JP6550606B2 - Communication device, communication method and integrated circuit - Google Patents

Description

  The present invention relates to a communication device, a communication method and an integrated circuit.

  In recent years, in the cellular mobile communication system, along with the multimediaization of information, it is becoming popular to transmit not only voice data but also large-capacity data such as still image data and moving image data. In LTE-Advanced (Long Term Evolution Advanced), studies are being actively conducted to achieve high transmission rates using wideband wireless bands, multiple-input multiple-output (MIMO) transmission technology, and interference control technology. There is.

  In LTE-Advanced, an extended control channel region called Enhanced PDCCH (EPDCCH), which is an extension of PDCCH (Physical Downlink Control CHannel) used for control signals, was designed. EPDCCH is arranged in a resource area (PDSCH (Physical Downlink Shared CHannel) area) to which downlink data is allocated. In addition, the base station defines a frequency resource (for example, RB (Resource Block)) for each terminal (also called UE (User Equipment)) in a resource region (EPDCCH region) where EPDCCH is arranged, and transmits a signal. Can be sent. For this reason, transmission power control for a control signal transmitted to a terminal existing near the cell edge, or interference control given from the own cell to another cell or interference given from another cell to the own cell by the transmitted control signal Control becomes feasible.

  Here, 1 RB has 12 subcarriers in the frequency direction, and has a width of 0.5 msec in the time direction. A unit obtained by combining two RBs in the time direction is called an RB pair. That is, the RB pair has 12 subcarriers in the frequency direction and has a width of 1 msec in the time direction. Further, when the RB pair represents a cluster of 12 subcarriers on the frequency axis, the RB pair may be simply referred to as RB. In the physical layer, the RP pair is also called a PRB pair (Physical RB pair). Also, a unit defined by one subcarrier and one OFDM symbol is a resource element (RE: Resource Element).

  In the EPDCCH region, a unit obtained by dividing each PRB pair into 16 resources is called EREG (Enhanced Resource Element Group), and a resource unit configured of 4 or 8 EREGs is called ECCE (Enhanced Control Channel Element). The number of ECCEs constituting the EPDCCH that transmits one control signal is called an aggregation level (AL). The EPDCCH can set a plurality of ALs (see, for example, Non-Patent Document 1). In each AL, “EPDCCH candidates” are defined in advance. Here, the EPDCCH candidate is a candidate of a region to which the control signal is mapped, and a search space which is a target of blind decoding (monitoring) by the terminal is configured by the plurality of EPDCCH candidates.

  In LTE-Advanced, it is possible to set a plurality of EPDCCH sets configured with ECCE sets (that is, control information allocation candidates) in which EPDCCH may be arranged per terminal. Since the position and the number N of PRB pairs to be used are set for each EPDCCH set, the flexibility of control signal arrangement is high.

  FIG. 1 shows an example in which an EPDCCH is mapped to a resource. The ECCE in which the EPDCCH is arranged is selected from the plurality of EPDCCH candidates. In FIG. 1, EPDCCH # 0 and EPDCCH # 1 are aggregation level 1 (AL1), EPDCCH # 2 is aggregation level 2 (AL2), and EPDCCH # 3 is aggregation level 4 (AL4). In FIG. 1, EPDCCH # 0 is arranged in ECCE # 0, EPDCCH # 1 is arranged in ECCE # 1, EPDCCH # 2 is arranged in ECCE # 2 and ECCE # 3, and EPDCCH # 3 is ECCE # 4, ECCE Located in # 5, ECCE # 6, and ECCE # 7. In FIG. 1, each ECCE is divided into four because it is arranged in four EREGs. As shown in FIG. 1, in the case of localized assignment, four EREGs are arranged in the same PRB pair, and in the case of distributed assignment, four EREGs are arranged in different PRB pairs.

  In addition, as an EPDCCH allocation method, there are “localized allocation” in which EPDCCHs are allocated together in positions close to each other on the frequency band, and “distributed allocation” in which EPDCCHs are distributed on the frequency band. The localized allocation is an allocation method for obtaining frequency scheduling gain, and can allocate the EPDCCH to a resource with good channel quality based on the channel quality information. In distributed allocation, EPDCCH can be distributed on the frequency axis to obtain frequency diversity gain. In LTE-Advanced, both search space for localized allocation and search space for distributed allocation can be set.

  Also, in LTE-Advanced, DL assignment for instructing data allocation in downlink (DL: Downlink) and UL grant for instructing data allocation in uplink (UL: Uplink) are transmitted by PDCCH or EPDCCH. The DL assignment notifies that the resource in the subframe in which this DL assignment is transmitted is allocated to the terminal. On the other hand, regarding UL grant, it is notified that resources in the target subframe predetermined by UL grant have been allocated to the terminal.

3GPP TS 36.213 V11.1.0, Physical layer procedures

  In LTE-Advanced, it is considered to arrange a small cell, which is a base station with low transmission power, to realize a high hot spot transmission rate. For example, as a carrier frequency for operating a small cell, a high frequency such as 3.5 GHz is a candidate. However, when a high-frequency wireless band is used, a high transmission rate can be expected at a short distance, but attenuation due to a transmission distance increases as the distance increases. Therefore, in the case of operating a mobile communication system using a high frequency radio band, there is a problem that the coverage area of the small cell becomes small. In the case of a small cell, it is also necessary to consider transmission power constraints, and the power that can be used for transmission per subframe is limited. Since the cell coverage area is determined by the range in which the control signal reaches, a technique for expanding the coverage area of the control signal is required for the small cell.

  Therefore, for example, it is conceivable to apply soft combining (sometimes called bundling) in which an EPDCCH including control information is arranged across a plurality of subframes. However, an EPDCCH arrangement method when applying soft combining has not been studied so far.

  An object of the present invention is to provide a communication apparatus, a communication method, and an integrated circuit capable of appropriately setting resources for allocating EPDCCH when soft combining is applied.

  A communication apparatus according to an aspect of the present invention receives a control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates repeated in a set of consecutive subframes in the downlink And, if uplink data to be transmitted is present in an uplink subframe determined based on the last subframe in the subframe set, the downlink data transmitted in the last subframe may be transmitted. When ACK / NACK information is multiplexed and transmitted on the uplink data, and there is no uplink data to be transmitted in the determined uplink subframe, the final sub-subject of the plurality of EPDCCH candidates Using the Physical Uplink Control Channel (PUCCH) resource associated with the EPDCCH candidate placed in the frame, the final It adopts a configuration comprising a transmission unit for transmitting the ACK / NACK information relating to downlink data transmitted in subframe, the.

  In the communication apparatus according to an aspect of the present invention, the transmission unit transmits a Physical Uplink Shared Channel (PUSCH) in an uplink subframe determined based on the last subframe.

  The communication method according to one aspect of the present invention receives control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates to be repeated in a set of consecutive subframes in the downlink, In the uplink subframe determined based on the last subframe of the set of subframes, if there is uplink data to be transmitted, ACK / NACK related to the downlink data transmitted in the last subframe. When there is no uplink data to be transmitted in the determined subframe when information is multiplexed with the uplink data and transmitted, the EPDCCH arranged in the last subframe among the plurality of EPDCCH candidates Transmitted in the last subframe, using the Physical Uplink Control Channel (PUCCH) resource associated with the candidate. It was to send the ACK / NACK information on the downlink data.

  An integrated circuit according to an aspect of the present invention is a receiving circuit that receives control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates to be repeated in a set of consecutive subframes in the downlink. And, if uplink data to be transmitted is present in an uplink subframe determined based on the last subframe in the subframe set, the downlink data transmitted in the last subframe may be transmitted. When ACK / NACK information is multiplexed and transmitted on the uplink data and there is no uplink data to be transmitted in the determined subframe, the ACK / NACK information is arranged in the last subframe among the plurality of EPDCCH candidates. Using the Physical Uplink Control Channel (PUCCH) resource associated with the selected EPDCCH candidate, Controlling a transmission circuit for transmitting the ACK / NACK information relating to downlink data transmitted with beam, a.

