidate subframes.

[0188] In this case, as Figure 15 shown, the start subframes of each of the X = 2 subframes are set as the next subframe of the SRS transmission candidate subframe and are subframes other than the SRS transmission candidate subframe. In Figure 15 , the start subframes of each of the X = 2 subframes are the 3rd subframe, the 8th subframe,..., the (5n + 3)th subframe.

[0189] In addition, Figure 15 in, the value of X (X = 2) is less than or equal to the number of consecutive subframes (3 subframes) that are not set as SRS transmission candidate subframes. In addition, for the case of srs-SubframeConfig = 8 where the numbers of the transmission interval (T SFC ) and Δ SFC are the same as those in the case of srs-SubframeConfig = 7, it is the same. That is, in the cases of srs-SubframeConfig = 7 and 8, multiple subframe channel estimation and symbol-level synthesis within the entire X = 2 subframe can be performed.

[0190] That is, the parameter X, which is the processing unit i of the multiple subframe channel estimation and symbol-level synthesis, is set to any value that is not set to the number of consecutive subframes of the SRS transmission candidate subframe. In this way, when the value of X is not set to the number of consecutive subframes of the SRS transmission candidate subframe, the terminal 200 can map the repeated signal to a subframe other than the SRS transmission candidate subframe. Thus, the terminal 200 can map the repeated signal that is the object of the multiple subframe channel estimation and symbol-level synthesis and is continuously transmitted in the X subframes, avoiding the SRS transmission candidate subframe.

[0191] In addition, Figure 15 In the example, the first subframe of X=2 subframes that continuously transmit repeated signals is set as the next subframe of the SRS transmission candidate subframe and is not set as the SRS transmission candidate subframe. In this way, the terminal 200 can maximize the use of the consecutive subframes that are not set as the SRS transmission candidate subframe to map the repeated signal. In particular, when the value of X is less than the number of consecutive subframes that are not set as the SRS transmission candidate subframe, the terminal 200 can reliably avoid the SRS transmission candidate subframe and map the repeated signal by setting the first subframe of the X subframe as the next subframe of the SRS transmission candidate subframe and is not set as the SRS transmission candidate subframe.

[0192] As described above, according to this embodiment, even in the transmission interval (T SFC ), the conflict between the repeated transmission of the MTC coverage extension terminal and the SRS transmission of the existing system can also be avoided. As a result, no phase discontinuity occurs in the repeatedly transmitted signal, so the channel estimation accuracy and reception quality can be improved by using multiple subframe channel estimation and symbol-level synthesis of the X subframe in the base station 100.

[0193] Furthermore, when the value of X is equal to or greater than the number of consecutive subframes not set as SRS transmission candidate subframes (not shown), as in Embodiment 3, as a format for transmitting data in an SRS transmission candidate subframe, the subframes are removed in the same manner as other subframes. Figure 1 After data is mapped to the 12 SC-FDMA symbols of the DMRS in the 1 subframe shown, the terminal 200 can truncate the final SC-FDMA symbol (equivalent to the SRS resource candidate). At this time, by aligning the subframe at the beginning of the repeated signal in the X-subframe continuous mode with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig and the subframe not set as the SRS transmission candidate subframe, as in embodiment 3, the influence of phase discontinuity on the channel estimation and symbol-level synthesis of multiple subframes can be avoided or the influence can be minimized.

[0194] The above has described various embodiments of the present invention.

[0195] Furthermore, in the above embodiments, the repeated transmission of PUSCH is described as an example, but it is not limited to PUSCH, as long as it is Figures 11 to 15 a signal transmitted in the resources (MTC narrowband) for MTC terminals as shown. For example, for the repeated transmission of the uplink control channel (PUCCH: Physical Uplink Control Channel), the repeated signal can also be transmitted in the same manner as in Embodiments 1 to 4. Specifically, in the case of PUCCH repetition, the start subframe of the X subframes that continuously transmit the repeated signal can also be aligned with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig, or the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig and a subframe that is not set as the SRS transmission candidate subframe. In this way, conflicts between the PUCCH repeated transmission of the MTC coverage extension terminal and the SRS of the existing system can be avoided. Therefore, the base station 100 can improve the channel estimation accuracy and reception quality by performing channel estimation and symbol-level synthesis for multiple subframes. In addition, as in Embodiments 3 and 4, in the case where one or more subframes in the transmission interval of the X subframe conflict with the SRS transmission candidate subframe, the Shortened PUCCH format for avoiding conflicts between SRSs can also be adopted for transmission.

