JP7108863B2 - Communication device, communication method and integrated circuit - Google Patents

Description

The present invention relates to communication devices, communication methods and integrated circuits.

In recent years, in a cellular mobile communication system, along with the multimediaization of information, it is becoming common 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), extensive studies are being conducted to achieve high transmission rates using wideband radio 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 extended PDCCH (Physical Downlink Control CHannel) used for control signals, has been designed. The EPDCCH is arranged in a resource region (PDSCH (Physical Downlink Shared CHannel) region) to which downlink data is allocated. Further, the base station defines frequency resources (for example, RB (Resource Block)) for each terminal (also called UE (User Equipment)) in a resource region (EPDCCH region) in which EPDCCH is allocated, and transmits a signal. can be sent. For this reason, transmission power control for control signals transmitted to terminals existing near cell edges, or interference control given from own cell to other cells by transmitted control signals, or interference given from other cells to own cell 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 in which two RBs are combined in the time direction is called an RB pair. That is, an RB pair has 12 subcarriers in the frequency direction and a width of 1 msec in the time direction. Also, when an RB pair represents a cluster of 12 subcarriers on the frequency axis, the RB pair may simply be called an RB. In the physical layer, an RP pair is also called a PRB pair (Physical RB pair). A unit defined by one subcarrier and one OFDM symbol is a resource element (RE).

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

In LTE-Advanced, it is possible to configure multiple EPDCCH sets per terminal, each of which is composed of a set of ECCEs (that is, control information allocation candidates) in which EPDCCHs may be allocated. Since the position and the number N of PRB pairs to be used are set for each EPDCCH set, control signal arrangement is highly flexible.

FIG. 1 shows an example in which EPDCCH is mapped to resources. ECCEs in which EPDCCHs are allocated are 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 mapped to ECCE#0, EPDCCH#1 is mapped to ECCE#1, EPDCCH#2 is mapped to ECCE#2 and ECCE#3, EPDCCH#3 is mapped to ECCE#4, ECCE #5, ECCE#6, and ECCE#7. Also, in FIG. 1, each ECCE is arranged in four EREGs, so it is divided into four. As shown in FIG. 1, for localized allocation, four EREGs are placed in the same PRB pair, and for distributed allocation, four EREGs are placed in different PRB pairs.

Further, EPDCCH allocation methods include "localized allocation" in which EPDCCHs are collectively allocated in positions close to each other on the frequency band, and "distributed allocation" in which EPDCCHs are distributed and allocated over the frequency band. Localized allocation is an allocation method for obtaining frequency scheduling gain, and EPDCCH can be allocated to resources with good channel quality based on channel quality information. Distributed allocation can obtain frequency diversity gain by distributing EPDCCHs on the frequency axis. In LTE-Advanced, both search spaces for localized allocation and search spaces for distributed allocation can be set.

Also, in LTE-Advanced, a DL assignment indicating downlink (DL) data allocation and a UL grant indicating uplink (UL) data allocation are transmitted by PDCCH or EPDCCH. The DL assignment notifies the terminal that resources in the subframe in which this DL assignment was transmitted have been allocated. On the other hand, regarding the UL grant, it is reported that the resource within the target subframe predetermined by the UL grant has been allocated to the terminal.

3GPP TS 36.213 V11.1.0, Physical layer procedures

In LTE-Advanced, it is being considered to deploy small cells, which are base stations with low transmission power, to achieve high transmission rates in hotspots. For example, high frequencies such as 3.5 GHz are candidates as carrier frequencies for operating small cells. However, when a high-frequency radio band is used, while a high transmission rate can be expected in short distances, attenuation due to transmission distance increases as the distance increases. Therefore, when operating a mobile communication system using a high-frequency radio band, there is a problem that the coverage area of small cells becomes small. In addition, in the case of small cells, it is necessary to consider transmission power restrictions, and the power that can be used for transmission per subframe is limited. Since the coverage area of a cell is determined by the reachable range of the control signal, there is a demand for a technique for expanding the coverage area of the control signal for the small cells.

Therefore, for example, it is conceivable to apply soft combining (sometimes called bundling) in which EPDCCH including control information is arranged across multiple subframes. However, no study has been made so far on how to allocate EPDCCHs when soft combining is applied.

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

A communication apparatus according to an aspect of the present invention receives one piece of control information indicating allocation of downlink data using a first set of subframes in downlink, and a receiving unit that receives the downlink data using a second set of subframes subsequent to the subframe; a transmission unit that transmits in a subframe, and when uplink data exists in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is transmitted, and in the uplink subframe When there is no uplink data, the ACK/NACK information is transmitted on a Physical Uplink Control Channel (PUCCH) resource.

In the communication apparatus according to one aspect of the present invention, when uplink data exists in the uplink subframe, the uplink data and the ACK/NACK information are stored in a Physical Uplink Shared Channel (PUSCH) in the uplink subframe. received at.

In a communication method according to one aspect of the present invention, a communication device receives one piece of control information indicating allocation of downlink data using a first set of subframes in the downlink; receiving the downlink data using a second set of subframes after the last subframe of the above, and sending ACK/NACK information on the downlink data received in the second set of subframes to the uplink and when uplink data exists in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is transmitted, and the uplink data is transmitted in the uplink subframe. If not present, the ACK/NACK information is transmitted on a Physical Uplink Control Channel (PUCCH) resource.

An integrated circuit according to one aspect of the present invention includes a process of receiving a piece of control information indicating allocation of downlink data using a first set of downlink subframes; a process of receiving the downlink data using a second set of subframes after the last subframe of the uplink, and sending ACK/NACK information about the downlink data received in the second set of subframes to the uplink and if there is uplink data in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is transmitted, and in the uplink subframe When there is no uplink data, the ACK/NACK information is transmitted on a Physical Uplink Control Channel (PUCCH) resource.

ADVANTAGE OF THE INVENTION According to this invention, the resource which arrange|positions EPDCCH when soft combining is applied can be set appropriately.

