WO2012098827A1 - Base station, terminal, transmission method, and reception method - Google Patents

Abstract

Provided is a base station capable of mapping the R-PHICH for a terminal to a conventional R-PDCCH area without changing the design of the R-PDCCH area. This device comprises a transmission area setting unit (131) for setting a resource area, which is mapped by a control channel, in each terminal in resource group units formed of a plurality of resource elements. A resource group includes a resource element candidate which is mapped by a reference signal, and a resource area which is formed of resource elements excluding said resource element candidate. A decision unit (132) determines a specific resource group from among a plurality of resource groups in which the resource areas set in each terminal are respectively included. An allocation unit (104) allocates a response signal for each terminal in which a resource area has been set, to a resource element candidate in the specific resource group.

Description

Base station, terminal, transmission method, and reception method

The present invention relates to a base station, a terminal, a transmission method, and a reception method.

In 3GPP-LTE (3rd Generation Partnership Project Project Radio Access Network Network Long Term Evolution (hereinafter LTE), OFDMA (Orthogonal Frequency Division Multiple Access) is adopted as the downlink communication method, and SC-FDMA (uplink communication method is used as the uplink communication method). Single Carrier Frequency Division Multiple Access) is employed (for example, see Non-Patent Documents 1, 2, and 3).

In LTE, a radio communication base station apparatus (hereinafter abbreviated as “base station” or referred to as “eNB”) uses a resource block (Resource Block: RB) in a system band for each time unit called a subframe. Communication is performed by assigning to a wireless communication terminal device (hereinafter abbreviated as “terminal” or referred to as “UE”). Also, the base station transmits downlink control information (L1 / L2 control information) for notifying the resource allocation result for downlink data and uplink data to the terminal. In LTE, DCI (Downlink Control Information) is transmitted as this downlink control information, and is transmitted to the terminal using a downlink control channel such as PDCCH (Physical Downlink Control Channel). .

Here, depending on the number of allocation target terminals and the like, the base station uses the amount of resources in the resource region used for PDCCH transmission (hereinafter sometimes referred to as “PDCCH region”) (that is, OFDM (used as the PDCCH region). Orthogonal Frequency Division Multiplexing) controls the number of symbols) in subframe units. Specifically, the PDCCH region is set over the entire system band in the frequency domain, and is variably set between the first OFDM symbol and the third OFDM symbol in one subframe in the time domain. However, when the system bandwidth is narrow or for an MBSFN (Multicast Broadcast Single Frequency Network) subframe, the PDCCH region is separately defined.

The control of the time domain of the PDCCH area is performed by notifying the terminal of a CFI (Control Format Indicator) transmitted by PCFICH (Physical Control Format Indicator Channel). CFI is control information indicating how many symbols are used as a PDCCH region starting from the first OFDM symbol of a subframe. That is, CFI represents the scale of the PDCCH region. The terminal receives PCFICH and receives PDCCH according to the detected CFI value.

In the PDCCH region, a CRS that is a common reference signal is transmitted to all terminals in the cell covered by the base station. In LTE, a frequency band having a maximum width of 20 MHz is supported as a system bandwidth.

Further, the base station uses HI (HARQ Indicator) indicating delivery confirmation information (ACK / NACK, that is, retransmission request notification) for uplink data, and a terminal using PHICH (Physical Hybrid ARQ Indicator Channel. Physical HARQ indication channel). (For example, refer nonpatent literature 1).

Here, there are the following two methods as a notification method of a retransmission request for uplink data transmitted in the PDCCH region.

The first method is a non-adaptive retransmission request using PHICH. In the non-adaptive retransmission request, the retransmission timing is a constant interval (for example, an interval of 8 ms), and the same resource as that used at the first transmission is used as a retransmission resource. In PHICH, ACK / NACK signals (response signals) for a maximum of 8 UEs can be multiplexed, and the amount of resources used is fixed at 3 REG (Resource Element Group). Here, REG is a unit composed of a plurality of REs (Resource Element) (for example, 1 REG is composed of 4 REs). The RE is a minimum unit constituting a resource, and is composed of one OFDM subcarrier and one OFDM symbol.

The second method is an adaptive retransmission request using PDCCH indicating resource allocation (UL grant) of uplink data. In the adaptive retransmission request, both the retransmission timing and the resource at the time of retransmission are variable. Whether or not PDCCH (UL grant) is used for the retransmission request is notified by NI (New Data Indicator) included in PDCCH (UL grant). In PDCCH (UL grant), it is impossible to multiplex signals from a plurality of terminals. Further, the amount of resources used in PDCCH (ULrantgrant) depends on the propagation environment and takes a variable value between 9REG and 72REG.

It is not notified whether the retransmission request notification method for uplink data is non-adaptive retransmission or adaptive retransmission. Therefore, the terminal first decodes PDCCH (UL grant). If PDCCH (UL grant) can be decoded (that is, if UL grant exists), it is determined to be adaptive retransmission, and PHICH is not decoded. On the other hand, if PDCCH (UL grant) cannot be decoded (if UL grant does not exist), it is determined as non-adaptive retransmission and PHICH is decoded.

Next, a PHICH generation procedure will be described with reference to FIG. 1 (for example, see Non-Patent Document 4).

As shown in FIG. 1, the ACK / NACK signal (1 bit indicating “0” or “1”) for uplink data is subjected to triple repetition (3 × petition) and generated data (“000” or BPSK modulation is applied to 3 bits of “111”. Then, orthogonal coding is performed on the data after BPSK modulation by using one orthogonal code among all eight orthogonal codes. Orthogonal data (ACK / NACK signals) for a maximum of 8 terminals obtained by performing these processes are multiplexed and subjected to a scrambling process to become 12-symbol data. Also, as shown in FIG. 1, the 12-symbol data is divided into three, and each of the divided data (4 symbols × 3) is assigned to 1 REG. The method of assigning each symbol to the REG is uniquely determined by various elements such as a PHICH parameter or a subframe type notified by RRC (Radio Resource Control) signaling. Here, a collection of PHICHs in which data for a maximum of eight terminals is multiplexed is called a PHICH group, and is mapped to the same resource for each PHICH group. As a method of grouping PHICH groups, a leading RB index indicating the leading RB of resources allocated when transmitting uplink data, and a DM-RS (DeModulation Signal Signal) set when transmitting uplink data ) To determine the PHICH group into which PHICH is grouped.

Next, a method of mapping to PHICH group time domain resources and frequency domain resources will be described. First, in the time domain, as shown in the following equation (1), PHICH group (normal PHICH duration and extended PHICH duration) notified by RRC signaling, subframe type (MBSFN subframe, etc.), etc. Is assigned to the first OFDM symbol or assigned over 3 OFDM symbols from the beginning.

Here, τ _i indicates the index of the OFDM symbol to which the PHICH group is mapped, i indicates the index of the OFDM symbol, i = 0 represents the first OFDM symbol, and i = 1 is the second OFDM symbol from the top. I = 2 represents the third OFDM symbol from the beginning. M represents an index of the PHICH group.

On the other hand, in the frequency domain, in order to obtain a frequency diversity effect, a PHICH group is assigned to a frequency index (REG index) roughly divided into three with respect to the entire system band. More specifically, the number of _REGs to which no PCFICH and CRS (Cell Specific Reference Signal) are assigned is n _τi in an OFDM symbol (τ _i ), and the REG is set to 0, 1 _,. , N _τi −1, the PHICH group is assigned to the frequency index f _i (i = 0, 1, 2) shown in the following equation (2).

In this way, in LTE, the allocation position of PHICH is uniquely determined for each terminal, so that the terminal does not need to determine the allocation position of PHICH, and the PHICH can be decoded without erroneously allocating the PHICH allocation position. It has become. Here, the terminal receives the PHICH, and always determines whether or not the uplink data transmitted by itself is normally received by the base station. If it is necessary for the terminal to also determine the PHICH allocation position, the terminal erroneously determines the PHICH allocation position, considers the signal at the incorrect allocation position as PHICH, decodes it, and receives ACK or NACK. There is a risk that it will always be judged as either of these. For example, if the terminal determines that the allocation position of PHICH is wrong and NACK is determined at the wrong allocation position even though ACK is transmitted at the correct allocation position of PHICH, the terminal performs retransmission. As a result, throughput is reduced. Also, for example, when the terminal determines that the PHICH allocation position is wrong and ACK is detected at the wrong allocation position even though NACK is transmitted at the correct PHICH allocation position, RRC with a larger delay is used. Retransmission results in a decrease in throughput.