  According to the present invention, it is possible to appropriately set a resource for arranging an EPDCCH when soft combining is applied.

Diagram used to explain EPDCCH Diagram to explain soft combining The block diagram which shows the principal part structure of the base station which concerns on Embodiment 1 of this invention. The block diagram which shows the principal part structure of the terminal which concerns on Embodiment 1 of this invention. Block diagram showing configuration of base station according to Embodiment 1 of the present invention Block diagram showing configuration of terminal according to Embodiment 1 of the present invention The figure which shows the timing of PDSCH and PUCCH which concern on Embodiment 1 of this invention. The figure which shows the timing of PUSCH which concerns on Embodiment 1 of this invention The figure which shows switching of soft combining application which concerns on Embodiment 1 of this invention A diagram showing a setting example of EPDCCH candidates according to Embodiment 2 of the present invention A diagram showing a setting example of a search space of EPDCCH according to Embodiment 2 of the present invention A diagram showing a setting example of a search space of EPDCCH according to Embodiment 2 of the present invention The figure which shows the number of EPDCCH candidates which concerns on Embodiment 2 of this invention A diagram showing a setting example of EPDCCH candidates according to Embodiment 3 of the present invention The figure which shows the PRB pair (EREG) by which ECCE which concerns on Embodiment 3 of this invention is arrange | positioned A diagram showing a setting example of the number of EPDCCH candidates according to another embodiment of the present invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiment, the same components are denoted by the same reference numerals, and the description thereof will be omitted because it is duplicated.

First Embodiment
[Outline of communication system]
The communication system according to the present embodiment includes base station 100 and terminal 200. This communication system is, for example, an LTE-Advanced system. The base station 100 is, for example, a base station that supports the LTE-Advanced system, and the terminal 200 is, for example, a terminal that supports the LTE-Advanced system.

  In this embodiment, when transmitting EPDCCH for terminal 200, base station 100 can apply soft combining that transmits EPDCCH (control information) across a plurality of subframes (see FIG. 2). The receiving side (terminal 200) combines control information transmitted across a plurality of subframes and performs reception processing. The EPDCCH transmitted across a plurality of subframes is composed of a bit string including information bits and redundant bits, which is generated by error correction coding on the information bits. In addition, when receiving EPDCCH transmitted across a plurality of subframes, terminal 200 receives or transmits data after completing reception of EPDCCH, and transmits or receives ACK / NACK (response signal). Determine the timing to do it.

  Also, subframes to which EPDCCH soft combining is applied are preset for the terminal 200 by higher layer signaling. The setting of the subframe may be different for each terminal. Further, a subframe to which soft combining is not applied and a subframe to which soft combining is applied may be included in the same frame. In this way, EPDCCH soft combining is applied according to the reception quality of each subframe, such as soft combining is not applied to subframes with little interference and soft combining is applied to subframes with much interference. You can switch whether or not to.

  Note that the base station 100 and the terminal 200 can transmit and receive control information (DL assignment or UL grant) using the PDCCH region or the EPDCCH region. However, in the following description, in the EPDCCH region, the description will be simplified. Only transmission and reception of control information will be described.

  FIG. 3 is a block diagram showing the main configuration of base station 100 according to the present embodiment.

  In base station 100, setting section 102 sets an EPDCCH set configured with ECCE for assigning control information (allocation information) transmitted over a plurality of subframes in the plurality of subframes. The signal allocation unit 105 allocates control information to one of the ECCEs in each PRB pair of a plurality of subframes.

  FIG. 4 is a block diagram showing the main configuration of terminal 200 according to the present embodiment.

  In terminal 200, setting section 205 specifies ECCEs to which control information (assignment information) transmitted across a plurality of subframes is allocated, and which constitutes an EPDCCH set set in the plurality of subframes. . The control signal receiving unit 206 receives control information assigned to any one of the ECCEs in the PRB pair of each of the plurality of subframes.

[Configuration of base station 100]
FIG. 5 is a block diagram showing a configuration of base station 100 according to the present embodiment. In FIG. 5, the base station 100 includes an allocation information generation unit 101, a setting unit 102, an error correction coding unit 103, a modulation unit 104, a signal allocation unit 105, a transmission unit 106, a reception unit 107, A demodulation unit 108 and an error correction decoding unit 109 are included.

  When there is a downlink data signal (DL data signal) to be transmitted and an uplink data signal (UL data signal) to be allocated to the uplink (UL), the allocation information generation unit 101 allocates a data signal (RB) To generate assignment information (DL assignment and UL grant). DL assignment includes information related to DL data signal assignment. The UL grant includes information on the allocation resource of the UL data signal transmitted from the terminal 200. The DL assignment is output to the signal assignment unit 105, and the UL grant is output to the signal assignment unit 105 and the reception unit 107.

  The setting unit 102 sets one or a plurality of EPDCCH search spaces for each terminal 200. Specifically, setting section 102 sets, for each terminal 200, a PRB pair number for allocating a search space for EPDCCH, an ECCE index for each aggregation level, and an allocation method (localized allocation or distributed allocation) of the search space (EPDCCH). Set The search space for EPDCCH is configured by a plurality of allocation candidates (EPDCCH candidates). Each "allocation candidate" is composed of the same number of ECCEs as aggregation levels.

  When setting a plurality of EPDCCH search spaces for terminal 200, setting section 102 allocates an ECCE index for each search space.

  The setting unit 102 sets, for the terminal 200 to which soft combining is applied, a subframe (see FIG. 2) to which soft combination is applied. Also, the setting unit 102 sets an EPDCCH set in a plurality of subframes to which soft combining is applied, for the terminal 200 to which soft combining is applied. At this time, PRB pairs corresponding to the ECCEs constituting the EPDCCH set are arranged in each of the plurality of subframes. Thereby, in each subframe used for soft combining, the above-described search space is set based on the set EPDCCH set.

  The setting unit 102 outputs information on the set search space and information on a subframe number to which soft combining of EPDCCH is applied to the signal allocation unit 105. The information related to the search space includes, for example, a PRB pair number, the number of PRB pairs, and the like. Further, setting section 102 outputs information on PRB pairs set in the search space and information on EPDCCH allocation method to error correction coding section 103 as control information.

  The error correction coding unit 103 receives the transmission data signal (DL data signal) and the control information received from the setting unit 102, performs error correction coding on the input signal, and outputs the signal to the modulation unit 104.

  Modulation section 104 performs modulation processing on the signal received from error correction coding section 103 and outputs the modulated data signal to signal allocation section 105.

  The signal allocating unit 105 assigns allocation information (DL assignment and UL grant) received from the allocation information generating unit 101 to an ECCE (ECC of allocation candidate unit) corresponding to the PRB pair number indicated in the search space information received from the setting unit 102. Assign to one of them. At this time, when soft combining is set for the assignment information, signal assignment section 105 performs PRB of each of the plurality of subframes corresponding to the subframe number indicated in the information regarding soft combining received from setting section 102. The allocation information is allocated to any ECCE in the pair. Thereby, the allocation information is allocated to the PRB pair in which ECCE is arranged (see, for example, FIG. 1). Further, signal allocation section 105 allocates the data signal received from modulation section 104 to the downlink resource corresponding to the allocation information (DL assignment) received from allocation information generation section 101.

  Thus, the allocation information and the data signal are allocated to predetermined resources to form a transmission signal. The formed transmission signal is output to the transmission unit 106. Also, the signal assignment unit 105 notifies the reception unit 107 of the ECCE index of the ECCE used for the transmission of the DL assignment. When soft combining is applied, the signal assignment unit 105 may be referred to as the last subframe (hereinafter referred to as “final subframe”) among a plurality of subframes used for DL assignment transmission. ) To the receiving unit 107.

  Transmitting section 106 performs radio transmission processing such as up-conversion on the input signal and transmits it to terminal 200 via the antenna.

