JP6748894B2 - Base station, communication method, and integrated circuit - Google Patents

Description

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

2. Description of the Related Art In recent years, in cellular mobile communication systems, it has become common to transmit not only audio data but also large-capacity data such as still image data and moving image data as information becomes multimedia. In addition, in LTE-Advanced (Long Term Evolution Advanced), studies are actively conducted to realize a high transmission rate by using a wideband radio band, Multiple-Input Multiple-Output (MIMO) transmission technology, and interference control technology. There is.

In LTE-Advanced, an enhanced control channel area called Enhanced PDCCH (EPDCCH), which is an extension of PDCCH (Physical Downlink Control CHannel) used for control signals, is designed. The EPDCCH is arranged in a resource area (PDSCH (Physical Downlink Shared CHannel) area) to which downlink data is allocated. Further, the base station defines a frequency resource (for example, RB (Resource Block)) for each terminal (which may be referred to as UE (User Equipment)) in a resource region (EPDCCH region) in which EPDCCH is arranged, and transmits a signal. Can be sent. Therefore, the transmission power control for the control signal transmitted to the terminal existing near the cell edge, or the interference control given from the own cell to another cell by the transmitted control signal or the interference given from the other cell to the 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, the RB pair has 12 subcarriers in the frequency direction and has a width of 1 msec in the time direction. Also, when the RB pair represents a block of 12 subcarriers on the frequency axis, the RB pair may be simply referred to as RB. Further, in the physical layer, the 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 area, a unit obtained by dividing each PRB pair into 16 resources is called an EREG (Enhanced Resource Element Group), and a resource unit formed by 4 or 8 EREGs is called an ECCE (Enhanced Control Channel Element). The number of ECCEs forming the EPDCCH that transmits one control signal is called an aggregation level (AL). EPDCCH can set a plurality of ALs (for example, see 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 constitutes a search space (Search Space) that is a target of blind decoding (monitoring) by the terminal.

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

FIG. 1 shows an example in which EPDCCH is mapped to resources. 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 placed in ECCE#0, EPDCCH#1 is placed in ECCE#1, EPDCCH#2 is placed in ECCE#2 and ECCE#3, and EPDCCH#3 is placed in ECCE#4, ECCE. It is placed in #5, ECCE#6, and ECCE#7. Further, in FIG. 1, each ECCE is arranged in four EREGs, and thus is divided into four. As shown in FIG. 1, in the case of localized allocation, four EREGs are arranged in the same PRB pair, and in the case of distributed allocation, four EREGs are arranged in different PRB pairs.

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

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

3GPP TS 36.213 V11.1.0, Physical layer procedures

In LTE-Advanced, it is considered that small cells, which are base stations with low transmission power, are arranged to realize a high transmission rate of hot spots. For example, a high frequency such as 3.5 GHz is a candidate as a carrier frequency for operating a small cell. However, when a high-frequency wireless band is used, a high transmission rate can be expected in a short distance, but the attenuation due to the 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 the small cell becomes small. Further, in the case of a small cell, it is necessary to consider the constraint of transmission power, and the power that can be used for transmission per subframe is limited. Since the coverage area of a cell is determined by the range that the control signal reaches, a technology 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 (also referred to as bundling) in which EPDCCH including control information is arranged over a plurality of subframes. However, so far no consideration has been given to the EPDCCH allocation method when soft combining is applied.

An object of the present invention is to provide a base station, a communication method, and an integrated circuit that can appropriately set resources for allocating EPDCCH when applying soft combining.

A base station according to an aspect of the present invention is a transmission unit that transmits control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates that are repeated in a set of consecutive subframes in a downlink. And a receiving unit that receives ACK/NACK information regarding downlink data transmitted in the final subframe of the set of subframes in an uplink subframe determined based on the final subframe. However, if there is uplink data to be transmitted in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is received, and the uplink data to be transmitted in the uplink subframe. When there is no ACK/NACK information, the ACK/NACK information is received by a Physical Uplink Control Channel (PUCCH) resource associated with the EPDCCH candidate arranged in the final subframe.

In the base station of one aspect of the present invention, when there is uplink data to be transmitted in the uplink subframe, the uplink data and the ACK/NACK information are Physical Uplink Shared Channel in the uplink subframe. (PUSCH).

A communication method according to an aspect of the present invention is such that a base station transmits 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 a downlink. Transmit, receive ACK/NACK information regarding the downlink data transmitted in the final subframe of the set of subframes in the uplink subframe determined based on the final subframe, the uplink When there is uplink data to be transmitted in the subframe, the ACK/NACK information multiplexed with the uplink data is received, and when there is no uplink data to be transmitted in the uplink subframe, the The ACK/NACK information is received by the Physical Uplink Control Channel (PUCCH) resource associated with the EPDCCH candidate arranged in the last subframe.