Also, standardization of 3GPP LTE-Advanced (hereinafter referred to as LTE-A), which realizes higher communication speed than LTE, has been started. LTE-A introduces base stations and terminals (hereinafter referred to as LTE-A terminals) capable of communicating at a wideband frequency of 40 MHz or more in order to realize a downlink transmission rate of 1 Gbps or more and an uplink transmission rate of 500 Mbps or more at the maximum. Is expected. The LTE-A system is required to accommodate not only LTE-A terminals but also terminals (hereinafter referred to as LTE terminals) corresponding to the LTE system. Thus, backward compatibility at the time of transition to a new system (LTE-A system) is very important.

Furthermore, in LTE-A, the introduction of a wireless communication relay device (hereinafter referred to as “relay station” or “RN: Relay Node”) has also been defined in order to achieve an increase in coverage. Accordingly, standardization regarding a downlink control channel (hereinafter referred to as “R-PDCCH (Relay-Physical Downlink Control CHannel)”) from the base station to the relay station is in progress (for example, Non-Patent Documents 5, 6, 7, 8). At the present stage, the following items are being considered for R-PDCCH. FIG. 2 shows an example of the R-PDCCH region.
(1) A resource region (hereinafter referred to as “R-PDCCH region”) used for R-PDCCH transmission is reported semi-static from the base station.
(2) R-PDCCH time domain mapping start position is fixed to the fourth OFDM symbol from the beginning of one subframe. This does not depend on the ratio of PDCCH to the time axis direction.
(3) As an R-PDCCH frequency domain mapping method, two allocation methods, distributed and localized, are supported.
(4) As reference signals for demodulation, CRS (Common Reference Signal) and DM-RS (Demodulation Reference Signal) are supported. Which reference signal is used is notified semi-static from the base station.
(5) Each R-PDCCH is divided into slot 0 (slot 0 or first slot) and slot 1 (slot 1 or second slot) within one subframe in the time domain.
(6) PDCCH (hereinafter referred to as DL grant) notifying downlink resource allocation is transmitted in slot 0, and PDCCH (hereinafter referred to as UL grant) notifying uplink resource allocation is transmitted in slot 1.
(7) In the R-PDCCH region, a data signal (hereinafter referred to as R-PDSCH) is transmitted using only slot 1 or both slot 0 and slot 1 (transmission using only slot 0 is not possible). ). Only when the R-PDSCH is transmitted from slot 0, the mapping start position in the time domain is notified from the base station to the semi-static.
(8) No signal corresponding to PHICH is transmitted in the R-PDCCH region. That is, the retransmission request notification for RN is notified only in the PDCCH region.
(9) The R-PDCCH is mapped to the REG excluding the resource to which the reference signal is mapped (see FIG. 2). In particular, in CSI-RS (quality measurement reference signal), resources for 8 ports corresponding to CSI-RS are always excluded from resources for R-PDCCH regardless of the number of ports actually used. CSI-RS is a cell-specific reference signal used for measurement of downlink channel quality information used for closed-loop control in single-user / multi-user MIMO transmission with a maximum of 8 layers.

Here, the reason why the signal corresponding to PHICH (retransmission request notification for RN) is not transmitted in the R-PDCCH region as described in (8) above will be described.

First, it is mentioned that the backhaul between the RN and the base station (macro base station, MeNB) is not constantly set. For this reason, as described above, the uplink retransmission data of the terminal (UE) transmitted at regular intervals (for example, 8 ms) using PHICH and the uplink retransmission data of the RN transmitted at irregular intervals are the base station. (See FIG. 3). Furthermore, generally, it is assumed that the propagation environment between the RN and the base station (MeNB) is better than the propagation environment between the terminal and the base station (MeNB). Therefore, even if only a retransmission request (adaptive retransmission request) using PDCCH is performed without performing a retransmission request (non-adaptive retransmission request) using PHICH, the amount of resources used (for example, the number of CCEs (Control channels)) It is because it was thought that it was possible to suppress a small amount.

In addition to the above-mentioned CRS, DM-RS, and CSI-RS, reference signals in the downlink include cell-specific reference signals used for MBMS (Multimedia Broadcast Multicast Service) transmission.

3GPP TS 36.211 V8.7.0, “Physical Channels and Modulation (Release 8),” September 2008 3GPP TS 36.212 V8.7.0, “Multiplexing and channel coding (Release 8),” September 2008 3GPP TS 36.213 V8.7.0, “Physical layer procedures (Release 8),” September 2008 Erik Dahlman, Stefan Parkvall, Johan Skold, Per Beming, "3G Evolution: HSPA and LTE for Mobile Broadband," Academic Press 3GPP TSG RAN WG1 meeting, R1-102700, “Backhaul Control Channel Design in Downlink,” May 2010 3GPP TSG RAN WG1 meeting, R1-102881, “R-PDCCH placement,” May 2010 3GPP TSG RAN WG1 meeting, R1-103040, “R-PDCCH search space design” May 2010 3GPP TSG RAN WG1 meeting, R1-103062, “Supporting frequency diversity and frequency selective R-PDCCH transmissions” May 2010

In the future, a Macro cell configured by a macro base station (Macro eNB: MeNB) and a Pico cell or a femto base station (referred to as Femto base station or Home eNB) configured by a pico base station (PicoＰeNB: PeNB) will be configured. It is considered that a heterogeneous network (hereinafter referred to as “HetNet”) in which cells formed by a plurality of LPNs (Low Power Node) such as Femto cells that are superimposed (mixed) is increased. In HetNet, it is considered that LPN (pico base station or femto base station) is usually retrofitted in an area covered by an already operated macro base station. For this reason, it is difficult to distinguish between a macro base station that has already been used and assigned a use frequency band and an LPN use frequency band, and as a result, a pico that uses the same frequency band as the use frequency band of the macro base station. There will be base stations and femto base stations.

Therefore, there arises a problem that inter-cell interference between the macro base station and the LPN (pico base station or femto base station) is unavoidable.

For example, between a Macro cell and a Femto cell, a terminal (macro terminal. Macro UE: MUE) connected to a macro base station that is Non-CSG (Non-Closed。Subscriber Group) enters the Femto cell. There is concern about interference from the femto base station to the MUE. Also, there is concern about interference from the macro base station to the terminal (pico terminal, Pico UE: PUE) that is connected to the pico base station by the Range expansion of the Pico cell between the Macro cell and the Pico cell. (See FIG. 4A). Note that Range 技術 expansion is a technique for improving the overall throughput of the Macro cell and Pico cell by adding an offset to the measurement result of the Pico cell by the MUE located at the Macro cell edge and connecting it to the Pico cell. is there. In the range expansion, the transmission power does not change in both the macro base station and the pico base station, so the interference from the macro base station to the terminal connected to the Pico cell by the range expansion is large.

Therefore, for example, it is proposed that the macro base station does not transmit (muting) data other than CRS that is essential for measurement between the Macro cell and the Pico cell as a countermeasure against interference (see FIG. 4B). For example, see “3GPP TSG RAN WG1 Meeting, R1-103264,“ Performance of eICIC with Channel Control, Coverage Limitation, ”May 2010.)

However, the CRS is mapped over the entire system band in the frequency domain (for example, CRS is mapped every 3 REs), and the CRS mapping start position in the frequency domain is set to be fixed for each cell. For example, FIG. 4B shows a case where a pico base station (Pico NB) maps PHICH to the first OFDM symbol and the macro base station (MeNB) is muting data other than CRS. Moreover, as shown to FIG. 4B, the mapping position of CRS has shifted | deviated between the pico base station (PeNB) and the macro base station (MeNB). Therefore, as shown in FIG. 4B, even if data other than CRS is not sent (muted) in the macro base station, the terminal (PUE) cannot avoid interference due to CRS from the macro base station. In addition, since the CRS is transmitted over a maximum of 2 OFDM symbols for a PDCCH region using a maximum of 3 OFDM symbols, the influence of interference by the CRS from the macro base station at the terminal (PUE) is large. In particular, it is very difficult to avoid interference with PHICH that is highly likely to be mapped to the first OFDM symbol or PCFICH (not shown) that is mapped to the first OFDM symbol.