Diagram for explanation of EPDCCH Diagram for explanation of soft combining FIG. 1 is a block diagram showing the main configuration of a base station according to Embodiment 1 of the present invention; FIG. 1 is a block diagram showing the main configuration of a terminal according to Embodiment 1 of the present invention; FIG. 1 is a block diagram showing the configuration of a base station according to Embodiment 1 of the present invention; Block diagram showing the configuration of a terminal according to Embodiment 1 of the present invention Diagram showing the timing of PDSCH and PUCCH according to Embodiment 1 of the present invention A diagram showing the timing of PUSCH according to Embodiment 1 of the present invention FIG. 4 is a diagram showing switching of application of soft combining according to the first embodiment of the present invention; A diagram showing a configuration example of EPDCCH candidates according to Embodiment 2 of the present invention A diagram showing a setting example of search spaces for EPDCCHs according to Embodiment 2 of the present invention A diagram showing a setting example of search spaces for EPDCCHs according to Embodiment 2 of the present invention A diagram showing the number of EPDCCH candidates according to Embodiment 2 of the present invention A diagram showing a configuration example of EPDCCH candidates according to Embodiment 3 of the present invention A diagram showing a PRB pair (EREG) in which ECCEs according to Embodiment 3 of the present invention are arranged A diagram showing a setting example of the number of EPDCCH candidates according to another embodiment of the present invention

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in the embodiments, the same constituent elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

[Embodiment 1]
[Outline of communication system]
The communication system according to this embodiment has base station 100 and terminal 200 . This communication system is, for example, the LTE-Advanced system. Base station 100 is, for example, a base station compatible with the LTE-Advanced system, and terminal 200 is, for example, a terminal compatible with the LTE-Advanced system.

In addition, in the present embodiment, when base station 100 transmits EPDCCH for terminal 200, it is possible to apply soft combining to transmit EPDCCH (control information) across multiple subframes (see FIG. 2). The receiving side (terminal 200) synthesizes control information transmitted over a plurality of subframes and performs reception processing. An EPDCCH transmitted over a plurality of subframes is composed of a bit string including information bits and redundant bits generated by performing error correction coding on information bits. In addition, when terminal 200 receives EPDCCH transmitted across a plurality of subframes, terminal 200 performs data reception or transmission after completion of EPDCCH reception, and performs transmission or reception of ACK/NACK (response signal). Decide when to do it.

Also, subframes to which EPDCCH soft combining is applied are set in advance for terminal 200 by higher layer signaling. The configuration of the subframes may be different for each terminal. Also, the same frame may include a subframe to which soft combining is not applied and a subframe to which soft combining is applied. In this way, EPDCCH soft combining is applied according to the reception quality of each subframe, such as applying soft combining to subframes with much interference without applying soft combining in subframes with little influence of interference. You can switch on or off.

Note that base station 100 and terminal 200 are capable of transmitting and receiving control information (DL assignment or UL grant) using the PDCCH region or the EPDCCH region, but in the following description, in order to simplify the description, 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 this embodiment.

In base station 100, configuration section 102 configures, in the plurality of subframes, an EPDCCH set composed of ECCEs for allocating control information (allocation information) transmitted over a plurality of subframes. Signal allocation section 105 allocates control information to one of 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, configuration section 205 specifies ECCEs to which control information (assignment information) transmitted across multiple subframes is allocated, and ECCEs configuring an EPDCCH set configured in multiple subframes. . Control signal receiving section 206 receives control information assigned to one of the ECCEs in each PRB pair of the plurality of subframes.

[Configuration of base station 100]
FIG. 5 is a block diagram showing the configuration of base station 100 according to this embodiment. 5, base station 100 includes allocation information generating section 101, setting section 102, error correction coding section 103, modulating section 104, signal allocation section 105, transmitting section 106, receiving section 107, It has demodulation section 108 and error correction decoding section 109 .

If there is a downlink data signal (DL data signal) to be transmitted and an uplink data signal (UL data signal) to be assigned to the uplink (UL), allocation information generating section 101 assigns a resource (RB) to which the data signal is assigned. and generate assignment information (DL assignment and UL grant). DL assignment includes information on assignment of DL data signals. The UL grant includes information about allocation resources for UL data signals transmitted from terminal 200 . The DL assignment is output to signal allocation section 105 and the UL grant is output to signal allocation section 105 and reception section 107 .

Configuration section 102 configures one or more EPDCCH search spaces for each terminal 200 . Specifically, configuration section 102 assigns a PRB pair number for arranging a search space for EPDCCH, an ECCE index for each aggregation level, and a search space (EPDCCH) allocation method (localized allocation or distributed allocation) to each terminal 200. set. The EPDCCH search space is composed of multiple allocation candidates (EPDCCH candidates). Each "allocation candidate" consists of as many ECCEs as there are aggregation levels.

When configuring multiple EPDCCH search spaces for terminal 200, configuration section 102 assigns an ECCE index to each search space.

Configuration section 102 configures subframes to which soft combining is applied (see FIG. 2) for terminal 200 to which soft combining is applied. In addition, configuration section 102 configures EPDCCH sets in a plurality of subframes to which soft combining is applied for terminal 200 to which soft combining is applied. At this time, PRB pairs corresponding to ECCEs forming an EPDCCH set are arranged in each of the plurality of subframes. As a result, in each subframe used for soft combining, the search space described above is set based on the set EPDCCH set.

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

Error correction coding section 103 receives a transmission data signal (DL data signal) and control information received from setting section 102 , performs error correction coding on the input signal, and outputs the result to modulation section 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 .

Signal allocation section 105 converts allocation information (DL assignment and UL grant) received from allocation information generation section 101 into ECCEs (ECCEs in allocation candidate units) corresponding to PRB pair numbers indicated in search space information received from configuration section 102. assign one of them. At this time, when soft combining is set for the allocation information, signal allocation section 105 sets the PRB for each of a plurality of subframes corresponding to the subframe number indicated in the information regarding soft combining received from configuration section 102. Allocate the allocation information to one of the ECCEs in the pair. As a result, allocation information is allocated to PRB pairs in which ECCEs are allocated (see FIG. 1, for example). Also, signal allocation section 105 allocates data signals received from modulation section 104 to downlink resources corresponding to allocation information (DL assignments) received from allocation information generation section 101 .