An integrated circuit according to an aspect of the present invention includes a process of transmitting control information arranged in at least one of a plurality of Enhanced Physical Downlink Control Channel (EPDCCH) candidates that are repeated in a set of consecutive subframes in a downlink. Controlling the ACK/NACK information regarding the downlink data transmitted in the final subframe of the set of subframes in the uplink subframe determined based on the final subframe, If there is uplink data to be transmitted in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is received, and there is uplink data to be transmitted in the uplink subframe. If not, the ACK/NACK information is received by the Physical Uplink Control Channel (PUCCH) resource associated with the EPDCCH candidate arranged in the final subframe.

According to the present invention, it is possible to appropriately set resources for allocating EPDCCH when soft combining is applied.

Diagram used to explain EPDCCH Diagram for explaining soft combining FIG. 3 is a block diagram showing the main configuration of the base station according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing the main configuration of the terminal according to Embodiment 1 of the present invention. Block diagram showing a configuration of a base station according to Embodiment 1 of the present invention Block diagram showing a configuration of a terminal according to Embodiment 1 of the present invention The figure which shows the timing of PDSCH and PUCCH which concerns 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. The figure which shows the example of setting of the EPDCCH candidate which concerns on Embodiment 2 of this invention. The figure which shows the example of setting the search space of EPDCCH which concerns on Embodiment 2 of this invention. The figure which shows the example of setting the search space of EPDCCH which concerns on Embodiment 2 of this invention. The figure which shows the EPDCCH candidate number which concerns on Embodiment 2 of this invention The figure which shows the example of setting of the EPDCCH candidate which concerns on Embodiment 3 of this invention. The figure which shows the PRB pair (EREG) in which ECCE concerning Embodiment 3 of this invention is arrange|positioned. The figure which shows the example of setting of the number of EPDCCH candidates which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in the embodiments, the same components are designated by the same reference numerals, and the description thereof will be omitted to avoid duplication.

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

Further, in the present embodiment, when transmitting EPDCCH for terminal 200, base station 100 can apply soft combining for transmitting EPDCCH (control information) over a plurality of subframes (see FIG. 2 ). The receiving side (terminal 200) synthesizes the control information transmitted over a plurality of subframes and performs a receiving process. The 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 the information bits. In addition, when the terminal 200 receives the EPDCCH transmitted over a plurality of subframes, it receives or transmits data after the EPDCCH reception is completed, and transmits or receives ACK/NACK (response signal). Determine the timing to do it.

Further, a subframe to which soft combining of EPDCCH is applied is preset for 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, soft combining of EPDCCH is applied according to the reception quality of each subframe, such that soft combining is not applied to subframes that are less affected by interference and soft combining is applied to subframes that are heavily interfered. You can switch whether or not to do it.

In addition, 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, but in the following description, in the EPDCCH region, in order to simplify the description. Only transmission and reception of control information will be described.

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

In base station 100, setting section 102 sets, in the plurality of subframes, an EPDCCH set including ECCEs to which control information (allocation information) transmitted over a plurality of subframes is assigned. Signal allocation section 105 allocates control information to any of ECCEs in each PRB pair of a plurality of subframes.

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

In terminal 200, setting section 205 identifies an ECCE to which control information (allocation information) transmitted over a plurality of subframes is allocated, and which constitutes an ECCCCH set in a plurality of subframes. .. The control signal receiving unit 206 receives the control information assigned to any of the ECCEs in each PRB pair 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. 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, and The demodulation unit 108 and the 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 assigned to the uplink (UL), the assignment information generation unit 101 assigns a resource (RB) to which the data signal is assigned. Is determined and allocation information (DL assignment and UL grant) is generated. The DL assignment includes information about assignment of DL data signals. The UL grant includes information related to resources allocated to UL data signals transmitted from the terminal 200. DL assignment is output to signal allocating section 105, and UL grant is output to signal allocating section 105 and receiving section 107.

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

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 a subframe (see FIG. 2) to which soft combining is applied to the terminal 200 to which soft combining is applied. Further, the setting unit 102 sets the 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, the PRB pair corresponding to the ECCE forming the EPDCCH set is arranged in each of the plurality of subframes. As a result, in each subframe used for soft combining, the above-described search space is set based on the set EPDCCH set.

The setting section 102 outputs information about the set search space and information about a subframe number to which soft combining of EPDCCH is applied to the signal allocating section 105. The information regarding the search space includes, for example, the PRB pair number, the number of PRB pairs, and the like. Further, setting section 102 outputs information regarding the PRB pair set in the search space and information regarding the EPDCCH allocation method to error correction encoding 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 allocation unit 105 receives the allocation information (DL assignment and UL grant) received from the allocation information generation unit 101 as the ECCE (ECCE 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 allocation information, the signal allocating unit 105 PRBs of each of the plurality of subframes corresponding to the subframe number indicated in the information about soft combining received from the setting unit 102. Allocate the allocation information to one of the ECCEs in the pair. As a result, the allocation information is allocated to the PRB pair in which the ECCE is arranged (for example, refer to FIG. 1). Further, the signal allocating unit 105 allocates the data signal received from the modulating unit 104 to the downlink resource corresponding to the allocation information (DL assignment) received from the allocation information generating unit 101.