When interference is received by PHICH and an ACK / NACK signal in HARQ is erroneously determined, especially when NACK is erroneously determined as ACK, the retransmission delay becomes very large, resulting in a decrease in throughput. Arise. Similarly, if the PCFICH receives interference and erroneously determines the number of OFDM symbols in the PDCCH region (that is, the start OFDM symbol in the data region subsequent to the PDCCH region), the terminal fails to receive downlink data. There arises a problem that the throughput is lowered. Here, the cell interference between the Macro cell and the Pico cell has been described, but the same problem occurs with respect to the cell interference between the Macro cell and the Femto cell.

For this reason, as described above, transmission of downlink control information for terminals that may be interfered with in the PDCCH region in the R-PDCCH region is also being studied.

As described above, the PHICH for RN is not transmitted in the R-PDCCH region. On the other hand, the terminal can ensure a retransmit timing at regular intervals (see FIG. 3). Therefore, even if a PHICH (non-adaptive retransmission request) for terminals is transmitted also in the R-PDCCH region, uplink retransmission data between a plurality of terminals does not collide. Also, it is assumed that the propagation environment is inferior between the terminal and the macro base station, and if a retransmission request notification is performed only in the PDCCH region, the amount of resources used may become enormous. For this reason, it is also expected to reduce the amount of used resources by transmitting a PHICH (non-adaptive retransmission request) for terminals also in the R-PDCCH region. For example, when the number of CCEs occupied by the PDCCH (CCE concatenation number: CCE aggregation level) is 8 and retransmission request notifications are transmitted for 8 terminals on the PDCCH (in the case of an adaptive retransmission request), the maximum use in the PDCCH region The resource amount is 72 REG × 8 terminals = 576 REG. On the other hand, when the retransmission request notification for 8 terminals is transmitted by PHICH (in the case of a non-adaptive retransmission request), the used resource amount of PHICH is 3REG (fixed value). Therefore, it is desirable to transmit a PHICH (non-adaptive retransmission request) for the terminal not only in the PDCCH region but also in the R-PDCCH region.

However, as described above, a signal corresponding to PHICH (hereinafter referred to as R-PHICH) is not defined in the R-PDCCH region for RN in the current LTE-A. Specifically, as described above, it has been agreed that the R-PDCCH region is mapped to the REG excluding the resource to which the reference signal is mapped, but the R-PDCCH mapping considering R-PHICH Not designed. For this reason, defining a new R-PHICH for the terminal in the R-PDCCH region changes the current R-PDCCH mapping design. Therefore, in addition to the R-PDCCH for the RN, the base station requires a circuit for mapping the R-PHICH for the terminal, which increases the circuit scale and increases the number of test steps. .

An object of the present invention is to provide a base station, a terminal, a transmission method, and a reception method capable of mapping R-PHICH for a terminal to the R-PDCCH region without changing the design of the conventional R-PDCCH region. It is to be.

The base station according to an aspect of the present invention is a unit that sets a resource region to which a control channel is mapped for each terminal in a resource group unit including a plurality of resource elements, and the resource group includes a reference signal A setting unit including resource element candidates to be mapped and the resource area including resource elements excluding the resource element candidates, and a plurality of resource groups each including the resource area set for each terminal. And determining means for determining a specific resource group, and allocating means for allocating a response signal for each terminal in which the resource region is set to resource element candidates in the specific resource group. .

A terminal according to an aspect of the present invention receives a control channel mapped to a resource area set in resource group units including a plurality of resource elements, and includes the resource areas set in each terminal. Means for receiving information indicating a specific resource group determined from a plurality of resource groups, wherein the resource group includes a resource element candidate to which a reference signal is mapped and a resource element excluding the resource element candidate. A configuration comprising: a receiving unit including the resource region to be configured; and a identifying unit that identifies any one of resource element candidates in the specific resource group as a mapping position of a response signal for the own device. take.

In the transmission method of one aspect of the present invention, a resource region to which a control channel is mapped is set for each terminal in a resource group unit including a plurality of resource elements, and the resource group is a resource to which a reference signal is mapped. A specific resource group is determined from a plurality of resource groups each including an element candidate and the resource area composed of resource elements excluding the resource element candidate, each including the resource area set in each terminal. Then, a response signal for each terminal in which the resource area is set is assigned to a resource element candidate in the specific resource group.

The reception method of one aspect of the present invention receives a control channel mapped to a resource area set in a resource group unit composed of a plurality of resource elements, and includes each of the resource areas set in each terminal. Receiving information indicating a specific resource group determined from a plurality of resource groups, and the resource group includes resource element candidates to which a reference signal is mapped and resource elements excluding the resource element candidates One of resource element candidates in the specific resource group including the resource area is specified as a mapping position of a response signal for the own device.

According to the present invention, it is possible to map R-PHICH for a terminal to the R-PDCCH region without changing the design of the conventional R-PDCCH region.

The figure which shows an example of the production | generation process of PHICH A diagram showing an example of an R-PDCCH region FIG. 5 is a diagram for explaining the occurrence of collision between retransmission data from the RN and retransmission data from the UE. Diagram for explaining heterogeneous network The figure which shows the transmission and reception processing with each device in the heterogeneous network Main configuration diagram of base station according to one embodiment of the present invention Main block diagram of terminal according to one embodiment of the present invention The block diagram which shows the structure of the base station which concerns on one embodiment of this invention The block diagram which shows the structure of the terminal which concerns on one embodiment of this invention The figure which shows the mapping design in the conventional R-PDCCH area | region The figure which shows matching with the system bandwidth and R-PHICH exclusive area | region which concerns on the example 1 of allocation of one embodiment of this invention The figure which shows the example of mapping of the R-PHICH exclusive area | region which concerns on the example 1 of allocation of one embodiment of this invention The figure which shows the example of a setting of the R-PHICH arrangement | positioning area | region which concerns on the example 2 of allocation of one embodiment of this invention The figure which shows the example of a setting of the other R-PHICH arrangement | positioning area | region which concerns on the example 2 of allocation of one embodiment of this invention The figure which shows the example of a setting of the R-PHICH arrangement | positioning area | region which concerns on the example 3 of allocation of one embodiment of this invention The figure which shows the example of a setting of the R-PHICH arrangement | positioning area | region which concerns on the example 4 of allocation of one embodiment of this invention The figure which shows the other variation of one embodiment of this invention

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

[Embodiment 1]
[Outline of communication system]
The communication system according to Embodiment 1 of the present invention includes a base station 100 and a terminal 200. The base station 100 is, for example, an LTE-A base station, and the terminal 200 is, for example, an LTE-A terminal. The base station 100 uses the downlink resource control information (that is, DCI) in the first resource region (that is, the R-PDCCH region) that can be used for both the downlink control channel region and the downlink data channel region, or downlink data. It is assigned to a second resource area (that is, a PDCCH area) that is not used as a channel area and can be used for a downlink control channel.

In the PDCCH region, CRS is used as a demodulation reference signal (RS). On the other hand, in the R-PDCCH region, CRS or DM-RS is used as a demodulation reference signal (RS).

FIG. 5 is a main configuration diagram of base station 100 according to Embodiment 1 of the present invention. In base station 100, transmission region setting section 131 sets a resource region to which a control channel (PDCCH) is mapped for each terminal in units of RBG (resource block group) composed of a plurality of REs (resource elements). Here, the RBG includes an RE candidate to which a reference signal is mapped, and a resource region (R-PDCCH region) configured by an RE excluding the RE candidate. The determining unit 132 determines a specific RBG from among a plurality of RBGs each including the R-PDCCH region set for each terminal, and the allocating unit 104 is for each terminal for which the R-PDCCH region is set. A response signal (PHICH) is assigned to an RE candidate in the specific RBG.

FIG. 6 is a main configuration diagram of terminal 200 according to Embodiment 1 of the present invention. In terminal 200, setting information receiving section 206 and PDCCH receiving section 207 receive a control channel (PDCCH) mapped to a resource area set in RBG units composed of a plurality of REs, and are set in each terminal. The information indicating the specific RBG determined from among the plurality of RBGs each including the resource area is received. Here, the RBG includes an RE candidate to which a reference signal is mapped, and a resource region (R-PDCCH region) configured by an RE excluding the RE candidate. The PHICH receiving unit 209 identifies one of RE candidates in a specific RBG as a mapping position of a response signal (PHICH) for the own device.