A transmission signal is formed by thus allocating the allocation information and the data signal to predetermined resources. The formed transmission signal is output to transmission section 106 . Also, signal allocation section 105 notifies reception section 107 of the ECCE index of the ECCE used to transmit the DL assignment. When applying soft combining, the signal allocation unit 105 uses the last subframe (hereinafter, sometimes referred to as the "last subframe") of the plurality of subframes used to transmit the DL assignment. ), the ECCE index of the ECCE is notified to the receiving unit 107 .

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

Receiving section 107 receives the signal transmitted from terminal 200 via an antenna and outputs the signal to demodulating section 108 . Specifically, receiving section 107 separates the signal corresponding to the resource indicated by the UL grant received from allocation information generating section 101 from the received signal, and performs reception processing such as down-conversion on the separated signal. It is then output to demodulation section 108 . Further, receiving section 107 extracts (receives) A/N signals from signals corresponding to PUCCH resources associated with ECCE indexes received from signal allocation section 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 to obtain the received data signal from terminal 200 .

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

Receiving section 201 receives a signal transmitted from base station 100 via an antenna, performs reception processing such as down-conversion, and then outputs the signal to signal separating section 202 .

Signal separating section 202 extracts a control signal related to resource allocation from the received signal received from receiving section 201 and outputs the extracted signal to control signal receiving section 206 . Further, the signal separating unit 202 extracts from the received signal a signal corresponding to the data resource indicated by the DL assignment output from the control signal receiving unit 206 (that is, the DL data signal), and sends the extracted signal to the demodulating unit 203. Output. In addition, when soft combining of EPDCCH is applied, signal separation section 202 is based on the last subframe of a plurality of subframes used for soft combining, based on the signal corresponding to the data resource (DL data signal) is extracted from the received signal.

Demodulator 203 demodulates the signal output from signal separator 202 and outputs the demodulated signal to error correction decoder 204 .

Error correction decoding section 204 decodes the demodulated signal output from demodulation section 203 and outputs the obtained reception data signal. Error correction decoding section 204, in particular, is transmitted from base station 100 as a control signal, "information on the PRB pair set in the search space" and "information on the subframe to which soft combining of EPDCCH is applied" to the setting unit 205.

Setting section 205 identifies a search space set in the terminal itself (terminal 200) that uses EPDCCH. For example, setting section 205 first identifies a PRB pair to be set in the search space based on information received from error correction decoding section 204 . Next, configuration section 205 identifies EPDCCHs to which soft combining is applied based on information on subframes to which soft combining of EPDCCHs is applied. Setting section 205 then determines the ECCE index of the search space corresponding to the PRB pair. By this means, setting section 205 identifies ECCEs to which EPDCCHs transmitted across a plurality of subframes are allocated (ECCEs forming an EPDCCH set set in the plurality of subframes). At this time, when a plurality of EPDCCH search spaces are set, setting section 205 allocates an ECCE index to each search space. Also, configuration section 205 specifies which ECCE index is to be configured as an EPDCCH candidate for each aggregation level according to a common rule between base station 100 and terminal 200 that is predetermined for each terminal 200 . For example, configuration section 205 identifies ECCE indexes that are EPDCCH candidates for each aggregation level based on the UE ID (terminal-specific ID) and whether or not soft combining is applied. Next, setting section 205 outputs information about the PRB pair and ECCE set as search spaces to control signal receiving section 206 .

Control signal receiving section 206 performs blind decoding on the ECCE corresponding to the PRB pair indicated in the information received from setting section 205 in the signal components received from signal separating section 202, thereby generating a control signal (DL assignment or UL grant). That is, control signal receiving section 206 receives a control signal assigned to one of the plurality of allocation candidates forming the search space set by setting section 205 . Note that when EPDCCH soft combining is applied, control signal receiving section 206 receives a control signal assigned to any ECCE in each PRB pair of a plurality of subframes. Control signal receiving section 206 outputs the detected DL assignment addressed to itself to signal separation section 202 and outputs the detected UL grant addressed to itself to signal allocation section 209 . Control signal receiving section 206 also outputs the ECCE index of the ECCE in which the DL assignment is detected to signal allocation section 209 .

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

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

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

[Operation of base station 100 and terminal 200]
Operations of base station 100 and terminal 200 having the above configurations will be described.

Below, when EPDCCH soft combining is applied, (1) PDSCH timing, (2) uplink A/N signal (UL ACK/NACK) timing, and (3) PUSCH timing I will explain each.

[PDSCH timing]
Base station 100 and terminal 200 set the PDSCH transmission timing (that is, the subframe in which PDSCH is arranged) 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 of a 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, subframe #0 and subframe #1, is applied, base station 100 uses PDSCH for terminal 200 as , is placed in subframe #1, which is the last subframe. That is, as shown in FIG. 7, a resource in subframe #1 is designated as a PDSCH resource for a DL assignment notified using EPDCCHs arranged in subframe #0 and subframe #1. be.

That is, base station 100 (signal allocation section 105) assigns downlink data (PDSCH) to which allocation is instructed by EPDCCH (DL assignment) to 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 DL assignments for Then, terminal 200 (signal separation section 202) extracts PDSCH (DL data signal) in subframe #1, which is the final subframe, based on the detected DL assignment.

Here, in terminal 200, the detection of the DL assignment notified using the EPDCCH to which soft combining is applied is performed after the final subframe is received. Then, after detecting the DL assignment, terminal 200 identifies that the PDSCH has been assigned to the PRB pair specified by the DL assignment, and starts PDSCH reception processing.