In this way, the transmission information is formed by allocating the allocation information and the data signal to the predetermined resource. The formed transmission signal is output to the transmission unit 106. Further, the signal allocating section 105 notifies the receiving section 107 of the ECCE index of the ECCE used for transmitting the DL assignment. When soft combining is applied, the signal allocating section 105 may be the last subframe (hereinafter, referred to as “final subframe”) among the plurality of subframes used for transmitting the DL assignment. The ECCE index of ECCE in () is notified to the receiving unit 107.

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

The receiving unit 107 receives the signal transmitted from the terminal 200 via the antenna and outputs the signal to the demodulating 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 received signal, and performs reception processing such as down conversion on the separated signal. It outputs to the demodulation unit 108 later. Further, receiving section 107 extracts (receives) an A/N signal from the signal corresponding to the PUCCH resource associated with the ECCE index received from signal allocating 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 and obtains a received data signal from terminal 200.

[Configuration of terminal 200]
FIG. 6 is a block diagram showing the configuration of terminal 200 according to the present 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 encoding section 207. The modulation unit 208, the signal allocation unit 209, and the transmission unit 210 are included.

The reception unit 201 receives the signal transmitted from the base station 100 via an antenna, performs reception processing such as down conversion, and outputs the signal to the signal separation unit 202.

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

The demodulation unit 203 demodulates the signal output from the signal separation unit 202 and outputs the demodulated signal to the error correction decoding unit 204.

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

The setting unit 205 specifies the search space set in the own device (terminal 200) using the EPDCCH. For example, the setting unit 205 first specifies the PRB pair to be set in the search space based on the information received from the error correction decoding unit 204. Next, the setting section 205 specifies the EPDCCH to which soft combining is applied based on the information about the subframe to which soft combining of EPDCCH is applied. Then, the setting unit 205 determines the ECCE index of the search space corresponding to the PRB pair. As a result, the setting unit 205 identifies the ECCE to which the EPDCCH to be transmitted over a plurality of subframes is assigned (the ECCE forming the 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 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 a UE ID (terminal-specific ID) and soft combining are applied. Next, setting section 205 outputs information regarding the PRB pair and ECCE set as the search space to control signal receiving section 206.

The control signal receiving unit 206 performs blind decoding on the ECCE corresponding to the PRB pair indicated by the information received from the setting unit 205 in the signal component received from the signal separating unit 202, and thereby the control signal (DL assignment or UL grant) is detected. That is, the control signal receiving unit 206 receives the control signal assigned to one of the plurality of assignment candidates forming 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 any of ECCEs in each PRB pair of a plurality of subframes. The control signal receiving 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 allocation 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 allocating unit 209.

Error correction coding section 207 receives the transmission data signal (UL data signal) as input, performs error correction coding on the transmission data signal, and outputs it 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 allocating section 209 allocates the signal received from modulating section 208 according to the UL grant received from control signal receiving section 206, and outputs the signal to transmitting section 210. At this time, when EPDCCH soft combining is applied, the 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. Further, the signal allocation unit 209 allocates 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 allocating section 209 multiplexes the transmission data signal with an A/N signal and outputs it to transmitting section 210. On the other hand, when there is no transmission data signal, signal allocating section 209 specifies the PUCCH resource based on the ECCE index received from control signal receiving section 206, allocates the A/N signal to the specified PUCCH resource, and the transmitting section Output to 210. At this time, when EPDCCH soft combining is applied, the signal allocating unit 209 determines the transmission subframe of the A/N signal based on the last subframe of the plurality of subframes to which soft combining is applied. To do.

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

[Operations of Base Station 100 and Terminal 200]
The operations of base station 100 and terminal 200 having the above configurations 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 explained.

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

FIG. 7 shows an example of PDSCH settings. As shown in FIG. 7, when soft combining using two subframes of subframe #0 and subframe #1 is applied, the base station 100 determines the PDSCH for the terminal 200 among the two subframes. , And is placed in subframe #1 which is the last subframe. That is, as shown in FIG. 7, the DL assignment notified using the EPDCCH arranged in subframe #0 and subframe #1 specifies the resource in subframe #1 as the resource for PDSCH. It

That is, the base station 100 (the signal allocating unit 105) uses the downlink data (PDSCH) whose allocation is instructed by the EPDCCH (DL assignment) and is 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 subframes #0 and #1 to which soft combining is applied, so that terminal 200 Detect DL assignments for. Then, terminal 200 (signal section separating 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, detection of the DL assignment notified using EPDCCH to which soft combining is applied is performed after the final subframe is received. Then, after detecting the DL assignment, terminal 200 specifies that the PDSCH has been 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 allocates the PDSCH as the PDSCH until the identification (detection) of the PRB pair allocated to the PDSCH is completed. The received signal received on all possible PRB pairs must be buffered.