[Configuration of Base Station 100]
FIG. 7 is a block diagram showing a configuration of base station 100 according to Embodiment 1 of the present invention.

7, the setting unit 101 adopts a configuration including a transmission area setting unit 131 and a determination unit 132. The transmission area setting unit 131 sets a resource area used for transmission of downlink control information for the terminal 200. Candidate resource regions to be set include a PDCCH region (that is, a resource region to which PDCCH is mapped) and an R-PDCCH region (resource region to which R-PDCCH is mapped). That is, transmission region setting section 131 sets for each terminal 200 whether to use a PDCCH region or an R-PDCCH region as a region (transmission region) for transmitting downlink control information. For example, the transmission region setting unit 131 determines that there is a concern that the PDCCH region will be tight because the number of terminals 200 communicating with the base station 100 is large, or it is determined that interference in the PDCCH region is large. In this case, an R-PDCCH region is set for terminal 200. However, the conditions for setting the transmission area for terminal 200 are not limited to these.

Also, when the R-PDCCH region is set, the transmission region setting unit 131 sets the R-PDCCH region for each terminal 200 in RBG (RB Group) units composed of a plurality of REs. Here, the RBG is composed of a plurality of RBs (that is, a plurality of REs).

Also, when the R-PDCCH region is set for the terminal 200, the setting unit 101 sets CRS or DM-RS as a reference signal to be used. The CRS is a reference signal for the terminal 200 of the entire cell formed by the base station 100, and the DM-RS is a reference signal specific to the terminal 200. As described above, the R-PDCCH is mapped to the REG excluding the resource candidates (RE candidates) to which the reference signal is mapped among the REs constituting the RBG. That is, the RBG includes RE candidates to which reference signals (CRS and DM-RS) are mapped, and an R-PDCCH region including REs excluding the RE candidates.

For example, when the reference signal to be used is DM-RS, precoding optimized for a certain terminal (weighting on the transmission side) is included in DM-RS itself and control information demodulated using DM-RS. Is done (with precoding). That is, since the DM-RS is precoded optimized for individual terminals in the frequency domain, the arrangement in the frequency domain is a concentrated arrangement (localized arrangement) for a certain frequency band. . Thereby, the received signal power of the control information for individual terminals can be improved. Therefore, the use of DM-RS is particularly effective for terminals located at cell edges or the like (terminals having a low received signal level).

On the other hand, when the reference signal to be used is CRS, precoding (weighting on the transmission side) is not performed on the CRS itself and control information demodulated using CRS (no precoding). In addition, since CRS is distributed in the entire frequency domain (that is, CRS is allocated over the entire frequency domain), control information to be demodulated using CRS has no restrictions on the allocation in the frequency domain. Information can also be distributed (distributed) over the entire system bandwidth, and a frequency diversity effect can be obtained for control information. Therefore, using CRS is particularly effective in reducing the influence of fluctuations in the received signal level in the frequency domain due to the terminal moving at high speed.

Therefore, for example, when the setting unit 101 determines that the terminal 200 is located at the cell edge and needs the received signal strength, the setting unit 101 sets the DM-RS as a reference signal for the terminal 200. Or the setting part 101 will set CRS as a reference signal for the said terminal 200, when it is judged that the terminal 200 is moving at high speed. The setting unit 101 sets a port number to be used when setting DM-RS. In addition, when setting the PDCCH region for terminal 200, setting section 101 sets CRS as a reference signal to be used.

The determination unit 132 of the setting unit 101 maps a specific RBG from a plurality of RBGs each including the R-PDCCH region set for each terminal 200 to a dedicated region (hereinafter, referred to as R-PHICH for all terminals 200). R-PHICH dedicated area or R-PHICH placement area).

Also, the setting unit 101 sets the transmission mode of each of the uplink and downlink of the terminal 200. The transmission mode is set for each terminal 200 to be set. Specifically, the setting unit 101 determines each uplink transmission mode and downlink transmission mode (for example, spatial multiplexing MIMO transmission, beamforming transmission, non-consecutive band) of each terminal 200 based on a propagation path condition for each terminal 200 and the like. Assign).

Also, the setting unit 101 reflects the resource allocation information in the R-PDCCH region, for example, in a bitmap or the like for each terminal 200 that has set the R-PDCCH region.

Also, the setting unit 101 sets control information (PHICH parameters such as “3GPPGPTS 36.331 V9.3.0," Radio Resource Control (RRC) Protocol specification (Release 9), "2010-06") related to PHICH. To do.

Then, the setting unit 101 transmits information (R) indicating a transmission area, a transmission mode, a reference signal (further port number in the case of DM-RS), a PHICH parameter, and an R-PHICH allocation resource set for each terminal 200. Setting information including information related to (PHICH dedicated area or R-PHICH allocation area) is output to allocation section 104, control section 105, search space setting section 106, encoding / modulation section 110, and transmission weight setting section 111. Note that these pieces of information included in the setting information are notified to each terminal 200 via the encoding / modulation section 108 as higher layer control information (referred to as RRC control information or RRC signaling).

The selection unit 102 selects, for each terminal 200, a notification method of a retransmission request for uplink data from the terminal 200. As described above, the retransmission request for uplink data includes an adaptive retransmission request using PDCCH (UL grant) and a non adaptive retransmission request using PHICH (ACK / NACK signal (response signal) for uplink data). There are two types. Which retransmission request notification method is selected by the selection unit 102 depends on the base station 100. The selection unit 102 notifies the control unit 105 of information (terminal information and information indicating presence / absence of a retransmission request for uplink data) of the terminal 200 for which the adaptive retransmission request is selected. On the other hand, selection section 102 outputs information (terminal information and ACK / NACK signal for uplink data) of terminal 200 for which the non-adaptive retransmission request is selected to PHICH generation section 103.

When the information of the terminal 200 for which the non-adaptive retransmission request is selected is input from the selection unit 102, the PHICH generation unit 103 performs repetition for the ACK / NACK signal for each terminal 200, for example, according to the procedure of FIG. Then, modulation, orthogonal coding, multiplexing, and scrambling are performed to generate PHICH (PHICH group, that is, acknowledgment information (ACK / NACK signal) for uplink data, sometimes called PHICH signal). The PHICH generation unit 103 outputs the generated PHICH signal to the allocation unit 104.

Allocation section 104 assigns the PHICH signal input from PHICH generation section 103 to the resource area based on the setting information input from setting section 101 (information indicating the downlink control information transmission area and R-PHICH allocation resource) Assign to. For example, when the transmission area of downlink control information is a PDCCH area, allocating section 104 allocates a PHICH signal in the PDCCH area. On the other hand, allocating section 104 allocates a PHICH signal (sometimes referred to as an R-PHICH signal) in the R-PDCCH region when the downlink control information transmission region is the R-PDCCH region. At this time, allocating section 104 allocates the R-PHICH signal for each terminal 200 in which the R-PDCCH region is set to the resource indicated by the information indicating the R-PHICH allocation resource input from setting section 101. . Then, allocation section 104 outputs allocation information indicating the resource allocation result of the PHICH signal (or R-PHICH signal) to control section 105 and transmission weight setting section 111, so that the PHICH signal allocated to the resource area (or R-PHICH signal) is output to multiplexing section 113. The details of the allocation process of the R-PHICH signal in the R-PDCH region in allocation section 104 will be described later.

The control unit 105 generates allocation control information according to the setting information received from the setting unit 101 and the allocation information received from the allocation unit 104.

Specifically, the control unit 105 generates allocation control information including HACS related information such as MCS information, resource (RB) allocation information, and NDI (New data indicator) for one transport block. Here, in the resource allocation information, uplink resource allocation information indicating uplink resources (for example, PUSCH (Physical-Uplink-Shared-Channel)) to which uplink data of the terminal 200 is allocated, or downlink resources to which downlink data addressed to the terminal 200 is allocated. For example, downlink resource allocation information indicating PDSCH (Physical Downlink Shared Shared Channel) and PDSCH (R-PDSCH (Relay-PDSCH)) transmitted in the R-PDCCH region is included.