Therefore, if PDSCH is allocated in a subframe before the last subframe, terminal 200 allocates PDSCH as PDSCH until the identification (detection) of the PRB pair allocated to PDSCH is completed. Received signals received on all possible PRB pairs must be buffered.

In contrast, in the present embodiment, the PDSCH is arranged in the final subframe of multiple subframes to which soft combining is applied. By doing so, it is possible to minimize the period during which the received signal is stored in the buffer from the PDSCH reception timing to the completion of EPDCCH detection. In other words, even if soft combining of EPDCCH is applied, the period during which the received signal is stored in the buffer from the reception timing of PDSCH to the completion of detection of EPDCCH is not applied (non soft combining of EPDCCH). ) can be the same as the period in question. As a result, it is possible to prevent the size of the buffer that terminal 200 should have from becoming large.

[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). Further, subframes in which uplink A/N signals are transmitted are determined in advance. Specifically, in the case of an FDD (Frequency Division Duplex) system, the subframe in which the uplink A/N signal is transmitted is set four subframes after the subframe to which the PDSCH is allocated, and is set to TDD (Time Division Duplex). ) system, it is defined for each TDD UL-DL configuration (timing setting for each subframe between downlink (DL) and uplink (UL) communication per frame). However, in both the FDD system and the TDD system, the transmission timing of the uplink A/N signal is always set four or more subframes after the PDSCH.

In the present embodiment, the transmission timing of uplink A/N signals (subframes for transmitting UL ACK/NACK) is defined according to PDSCH reception subframes. In the case of the FDD system, it is set four subframes after the PDSCH reception subframe, and in the case of the TDD system, it is based on the PDSCH reception subframe and follows the regulations for each TDD UL-DL configuration. Uplink A/N signals are transmitted in the PUSCH region when there is PUSCH transmission, and are transmitted in the PUCCH region when there is no PUSCH transmission.

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

Therefore, when EPDCCH soft combining is applied, base station 100 and terminal 200 identify PUCCH resources associated with ECCE numbers of EPDCCHs arranged in subframes in which PDSCHs are transmitted.

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

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

By doing so, even when the EPDCCH search space is shared between a terminal to which EPDCCH soft combining is applied and a terminal to which EPDCCH soft combining is not applied, base station 100 can ECCE numbers used for EPDCCHs for these terminals are assigned in subframes to which PDSCHs for these terminals are assigned. As a result, in this subframe, ECCE numbers are assigned to these terminals in consideration of PUCCH resource collisions, so that PUCCH resources are automatically (implicitly) assigned so as not to collide between terminals. .

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

Also, after detecting the UL grant, the terminal identifies that the PRB pair specified by the UL grant has been assigned to the PUSCH, and determines the size and transmission method of data (PUSCH). Therefore, in the terminal, among the subframes to which soft combining of EPDCCH is applied, PUSCH unless a certain interval (4 subframes or more in LTE-Advanced) is provided from the final subframe (at the time of completion of detection of UL grant). cannot be prepared for transmission.

Therefore, in the present embodiment, the transmission timing of the PUSCH specified by the UL grant that is transmitted using the EPDCCH to which soft combining is applied is set to Identify the last subframe as a reference. By specifying the transmission timing of PUSCH (subframe for transmitting and receiving PUSCH) based on the final subframe of soft combining, the interval from the detection timing of UL grant to preparation for transmission of PUSCH is applied by soft combining of EPDCCH. You can do the same if you don't.

In particular, in the TDD system, defined for each UL-DL configuration, according to the correspondence between the transmission/reception timing of the UL grant and the transmission/reception timing of the PUSCH (UL grant-PUSCH timing), even in the DL subframe, the UL grant is There are subframes that are not transmitted. Therefore, in the case of the TDD system, the subframe at the end of the multiple subframes used for soft combining is the same as the EPDCCH transmission subframe containing the UL grant.

FIG. 8 shows subframes for 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 , and subframes #2, #3, #7, and #8 are UL subframes. Further, as shown in FIG. 8, the UL grant-PUSCH timing is defined in advance, and the subframes in which the UL grant can be arranged are subframes #1, #4, #6, and #9, and are notified in each subframe. PDSCHs are allocated in UL subframes #7 and #8, subframe #2 of the next frame (not shown), and subframe #3 of the next frame, respectively.

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 the present embodiment, when the soft combining of the EPDCCH including the UL grant is applied, the final subframe of the subframes in which the EPDCCH to which the soft combining is applied is arranged, when the soft combining is not applied. A subframe in which a UL grant can be transmitted.

By doing so, soft combining can be operated 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, EPDCCH soft combining including UL grant is configured in subframes #0 and #1 and subframes #5 and #6. As shown in FIG. 8, EPDCCHs including UL grants are also placed in subframes #0 and #5 in which UL grants are not placed when soft combining is not applied. Even in this case, the PUSCH transmission timing for the UL grant notified using the EPDCCH is specified based on the last subframe of the subframes in which the EPDCCH was transmitted. In other words, when soft combining including the UL grant is applied, the timing of the PUSCH specified by the UL grant transmitted using the EPDCCH to which the soft combining is applied (the first transmission subframe of the PUSCH) is applied with the soft combining. It is determined based on the last subframe in which the EPDCCH is allocated. This makes it possible to operate soft combining without changing the relationship between the detection timing of UL grant and the timing of PUSCH, compared to the case where soft combining is not applied.

In addition, if the designation of the subframe to which the soft combining of EPDCCH is applied is common to the DL assignment and the UL grant, regarding the UL grant, the final subframe can transmit the UL grant when the soft combining is not applied. Soft combining is performed only when subframes are used, and if this condition is not met, soft combining may not be performed.

The timing of each signal (PDSCH, UL ACK/NACK, PUSCH) when EPDCCH soft combining is applied has been described above.

Next, a case of switching between the presence and absence of application of soft combining will be described.

For example, in subframes 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 doing so, it is possible to flexibly switch whether or not to apply soft combining depending on the EPDCCH candidate used in the same subframe, 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 the aggregation level (L), PRB pairs, and the number of EPDCCH candidates in LTE-Advanced.