On the other hand, in the present embodiment, PDSCH is arranged in the final subframe of a plurality of subframes to which soft combining is applied. By doing so, it is possible to minimize the period during which the received signal received from the PDSCH reception timing to the time when the EPDCCH detection is completed is stored in the buffer. In other words, even when EPDCCH soft combining is applied, the period during which the received signal received from the PDSCH reception timing to the completion of EPDCCH detection is stored in the buffer is not applied (non soft combining). ) Can be the same as the period. This can prevent the size of the buffer that the terminal 200 should have from increasing.

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

In the present embodiment, the transmission timing of the uplink A/N signal (subframe for transmitting UL ACK/NACK) is defined according to the PDSCH reception subframe. In the case of the FDD system, it is set 4 subframes after the PDSCH reception subframe, and in the case of the TDD system, the PDSCH reception subframe is used as a reference and follows the rules for each UL-DL configuration of the TDD. 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 an uplink A/N signal in the PUCCH region, the minimum ECCE number among the ECCEs configuring the EPDCCH in which the DL assignment is arranged (that is, the EPDCCH of the subframe in which PDSCH is transmitted) By specifying the PUCCH resource (the resource indicated by implisit) associated with, the PUCCH resource between terminals is automatically allocated (to implisit) so as not to collide.

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

That is, terminal 200 is associated with an ECCE arranged in a subframe to which downlink data (PDSCH) whose allocation is instructed by EPDCCH (DL assignment) is allocated 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 transmitting the A/N signal is not necessarily the smallest ECCE number among the ECCEs that make up the EPDCCH. Similarly, the base station 100 (reception unit 107) is arranged in a subframe to which downlink data (PDSCH) whose allocation is instructed by EPDCCH (DL assignment) is allocated among a plurality of subframes used for soft combining. In the PUCCH associated with the ECCE, the A/N signal (response signal) for the downlink data is received.

For example, when PDSCH is arranged in the last subframe among a plurality of subframes to which soft combining of EPDCCH is applied, base station 100 and terminal 200 use ECCE numbers of EPDCCH arranged in the last subframe. , Specify the PUCCH resource to which the uplink A/N signal for the PDSCH is assigned. Specifically, in FIG. 7, PDSCH is arranged in subframe #1 which is the final subframe among subframes #0 and #1 to which soft combining of EPDCCH is applied. Therefore, in FIG. 7, the base station 100 and the terminal 200 allocate the PUCCH resource associated with the ECCE number of the EPDCCH arranged in subframe #1 in subframe #5 after 4 subframes of subframe #1. , PDSCH is specified as a PUCCH resource to which an uplink A/N signal is allocated.

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

[PUSCH timing]
In LTE-Advanced, a terminal transmits PUSCH after receiving UL grant. The subframe in which PUSCH is transmitted is predetermined. Specifically, the subframe in which PUSCH is transmitted is set 4 subframes after the subframe to which UL grant is assigned in the case of FDD system, and is specified for each UL-DL configuration of TDD in the case of TDD system. Has been done. Further, when the number of UL subframes is larger than the number of DL subframes in one frame, PUSCHs of a plurality of UL subframes can be designated in one DL subframe. However, also in this case, the subframe in which the PUSCH is transmitted is always set 4 or more subframes after the UL grant.

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

Therefore, in the present embodiment, the transmission timing of the PUSCH specified by UL grant transmitted using EPDCCH to which soft combining is applied, among the plurality of subframes in which EPDCCH to which soft combining is applied is arranged The last subframe is specified as a reference. The PUSCH transmission timing (subframes that transmit and receive PUSCH) is specified based on the last subframe of soft combining, and the EPDCCH soft combining applies the interval from the UL grant detection timing to the PUSCH transmission preparation. You can do the same as if not.

In particular, in the TDD system, UL grants are set even in DL subframes according to the UL grant-PUSCH timing association (UL grant-PUSCH timing) specified for each UL-DL configuration. There are subframes that are not transmitted. Therefore, in the case of the TDD system, the last subframe among the plurality of subframes used for soft combining is the same as the EPDCCH transmission subframe including the 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 that can be used for transmission of subframes), and subframes #2, #3, #7, and #8 are UL subframes. Further, as shown in FIG. 8, UL grant-PUSCH timing is specified in advance, and subframes in which UL grant can be arranged are subframes #1, #4, #6, and #9, which are notified in each subframe. For UL grant, PDSCHs are assigned in UL subframes #7, #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 grant may be arranged even in a subframe in which UL grant is not transmitted. Therefore, in the present embodiment, when soft combining of EPDCCH including UL grant is applied, the last subframe of subframes in which EPDCCH to which Soft combining is applied is applied, when Soft combining is not applied. It is a subframe that can transmit UL grant.