  The receiving unit 107 receives a signal transmitted from the terminal 200 via an antenna and outputs the signal to the demodulation unit 108. Specifically, the reception unit 107 separates the signal corresponding to the resource indicated by the UL grant received from the allocation information generation unit 101 from the reception signal, and performs reception processing such as down conversion on the separated signal. It is output to the demodulation unit 108 later. The receiving unit 107 extracts (receives) an A / N signal from a signal corresponding to the PUCCH resource associated with the ECCE index received from the signal allocating unit 105.

  Demodulation section 108 performs demodulation processing on the input signal, and outputs the obtained signal to error correction decoding section 109.

  Error correction decoding section 109 decodes the input signal and obtains a received data signal from terminal 200.

[Configuration of terminal 200]
FIG. 6 is a block diagram showing a configuration of terminal 200 according to the present embodiment. In FIG. 6, a terminal 200 includes a receiving unit 201, a signal separating unit 202, a demodulating unit 203, an error correction decoding unit 204, a setting unit 205, a control signal receiving unit 206, an error correction coding unit 207, , A modulation unit 208, a signal assignment unit 209, and a transmission unit 210.

  The receiving unit 201 receives a signal transmitted from the base station 100 via an antenna, performs a receiving process such as down-conversion, and outputs the signal to the signal separating unit 202.

  The signal separation unit 202 extracts a control signal related to resource allocation from the reception signals received from the reception unit 201, and outputs the extracted signal to the control signal reception unit 206. Also, the signal separation unit 202 extracts a signal (that is, a DL data signal) corresponding to the data resource indicated by the DL assignment output from the control signal reception unit 206 from the reception signal, and transmits the extracted signal to the demodulation unit 203. Output. Note that, when EPDCCH soft combining is applied, the signal separation unit 202 is a signal corresponding to a data resource (DL data signal) based on the last subframe among a plurality of subframes used for soft combining. Are extracted from the received signal.

  Demodulation section 203 demodulates the signal output from signal separation section 202 and outputs the demodulated signal to error correction decoding section 204.

  The error correction decoding unit 204 decodes the demodulated signal output from the demodulation unit 203, and outputs the obtained received data signal. In particular, the error correction decoding unit 204 sets “information about the PRB pair set in the search space” and “information about the subframe to which EPDCCH soft combining is applied” transmitted from the base station 100 as a control signal. Output to 205.

  The setting unit 205 identifies the search space set in the own device (terminal 200) that uses EPDCCH. For example, the setting unit 205 first specifies a PRB pair to be set in the search space based on information received from the error correction decoding unit 204. Next, the setting unit 205 identifies an EPDCCH to which soft combining is applied based on information on a subframe to which soft combining of EPDCCH is applied. Then, setting section 205 determines the ECCE index of the search space corresponding to the PRB pair. Thereby, the setting unit 205 specifies an ECCE to which an EPDCCH transmitted across a plurality of subframes is allocated (an ECCE configuring an EPDCCH set in the plurality of subframes). At this time, when a plurality of EPDCCH search spaces are set, the setting unit 205 allocates an ECCE index for each search space. Also, the setting unit 205 specifies which ECCE index is set as an EPDCCH candidate for each aggregation level according to a common rule between the base station 100 and the terminal 200 that is predetermined for each terminal 200. For example, the setting unit 205 specifies an ECCE index that is an EPDCCH candidate for each aggregation level, based on whether UE ID (terminal-specific ID) and soft combining are applied. Next, setting section 205 outputs, to control signal receiving section 206, information on the PRB pair and ECCE set as the search space.

  The control signal reception unit 206 performs blind decoding on the ECCE corresponding to the PRB pair indicated in the information received from the setting unit 205 in the signal component received from the signal separation unit 202, thereby controlling the control signal (DL Detect assignment or UL grant). That is, the control signal receiving unit 206 receives a control signal allocated to one of a plurality of allocation candidates that configure the search space set by the setting unit 205. When EPDCCH soft combining is applied, control signal receiving section 206 receives a control signal assigned to one of ECCEs in each PRB pair of a plurality of subframes. The control signal reception unit 206 outputs the detected DL assignment addressed to the own device to the signal separation unit 202, and outputs the detected UL grant addressed to the own device to the signal assignment unit 209. In addition, the control signal receiving unit 206 outputs the ECCE index of the ECCE in which the DL assignment is detected to the signal assignment unit 209.

  Error correction coding section 207 receives the transmission data signal (UL data signal) as an input, performs error correction coding on the transmission data signal, and outputs the result to modulation section 208.

  Modulating section 208 modulates the signal received from error correction coding section 207, and outputs the modulated signal to signal allocation section 209.

  The signal allocation unit 209 allocates the signal received from the modulation unit 208 according to the UL grant received from the control signal reception unit 206 and outputs the signal to the transmission unit 210. At this time, when EPDCCH soft combining is applied, the signal allocating unit 209 determines a transmission subframe of the signal based on a final subframe among a plurality of subframes to which soft combining is applied. Further, the signal assignment unit 209 assigns the A / N signal received from the error correction decoding unit 204 to a predetermined resource. Specifically, when there is a transmission data signal, signal allocation section 209 multiplexes the transmission data signal with the A / N signal and outputs the multiplexed signal to transmission section 210. On the other hand, when there is no transmission data signal, the signal allocation unit 209 identifies a PUCCH resource based on the ECCE index received from the control signal reception unit 206, allocates an A / N signal to the identified PUCCH resource, Output to 210. At this time, when EPDCCH soft combining is applied, the signal allocation unit 209 determines an A / N signal transmission subframe based on the last subframe among a plurality of subframes to which soft combining is applied. Do.

  The transmission unit 210 performs transmission processing such as up-conversion on the input signal and transmits it.

[Operation of Base Station 100 and Terminal 200]
The operations of base station 100 and terminal 200 having the above configuration will be described.

  In the following, (1) PDSCH timing, (2) uplink A / N signal (UL ACK / NACK) timing, and (3) PUSCH timing when EPDCCH soft combining is applied. Each will be described.

[PDSCH timing]
The base station 100 and the terminal 200 use the PDDC transmission timing (that is, the subframe in which the PDSCH is allocated) specified by the DL assignment notified using the EPDCCH to which soft combining is applied to the EPDCCH to which soft combining is applied. Is set to the last subframe among the plurality of subframes in which is arranged.

  FIG. 7 shows a setting example of PDSCH. As shown in FIG. 7, when soft combining using two subframes of subframe # 0 and subframe # 1 is applied, base station 100 selects PDSCH for terminal 200 as one of the two subframes. , And are arranged in subframe # 1, which is the final subframe. That is, as shown in FIG. 7, in DL assignment notified using EPDCCH arranged in subframe # 0 and subframe # 1, a resource in subframe # 1 is designated as a resource for PDSCH. Ru.

  That is, base station 100 (signal allocation section 105) uses downlink data (PDSCH) instructed by EPDCCH (DL assignment) as the last subframe among a plurality of subframes used for soft combining. Assign to

  On the other hand, in FIG. 7, terminal 200 (control signal receiving section 206) performs blind decoding on ECCEs arranged in subframe # 0 and subframe # 1 to which soft combining is applied, so that terminal 200 Detect a DL assignment for Then, the terminal 200 (the signal separation unit 202) extracts a PDSCH (DL data signal) in subframe # 1, which is the final subframe, based on the detected DL assignment.

  Here, in terminal 200, detection of DL assignment notified using EPDCCH to which soft combining is applied is performed after receiving the last subframe. Then, after detecting the DL assignment, the terminal 200 specifies that the PDSCH is assigned to the PRB pair designated by the DL assignment, and starts PDSCH reception processing.

  Therefore, if the PDSCH is arranged in a subframe before the last subframe, the terminal 200 assigns it as a PDSCH until the identification (detection) of the PRB pair assigned to the PDSCH is completed. Received signals received in all possible PRB pairs must be stored in a buffer.

  On the other hand, in the present embodiment, PDSCH is arranged in the last subframe among a plurality of subframes to which soft combining is applied. By so doing, it is possible to minimize the period for storing the received signal received in the buffer from the PDSCH reception timing until the EPDCCH detection is completed. In other words, even if the EPDCCH soft combining is applied, if the EPDCCH soft combining is not applied for the period for storing the received signal received from the PDSCH reception timing to the completion of the EPDCCH detection timing in the buffer (non soft combining It can be made to be the same as the said period in. This can prevent an increase in the size of the buffer that the terminal 200 should have.