FIG. 9B shows an example in which the EPDCCH candidates shown in FIG. 9A are divided into EPDCCH candidates for soft combining when switching between application of soft combining and EPDCCH candidates to which soft combining is not applied.

For example, one of the three methods 1 to 3 may be applied as an EPDCCH operation that does not apply soft combining.

(Method 1)
In method 1, the EPDCCH to which soft combining is not applied can be placed in any subframe, but the PDSCH notified by the EPDCCH is placed in the subframe corresponding to the final subframe of the subframes to which soft combining is applied. The PUSCH notified by the EPDCCH is arranged in a subframe specified 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 Method 1, the PDSCH and PUSCH timings for soft combining can be used even when soft combining is not applied, so scheduling is simplified. In particular, in UL HARQ, since the UL HARQ process number is determined by subframe, it is possible to switch between the application of soft combining and non-application without changing the UL HARQ process number.

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

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

According to method 2, the subframes to be monitored for EPDCCH candidates are distributed according to whether or not soft combining is applied, so the number of EPDCCH candidates monitored by 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 transmitted and a subframe in which a PDSCH notified by the EPDCCH is transmitted may be set to different subframes. By doing so, it is possible to separate subframes for EPDCCH and subframes for data (PDSCH), so when power is required for data transmission, the power that can be used for EPDCCH transmission is used for data transmission. Can be used for transmission.

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

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

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

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

So far, the case of switching the presence or absence of application of soft combining has been described.

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

In addition, it is conceivable that PDSCH and PUSCH soft combining (sometimes called TTI bundling) is applied together with the EPDCCH soft combining described above. In this case, the leading position (leading subframe) of the DL data (PDSCH) for which allocation is indicated using the DL assignment is arranged in the last subframe of the multiple subframes in which the EPDCCH containing the DL assignment is transmitted. may As a result, the interval for storing the received signal (a signal that may be PDSCH) in the buffer from the PDSCH reception timing to the completion of the EPDCCH detection process is the same as when the EPDCCH soft combining is not applied. can be

[Embodiment 2]
In the present embodiment, resource allocation (search space setting) of EPDCCHs in a plurality of subframes in which EPDCCHs to which soft combining is applied will be described.

Since the base station and terminal according to this embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, they will be described with reference to FIGS.

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

Note that the number of PRB pairs and PRB pair numbers (frequency resources, that is, positions of PRB pairs) are set for each EPDCCH set. Also, N _ECCE , which is the number of ECCEs in the EPDCCH set, is determined by the number of PRB pairs, and ECCEs of ECCE#0 to ECCE#N _ECCE −1 are arranged.

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

In the present embodiment, each EPDCCH is divided into two, the ECCE of EPDCCH set 0 (EPDCCH set corresponding to subframe #0) and the ECCE of EPDCCH set 1 (EPDCCH set corresponding to subframe #1). 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 allocated to AL1 EPDCCH candidates (one ECCE) of EPDCCH set 0 and EPDCCH set 1, respectively. Similarly, EPDCCH#1 is divided into EPDCCH#1a and EPDCCH#1b and allocated to AL1 EPDCCH candidates (one ECCE) of EPDCCH set 0 and EPDCCH set 1, respectively. Similarly, EPDCCH#2 is divided into EPDCCH#2a and EPDCCH#2b and allocated to AL2 EPDCCH candidates (two ECCEs) of EPDCCH set 0 and EPDCCH set 1, respectively.

That is, base station 100 (configuration section 102) configures an EPDCCH set for each of a plurality of subframes used for soft combining. In addition, base station 100 (signal allocation section 105) divides EPDCCH (control information) by the same number as the number of the plurality of subframes in ECCE units, and assigns each divided EPDCCH to each of the plurality of subframes. Allocate to one of the ECCEs that make up the set EPDCCH set.

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

In equations (1) and (2), L represents the aggregation level (AL), Y _p,k represents the UE ID (terminal ID), K represents the subframe number, and p represents the search space set number. show. Also, i takes values of 0, 1, ..., L-1.

Also, m' is a parameter used when cross-carrier scheduling is set, and is represented by the following equation.

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

Also, m is represented by the following equation.

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

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

In this way, the number of EPDCCH candidates to be used can be shared between subframes to which soft combining is applied. Specifically, in subframes (here, 2 subframes) to which soft combining is applied, a combination of EPDCCH candidates that becomes M _p ^(L) * M _p ^(L) pattern for each aggregation level (AL) , M _p ^(L) patterns. Also, even when EPDCCH candidates with the same number m are used in each subframe, the EPDCCH candidates (ECCE) are different for each subframe. That is, even for EPDCCH candidates (ECCEs) with the same number m, frequency resources assigned to each subframe are different, so that a frequency diversity effect can be obtained. Also, if the number of REs actually assigned differs for each ECCE number, the number of REs can be averaged.

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

(Method 1: When EPDCCH sets configured in two subframes are the same)
FIG. 11A shows EPDCCH sets configured during non soft combining, and FIG. 11B shows EPDCCH sets configured during soft combining.

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

As a result, as shown in FIG. 11B, the EPDCCH sets arranged in each subframe have the same number of PRB pairs (4) and the same PRB number (same PRB pair arrangement position). However, ECCEs corresponding to EPDCCH candidates forming each EPDCCH set differ for each subframe.

By doing so, EPDCCH candidates for each aggregation level (AL) are equal between EPDCCH sets (that is, between subframes to which the same EPDCCH is allocated). Therefore, all EPDCCH candidates can be used as search spaces for EPDCCH soft combining.

In addition, since the EPDCCH is arranged in the same PRB pair in a plurality of subframes, the precoding of the demodulation reference signal (DMRS), which is the reference signal used for the EPDCCH, is common among the subframes to which soft combining is applied. good too. By doing this, for example, when the moving speed of terminal 200 is slow, it can be assumed that the channel fluctuates little between consecutive subframes. Institutions can be improved.