Further, based on the setting information received from setting unit 101, control unit 105 allocates control information (either DCI 0A or 0B) according to the uplink transmission mode of terminal 200, or according to the downlink transmission mode. Allocation control information (DCI 1, 1B, 1D, 2, 2A) or allocation control information common to all terminals (DCI 0 / 1A) is generated for each terminal 200.

For example, during normal data transmission, the control unit 105 allocates control information (DCI 1) according to the transmission mode of each terminal 200 so that data transmission can be performed in the transmission mode set for each terminal 200 in order to improve throughput. , 1B, 1D, 2, 2A, 0A, or 0B). Thereby, since data transmission can be performed in the transmission mode set in each terminal 200, the throughput can be improved.

However, depending on an abrupt change in propagation path conditions or a change in interference from neighboring cells, a situation in which data reception errors frequently occur in the transmission mode set in each terminal 200 may occur. In this case, the control unit 105 generates allocation control information in a format common to all terminals (DCI 0 / 1A, etc.), and transmits data using a robust default transmission mode. As a result, more robust data transmission is possible even when the propagation environment changes suddenly.

Also, when transmitting control information (RRC 情報 signaling) of an upper layer for notifying a change in transmission mode when the propagation path condition deteriorates, the control unit 105 assigns allocation control information (DCI 0 / 1A common to all terminals). Etc.) and transmit information using the default transmission mode. Here, the number of information bits of DCI 0 / 1A common to all terminals is smaller than the number of information bits of DCI 1, 2, 2A, 0A, 0B depending on the transmission mode. For this reason, when the same CCE number is set, DCI 0 / 1A can transmit at a lower coding rate than DCI 1, 2, 2A, 0A, 0B. Therefore, when the propagation path condition deteriorates, the control unit 105 can use DCI 0 / 1A to receive the allocation control information (and data) with a good error rate even in a terminal with a poor propagation path condition. .

In addition to the allocation control information for individual terminal data allocation, the control unit 105 allocates common channel allocation control information (for example, DCI 1C) for data allocation common to a plurality of terminals such as broadcast information and paging information. , 1A, etc.).

Then, the control unit 105 outputs MCS information and NDI to the PDCCH generation unit 107 among the generated allocation control information for terminal-specific data allocation, and outputs uplink resource allocation information to the PDCCH generation unit 107 and the extraction unit 121. Then, the downlink resource allocation information is output to PDCCH generation section 107 and multiplexing section 113. In addition, control section 105 outputs the generated common channel assignment control information to PDCCH generation section 107. Further, based on information on terminal 200 (terminal information and presence / absence of retransmission request) input from selection section 102, control section 105 allocates a retransmission request for uplink data of terminal 200 according to the adaptive retransmission request notification method. Set resources. Then, control section 105 outputs a retransmission request for uplink data and a resource allocation result to PDCCH generation section 107.

The search space setting unit 106 uses the common search space (C-SS) and the individual search space (C-SS) and the individual search space (based on the setting information (the transmission area of downlink control information and the reference signal to be used)) input from the setting unit 101. UE-SS). The common search space (C-SS) is a search space common to all terminals, and the individual search space (UE-SS) is an individual search space for each terminal. Search space setting section 106 outputs search space information indicating the set C-SS and the UE-SS of each terminal to allocation section 109 and encoding / modulation section 110.

The PDCCH generation unit 107 receives downlink control information that is received from the control unit 105 and includes allocation control information for data allocation for each terminal (that is, MCS information, HARQ information, and the like, and uplink resource allocation information or downlink resource allocation information for each terminal). Control signal (referred to as DCI or PDCCH signal), allocation control information for common channel (that is, broadcast information and paging information common to terminals, etc.), or downlink control signal (DCI or (Referred to as a PDCCH signal). The PDCCH generation unit 107 adds CRC bits to uplink allocation control information and downlink allocation control information generated for each terminal 200, and further masks (or scramblings) the CRC bits with a terminal ID (or UE-ID). ) Then, PDCCH generation section 107 outputs the masked PDCCH signal to encoding / modulation section 108.

Encoding / modulating section 108 modulates the PDCCH signal received from PDCCH generating section 107 after channel coding, and outputs the modulated signal to allocating section 109. Here, encoding / modulation section 108 sets the coding rate based on channel quality information (CQI: Channel Quality Indicator) information reported from each terminal so that each terminal can obtain sufficient reception quality. . For example, the coding / modulation section 108 sets a lower coding rate as the terminal is located near the cell boundary (that is, as the terminal has poor channel quality).

Allocation section 109 receives a PDCCH signal including allocation control information for common channels and a PDCCH signal including allocation control information for terminal-specific data allocation for each terminal, input from encoding / modulation section 108, as search space The CCE or R-CCE in the C-SS indicated in the search space information input from the setting unit 106 or the CCE or R-CCE in the UE-SS for each terminal is allocated.

Here, the number of concatenated CCEs assigned to one DCI varies depending on the coding rate and the number of bits of the PDCCH signal (that is, the amount of information in the assignment control information). For example, since the coding rate of the PDCCH signal addressed to the terminal located near the cell boundary is set low, more physical resources are required. Therefore, assignment section 109 assigns more CCEs to DCI addressed to terminals located near cell boundaries.

For example, the allocation unit 109 selects one allocation candidate from the allocation candidate group in the C-SS. Then, allocating section 109 refers to the PDCCH signal including the allocation control information for the common channel as CCE (or R-CCE in the selected allocation candidate, hereinafter, without distinguishing CCE and R-CCE). Is assigned). Here, as described above, the CCE is a resource unit constituting the PDCCH, and the R-CCE is a resource unit constituting the R-PDCCH.

Further, when the DCI format for the allocation target terminal is a transmission mode dependent DCI format (for example, DCI 1, 1B, 1D, 2, 2A, 0A, 0B), the allocation unit 109 sets the allocation target terminal to the allocation target terminal. The CCE in the UE-SS configured for the PDCCH signal is allocated. On the other hand, when the DCI format for the allocation target terminal is a format common to all terminals (for example, DCI 0 / 1A), the allocation unit 109 applies to the CCE in the C-SS or the allocation target terminal. The CCE in the configured UE-SS is assigned to the PDCCH signal.

Then, allocating section 109 outputs information on CCE to which the PDCCH signal is allocated to multiplexing section 113 and ACK / NACK receiving section 124. Also, assignment section 109 outputs the encoded / modulated PDCCH signal to multiplexing section 113.

The encoding / modulation unit 110 modulates the setting information input from the setting unit 101 and the search space information input from the search space setting unit 106 (that is, control information of the higher layer) after channel encoding, The modulated setting information and search space information are output to multiplexing section 113.

Based on the setting information input from setting section 101 and the allocation information input from allocation section 104, transmission weight setting section 111 transmits a transmission weight for terminal 200 that uses DM-RS as a demodulation reference signal ( precoding weight) is set, and the set transmission weight is output to multiplexing section 113.

The encoding / modulation unit 112 modulates the input transmission data (downlink data) after channel encoding, and outputs the modulated transmission data signal to the multiplexing unit 113.

The multiplexing unit 113 receives the encoded / modulated PDCCH signal received from the allocating unit 109, the post-modulation setting information received from the encoding / modulating unit 110, and search space information (that is, control information of the upper layer), The received PHICH signal (R-PHICH signal) and the data signal received from the encoding / modulation unit 112 (that is, the PDSCH signal) are multiplexed in the time domain and the frequency domain. A PCFICH signal (not shown) indicating which OFDM symbol in the time axis direction of the PDCCH region occupies the PDCCH is arranged in the PDCCH region and transmitted as a PDCCH signal. The multiplexing unit 113 also multiplexes band information indicating the reception band and transmission band of each terminal 200. In addition, in the multiplexing unit 113, information indicating the terminal ID of each terminal 200 is also multiplexed.

Here, multiplexing section 113 transmits transmission weight setting section 111 for downlink control information (PDCCH signal) in the R-PDCCH region for terminals using DM-RS as a reference signal for demodulation, PDSCH signal, or the like. Is multiplied by the transmission weight input from the signal, and output to an IFFT (Inverse Fast Fourier Transform) unit 114 for each antenna 117. Further, multiplexing section 113 performs SFBC (Spatial frequency block coding) processing on a signal for which no transmission weight is set (that is, DCI in the PDCCH region), and outputs the result to IFFT portion 114 for each antenna 117. Further, the multiplexing unit 113 maps the PDCCH signal and the data signal (PDSCH signal) based on the downlink resource allocation information received from the control unit 105. Note that the multiplexing unit 113 may map the setting information and the search space information to the PDSCH.