[UL ACK / NACK timing]
In LTE-Advanced, after receiving the PDSCH, the terminal performs reception determination (error determination) and transmits an uplink A / N signal (UL ACK / NACK) to the base station 100 (not shown). Also, subframes in which uplink A / N signals are transmitted are predetermined. Specifically, in the case of an FDD (Frequency Division Duplex) system, a subframe in which an uplink A / N signal is transmitted is set after 4 subframes of a subframe to which a PDSCH is assigned, and is set to TDD (Time Division Duplex). In the case of the system, TDD UL-DL configuration (timing setting in units of subframes of downlink communication (DL) and uplink communication (UL) per frame) is defined. However, in any of the FDD system and the TDD system, the transmission timing of the uplink A / N signal is always set four or more subframes of PDSCH or more.

  In this embodiment, uplink A / N signal transmission timing (a subframe in which UL ACK / NACK is transmitted) is defined according to a PDSCH reception subframe. In the case of the FDD system, it is set after 4 subframes of the PDSCH reception subframe. In the case of the TDD system, the PDSCH reception subframe is used as a reference, and the specification is followed for each TDD UL-DL configuration. The uplink A / N signal is transmitted in the PUSCH region when there is PUSCH transmission, and is transmitted in the PUCCH region when there is no PUSCH transmission.

  In LTE-Advanced, when transmitting uplink A / N signals in the PUCCH region, the smallest ECCE number among the ECCEs constituting the EPDCCH in which the DL assignment is arranged (that is, the EPDCCH in the subframe in which the PDSCH is transmitted) By specifying the PUCCH resource (resource instructed by implisit) associated with, the PUCCH resource between terminals is automatically assigned (implisit) so as not to collide.

  Therefore, when the EPDCCH soft combining is applied, the base station 100 and the terminal 200 specify the PUCCH resource associated with the EPDCCH ECCE number arranged in the subframe in which the PDSCH is transmitted.

  That is, terminal 200 is associated with ECCEs arranged in subframes to which downlink data (PDSCH) assigned by EPDCCH (DL assignment) is assigned among a plurality of subframes used for soft combining. In the PUCCH, an A / N signal (response signal) for the downlink data is transmitted. Therefore, when the ECCE numbers assigned by the subframes are different, the ECCE associated with the PUCCH resource used for A / N signal transmission is not necessarily the smallest ECCE number among the ECCEs constituting the EPDCCH. Similarly, base station 100 (receiving section 107) is arranged in a subframe to which downlink data (PDSCH) instructed to be assigned by EPDCCH (DL assignment) is assigned among a plurality of subframes used for soft combining. The PUCCH associated with the received ECCE receives an A / N signal (response signal) for the downlink data.

  For example, when a PDSCH is arranged in the last subframe among a plurality of subframes to which EPDCCH soft combining is applied, the base station 100 and the terminal 200 use the EPDCCH ECCE number arranged in the last subframe. The PUCCH resource to which the uplink A / N signal for the PDSCH is allocated is specified. Specifically, in FIG. 7, PDSCH is arranged in subframe # 1 which is the final subframe among subframe # 0 and subframe # 1 to which soft combining of EPDCCH is applied. Therefore, in FIG. 7, base station 100 and terminal 200 assign PUCCH resources associated with the ECCE number of the EPDCCH arranged in subframe # 1 in subframe # 5 after four subframes of subframe # 1. , And identifies the PUCCH resource to which the uplink A / N signal for PDSCH is allocated.

  By doing in this way, even when a terminal to which EPDCCH soft combining is applied and a terminal to which EPDCCH soft combining is not applied share an EPDCCH search space, the base station 100 can both In the subframe to which the PDSCH for the terminal is assigned, the ECCE number used for the EPDCCH for these terminals is assigned. As a result, in this subframe, ECCE numbers are assigned to these terminals in consideration of collision of PUCCH resources, so PUCCH resources are automatically assigned (implisit) so as not to collide between terminals. .

[PUSCH timing]
In LTE-Advanced, the terminal transmits PUSCH after receiving UL grant. A subframe in which PUSCH is transmitted is determined in advance. Specifically, in the case of an FDD system, the subframe to which PUSCH is transmitted is set after 4 subframes of the subframe to which a UL grant is assigned. In the case of a TDD system, the subframe is specified for each TDD UL-DL configuration. Has been. Further, when the number of UL subframes is larger than the number of DL subframes in one frame, it is also possible to specify PUSCHs of a plurality of UL subframes in one DL subframe. However, also in this case, the subframe in which the PUSCH is transmitted is always set four or more subframes after UL grant.

  In addition, after detecting UL grant, the terminal identifies that the PRB pair designated by UL grant is assigned to PUSCH, and determines the size and transmission method of data (PUSCH). Therefore, in the UE, if a certain interval (4 subframes or more in LTE-Advanced) is not provided from the last subframe (when UL grant detection is completed) among the subframes to which EPDCCH soft combining is applied, the PUSCH Can not prepare for the sending process of

  Therefore, in the present embodiment, the PUSCH transmission timing specified by the UL grant that is transmitted using the EPDCCH to which soft combining is applied is selected from among a plurality of subframes in which the EPDCCH to which soft combining is applied is arranged. Identify the last subframe as a reference. EPSCHCH soft combining applies the interval from UL grant detection timing to PUSCH transmission preparation by specifying PUSCH transmission timing (subframe for transmitting and receiving PUSCH) based on the final subframe of soft combining. If not, it can be done the same way.

  In particular, in a TDD system, UL grants are made even for DL subframes according to the correspondence between UL grant transmit / receive timing and PUSCH transmit / receive timing (UL grant-PUSCH timing) defined for each UL-DL configuration. There are subframes that are not transmitted. Therefore, in the case of the TDD system, the last subframe of the plurality of subframes used for soft combining is the same as the transmission subframe of EPDCCH including UL grant.

  FIG. 8 shows a subframe in the case of UL-DL configuration # 1 as an example. As shown in FIG. 8, in UL-DL configuration # 1, subframes # 0, # 4, # 5, and # 9 are DL subframes, and subframes # 1 and # 6 are special subframes (EPDCCH and PDSCH). Subframes # 2, # 3, # 7, and # 8 are UL subframes. Also, as shown in FIG. 8, UL grant-PUSCH timing is defined in advance, and subframes where UL grant can be placed are subframes # 1, # 4, # 6, and # 9, and are notified in each subframe. For the UL grant, PDSCH is allocated in UL subframes # 7 and # 8, subframe # 2 of the next frame (not shown), and subframe # 3 of the next frame.

  On the other hand, as shown in FIG. 8, when soft combining is applied, UL grants may be arranged even in subframes in which UL grants are not transmitted. Therefore, in this embodiment, when soft combining of EPDCCH including UL grant is applied, the final subframe of the subframes in which EPDCCH to which soft combining is applied is applied, when soft combining is not applied. Let UL grant be a subframe that can be transmitted.

  By doing this, it is possible to operate soft combining without changing the PUSCH timing from the UL grant detection timing.

  For example, in FIG. 8, only subframes # 1, # 4, # 6 and # 9 are set as the last subframe of soft combining. Specifically, in FIG. 8, soft combining of EPDCCH including UL grant is set in subframes # 0 and # 1 and subframes # 5 and # 6. As shown in FIG. 8, the EPDCCH including the UL grant is also allocated to subframes # 0 and # 5 where the UL grant is not allocated when soft combining is not applied. Even in this case, the transmission timing of the PUSCH for the UL grant notified using the EPDCCH is specified based on the final subframe of the subframes in which the EPDCCH is transmitted. That is, when soft combining including UL grant is applied, soft combining is applied to the PUSCH timing (the first transmission subframe of PUSCH) specified by UL grant transmitted using the EPDCCH to which Soft combining is applied (the first transmission subframe of PUSCH). The final subframe in which the EPDCCH is allocated is determined as a reference. As a result, compared to the case where soft combining is not applied, soft combining can be operated without changing the relationship from UL grant detection timing to PUSCH timing.