Also, in LTE-Advanced, two EPDCCH sets can be configured 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, and the operation can be dynamically switched.

(Method 2: When EPDCCH sets configured in two subframes are different)
FIG. 12A shows EPDCCH sets configured during non soft combining, and FIG. 12B shows EPDCCH sets configured during soft combining.

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

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

As shown in FIGS. 12A and 12B, for each EPDCCH set set in each of a plurality of subframes used for soft combining, the number of PRB pairs, the PRB number (placement position of the PRB pair), the allocation method (distributed allocation or localized allocation) can be set. That is, in Method 2, soft combining can be performed using EPDCCH sets with different designs.

For example, in FIG. 12B, of the two subframes to which EPDCCH soft combining is applied, the number of PRB pairs in the EPDCCH set set in the 1st subframe is 4 (N=4), and set in the 2nd subframe. The number of PRB pairs in the EPDCCH set is two (N=2). Since the number of PRB pairs differs between subframes (between EPDCCH sets) in this way, the number of EPDCCH candidates for each aggregation level (AL) also differs. For example, as shown in FIG. 13, the number of EPDCCH candidates with the number 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 the number of PRB pairs 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. However, L = 2 when soft combining is applied), there are four EPDCCH candidates for the EPDCCH set with the number of PRB pairs N = 2 (EPDCCH candidate number m = 0, 1, 2, 3), and the number of EPDCCH candidates in the EPDCCH set with the number of PRB pairs N = 4 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 used as EPDCCH candidates for soft combining, and the remaining EPDCCH candidates (PRB pair number N=2 2 EPDCCH candidates (m=2,3) are used as EPDCCH candidates for non-soft combining, and the same is true for other ALs.

That is, in method 2, since EPDCCH candidates for each AL differ between EPDCCH sets, when the number of EPDCCH candidates differs, EPDCCH candidates for the smaller number of candidates are used as search spaces for soft combing. In this case, the remaining EPDCCH candidates in the larger EPDCCH set can be used as search spaces for non soft combing.

Also, according to method 2, the region used for the EPDCCH can be changed for each subframe. For example, among the subframes used for soft combining, when the PDSCH is arranged in the final subframe (2nd subframe in FIG. 12B), compared with other subframes (1st subframe in FIG. 12B), the final subframe The PDSCH area can be secured by reducing the number of EPDCCH areas arranged in 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 configure resource allocation for allocating EPDCCHs when soft combining is applied.

Note that in LTE-Advanced EPDCCH, the number of EPDCCH candidates for each AL differs depending on conditions such as the DCI format, bandwidth, type of subframe, number of subcarriers, and the like. 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 support AL1 (L=1 ) and above. Therefore, with the present embodiment, a case has been described where EPDCCHs of AL2 or higher are assumed, but by applying soft combing, EPDCCHs of AL1 can be handled as EPDCCHs of AL2 or higher. That is, in the present embodiment, not only case 1 in which the number of EPDCCH candidates equal to or greater than AL2 is prepared, but also Case 2 or Case 3 prepared from the number of EPDCCH candidates in AL1 may be applied to all DCI formats. By doing so, it is possible to prevent AL from becoming too large during soft combining.

[Embodiment 3]
In Embodiment 2, a case has been described where soft combining is performed by concatenating multiple EPDCCH sets configured in multiple subframes to which soft combining is applied. In contrast, the present embodiment describes a case where PRB pairs of one EPDCCH set are distributed to multiple subframes to which soft combining is applied.

Since the base station and terminal according to this embodiment have the same basic configuration as base station 100 and terminal 200 according to Embodiment 1, they will be described with reference to FIGS.

Specifically, base station 100 (configuration section 102) configures one EPDCCH set for all of the multiple subframes used for soft combining. However, the PRB pairs corresponding to the ECCEs forming the single EPDCCH set are distributed and arranged in multiple subframes used for soft combining.

For example, when the number of PRB pairs in an 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 shows an example in which EPDCCH soft combining is performed in two subframes (M=2). In FIG. 14, the number of PRB pairs in the EPDCCH set is 4 (N=4). Therefore, in FIG. 14, two (=N/M) PRB pairs are arranged per subframe. In addition, in FIG. 14, EPDCCH#0 and EPDCCH#1 are AL1, and EPDCCH#2 is AL2. Also, each EPDCCH is arranged according to the ECCE assignment formula in EPDCCH set 0.

In FIG. 14, EPDCH#0 is mapped to ECCE#0, EPDCCH#1 is mapped to ECCE#1, and EPDCCH#2 is mapped to ECCE#2 and #3. Each ECCE is then assigned to four PRB pairs of EPDCCH set 0 (for example, PRB index #0, #1, #2, #3), respectively. However, in FIG. 14, PRB indexes #0 and #2 are arranged in subframe #0, and PRB indexes #1 and #3 are arranged in subframe #1. That is, one EPDCCH set 0 is divided and arranged in multiple subframes to which soft combining is applied.

By doing so, in the present embodiment, soft combining can be applied even when AL1 is used. In addition, since the resource amount of the EPDCCH region per subframe used for soft combining can be reduced, resources not used for EPDCCH can be used for PDSCH.

[Variation when N=8]
FIG. 15 shows an example of correspondence 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 are different depending on the ECCE. Specifically, an even-numbered (index) ECCE is mapped to an even-numbered PRB pair, and an odd-numbered ECCE is mapped to an odd-numbered PRB pair.

Variations 1 and 2 of dividing an EPDCCH set (PRB pair) into multiple subframes (here, two) used for soft combining in this case will be described.

(Variation 1)
In variation 1, soft combining is divided into subframes in which even-numbered PRB pairs are allocated and subframes in which odd-numbered PRB pairs are allocated. For example, when soft combining is performed using two subframes, even-numbered PRB pairs are arranged in the 1st subframe and odd-numbered PRB pairs are arranged in the 2nd subframe.