By doing this, soft combining can be operated without changing the PU grant timing from the UL grant detection timing.

For example, in FIG. 8, only subframes #1, #4, #6, and #9 are set as the final subframes for 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, respectively. As shown in FIG. 8, EPDCCHs including UL grants are also arranged in subframes #0 and #5 in which UL grants are not arranged 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 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 EPDCCH to which Soft combining is applied. It is determined based on the last subframe in which the EPDCCH is assigned. By this means, compared to the case where soft combining is not applied, soft combining can be operated without changing the relationship from the UL grant detection timing to the PUSCH timing.

It should be noted that the specification of the subframe to which Soft combining of EPDCCH is applied is common in the DL assignment and the UL grant, with respect to UL grant, the final subframe can be transmitted the UL grant when Soft combining is not applied. Soft combining is performed only when it is a subframe, and when this condition is not satisfied, soft combining may not be performed.

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

Next, the case of switching the presence/absence of application of soft combining 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 doing so, it is possible to flexibly switch whether or not to apply soft combining depending on the instantaneous channel quality depending on the EPDCCH candidates used in the same subframe.

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 candidates shown in FIG. 9A are divided into EPDCCH candidates for soft combining when switching the presence/absence of soft combining application and EPDCCH candidates to which soft combining is not applied.

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

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

(Method 2)
In method 2, the EPDCCH to which soft combining is not applied is arranged in a subframe other than the subframe corresponding to the final subframe of the subframe to which soft combining is applied. Specifically, when the number of subframes to which soft combining is applied is 2, the EPDCCH to which soft combining is not applied is arranged in the first 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 the method 2, since the subframes to be monitored for EPDCCH candidates are dispersed according to whether soft combining is applied, the number of EPDCCH candidates monitored by the terminal 200 can be averaged for each subframe.

In the downlink, the subframe in which the EPDCCH to which soft combining is not applied is transmitted and the subframe in which the PDSCH notified by the EPDCCH is transmitted may be set to different subframes. By doing this, the subframe for EPDCCH and the subframe for data (PDSCH) can be separated. Therefore, when power is required for data transmission, the power available for EPDCCH transmission is Can be used for transmission.

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

In this case, the 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.

Further, the PDSCH may be arranged in any subframe, and the PUSCH is arranged in a subframe specified based on the subframe in which the EPDCCH is detected.

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

Heretofore, the case of switching the presence/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 applying soft combining.

Note that it is also possible to apply PDSCH and PUSCH soft combining (sometimes called TTI bundling) in addition to the EPDCCH soft combining described above. In this case, the start position (start subframe) of DL data (PDSCH), which is instructed to be assigned using the DL assignment, is placed in the final subframe of the multiple subframes in which the EPDCCH including the DL assignment is transmitted. May be. As a result, the interval at which the received signal (the signal that may be PDSCH) is saved in the buffer between the PDSCH reception timing and the completion of the EPDCCH detection processing is the same as when EPDCCH soft combining is not applied. Can be

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

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, and therefore will be described with reference to FIGS. 5 and 6.

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

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. 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 transmitted EPDCCH bit string is set in advance to have 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 parts, an ECCE of EPDCCH set 0 (EPDCCH set corresponding to subframe #0) and an ECCE of EPDCCH set 1 (EPDCCH set corresponding to subframe #1). Will 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 arranged in EPDCCH candidates of AL1 of EPDCCH set 0 and EPDCCH set 1 (one ECCE), respectively. Similarly, EPDCCH#2 is divided into EPDCCH#2a and EPDCCH#2b and arranged in EPDCCH candidates (two ECCEs) of AL2 of EPDCCH set 0 and EPDCCH set 1, respectively.

That is, base station 100 (setting section 102) sets an EPDCCH set for each of a plurality of subframes used for soft combining. Also, the base station 100 (signal allocating unit 105) divides EPDCCH (control information) by the same number as the plurality of subframes in ECCE units, and divides each divided EPDCCH into 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, in subframe #0 and subframe #1, the divided EPDCCHs are arranged in different EPDCCH candidates. In LTE-Advanced, the following two equations are being studied as equations indicating EPDCCH candidates for each terminal 200.

In Expressions (1) and (2), L represents an aggregation level (AL), Y _p,k represents a UE ID (terminal ID), K represents a subframe number, and p represents a search space set number. Show. Moreover, i takes the value of 0, 1,..., L-1.