The IFFT unit 114 converts the multiplexed signal for each antenna received from the multiplexing unit 113 into a time waveform, and the CP adding unit 115 adds the CP to the time waveform to obtain an OFDM signal.

The transmission RF unit 116 performs transmission radio processing (up-conversion, digital analog (D / A) conversion, etc.) on the OFDM signal received from the CP adding unit 115 and transmits the signal via the antenna 117.

On the other hand, the reception RF unit 118 performs reception radio processing (down-conversion, analog digital (A / D) conversion, etc.) on the reception radio signal received in the reception band via the antenna 117, and the obtained reception signal is processed. The data is output to the CP removal unit 119.

CP removing section 119 removes the CP from the received signal, and FFT (Fast Fourier Transform) section 120 converts the received signal after the CP removal into a frequency domain signal.

Based on the uplink resource allocation information received from the control unit 105, the extraction unit 121 extracts uplink data from the frequency domain signal received from the FFT unit 120, and the IDFT unit 122 converts the extraction signal into a time domain signal. The time domain signal is output to data receiving section 123 and ACK / NACK receiving section 124.

The data receiving unit 123 decodes the time domain signal input from the IDFT unit 122. Then, the data reception unit 123 outputs the decoded uplink data as reception data. Further, the data reception unit 123 performs error detection on the uplink data, and outputs an error detection result for the uplink data to the selection unit 102 as an ACK / NACK signal (response signal) for the uplink data.

The ACK / NACK receiver 124 extracts an ACK / NACK signal from each terminal 200 for downlink data (PDSCH signal) from the time domain signal received from the IDFT unit 122. Specifically, the ACK / NACK receiving unit 124 extracts the ACK / NACK signal from the uplink control channel (for example, PUCCH (Physical Uplink Control Channel)) based on the information received from the assigning unit 109. The uplink control channel is an uplink control channel associated with the CCE used for transmission of downlink allocation control information corresponding to the downlink data.

Then, the ACK / NACK receiving unit 124 performs ACK / NACK determination of the extracted ACK / NACK signal.

Here, the CCE and PUCCH are associated with each other in order to eliminate the need for signaling for the terminal to notify each terminal of the PUCCH used for transmitting the ACK / NACK signal. Thereby, downlink communication resources can be used efficiently. Accordingly, each terminal determines the PUCCH used for transmitting the ACK / NACK signal based on the CCE in which the downlink allocation control information (DCI) to the terminal is mapped according to this association.

[Configuration of terminal 200]
FIG. 8 is a block diagram showing a configuration of terminal 200 according to Embodiment 1 of the present invention. Terminal 200 receives downlink data and transmits an ACK / NACK signal for the downlink data to base station 100 using PUCCH that is an uplink control channel. Further, terminal 200 uses PUSCH for transmission data (uplink retransmission data) according to a retransmission request notification for uplink data notified using a downlink control channel (PDCCH (UL grant) or PHICH or R-PHICH). To the base station 100.

In the terminal 200 shown in FIG. 8, the reception RF unit 202 sets a reception band based on the band information received from the setting information reception unit 206. The reception RF unit 202 performs reception radio processing (down-conversion, analog digital (A / D) conversion, etc.) on a radio signal (here, an OFDM signal) received in the reception band via the antenna 201, and is obtained. The received signal is output to the CP removing unit 203. The received signal may include PDSCH signals, PDCCH signals, and higher layer control information including setting information and search space information. The PDCCH signal includes a PCFICH signal and a PHICH signal (R-PHICH signal) in addition to the allocation control information. Further, the PDCCH signal (allocation control information) addressed to the terminal 200 is a common search space (C-SS) set for the terminal 200 and other terminals, or an individual search set for the terminal 200. Allocated to space (UE-SS).

CP removing section 203 removes the CP from the received signal, and FFT section 204 converts the received signal after the CP removal into a frequency domain signal. This frequency domain signal is output to the separation unit 205.

Separating section 205 sends components that may contain a PDCCH signal (DCI) out of signals received from FFT section 204 (that is, signals extracted from the PDCCH region and R-PDCCH region) to PDCCH receiving unit 207. Output. Separating section 205 outputs a higher layer control signal including setting information (for example, RRC signaling) to setting information receiving section 206, and outputs a data signal (that is, PDSCH signal) to PDSCH receiving section 208.

The setting information receiving unit 206 receives the band information, the information indicating the terminal ID, the search space information, and the reference signal (in the case of DM-RS) set in the own terminal from the upper layer control signal input from the separating unit 205. Is information indicating a port number), information indicating a transmission mode, information indicating a resource region (PDCCH region or R-PDCCH region) to which downlink control information is transmitted, information indicating a resource to which downlink control information is transmitted, a PHICH parameter, Further, information (R-PHICH dedicated area or R-PHICH allocation area) indicating the R-PHICH allocation resources set in all terminals is read.

Then, the band information is output to the PDCCH reception unit 207, the reception RF unit 202, and the transmission RF unit 218. Information indicating the terminal ID is output to the PDCCH receiving unit 207 as terminal ID information. The search space area information is output to PDCCH receiving section 207. Information indicating the reference signal is output to the PDCCH receiving unit 207 as reference signal information. When the reference signal information indicates DM-RS, information indicating the port number of the resource used for the reference signal is further provided as port number information. The data is output to PDCCH receiving unit 207. Information indicating the transmission mode is output to the PDCCH receiving unit 207 as transmission mode information. Information indicating a resource region to which downlink control information is transmitted is output to PDCCH receiving section 207 as downlink control signal transmission region information. Information indicating resources to which downlink control information is transmitted is output to PDCCH reception section 207 as downlink control signal resource information. The PHICH parameter is output to the PHICH receiving unit 209. Information indicating the R-PHICH allocation resource is output to the PDCCH reception unit 207 and the PHICH reception unit 209 as R-PHICH allocation information.

The PDCCH reception unit 207 performs blind decoding (monitoring) on the signal input from the separation unit 205 to obtain a PDCCH signal addressed to the terminal itself. Here, the PDCCH receiving unit 207 has a DCI format for data allocation common to all terminals (for example, DCI 0 / 1A) and a DCI format (for example, DCI 1, 1B, 1D, 2, 2A, 0A, 0B) and a DCI format (for example, DCI 1C, 1A) for common channel allocation common to all terminals, are subjected to blind decoding. Thereby, a PDCCH signal including allocation control information of each DCI format is obtained.

Specifically, when the downlink control signal transmission region information indicates the PDCCH region, the PDCCH reception unit 207 extracts the CCE resource in the PDCCH region from the received signal. Then, when the area indicated by the search space area information received from setting information receiving section 206 is a PDCCH area, PDCCH receiving section 207 directs the common channel allocation to C-SS indicated by the search space area information. DCI format (DCI 1C, 1A) and DCI format for data allocation common to all terminals (DCI 0 / 1A) are subjected to blind decoding. Then, PDCCH receiving section 207 demasks the CRC bits with a common ID among a plurality of terminals for the decoded signal. Then, the PDCCH receiving unit 207 determines that the signal in which CRC = OK (no error) as a result of the demasking is DCI including the allocation control information for the common channel. Also, PDCCH receiving section 207 demasks the CRC bits with the terminal ID of its own terminal indicated by the terminal ID information for the decoded signal. Then, the PDCCH receiving unit 207 determines that the signal with CRC = OK (no error) as a result of demasking is a PDCCH signal including allocation control information for the terminal itself.

Also, PDCCH receiving section 207 calculates the UE-SS of the own terminal for each CCE connection number using the terminal ID of the own terminal indicated in the terminal ID information input from setting information receiving section 206. . PDCCH receiving section 207 then sets the transmission mode (transmission mode indicated in the transmission mode information) set for the terminal for each blind decoding region candidate (CCE candidate for each number of CCE connections) in the calculated UE-SS. It demodulates and decodes the corresponding DCI format size and the DCI format common to all terminals (DCI 0 / 1A). Then, PDCCH receiving section 207 demasks the CRC bits with the terminal ID of the terminal itself for the decoded signal. Then, the PDCCH receiving unit 207 determines that the signal with CRC = OK (no error) as a result of demasking is a PDCCH signal addressed to the terminal itself.