By doing so, the AL1 EPDCCH configured with one ECCE is arranged in either the 1st subframe or the 2nd subframe. That is, soft combining is not applied only to EPDCCH of AL1. This allows switching between soft combining and non-soft combining by selecting AL.

In addition, as described above, in Variation 1, soft combining can be applied from AL2 EPDCCH. Therefore, in LTE-Advanced, Case 1 prepared from the number of AL2 EPDCCH candidates (see Non-Patent Document 1) may be applied to all DCI formats. By doing so, soft combining can be applied to all EPDCCH candidates.

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

By doing so, even an AL1 EPDCCH composed of one ECCE is arranged in the 1st subframe and the 2nd subframe, respectively. As a result, soft combining can be applied to AL1 EPDCCH as well.
In the above, variations of dividing an EPDCCH set (PRB pair) into a plurality of subframes have been described.

As described above, according to the present embodiment, as in the case of the second embodiment, resource allocation for allocating EPDCCHs when soft combining is applied can be set appropriately.

Each embodiment of the present invention has been described above.

(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 soft combining) for each AL after change. In FIG. 16B, the number of low AL (L=1) EPDCCH candidates is reduced, while the number of high AL (L=8) EPDCCH candidates is increased compared to FIG. 16A. In this way, especially by increasing the number of EPDCCH candidates with high AL, the effect of soft combining is enhanced.

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

[3] When EPDCCH soft combining is performed in Embodiments 2 and 3, it may be assumed that the DMRS precoding of each subframe is the same depending on the conditions.

An example of the condition is, for example, the 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, the same EPDCCH set is used in multiple subframes used for soft combining, so it can be assumed that DMRS precoding is the same for each subframe.

Another example of another condition is, for example, a case where PRB pairs in which EPDCCHs are arranged are arranged within a certain range in each subframe to which soft combining is applied. “Within a certain range” means, for example, adjacent PRB pair indexes.

Alternatively, as an example of the condition, in each subframe to which soft combining is applied, a PRB pair in which EPDCCH is arranged is arranged 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.

Moreover, in Embodiment 3, the PRB pairs (positions) are always different between a plurality of subframes, and it is difficult to make DMRS precoding the same between subframes. Therefore, when applying Embodiment 3, the same PRB pair may be used between subframes used for soft combining. For example, in the 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 position may be shifted.

[4] Further, in the above embodiment, a case has been described where soft combining is performed across a plurality of subframes (that is, time domains). However, the above embodiments may be applied to the frequency domain (for example, carrier aggregation). In this case, instead of allocating EPDCCHs to multiple subframes in the above embodiment, EPDCCHs may be allocated across multiple Component Carriers (CCs). Also, for example, in Embodiment 1, the PUCCH resource is implicitly indicated by the ECCE (index) of the EPDCCH arranged in the last subframe of a plurality of subframes. On the other hand, during carrier aggregation, PUCCH resources may be implicitly indicated by ECCE (index) of EPDCCH allocated to PCell among a plurality of carrier components.

[5] Further, the EPDCCH soft combining in Embodiment 2 may be applied to two EPDCCH sets within the same subframe. By doing so, it is possible to increase the maximum AL within one subframe and improve the reception quality of the EPDCCH in subframes with poor reception quality.

[6] In each of the above embodiments, the case where the present invention is configured by hardware has been described as an example, but the present invention can also be implemented by software in cooperation with hardware.

Moreover, each functional block used in the description of each of the above embodiments is typically realized as an LSI, which is an integrated circuit. These may be made into one chip individually, or may be made into one chip so as to include part or all of them. Although LSI is used here, it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Also, the method of circuit integration is not limited to LSI, and may be realized 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 connections or settings of circuit cells inside the LSI may be used.

Furthermore, if an integration technology that replaces the LSI appears due to advances in semiconductor technology or another derived technology, the technology may naturally be used to integrate the functional blocks. Application of biotechnology, etc. is possible.

As described above, the base station of the present disclosure assigns an Enhanced Physical Downlink Control Channel (EPDCCH) set composed of Enhanced Control Channel Elements (ECCE) that allocate control information transmitted across a plurality of subframes to the plurality of subframes. A configuration including a setting unit for setting and an allocation unit for allocating the control information to one of the ECCEs in each Physical Resource Block (PRB) pair of the plurality of subframes is adopted.

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 allocation unit assigns the control information to the same number as the number of the plurality of subframes. is divided in units of the ECCE, and each of the divided control information is allocated to one of the ECCEs forming the EPDCCH set set in each of the plurality of subframes.

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

Also, in the base station of the present disclosure, the EPDCCH sets configured in each of the plurality of subframes are different.

Further, in the base station of the present disclosure, the configuration unit configures one EPDCCH set for the entire plurality of subframes, and the PRB pairs corresponding to the ECCEs constituting the one EPDCCH set are the It is distributed and arranged in a plurality of subframes.

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

Further, in the base station of the present disclosure, among the plurality of subframes, a Physical Uplink Control Channel ( PUCCH), further comprising a receiving unit that receives a response signal to the downlink data.

Further, in the base station of the present disclosure, the transmission subframe of the control information instructing allocation of uplink data is associated with the reception subframe of the uplink data, and among the plurality of subframes, the last is the same as the transmission subframe.

Further, the terminal of the present disclosure is an Enhanced Control Channel Element (ECCE) to which control information transmitted across a plurality of subframes is assigned, and an Enhanced Physical Downlink Control Channel (EPDCCH) set in the plurality of subframes. ) a setting unit that identifies the ECCEs that make up the 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. Adopt a configuration that is provided.

Further, the transmission method of the present disclosure provides an Enhanced Physical Downlink Control Channel (EPDCCH) set composed of Enhanced Control Channel Elements (ECCE) that allocate control information transmitted across a plurality of subframes, to the plurality of subframes. and transmit the control information assigned to one of the ECCEs in each Physical Resource Block (PRB) pair of the plurality of subframes.