Further, 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 to be 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.

Further, m is expressed by the following equation.

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

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

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

Next, methods 1 and 2 for setting the EPDCCH search space in a subframe to which soft combining is applied will be described. Note that, as an example, a case where soft combining is applied across two subframes will be described below. However, the subframe used for soft combining is not limited to 2 subframes, and may be 3 subframes or more.

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

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

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

By doing so, the EPDCCH candidates for each aggregation level (AL) become equal between 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 soft combining of EPDCCHs.

In addition, since EPDCCHs are arranged in the same PRB pair in multiple subframes, precoding of DMRS (Demodulation reference signal), which is a reference signal used in EPDCCH, is common between subframes to which soft combining is applied. Good. By doing so, for example, when the moving speed of terminal 200 is slow, it can be assumed that the channel fluctuation between successive subframes is small, and therefore terminal 200 combines reference signals of a plurality of subframes and performs channel estimation. The system can be improved.

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

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

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

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

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

For example, in FIG. 12B, of the two subframes to which soft combining of EPDCCH 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 2 (N=2). In this way, since the number of PRB pairs differs between subframes (between EPDCCH sets), 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, and 1 for each AL (L=1, 2, 4, 8, 16).

Here, focusing on AL1 (L=1, but L=2 when soft combining is applied) in FIG. 13, there are four EPDCCH candidates (EPDCCH candidate number m for the EPDCCH set with the number of PRB pairs N=2). =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 the base station 100 and the terminal 200, only two EPDCCH candidates (m=0,1) that are common to two EPDCCH sets are used as EPDCCH candidates for soft combining, and the remaining EPDCCH candidates (the number of PRB pairs N=2). The 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 EPDCCH candidates for each AL are different between EPDCCH sets, when the number of EPDCCH candidates is different, the EPDCCH candidates for the smaller number of candidates are used as the 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 area used for EPDCCH can be changed for each subframe. For example, when PDSCH is arranged in the last subframe (2nd subframe in FIG. 12B) of subframes used for soft combining, the last subframe is compared with other subframes (1st subframe in FIG. 12B). The PDSCH area can be secured by reducing the EPDCCH area arranged in the.

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

As described above, according to the present embodiment, resource allocation for allocating EPDCCH when applying soft combining can be appropriately set.

Note that in the LTE-Advanced EPDCCH, the number of EPDCCH candidates for each AL differs depending on conditions such as DCI format, bandwidth, type of subframe, 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 support AL1 (L=1 ) Supports the above. Therefore, although a case has been described with the present embodiment where an EPDCCH of AL2 or higher is assumed, the EPDCCH of AL1 can be treated as an EPDCCH of AL2 or higher by applying soft combing. That is, in the present embodiment, Case 2 or Case 3 prepared from the number of EPDCCH candidates of AL1 may be applied to all DCI formats as well as case 1 in which the number of EPDCCH candidates of AL2 or more is prepared. By doing this, it is possible to prevent the AL from becoming too large during soft combining.

[Third Embodiment]
In the second embodiment, a case has been described in which a plurality of EPDCCH sets set in each of a plurality of subframes to which soft combining is applied are combined to perform soft combining. On the other hand, the present embodiment describes a case where PRB pairs of one EPDCCH set are distributed to a plurality of subframes to which soft combining is applied.

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, and therefore will be described with reference to FIGS. 5 and 6.

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

For example, when 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 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 FIG. 14, EPDCCH#0 and EPDCCH#1 are AL1, and EPDCCH#2 is AL2. Further, each EPDCCH is arranged according to the ECCE allocation formula in EPDCCH set 0.

In FIG. 14, EPDCH#0 is arranged in ECCE#0, EPDCCH#1 is arranged in ECCE#1, and EPDCCH#2 is arranged in ECCE#2, #3. Then, each ECCE is arranged in four PRB pairs (for example, PRB index #0, #1, #2, #3) of EPDCCH set 0, 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 a plurality of subframes to which soft combining is applied.

By doing so, in this embodiment, soft combining can be applied even if AL1 is used. Also, the resource amount of the EPDCCH region per subframe used for soft combining can be reduced, so that resources not used for EPDCCH can be used for PDSCH.

[Variation when N=8]
FIG. 15 shows an example of the correspondence relationship between ECCE 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 4. In FIG. 15, the PRB pairs to be arranged differ depending on the ECCE. Specifically, even-numbered (index) ECCEs are arranged in even-numbered PRB pairs, and odd-numbered ECCEs are arranged in odd-numbered PRB pairs.

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

(Variation 1)
In variation 1, when soft combining is performed, it 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 1st subframe and odd-numbered PRB pairs are arranged in the 2nd subframe.