[0196] In addition, in the above embodiments, the case where the start subframe of the X subframes that continuously transmit the repeated signal is aligned with the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig, or the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig and a subframe that is not set as the SRS transmission candidate subframe is described. However, in the standard, it is also considered that only the start subframe of the N Rep times repeated signal is defined. For example, if the last subframe of the PDCCH for MTC repeated transmission is set as n, it can also be defined such that the PUSCH repeated transmission starts from the n + k subframe (k is the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig, or a subframe that is the next subframe of the SRS transmission candidate subframe notified by srs-SubframeConfig and satisfies k≥4 in the subframes that are not set as the SRS transmission candidate subframe).

[0197] In addition, the number of repetitions, the values of the parameters X or Y, and the values of the parameters defined by srs-SubframeConfig used in the above embodiments are examples, but are not limited to them.

[0198] In addition, in each of the above-described embodiments, one mode of the present invention has been described by way of an example of being configured by hardware, but the present invention may also be implemented by software in cooperation with hardware.

[0199] In addition, each functional block used in the description of the above embodiments is generally implemented as an integrated circuit, i.e., an LSI. The integrated circuit controls each functional block used in the description of the above embodiments, and may also include inputs and outputs. These functional blocks may be individually integrated into a single chip, or may be partially or entirely integrated into a single chip. Although referred to as an LSI here, depending on the degree of integration, it may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI.

[0200] In addition, the method of the integrated circuit is not limited to an LSI, and may also be implemented by a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, or a reconfigurable processor that can reconfigure the connection and setting of circuit units inside the LSI may also be used.

[0201] Furthermore, with the progress of semiconductor technology or other technologies derived therefrom, if there appears an integrated circuit technology that can replace the LSI, of course, such technology can be used for the integration of functional blocks. There is also a possibility of applying biotechnology and the like.

[0202] The structure adopted by the terminal of the present invention includes: a repetition unit that repeats an uplink signal within a plurality of subframes to generate a repeated signal; a control unit that sets the timing for transmitting the repeated signal based on information of a transmission candidate subframe of a sounding reference signal (SRS) indicating a measurement of reception quality for the uplink; and a transmission unit that transmits the repeated signal at the set timing.

[0203] In the terminal of the present invention, the repeated signal is in-phase synthesized by the base station for each of a continuous specified number of subframes among the plurality of subframes, and the first subframe of the specified number of subframes is the next subframe of the transmission candidate subframe.

[0204] In the terminal of the present invention, the repeated signal is in-phase synthesized by the base station for each of a continuous specified number of subframes among the plurality of subframes, the specified number is lower than the transmission interval of the SRS, and the specified number of subframes is a continuous subframe not set as the transmission candidate subframe.

[0205] In the terminal of the present invention, the repeated signal is in-phase synthesized by the base station for each of a consecutive specified number of subframes among the plurality of subframes. For the repeated signal, frequency hopping is performed for each of the specified number of subframes. When the transmission interval of the SRS is n times (n is an integer of 2 or more) or more the sum value of the specified number and the number of subframes required for switching the frequency hopping band, the subframe at the start of the subset composed of n groups of the specified number of subframes is the next subframe of the transmission candidate subframe.

[0206] In the terminal of the present invention, during the transmission interval of the SRS, frequency hopping is performed (n - 1) times for the repeated signal.

[0207] In the terminal of the present invention, the repeated signal is in-phase synthesized by the base station for each of a consecutive specified number of subframes among the plurality of subframes. When the specified number is equal to or greater than the transmission interval of the SRS, the control unit punctures the symbols in the transmission candidate subframe among the subframes for transmitting the repeated signal that are candidates for mapping the SRS.

[0208] In the terminal of the present invention, the repeated signal is in-phase synthesized by the base station for each of a consecutive specified number of subframes among the plurality of subframes. The start subframe of the specified number of subframes is the next subframe of the transmission candidate subframe and is a subframe other than the transmission candidate subframe.