In addition, when the PDCCH receiving unit 207 detects a retransmission request for uplink data (that is, an adaptive retransmission request) from the extracted PDCCH signal, the PDCCH receiving unit 207 outputs information indicating the retransmission request to the switching unit 213.

In addition, the PDCCH receiving unit 207 identifies the reference signal (CRS or DM-RS) set in the own device using the reference signal information and the port number information input from the setting information receiving unit 206. The identified reference signal is used for demodulation processing in terminal 200.

When the downlink control signal transmission region information indicates the R-PDCCH region, the PDCCH reception unit 207 extracts a PDCCH signal mapped to the R-PDCCH region based on the search space region information in the same manner as the PDCCH region. Then, PDCCH receiving section 207 outputs the PDCCH signal mapped to the R-PDCCH area to PHICH receiving section 209.

When there is no search space area information (search space allocation) (when base station 100 does not transmit search space area information), terminal 200 may perform blind decoding without being aware of search space allocation. .

Then, the PDCCH receiving unit 207 outputs downlink resource allocation information included in the PDCCH signal addressed to the terminal itself to the PDSCH receiving unit 208, and outputs the uplink resource allocation information to the mapping unit 215. In addition, the PDCCH receiving unit 207, when the PDCCH signal addressed to the terminal itself is detected (CCE used to transmit the signal with CRC = OK) is the first CCE number (when there are multiple CCE concatenations) CCE number of CCE) is output to mapping section 215.

The PDSCH receiving unit 208 extracts received data (downlink data) from the PDSCH signal received from the separating unit 205 based on the downlink resource allocation information received from the PDCCH receiving unit 207. PDSCH receiving section 208 also performs error detection on the extracted received data (downlink data). Then, as a result of error detection, the PDSCH receiving unit 208 generates a NACK signal as an ACK / NACK signal for the downlink data when there is an error in the received data, and when there is no error in the received data, the PDSCH receiving unit 208 An ACK signal is generated as an ACK / NACK signal for data. This ACK / NACK signal is output to modulation section 210.

Based on the PHICH parameter and R-PHICH arrangement information input from the setting information reception unit 206, the PHICH reception unit 209 receives the PDCCH signal (PDCCH signal mapped to the R-PDCCH region) input from the PDCCH reception unit 207. Obtain the R-PHICH signal. Then, the PHICH receiving unit 209 outputs the content (ACK or NACK) of the obtained R-PHICH signal to the switching unit 213.

Modulation section 210 modulates the ACK / NACK signal input from PDSCH reception section 208 and outputs the modulated ACK / NACK signal to DFT (Discrete-Fourier-Transform) section 214.

Modulation section 211 modulates transmission data (uplink data) and outputs the modulated data signal to buffer 212 and switching section 213.

The buffer 212 buffers the data signal input from the modulation unit 211 and outputs it to the switching unit 213.

When the retransmission request is input from the PDCCH receiving unit 207 or the NACK is input from the PHICH receiving unit 209, the switching unit 213 outputs the buffer 212 (buffered data signal, ie, uplink retransmission data). Is output to the DFT unit 214. On the other hand, when the retransmission request is not input from the PDCCH receiving unit 207 or when the ACK is input from the PHICH receiving unit 209, the switching unit 213 outputs the output of the modulating unit 211 (that is, a new data signal) to the DFT unit 214. Output to.

The DFT unit 214 converts an ACK / NACK signal for downlink data input from the modulation unit 210 or a data signal input from the switching unit 213 into a frequency domain, and maps a plurality of obtained frequency components to the mapping unit 215. Output to.

The mapping unit 215 maps a plurality of frequency components received from the DFT unit 214 to the PUSCH according to the uplink resource allocation information received from the PDCCH receiving unit 207. In addition, mapping section 215 specifies PUCCH according to the CCE number received from PDCCH receiving section 207. Then, mapping section 215 maps the frequency component corresponding to the ACK / NACK signal or the code resource among the plurality of frequency components input from DFT section 214 to the specified PUCCH.

The IFFT unit 216 converts a plurality of frequency components mapped to the PUSCH into a time domain waveform, and the CP adding unit 217 adds a CP to the time domain waveform.

The transmission RF unit 218 is configured to be able to change the transmission band. The transmission RF unit 218 sets the transmission band based on the band information received from the setting information reception unit 206. The transmission RF unit 218 performs transmission radio processing (up-conversion, digital analog (D / A) conversion, etc.) on the signal to which the CP is added, and transmits the signal via the antenna 201.

[Operations of base station 100 and terminal 200]
The operations of base station 100 and terminal 200 having the above configuration will be described.

In the following description, for example, FIG. 9 shows an example of mapping design of the R-PDCCH region in the prior art (current LTE-A). That is, as shown in FIG. 9, in the RBG including the R-PDCCH region, CRS and DM-RS are supported as demodulation reference signals. Also, as shown in FIG. 9, the R-PDCCH region is divided into slot 0 (1st slot) and slot 1 (2ndlotslot) within one subframe in the time domain. Further, the R-PDCCH region is mapped to REG excluding resources (RE) to which reference signals (CRS and DM-RS) are mapped.

Note that FIG. 9 shows a subframe in which CRS and DM-RS are used in the RBG including the R-PDCCH region.

Hereinafter, R-PHICH allocation examples 1 to 4 will be described.

<Allocation example 1>
In the allocation example 1, the base station 100 sets a resource area of the number of PRBs (Physical Resource Blocks) corresponding to the system bandwidth (System Bandwidth) as an R-PHICH mapping area (R-PHICH dedicated area).

In the base station 100, a resource area is allocated to each terminal 200 in units of RBGs. Also, as shown in FIG. 10, the size of the RBG composed of a plurality of PRBs, that is, the number of PRBs constituting one RBG is associated with the system bandwidth. Therefore, in allocation example 1, as shown in FIG. 10, the number of PRBs used as the R-PHICH dedicated area and the RBG including the R-PHICH dedicated area among the PRBs in one RBG, according to the system bandwidth. The position of is set.

For example, as shown in FIG. 10, when the system bandwidth is 10 RBs or less (when the RBG size is 1 RB), the RBG having the lowest frequency (lowest frequency) in the system band is set as the R-PHICH dedicated area. . Similarly, as shown in FIG. 10, when the system bandwidth is 11 RB to 26 RB (when the RBG size is 2 RBs), the lowest frequency (lowest frequency) RBG and the highest frequency (highest frequency) of the system band Are set as R-PHICH dedicated areas (see, for example, FIG. 11).

Similarly, as shown in FIG. 10, when the system bandwidth is 27 RB to 63 RB (when the RBG size is 3 RBs), the lowest frequency (lowest frequency) RBG and the highest frequency (highest frequency) of the system band Are set as the R-PHICH dedicated area. At this time, in each RBG used as the R-PHICH dedicated area, two RBs among the 3RBs constituting each RBG are used as the R-PHICH dedicated area. Similarly, as shown in FIG. 10, when the system bandwidth is 64 RB to 110 RB (when the RBG size is 4 RBs), the lowest frequency (lowest frequency) RBG and the middle frequency (middle frequency) in the system band RBG and the highest frequency (highest frequency) RBG are set as the R-PHICH dedicated area. At this time, in each RBG used as the R-PHICH dedicated region, three RBs among the 4RBs constituting each RBG are used as the R-PHICH dedicated region.

That is, as the system bandwidth becomes wider, the amount of resources set as the R-PHICH dedicated area becomes larger.

Therefore, the allocation unit 104 allocates the R-PHICH generated by the PHICH generation unit 103 to the R-PHICH dedicated region based on the association between the system bandwidth and the R-PHICH dedicated region shown in FIG.

Here, as an R-PHICH signal allocation method in the resource area set in the R-PHICH dedicated area, for example, the conventional method shown in Expression (2) may be used in the frequency domain. At this time, physical resources may be numbered by regarding them as virtually continuous REGs. Further, in the time domain, assignment section 104 may determine OFDM symbol τ _i to which an R-PHICH signal is assigned according to the following equation (3), for example.