By doing so, 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 EPDCCH of AL1. As a result, by selecting AL, it is possible to switch between soft combining and non soft combining.

As described above, in variation 1, soft combining can be applied from EPDCCH of AL2. 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. By doing this, soft combining can be applied to all EPDCCH candidates.

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

By doing so, even the AL1 EPDCCH configured by one ECCE is arranged in each of the 1st subframe and the 2nd subframe. By this means, soft combining can be applied to the ALDC EPDCCH.
The variations of division of the EPDCCH set (PRB pair) into a plurality of subframes have been described above.

Thus, according to the present embodiment, resource allocation for allocating EPDCCH when soft combining is applied can be appropriately set, as in the case of Embodiment 2.

The embodiments of the present invention have been described above.

(Other embodiments)
[1] When soft combining is applied, 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). 16B, the number of low-AL (L=1) EPDCCH candidates is reduced, while the number of high-AL (L=8) EPDCCH candidates is increased in FIG. 16B. In this way, the effect of soft combining is enhanced by increasing the number of EPDCCH candidates with a particularly high AL.

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

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

An example of the condition is a case where the 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 the DMRS precoding of each subframe is the same.

Further, as an example of another condition, for example, in each subframe to which soft combining is applied, a PRB pair in which EPDCCH is arranged is arranged within a certain range. “Within a certain range” is, for example, an 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 EPDCCH is arranged is arranged within the range of PRB bundling. The range of PRB bundling is a value determined by the bandwidth, and there are patterns of 1,2,3 PRB pairs.

Further, in Embodiment 3, PRB pairs (positions) are always different among 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 two subframes used for soft combining, the PRB pair used in the 2nd subframe should be the same as the PRB pair used in the 1st subframe. The position of may be shifted.

[4] Also, in the above embodiment, a case has been described where soft combining is performed over a plurality of subframes (that is, time domains). However, the above embodiment may be applied to the frequency domain (for example, carrier aggregation). In this case, instead of arranging EPDCCHs in a plurality of subframes in the above embodiment, EPDCCHs may be arranged over 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 arranged in the last subframe of the plurality of subframes. On the other hand, at the time of carrier aggregation, the PUCCH resource may be instructed to implisit by the ECCE (index) of the EPDCCH arranged in the PCell among a plurality of carrier components.

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

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

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 individually made into one chip, or may be made into one chip so as to include some or all of them. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and it may be realized by a dedicated circuit or a general-purpose processor. A field programmable gate array (FPGA) that can be programmed after the LSI is manufactured, 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. The application of biotechnology is possible.

As described above, the base station of the present disclosure assigns an enhanced physical downlink control channel (EPDCCH) set configured with an enhanced control channel element (ECCE) that allocates control information transmitted over a plurality of subframes to the plurality of subframes. The configuration includes a setting unit configured to set, and an assigning unit that assigns the control information to any 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 assigning unit sets the control information to the same number as the plurality of subframes. However, each of the divided control information is assigned to any one of the ECCEs configuring the EPDCCH 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.

Also, 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 all of the plurality of subframes, and the PRB pair corresponding to the ECCE that constitutes the one EPDCCH set is It is distributed and arranged in a plurality of subframes.

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

Further, in the base station of the present disclosure, among the plurality of subframes, Physical Uplink Control Channel (corresponding to the ECCE arranged in a subframe to which downlink data instructed to be allocated by the control information is allocated is assigned. PUCCH) further includes 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 and a reception subframe of the uplink data are associated with each other, and the last subframe of the plurality of subframes is associated. The subframe of 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 ECCE that configures the set, and a receiving unit that receives the control information assigned to any of the ECCEs in each Physical Resource Block (PRB) pair of the plurality of subframes. Adopt a configuration that has.

Further, the transmission method of the present disclosure, an Enhanced Physical Downlink Control Channel (EPDCCH) set configured with Enhanced Control Channel Element (ECCE) that allocates control information transmitted over a plurality of subframes, the plurality of subframes. And transmit the control information assigned to any of the ECCEs in each Physical Resource Block (PRB) pair of each of the plurality of subframes.

Further, the receiving 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) specifies the ECCE that constitutes the set, and receives the control information assigned to any of the ECCEs in each Physical Resource Block (PRB) pair of the plurality of subframes.