  In addition, when the designation of the subframe to which Soft combining of EPDCCH is applied is common to DL assignment and UL grant, with regard to UL grant, the above-mentioned last subframe can transmit UL grant when Soft combining is not applied. Soft combining may be performed only when it is a subframe, and soft combining may not be performed when this condition is not satisfied.

  In the above, the timing of each signal (PDSCH, UL ACK / NACK, PUSCH) in a case where soft combining of EPDCCH is applied has been described.

  Next, a case where the presence / absence of soft combining application is switched will be described.

  For example, in a subframe to which soft combining of EPDCCH is applied, EPDCCH candidates in the same subframe may be divided into EPDCCH candidates for soft combining and EPDCCH candidates to which soft combining is not applied. By this means, with the EPDCCH candidate used in the same subframe, it is possible to flexibly switch the presence / absence of soft combining application according to the instantaneous channel quality.

  Here, the number of EPDCCH candidates for soft combining is K1, and the number of EPDCCH candidates to which soft combining is not applied is K2. FIG. 9A shows an example of the relationship between aggregation levels (L) and PRB pairs and the number of EPDCCH candidates in LTE-Advanced.

  FIG. 9B shows an example in which the EPDCCH candidate shown in FIG. 9A is divided into an EPDCCH candidate for soft combining when switching whether to apply soft combining and an EPDCCH candidate to which soft combining is not applied.

  For example, it is conceivable to apply any one of three methods 1 to 3 as the operation of EPDCCH to which soft combining is not applied.

(Method 1)
In Method 1, an EPDCCH to which soft combining is not applied can be arranged in any subframe, but a PDSCH notified by the EPDCCH is arranged in a subframe corresponding to the final subframe of the subframe to which soft combining is applied. The PUSCH notified by the EPDCCH is allocated to a subframe identified based on the last subframe.

  In this case, terminal 200 monitors (blind decoding) K2 EPDCCH candidates in subframes other than the final subframe, and monitors K1 + K2 EPDCCH candidates in the final subframe.

  According to the first method, scheduling can be simplified because each PDSCH and PUSCH timing for soft combining can be used even when soft combining is not applied. In particular, in UL HARQ, since the UL HARQ process number is determined by the subframe, it is possible to switch the soft combining application without changing the UL HARQ process number.

(Method 2)
In the method 2, the EPDCCH to which soft combining is not applied is arranged in subframes other than the subframe corresponding to the last subframe of subframes to which soft combining is applied. Specifically, when the number of subframes to which soft combining is applied is 2, an EPDCCH to which soft combining is not applied is placed in the first subframe (1st subframe).

  In this case, terminal 200 monitors K2 EPDCCH candidates in subframes other than the last subframe, and monitors K1 EPDCCH candidates in the last subframe.

  According to method 2, subframes to be monitored by the EPDCCH candidates are dispersed according to the presence or absence of application of soft combining, so the number of EPDCCH candidates monitored by the terminal 200 can be averaged for each subframe.

  In the downlink, a subframe in which an EPDCCH to which soft combining is not applied may be set to a different subframe from a subframe in which a PDSCH notified by the EPDCCH is transmitted. In this way, since the EPDCCH subframe and the data (PDSCH) subframe can be separated, if power is required for data transmission, the power available for EPDCCH transmission is set to the data It can be used for transmission.

(Method 3)
In the method 3, the EPDCCH to which soft combining is not applied can be placed in any subframe.

  In this case, terminal 200 monitors K2 EPDCCH candidates in subframes other than the subframe corresponding to the final subframe to which soft combining is applied, and K1 + in the subframe corresponding to the final subframe. Monitor K2 EPDCCH candidates.

  Also, the PDSCH may be allocated to any subframe, and the PUSCH is allocated to a subframe identified based on the subframe in which the EPDCCH is detected.

  According to method 3, the flexibility of PDSCH / PUSCH assignment is increased when soft combining is not applied.

  The case where the presence / absence of soft combining application is switched has been described above.

  As described above, according to the present embodiment, it is possible to appropriately set the transmission / reception timing (resource allocation of each signal) of each signal when soft combining is applied.

  It is also possible to apply PDSCH and PUSCH soft combining (sometimes referred to as TTI bundling) in combination with the above-described EPDCCH soft combining. In this case, the start position (start subframe) of DL data (PDSCH) for which assignment is instructed using DL assignment is arranged in the last subframe among a plurality of subframes to which the EPDCCH including the DL assignment is transmitted. May be. As a result, the interval for storing the received signal (a signal that may be PDSCH) in the buffer between the PDSCH reception timing and the end of the EPDCCH detection process is the same as when EPDCCH soft combining is not applied. Can be.

Second Embodiment
In the present embodiment, resource allocation (search space configuration) of EPDCCH in a plurality of subframes in which the EPDCCH to which soft combining is applied will be described.

  Since the base station and terminal according to the present embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, they will be described using FIG. 5 and FIG.

  In the present embodiment, one EPDCCH set is respectively set for each of a plurality of subframes used for soft combining. That is, the EPDCCH soft combining is performed by concatenating the plurality of EPDCCH sets set in each of the plurality of subframes.

Note that the number of PRB pairs and the PRB pair number (frequency resource, that is, the position of the PRB pair) are set for each EPDCCH set. Further, N _ECCE which is the number of ECCEs in the EPDCCH set is determined by the number of PRB pairs, and an ECCE of ECCE # 0 to ECCE #N _ECCE -1 is arranged.

  FIG. 10 illustrates an example in which soft combining of EPDCCH is performed using two subframes. Note that the EPDCCH bit string to be transmitted is set in advance to an aggregation level corresponding to 2 or higher (AL2 or higher). In FIG. 10, EPDCCH # 0 and EPDCCH # 1 are AL2 and EPDCCH # 2 is AL4.

  In this embodiment, each EPDCCH is divided into two, and the ECCE of EPDCCH set 0 (the EPDCCH set corresponding to subframe # 0) and the ECCE of EPDCCH set 1 (the EPDCCH set corresponding to subframe # 1) are respectively generated. Be placed. That is, each EPDCCH is divided in ECCE units.

  For example, in FIG. 10, EPDCCH # 0 is divided into EPDCCH # 0a and EPDCCH # 0b, and arranged in EPDCCH candidates (one ECCE) of AL1 of EPDCCH set 0 and EPDCCH set 1, respectively. Similarly, EPDCCH # 1 is divided into EPDCCH # 1a and EPDCCH # 1b, and is allocated to EPDCCH candidates (one ECCE) of AL1 of EPDCCH set 0 and EPDCCH set 1, respectively. Similarly, EPDCCH # 2 is divided into EPDCCH # 2a and EPDCCH # 2b, and is arranged in EPDCCH candidates (two ECCEs) of AL2 for EPDCCH set 0 and EPDCCH set 1, respectively.

  That is, the base station 100 (setting unit 102) sets an EPDCCH set for each of a plurality of subframes used for soft combining. Also, base station 100 (signal allocation section 105) divides EPDCCH (control information) by the same number as the plurality of subframes in ECCE units, and divides each of the divided EPDCCHs into each of the plurality of subframes. Assign to any of the ECCEs that make up the configured EPDCCH set.

At this time, the EPDCCH candidates for each terminal 200 differ depending on the subframe number. Therefore, as shown in FIG. 10, in subframe # 0 and subframe # 1, the divided EPDCCHs are allocated to different EPDCCH candidates. In LTE-Advanced, the following two equations are considered as equations indicating EPDCCH candidates for each terminal 200.

In Expressions (1) and (2), L indicates an aggregation level (AL), Y _{p, k} indicates a UE ID (terminal ID), K indicates a subframe number, and p indicates a search space set number. Show. I takes values of 0, 1,..., L-1.

Also, m ′ is a parameter used when cross carrier scheduling is set, and is expressed by the following equation.