[0209] The structure adopted by the base station of the present invention includes: a control unit that sets the timing for a terminal to transmit a repeated signal generated by repeating an uplink signal within a plurality of subframes based on information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; a receiving unit that receives the repeated signal; and a synthesizing unit that in-phase synthesizes the repeated signals of the plurality of subframes based on the set timing.

[0210] The transmission method of the present invention includes the following steps: generating a repeated signal by repeating an uplink signal within a plurality of subframes; setting the timing for transmitting the repeated signal based on information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; and transmitting the repeated signal at the set timing.

[0211] The receiving method of the present invention includes the following steps: setting the timing for a terminal to transmit a repeated signal generated by repeating an uplink signal within a plurality of subframes based on information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink, receiving the repeated signal, and in-phase synthesizing the repeated signals of the plurality of subframes based on the set timing.

[0212] Industrial Applicability

[0213] One embodiment of the present invention is useful for a mobile communication system or the like.

[0214] Reference Signs Explanation

[0215] 100 Base station

[0216] 200 Terminal

[0217] 101, 206 Control unit

[0218] 102 Control signal generation unit

[0219] 103, 208 Encoding unit

[0220] 104, 209 Modulation unit

[0221] 105, 213 Signal distribution unit

[0222] 106, 214 IFFT unit

[0223] 107, 215 CP addition unit

[0224] 108, 216 Transmission unit

[0225] 109, 201 Antenna

[0226] 110, 202 Reception unit

[0227] 111, 203 CP removal unit

[0228] 112, 204 FFT unit

[0229] 113 Combining unit

[0230] 114 Demapping unit

[0231] 115 Channel estimation unit

[0232] 116 Equalization unit

[0233] 117 Demodulation unit

[0234] 118 Decoding unit

[0235] 119 Decision unit

[0236] 205 Extraction unit

[0237] 207 DMRS generation unit

[0238] 210 Multiplexing unit

[0239] 211 DFT unit

[0240] 212 repeat unit

Claims

1. Base station, comprising: A transmitting unit that transmits information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; And A receiving unit that receives a repeated signal which is generated by repeating a PUSCH and a PUCCH over a plurality of subframes; Regarding the transmitting unit, in the transmission candidate subframe of the SRS, the repeated signal of the PUCCH is generated using a shortened PUCCH format, The repeated signal of the PUSCH in the last SC-FDMA symbol configured in the transmission candidate subframe of the SRS is truncated.

2. The base station according to claim 1, The transmitting unit transmits information for indicating a transmission candidate subframe through a cell-specific high-layer signal.

3. The base station according to claim 1, The information represents a transmission candidate subframe of the SRS selected from a plurality of transmission candidate subframes of the SRS.

4. The base station according to claim 1, Regarding the number of consecutive subframes in which the repeated signal is transmitted, it is notified by the transmitting unit before the repeated signal of the PUCCH is generated.

5. The base station according to claim 1, After the repeated signal is generated, it is frequency-hopped every consecutive predetermined number of subframes.

6. The base station according to claim 1, The base station supports the MTC coverage enhancement mode.

7. Communication method of a base station, comprising: A transmitting step of transmitting information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; And A receiving step of receiving a repeated signal which is generated by repeating a PUSCH and a PUCCH over a plurality of subframes, In the transmitting step, in the transmission candidate subframe of the SRS, the repeated signal of the PUCCH is generated using a shortened PUCCH format, and the repeated signal of the PUSCH in the last SC-FDMA symbol configured in the transmission candidate subframe of the SRS is truncated.

8. Integrated circuit for a base station, processing: A transmitting step of transmitting information on a transmission candidate subframe of a sounding reference signal (SRS) representing a measurement of reception quality for the uplink; and A receiving step of receiving a repeated signal which is generated by repeating a PUSCH and a PUCCH over a plurality of subframes, In the transmitting step, in the transmission candidate subframe of the SRS, the repeated signal of the PUCCH is generated using a shortened PUCCH format, and the repeated signal of the PUSCH in the last SC-FDMA symbol configured in the transmission candidate subframe of the SRS is truncated.

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