The present invention is useful in 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 (27)

One control information indicating downlink data allocation is transmitted using the first subframe set in the downlink , and the second subframe after the last subframe of the first subframe set is transmitted. A transmitter for transmitting the downlink data using a set ,
Comprising a receiving section for receiving the sub-frame of the upper Ri line the ACK / NACK information on the downlink data transmitted by the set of the second sub-frame,
When said upper Ri line data Te subframe smell uplink there is received the ACK / NACK information the is uplink data and multiplexed, when said upper Ri line data Te subframe smell uplink does not exist Is the Physical Uplink Control Channel (PUCCH) resource on which the ACK/NACK information is received,
base station. When said upper Ri line data Te subframe smell uplink exists, the ACK / NACK information and the uplink data is received at the Physical Uplink Shared Channel (PUSCH) in the subframe of the uplink,
The base station according to claim 1. An EPDCCH set designed in each subframe in the first set of 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 there,
The base station according to claim 1. The EPDCCH set designed in each subframe in the first set of subframes differs in at least one of the number of PRB pairs or the frequency position of PRB pairs,
The base station according to claim 1. Transmitting the downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the second set of subframes,
The base station according to claim 1. The ACK / NACK information, Ru is received in subframe determined based on the final sub-frame in which the downlink data is located,
The base station according to claim 1. In the first set of subframes, precoding of reference signals used for one control information indicating allocation of the downlink data is common .
The base station according to claim 1. When the number of repetitions in the first set of subframes is 1 or more, the number of EPDCCH candidates associated with at least one aggregation level is small as compared with the case where the number of repetitions is 1.
The base station according to claim 1. The transmitter transmits one piece of control information indicating allocation of uplink data by using a third set of subframes in the downlink,
The receiving unit receives the uplink data using a subframe determined based on a final subframe of the third set of subframes,
The base station according to claim 1. One control information indicating the allocation of the downlink data includes information about the second set of subframes,
The base station according to claim 1. One piece of control information indicating allocation of the uplink data includes information about the set of the third subframes,
The base station according to claim 9. The base station
Transmitting one piece of control information indicating downlink data allocation using the first set of subframes in the downlink,
Transmitting the downlink data using a second set of subframes after the last subframe of the first set of subframes,
The ACK / NACK information relating to downlink data transmitted by the set of the second sub-frame received at the sub-frame above Ri line,
When said upper Ri line data Te subframe smell uplink there is received the ACK / NACK information the is uplink data and multiplexed, when said upper Ri line data Te subframe smell uplink does not exist Is the Physical Uplink Control Channel (PUCCH) resource on which the ACK/NACK information is received,
Communication method. When said upper Ri line data Te subframe smell uplink exists, the ACK / NACK information and the uplink data is received at the Physical Uplink Shared Channel (PUSCH) in the subframe of the uplink,
The communication method according to claim 12 . An EPDCCH set designed in each subframe in the first set of 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 there,
The communication method according to claim 12 . The EPDCCH set designed in each subframe in the first set of subframes differs in at least one of the number of PRB pairs or the frequency position of PRB pairs,
The communication method according to claim 12 . Transmitting the downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the second set of subframes,
The communication method according to claim 12 . The ACK/NACK information is received in a subframe determined based on the final subframe in which the downlink data is arranged,
The communication method according to claim 12 . In the first set of subframes, precoding of reference signals used for one control information indicating allocation of the downlink data is common.
The communication method according to claim 12 . When the number of repetitions in the first set of subframes is 1 or more, the number of EPDCCH candidates associated with at least one aggregation level is small as compared with the case where the number of repetitions is 1.
The communication method according to claim 12 . A process of transmitting one piece of control information indicating allocation of downlink data using the first set of subframes in the downlink,
Transmitting the downlink data using a second set of subframes after the last subframe of the first set of subframes;
Controlling a process of receiving ACK/NACK information regarding downlink data transmitted in the second set of subframes in an uplink subframe,
When uplink data is present in the uplink subframe, the ACK/NACK information multiplexed with the uplink data is received, and when uplink data is not present in the uplink subframe, Physical Uplink Control The ACK/NACK information is received on a Channel (PUCCH) resource,
Integrated circuit. When said upper Ri line data Te subframe smell uplink exists, the ACK / NACK information and the uplink data is received at the Physical Uplink Shared Channel (PUSCH) in the subframe of the uplink,
The integrated circuit according to claim 20 . An EPDCCH set designed in each subframe in the first set of 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 there,
The integrated circuit according to claim 20 . The EPDCCH set designed in each subframe in the first set of subframes differs in at least one of the number of PRB pairs or the frequency position of PRB pairs,
The integrated circuit according to claim 20 . Transmitting the downlink data arranged in a Physical Downlink Shared Channel (PDSCH) region of each subframe in the second set of subframes,
The integrated circuit according to claim 20 . The ACK/NACK information is received in a subframe determined based on the final subframe in which the downlink data is arranged,
The integrated circuit according to claim 20 . In the first set of subframes, precoding of reference signals used for one control information indicating allocation of the downlink data is common.
The integrated circuit according to claim 20 . When the number of repetitions in the first set of subframes is 1 or more, the number of EPDCCH candidates associated with at least one aggregation level is small as compared with the case where the number of repetitions is 1.
The integrated circuit according to claim 20 .

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