M _p ^(L) indicates the number of EPDCCH candidates monitored at the aggregation level (L) in the search space set p, and n _CI indicates a parameter (carrier indicator field value) used for setting cross carrier scheduling. In the equation (3), m '= m when cross scheduling is not set.

Also, m is expressed by the following equation.

  That is, m represents the number of the EPDCCH candidate for each aggregation level (L).

  In the present embodiment, each of the divided EPDCCHs is arranged in an EPDCCH candidate indicated by “m” (the same number between subframes) in each subframe to which soft combining is applied.

In this way, the numbers of EPDCCH candidates used can be made common among subframes to which soft combining is applied. Specifically, in a subframe to which soft combining is applied (here, two subframes), for each aggregation level (AL), a combination of EPDCCH candidates that become M _p ^(L) * M _p ^(L) patterns is selected. , M _p ^(L) pattern. Further, even when an EPDCCH candidate having the same number m is used in each subframe, the EPDCCH candidate (ECCE) is different for each subframe. That is, even if the EPDCCH candidate (ECCE) has the same number m, the frequency resource allocated to each subframe is different, so that a frequency diversity effect can be obtained. Further, when the number of REs actually allocated is different for each ECCE number, the number of REs can be averaged.

  Next, EPDCCH search space setting methods 1 and 2 in a subframe to which soft combining is applied will be described. In the following, a case where soft combining is applied across two subframes will be described as an example. However, the subframe used for soft combining is not limited to two subframes, and may be three or more subframes.

(Method 1: When the EPDCCH sets set in two subframes are the same)
FIG. 11A shows an EPDCCH set set at the time of non soft combining, and FIG. 11B shows an EPDCCH set set at the time of soft combining.

  As shown in FIG. 11B, EPDCCH set 0 and EPDCCH set 1 set in two subframes (1st subframe and 2nd subframe) to which soft combining is applied are the same.

  Accordingly, as shown in FIG. 11B, the EPDCCH sets arranged for each subframe have the same number of PRB pairs (four) and the same PRB number (the same PRB pair arrangement position). However, ECCE corresponding to EPDCCH candidates constituting each EPDCCH set is different for each subframe.

  By doing this, the EPDCCH candidates for each aggregation level (AL) become equal between the EPDCCH sets (that is, between subframes to which the same EPDCCH is assigned). Therefore, all EPDCCH candidates can be used as a search space for EPDCCH soft combining.

  In addition, since EPDCCH is arranged in the same PRB pair in a plurality of subframes, DMRS (Demodulation reference signal) precoding that is a reference signal used for EPDCCH is made common between subframes to which soft combining is applied. It is also good. In this way, for example, when the moving speed of the terminal 200 is slow, it can be assumed that the channel fluctuation between consecutive subframes is small. Therefore, the terminal 200 combines the reference signals of a plurality of subframes, and performs channel estimation. It can improve the system.

  Moreover, in LTE-Advanced, two EPDCCH sets can be set for each terminal. Therefore, one EPDCCH set can be used for soft combining, and the other EPDCCH set can be used for non soft combining, so that the operation can be dynamically switched.

(Method 2: When the EPDCCH sets set in two subframes are different)
FIG. 12A shows an EPDCCH set set at the time of non soft combining, and FIG. 12B shows an EPDCCH set set at the time of soft combining.

  As illustrated in FIG. 12B, EPDCCH set 0 and EPDCCH set 1 which are respectively set to two subframes (1st subframe and 2nd subframe) to which soft combining is applied are different.

  As shown in FIG. 12B, in subframes to which soft combining is applied, one EPDCCH set is arranged for each subframe, and as shown in FIG. 12A, in subframes to which soft combining is not applied, two EPDCCH sets are Be placed.

  As shown in FIG. 12A and FIG. 12B, the number of PRB pairs, the PRB number (placement position of the PRB pair), the allocation method (distributed allocation or You can set localized assignment). That is, in method 2, soft combining can be performed using EPDCCH sets of different designs.

  For example, in FIG. 12B, among the two subframes to which EPDCCH soft combining is applied, the number of PRPD pairs in the EPDCCH set set in the first subframe is four (N = 4), and is set in the 2nd subframe. The number of PRB pairs in the EPDCCH set is 2 (N = 2). Thus, since the number of PRB pairs is different between subframes (between EPDCCH sets), the number of EPDCCH candidates for each aggregation level (AL) is also different. For example, as shown in FIG. 13, the number of EPDCCH candidates for the number N of PRB pairs N = 2 is 4, 2, 1, 1, 0 for each AL (L = 1, 2, 4, 8, 16). On the other hand, the number of EPDCCH candidates with PRB pair number N = 4 is 2, 3, 2, 1, 1 for each AL (L = 1, 2, 4, 8, 16).

  Here, in FIG. 13, focusing on AL1 (L = 1, where L = 2 when soft combining is applied), there are four EPDCCH candidates (EPDCCH candidate number m for the EPDCCH set with N = 2 PRB pairs). It is = 0, 1, 2, 3), and the number of EPDCCHs of the EPDCCH set with N = 4 PRB pairs is 2 (EPDCCH candidate number m = 0, 1). In this case, in base station 100 and terminal 200, only two EPDCCH candidates (m = 0, 1) common to two EPDCCH sets are regarded as EPDCCH candidates for soft combining, and the remaining EPDCCH candidates (number of PRB pairs N = 2) These two EPDCCH candidates (m = 2, 3) are used as EPDCCH candidates for non soft combining, and the same applies to other ALs.

  That is, in Method 2, since the EPDCCH candidates for each AL differ between EPDCCH sets, when the number of EPDCCH candidates is different, EPDCCH candidates corresponding to the smaller number of candidates are used as a search space for soft combing. In this case, the remaining EPDCCH candidates in the larger EPDCCH set can be used as a search space for non soft combing.

  Further, according to method 2, the region used for the EPDCCH can be changed for each subframe. For example, when the PDSCH is arranged in the last subframe (second subframe in FIG. 12B) among the subframes used for soft combining, the final subframe is compared with the other subframes (1st subframe in FIG. 12B). The PDSCH region can be secured by reducing the EPDCCH region allocated to the

  The search space setting methods 1 and 2 have been described above.

  As described above, according to the present embodiment, it is possible to appropriately set the resource arrangement for arranging the EPDCCH in the case of applying the soft combining.

  In LTE-Advanced EPDCCH, the number of EPDCCH candidates for each AL varies depending on conditions such as DCI format, bandwidth, subframe type, and number of subcarriers. Specifically, in LTE-Advanced, the above conditions are divided into Cases 1, 2, and 3, Case 1 supports AL2 (L = 2) or higher, and Case 2 and Case 3 are AL1 (L = 1 ) Support more. Thus, in the present embodiment, the case where an EPDCCH of AL2 or higher is assumed has been described, but by applying soft combing, the EPDCCH of AL1 can be handled as an EPDCCH of AL2 or higher. That is, in this embodiment, not only Case 1 in which the number of EPDCCH candidates equal to or greater than AL2 is prepared, but Case 2 or Case 3 prepared from the number of EPDCCH candidates in AL1 may be applied to all DCI formats. This will prevent the AL from becoming too large during Soft combining.

[Embodiment 3]
The second embodiment has described the case where soft combining is performed by concatenating a plurality of EPDCCH sets set in each of a plurality of subframes to which soft combining is applied. On the other hand, in the present embodiment, a case will be described where PRB pairs of one EPDCCH set are distributed to a plurality of subframes to which soft combining is applied.

  Since the base station and terminal according to the present embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, they will be described using FIG. 5 and FIG.

  Specifically, the base station 100 (setting unit 102) sets one EPDCCH set for all of a plurality of subframes used for soft combining. However, PRB pairs corresponding to ECCEs constituting one EPDCCH set are distributed and arranged in a plurality of subframes used for soft combining.

  For example, if the number of PRB pairs in the EPDCCH set is N and the number of subframes used for soft combining is M, N / M PRB pairs are arranged per subframe.