Further, 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 assigned, and an Enhanced Physical Downlink Control Channel (ECCE) set in the plurality of subframes ( EPDCCH) set, and receives the control information assigned to one of the ECCEs in a Physical Resource Block (PRB) pair of each of the plurality of subframes.

INDUSTRIAL APPLICABILITY The present invention is useful for mobile communication systems.

REFERENCE SIGNS LIST 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 decoder 202 signal separator 206 control signal receiver

Claims (27)

receiving one piece of control information indicating allocation of downlink data using a plurality of first subframes in the downlink, and receiving second subframes after the last subframe among the plurality of first subframes; a receiving unit that receives the downlink data using
a transmitting unit configured to transmit, in an uplink subframe, ACK/NACK information regarding the downlink data received in the second subframe ;
When there is uplink data in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is transmitted, and when there is no uplink data in the uplink subframe, Physical Uplink Control the ACK/NACK information is transmitted on a Channel (PUCCH) resource;
Communication device. When uplink data exists in the uplink subframe, the uplink data and the ACK/NACK information are transmitted in a Physical Uplink Shared Channel (PUSCH) in the uplink subframe,
2. A communication device according to claim 1. The EPDCCH set designed in each subframe in the plurality of first subframes occupies a plurality of Physical Resource Block (PRB) pairs, and each EPDCCH set is a set of EPDCCH candidates in one downlink subframe. is
2. A communication device according to claim 1. EPDCCH sets designed in each subframe in the plurality of first subframes are different in at least one of the number of PRB pairs or the frequency position of PRB pairs,
2. A communication device according to claim 1. The downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the second subframe is received;
2. A communication device according to claim 1. the ACK/NACK information is transmitted in a subframe determined based on the last subframe in which the downlink data is arranged;
2. A communication device according to claim 1. In the plurality of first subframes , common precoding of reference signals used for one control information indicating allocation of the downlink data;
2. A communication device according to claim 1. When the number of subframes in which the control information is arranged in the plurality of first subframes is plural, and in the case where the number of subframes in which the control information is arranged in the plurality of first subframes is 1 Comparatively, the number of EPDCCH candidates associated with at least one aggregation level is small,
2. A communication device according to claim 1. The receiving unit receives one piece of control information indicating allocation of uplink data using a plurality of third subframes in the downlink,
The transmitting unit transmits the uplink data using a subframe determined based on a final subframe among the plurality of third subframes.
2. A communication device according to claim 1. One piece of control information indicating allocation of the downlink data includes information about the second subframe,
2. A communication device according to claim 1. one piece of control information indicating allocation of uplink data includes information about the plurality of third subframes;
10. A communication device according to claim 9. the communication device
receiving a piece of control information indicating allocation of downlink data using a plurality of first subframes in the downlink;
receiving the downlink data using a second subframe after the last subframe of the plurality of first subframes;
transmitting, in an uplink subframe, ACK/NACK information regarding the downlink data received in the second subframe ;
When there is uplink data in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is transmitted, and when there is no uplink data in the uplink subframe, Physical Uplink Control the ACK/NACK information is transmitted on a Channel (PUCCH) resource;
Communication method. When uplink data exists in the uplink subframe, the uplink data and the ACK/NACK information are transmitted in a Physical Uplink Shared Channel (PUSCH) in the uplink subframe,
13. The communication method according to claim 12. The EPDCCH set designed in each subframe in the plurality of first subframes occupies a plurality of Physical Resource Block (PRB) pairs, and each EPDCCH set is a set of EPDCCH candidates in one downlink subframe. is
13. The communication method according to claim 12. EPDCCH sets designed in each subframe in the plurality of first subframes are different in at least one of the number of PRB pairs or the frequency position of PRB pairs,
13. The communication method according to claim 12. The downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the second subframe is received;
13. The communication method according to claim 12. the ACK/NACK information is transmitted in a subframe determined based on the last subframe in which the downlink data is arranged;
13. The communication method according to claim 12. In the plurality of first subframes , common precoding of reference signals used for one control information indicating allocation of the downlink data;
13. The communication method according to claim 12. When the number of subframes in which the control information is arranged in the plurality of first subframes is plural, and in the case where the number of subframes in which the control information is arranged in the plurality of first subframes is 1 Comparatively, the number of EPDCCH candidates associated with at least one aggregation level is small,
13. The communication method according to claim 12. a process of receiving a piece of control information indicating allocation of downlink data using a plurality of first subframes in the downlink;
a process of receiving the downlink data using a second subframe after the final subframe among the plurality of first subframes;
controlling a process of transmitting ACK/NACK information regarding the downlink data received in the second subframe in an uplink subframe;
When there is uplink data in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is transmitted, and when there is no uplink data in the uplink subframe, Physical Uplink Control the ACK/NACK information is transmitted on a Channel (PUCCH) resource;
integrated circuit. When uplink data exists in the uplink subframe, the uplink data and the ACK/NACK information are transmitted in a Physical Uplink Shared Channel (PUSCH) in the uplink subframe,
21. The integrated circuit of Claim 20. The EPDCCH set designed in each subframe in the plurality of first subframes occupies a plurality of Physical Resource Block (PRB) pairs, and each EPDCCH set is a set of EPDCCH candidates in one downlink subframe. is
21. The integrated circuit of Claim 20. EPDCCH sets designed in each subframe in the plurality of first subframes are different in at least one of the number of PRB pairs or the frequency position of PRB pairs,
21. The integrated circuit of Claim 20. The downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the second subframe is received;
21. The integrated circuit of Claim 20. the ACK/NACK information is transmitted in a subframe determined based on the last subframe in which the downlink data is arranged;
21. The integrated circuit of Claim 20. In the plurality of first subframes , common precoding of reference signals used for one control information indicating allocation of the downlink data;
21. The integrated circuit of Claim 20. When the number of subframes in which the control information is arranged in the plurality of first subframes is plural, and in the case where the number of subframes in which the control information is arranged in the plurality of first subframes is 1 Comparatively, the number of EPDCCH candidates associated with at least one aggregation level is small,
21. The integrated circuit of Claim 20.

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