  FIG. 14 illustrates an example in which soft combining of EPDCCH is performed in two subframes (M = 2). In FIG. 14, the number of PRB pairs in the EPDCCH set is 4 (N = 4). Accordingly, in FIG. 14, two (= N / M) PRB pairs are arranged per subframe. In FIG. 14, EPDCCH # 0 and EPDCCH # 1 are AL1, and EPDCCH # 2 is AL2. Each EPDCCH is arranged according to the ECCE allocation formula in EPDCCH set 0.

  In FIG. 14, the EPDCH # 0 is arranged in the ECCE # 0, the EPDCCH # 1 is arranged in the ECCE # 1, and the EPDCCH # 2 is arranged in the ECCEs # 2 and # 3. Then, each ECCE is arranged in four PRB pairs of EPDCCH set 0 (for example, PRB indexes # 0, # 1, # 2, # 3). However, in FIG. 14, PRB index # 0 and # 2 are allocated to subframe # 0, and PRB index # 1 and # 3 are allocated to subframe # 1. That is, one EPDCCH set 0 is divided into a plurality of subframes to which soft combining is applied.

  In this way, in this embodiment, soft combining can be applied even if AL1 is used. Also, since the amount of resources of the EPDCCH region per subframe used for soft combining can be reduced, resources not used for the EPDCCH can be used for the PDSCH.

[Variation for N = 8]
FIG. 15 shows an example of a correspondence relationship between ECCEs and PRB pairs when the number of PRB pairs in the search space set is N = 8 and the number of EREGs per ECCE is four. In FIG. 15, the PRB pairs to be arranged differ depending on ECCE. Specifically, even-numbered ECCEs are arranged in even-numbered PRB pairs, and odd-numbered ECCEs are arranged in odd-numbered PRB pairs.

  The variations 1 and 2 of the division of the EPDCCH set (PRB pair) into a plurality of subframes (two in this case) used for soft combining in this case will be described.

(Variation 1)
In the first variation, when soft combining is performed, the subframe is divided into subframes in which even-numbered PRB pairs are arranged and subframes in which odd-numbered PRB pairs are arranged. For example, when soft combining is performed using two subframes, even-numbered PRB pairs are arranged in the first subframe, and odd-numbered PRB pairs are arranged in the second subframe.

  By doing this, the EPDCCH of AL1 configured by one ECCE is arranged in one of the 1st subframe and the 2nd subframe. That is, soft combining is not applied only to the EP1CH of AL1. Thereby, soft combining and non soft combining can be switched by selecting AL.

  As described above, in variation 1, soft combining can be applied rather than AL2 EPDCCH. Therefore, in LTE-Advanced, Case 1 (see Non-Patent Document 1) prepared from the number of EPDCCH candidates for AL2 may be applied to all DCI formats. In this way, soft combining can be applied to all EPDCCH candidates.

(Variation 2)
In the second variation, when performing soft combining, a pair of PRB pairs including even-numbered PRB pairs and odd-numbered PRB pairs is arranged in one subframe. For example, when soft combining is performed using two subframes, PRB pairs of PRB pairs # 0, # 1, # 4, and # 5 are arranged in the 1st subframe in FIG. 15, and in the 2nd subframe, PRB pair PRB pairs # 2, # 3, # 6 and # 7 are arranged.

In this way, even the AL1 EPDCCH configured with one ECCE is arranged in the 1st subframe and the 2nd subframe, respectively. As a result, soft combining can be applied to the AL1 EPDCCH.
Heretofore, variations of the division of the EPDCCH set (PRB pair) into a plurality of subframes have been described.

  As described above, according to the present embodiment, as in the second embodiment, it is possible to appropriately set the resource arrangement for arranging the EPDCCH in the case of applying soft combining.

  Hereinabove, the embodiments of the present invention have been described.

(Other embodiments)
[1] When applying soft combining, the number of EPDCCH candidates for each AL may be changed. For example, FIG. 16A shows the number of EPDCCH candidates for each AL before change, and FIG. 16B shows the number of EPDCCH candidates for each AL after change (for soft combining). In FIG. 16B, the number of EPDCCH candidates with a low AL (L = 1) is reduced, while the number of EPDCCH candidates with a high AL (L = 8) is increased, compared to FIG. 16A. Thus, particularly by increasing the number of high AL EPDCCH candidates, the effect of soft combining is increased.

  [2] For example, as shown in FIGS. 7 and 8, although the case of using continuous subframes as subframes used for soft combining has been described, subframes used for soft combining are not necessarily consecutive sub-frames. It may be not subframes but discontinuous subframes.

  [3] When performing soft combining of EPDCCH in the second and third embodiments, it may be assumed that precoding of DMRS in each subframe is identical depending on conditions.

  An example of the condition is, for example, a case where PRB pairs in which EPDCCHs to which soft combining is applied are arranged are the same between subframes. For example, in (Method 1) of Embodiment 2, since the same EPDCCH set is used in a plurality of subframes used for soft combining, it can be assumed that precoding of DMRS in each subframe is identical.

  Further, as another example of the condition, for example, in each subframe to which soft combining is applied, a PRB pair in which the EPDCCH is arranged is arranged within a certain range. Within the certain range is, for example, the adjacent PRB pair index.

  Alternatively, as an example of the condition, in each subframe to which soft combining is applied, a PRB pair in which the EPDCCH is disposed is disposed within the range of PRB bundling. The PRB bundling range is a value determined by the bandwidth, and there are 1, 2 and 3 PRB pair patterns.

  Further, in the third embodiment, PRB pairs (positions) are necessarily different between a plurality of subframes, and it is difficult to make DMRS precoding identical between subframes. Therefore, in the case of applying the third embodiment, the same PRB pair may be used between subframes used for soft combining. For example, in two subframes used for soft combining, the PRB pair used in the 2nd subframe so that the PRB pair used in the 2nd subframe is the same as the PRB pair used in the 1st subframe. The position of may be shifted.

  [4] In the above embodiment, the case where soft combining is performed across a plurality of subframes (that is, time domains) has been described. However, the above embodiments may be applied to the frequency domain (eg, Carrier aggregation). In this case, instead of arranging the EPDCCH in a plurality of subframes in the above embodiment, the EPDCCH may be arranged across a plurality of Component Carriers (CCs). Also, for example, in the first embodiment, the PUCCH resource is instructed to implisit by the ECCE (index) of the EPDCCH placed in the last subframe of the plurality of subframes. On the other hand, during Carrier aggregation, the PUCCH resource may be indicated to the implisit by the ECCE (index) of the EPDCCH allocated to the PCell among a plurality of Carrier Components.

  [5] Also, soft combining of EPDCCHs in Embodiment 2 may be applied to two EPDCCH sets in the same subframe. In this way, the maximum AL in one subframe can be increased, and the reception quality of EPDCCH can be improved in a subframe with poor reception quality.

  [6] In the above embodiments, the present invention has been described by way of hardware as an example, but the present invention can also be realized by software in cooperation with hardware.

  Each function block employed in the description of each of the aforementioned embodiments may typically be implemented as an LSI constituted by an integrated circuit. These may be individually made into one chip, or may be made into one chip so as to include some or all. Although an LSI is used here, it may be called an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. After the LSI is manufactured, a field programmable gate array (FPGA) that can be programmed or a reconfigurable processor that can reconfigure connection or setting of circuit cells inside the LSI may be used.

  Furthermore, if integrated circuit technology comes out to replace LSI's as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using this technology. Biotechnology can be applied.

  As described above, the base station of the present disclosure has an Enhanced Physical Downlink Control Channel (EPDCCH) set configured by an Enhanced Control Channel Element (ECCE) that allocates control information transmitted across a plurality of subframes in the plurality of subframes. A configuration comprising: a setting unit to set, and an assignment unit to assign the control information to any one of the ECCEs in a Physical Resource Block (PRB) pair of each of the plurality of subframes.

  Further, in the base station of the present disclosure, the setting unit sets the EPDCCH set for each of the plurality of subframes, and the allocating unit has the same number of the control information as the number of the plurality of subframes. , And each of the divided control information is allocated to any of the ECCEs constituting the EPDCCH set set in each of the plurality of subframes.

  Further, in the base station of the present disclosure, the EPDCCH set set in each of the plurality of subframes is the same.

  Further, in the base station of the present disclosure, the EPDCCH set set in each of the plurality of subframes is different.

  Further, in the base station of the present disclosure, the setting unit sets one EPDCCH set for the entire plurality of subframes, and the PRB pair corresponding to the ECCE configuring the one EPDCCH set is the It is distributed and arranged in a plurality of subframes.

  Further, in the base station of the present disclosure, the allocation unit allocates downlink data instructed to be allocated by the control information to the last subframe among the plurality of subframes.

  In the base station of the present disclosure, a Physical Uplink Control Channel (Physical Uplink Control Channel) associated with the ECCE allocated to a subframe to which downlink data instructed to be allocated by the control information is allocated among the plurality of subframes. (PUCCH), further comprising: a receiving unit that receives a response signal to the downlink data.

  Further, in the base station of the present disclosure, a transmission subframe of the control information instructing allocation of uplink data is associated with a reception subframe of the uplink data, and the last of the plurality of subframes The sub-frame of is identical to the transmission sub-frame.

  The terminal of the present disclosure is an enhanced control channel element (ECCE) to which control information transmitted across a plurality of subframes is allocated, and an enhanced physical downlink control channel (EPDCCH) set in the plurality of subframes. ) A setting unit that identifies the ECCE that constitutes a set; and a receiving unit that receives the control information assigned to one of the ECCEs in each Physical Resource Block (PRB) pair of the plurality of subframes. Take the structure to be equipped.

  In addition, the transmission method of the present disclosure includes an enhanced physical downlink control channel (EPDCCH) set configured by an enhanced control channel element (ECCE) that assigns control information transmitted across a plurality of subframes, and the plurality of subframes. And transmit the control information assigned to any one of the ECCEs in a Physical Resource Block (PRB) pair of each of the plurality of subframes.

  In addition, the reception method of the present disclosure is an enhanced control channel element (ECCE) to which control information transmitted across a plurality of subframes is allocated, and an enhanced physical downlink control channel (ECCE) set in the plurality of subframes (ECCE). Identifying the ECCEs that make up the EPDCCH) set, and receiving the control information assigned to any of the ECCEs in a Physical Resource Block (PRB) pair of each of the plurality of subframes.

  The present invention is useful for mobile communication systems.

100 base station 200 terminal 101 allocation information generation unit 102, 205 setting unit 103, 207 error correction coding unit 104, 208 modulation unit 105, 209 signal allocation unit 106, 210 transmission unit 107, 201 reception unit 108, 203 demodulation unit 109 204 Error correction decoding unit 202 Signal separating unit 206 Control signal receiving unit

Claims (24)

A receiving unit that receives control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates to be repeated in a set of consecutive subframes in the downlink;
In the uplink subframe determined based on the last subframe of the set of subframes, if there is uplink data to be transmitted, ACK / for the downlink data transmitted in the last subframe When NACK information is multiplexed and transmitted on the uplink data and there is no uplink data to be transmitted in the determined uplink subframe, the final subframe of the plurality of EPDCCH candidates is transmitted. Using a Physical Uplink Control Channel (PUCCH) resource associated with the arranged EPDCCH candidates, a transmitter that transmits ACK / NACK information related to downlink data transmitted in the last subframe;
A communication apparatus comprising: The transmission unit transmits a Physical Uplink Shared Channel (PUSCH) in an uplink subframe determined based on the final subframe.
The communication device according to claim 1. The EPDCCH set designed in each subframe in the subframe set occupies a plurality of Physical Resource Block (PRB) pairs, and each EPDCCH set is a set of EPDCCH candidates in one downlink subframe.
The communication device according to claim 1. The EPDCCH set designed in each subframe in the set of subframes is different in at least one of the number of PRB pairs or the frequency position of PRB pairs.
The communication device according to claim 1. The receiving unit receives the downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the set of subframes;
The communication device according to claim 1. The transmission unit transmits ACK / NACK information using the PUCCH resource associated with one or more ECCE numbers of one or more Enhanced Control Channel Element (ECCE) in the last subframe in which the downlink data is arranged. ,
The communication device according to claim 1. In the set of subframes, common precoding is used to generate an EPDCCH signal,
The communication device according to claim 1. When the number of repetitions is one or more, the number of EPDCCH candidates associated with at least one aggregation level is smaller than when the number of repetitions is one,
The communication device according to claim 1. The communication device
Receiving control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates to be repeated in a set of downlink consecutive subframes,
In the uplink subframe determined based on the last subframe of the set of subframes, if there is uplink data to be transmitted, ACK / for the downlink data transmitted in the last subframe When NACK information is multiplexed and transmitted on the uplink data and there is no uplink data to be transmitted in the determined subframe, the NACK information is arranged in the last subframe among the plurality of EPDCCH candidates Using Physical Uplink Control Channel (PUCCH) resources associated with EPDCCH candidates, transmitting ACK / NACK information related to downlink data transmitted in the final subframe,
Communication method. The communication device is
Transmit Physical Uplink Shared Channel (PUSCH) in uplink subframes determined based on the last subframe,
The communication method according to claim 9. The EPDCCH set designed in each subframe in the subframe set occupies a plurality of Physical Resource Block (PRB) pairs, and each EPDCCH set is a set of EPDCCH candidates in one downlink subframe.
The communication method according to claim 9. The EPDCCH set designed in each subframe in the set of subframes is different in at least one of the number of PRB pairs or the frequency position of PRB pairs.
The communication method according to claim 9. The communication device is
Receiving the downlink data arranged in the Physical Downlink Shared Channel (PDSCH) region of each subframe in the set of subframes;
The communication method according to claim 9. The communication device is
Transmitting ACK / NACK information using the PUCCH resource associated with one or more ECCE numbers of one or more Enhanced Control Channel Element (ECCE) in the final subframe in which the downlink data is arranged;
The communication method according to claim 9. In the subframe, common precoding is used to generate an EPDCCH signal,
The communication method according to claim 9. When the number of repetitions is one or more, the number of EPDCCH candidates associated with at least one aggregation level is smaller than when the number of repetitions is one,
The communication method according to claim 9. A receiving circuit for receiving control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates to be repeated in a set of downlink continuous subframes;
In the uplink subframe determined based on the last subframe of the set of subframes, if there is uplink data to be transmitted, ACK / for the downlink data transmitted in the last subframe When NACK information is multiplexed and transmitted on the uplink data and there is no uplink data to be transmitted in the determined subframe, the NACK information is arranged in the last subframe among the plurality of EPDCCH candidates Using a Physical Uplink Control Channel (PUCCH) resource associated with an EPDCCH candidate, a transmission circuit that transmits ACK / NACK information related to downlink data transmitted in the final subframe;
Integrated circuit to control. The transmission circuit transmits a Physical Uplink Shared Channel (PUSCH) in an uplink subframe determined based on the final subframe.
The integrated circuit of claim 17. The EPDCCH set designed in each subframe in the subframe set occupies a plurality of Physical Resource Block (PRB) pairs, and each EPDCCH set is a set of EPDCCH candidates in one downlink subframe.
The integrated circuit of claim 17. The EPDCCH set designed in each subframe in the set of subframes is different in at least one of the number of PRB pairs or the frequency position of PRB pairs.
The integrated circuit of claim 17. The receiving circuit receives the downlink data arranged in the Physical Downlink Shared Channel (PDSCH) region of each subframe in the set of subframes;
The integrated circuit of claim 17. The transmission circuit transmits ACK / NACK information using the PUCCH resource associated with one or more ECCE numbers of one or more Enhanced Control Channel Element (ECCE) in the final subframe in which the downlink data is arranged. ,
The integrated circuit of claim 17. In the set of subframes, common precoding is used to generate an EPDCCH signal,
The integrated circuit of claim 17. When the number of repetitions is one or more, the number of EPDCCH candidates associated with at least one aggregation level is smaller than when the number of repetitions is one,
The integrated circuit of claim 17.

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