Here, n = duration indicates an OFDM symbol length that allows allocation of an R-PHICH signal. For example, focusing on the fact that slot 1 (2nd slot) can be allocated without UL grant, the R-PHICH signal is placed only in slot 0 (1st slot) in order to improve resource utilization efficiency. In this case, n = 4 (in the case of normal CP) may be set. Further, i = index_of_REGs indicates three REG indexes (i = 0, 1, 2) to which the R-PHICH signal is assigned. d = time-Interval indicates an OFDM symbol interval to which the R-PHICH signal is assigned. For example, when d = 0, an R-PHICH signal is assigned to the same OFDM symbol, and when d = 1, an R-PHICH signal is assigned to consecutive adjacent OFDM symbols.

On the other hand, when the R-PDCCH region is set as the downlink control information transmission region, the PHICH receiving unit 209 of the terminal 200 associates the system bandwidth with the R-PHICH dedicated region and R-PHICH arrangement shown in FIG. Based on the information, the R-PHICH dedicated area to which the R-PHICH signal is allocated is specified. Also, as with the base station 100, the PHICH receiving unit 209 identifies the resource to which the R-PHICH signal for the own device is allocated in the R-PHICH dedicated area, for example, according to the equations (2) and (3). To do.

As described above, in the allocation example 1, the base station 100 sets the R-PHICH dedicated area according to the system bandwidth, so that in the resource area other than the R-PHICH dedicated area in the R-PDCCH area, PDCCH can be mapped in the same manner as in FIG. That is, in the resource area other than the R-PHICH dedicated area, it is not necessary to change the R-PDCCH mapping design by assigning the R-PHICH signal for the terminal 200. Therefore, according to the allocation example 1, the base station 100 does not require a new circuit for mapping the R-PDCCH for the terminal 200, and can suppress an increase in circuit scale and an increase in the number of test steps.

<Allocation example 2 (FIG. 12)>
In the allocation example 2, the setting unit 101 of the base station 100 transmits a transmission mode for the terminal 200 in which the R-PDCCH region is set or a CQI (Channel Quality Indicator) notified from the terminal 200 in which the R-PDCCH region is set. ) To determine a region (R-PHICH placement region) for mapping R-PHICH.

Specifically, the setting unit 101 (determination unit 132) selects a specific RBG from a plurality of RBGs each including the R-PDCCH region set in each terminal 200 by the setting unit 101 (transmission region setting unit 131). RBG is determined as the R-PHICH placement area. For example, the setting unit 101 includes an RBG (partial or all regions) including an R-PDCCH region set in a terminal 200 (partial or all terminals) that is not subjected to spatial multiplexing such as DCI format 1 or 1A. Is set in the R-PHICH placement area. Furthermore, the setting unit 101 sets the RBG having the best CQI among the RBGs including the R-PDCCH region set in the terminal 200 that is not spatially multiplexed such as DCI format 1 or 1A in the R-PHICH arrangement region. It may be set.

The R-PHICH allocation area set by the setting unit 101 is notified to all terminals using R-PHICH.

Also, the setting unit 101 sets CRS instead of DM-RS as a reference signal in the R-PDCCH region and R-PDSCH region set as the R-PHICH allocation region. Therefore, even if the reference signal set for each terminal 200 is a DM-RS, CRS is applied in the R-PHICH arrangement area, so the transmission weight setting section 111 is for the terminal 200 for which DM-RS is set. It operates so as not to set the transmission weight (precoding weight).

The assigning unit 104 assigns an R-PHICH signal to a resource in the R-PHICH arrangement area input from the setting unit 101. Specifically, allocating section 104 transmits an R-PHICH signal (that is, an ACK / NACK signal) for each terminal 200 in which the R-PDCCH region is set, to DM in the R-PHICH arrangement region (specific RBG). -Assign to resource candidates (RE candidates, eg, port numbers {7, 8, 9, 10}) to which the RS is mapped.

For example, FIG. 12 shows an example of PHICH allocation processing. In FIG. 12, the setting unit 101 of the base station 100 sets R-PDCCH regions for RN # 0, UE # 0, and UE # 1. Also, as shown in FIG. 12, setting section 101 sets the RBG including the R-PDCCH area set for UE # 0 as the R-PHICH arrangement area. Therefore, the R-PHICH allocation region is notified to terminal 200 (including UE # 0 and UE # 1) in which R-PHICH is set.

In FIG. 12, allocating section 104 assigns the R-PHICH signal for UE # 0 and UE # 1 to the DM-RS mapping position (R-PHICH) in RBG (R-PHICH placement area) set to UE # 0. Assign to one of the placement candidates).

That is, in FIG. 12, in the RBG set for UE # 1, the DM-RS is mapped in the same manner as in the conventional case (FIG. 9), whereas the RBG set for UE # 0 (R-PHICH arrangement) In the area), R-PHICH is mapped instead of DM-RS. That is, in the R-PHICH arrangement region, the resource region to which the DM-RS is mapped in the prior art (FIG. 9) is a dedicated resource for R-PHICH. For example, in FIG. 12, when the RBG size is 1, the resource for 16 terminals (RE candidate for the DM-RS within 1 RBG: 16RE) is the resource for R-PHICH, and when the RBG size is 4, the resource for 64 terminals The resource (64RE = 16RE × 4RBG) becomes an R-PHICH resource, and a sufficient resource amount can be secured as the R-PHICH resource.

As a method for assigning the R-PHICH signal in the R-PHICH arrangement area, for example, the conventional method shown in Expression (2) may be used in the frequency domain. At this time, physical resources may be numbered by regarding them as virtually continuous REGs. For example, the DM-RS discrete mapping positions (RE candidates) may be numbered by regarding them as virtual continuous REGs in the frequency domain. In the time domain, an OFDM symbol τ _i to which R-PHICH is assigned may be determined according to Equation (3). For example, similarly to the allocation example 1, when the R-PHICH is arranged only in the slot 0 (1st slot), it is only necessary to set n = 2. Also, although the arrangement of DM-RS differs depending on the CP length or the number of Ranks, there is no point to change Equation (2) and Equation (3) because the arrangement of DM-RS is different. R-PHICH is mapped according to the designated arrangement.

On the other hand, in addition to information indicating a control channel (PDCCH or R-PDCCH) mapped from the base station 100 to a transmission area set for each terminal 200, the terminal 200 adds an R-PHICH arrangement area (specific RBG). Information indicating is notified. When the R-PDCCH region is set as the downlink control information transmission region, the PHICH reception unit 209 of the terminal 200 maps the DM-RS in the R-PHICH arrangement region (specific RBG) as in the base station 100. It is determined (specified) that the R-PHICH signal for the own device is allocated to any of the resource candidates (RE candidates, for example, port numbers {7, 8, 9, 10}). Also, as with the base station 100, the PHICH receiving unit 209 identifies the resource to which the R-PHICH signal for the own device is allocated in the R-PHICH arrangement area, for example, according to the equations (2) and (3). To do.

Further, even when each terminal 200 is notified that the reference signal is DM-RS, the CRS is regarded as a reference signal in the R-PHICH arrangement area.

As described above, in the allocation example 2, the base station 100 performs the DM-RS mapping rule in the resource area other than the R-PHICH allocation area (FIG. 9) and the R-PHICH mapping rule in the R-PHICH allocation area. (Refer to the R-PHICH placement area in FIG. 12). In addition, the base station 100 separately notifies the terminal 200 in which the R-PDCCH region is set, information on the RBG that is the R-PHICH placement region. Thereby, terminal 200 receives DM-RS in the resource area other than the R-PHICH arrangement area as in the conventional case (FIG. 9), whereas in terminal area in the R-PHICH arrangement area (FIG. 9). Then, DM-RS resources are regarded as resources to which R-PHICH is allocated.

That is, in the base station 100, although signals (DM-RS and R-PHICH signals) to be allocated to the conventional DM-RS resource candidates (DM-RS and R-PHICH signals) are switched depending on whether or not the R-PHICH allocation region, R- The REG excluding resources in the PDCCH region, that is, resources to which the reference signal is mapped remains unchanged.

Therefore, in the allocation example 2, the base station 100 can map the R-PDCCH for the terminal 200 without changing the conventional R-PDCCH mapping design (FIG. 9). That is, R-PHICH for terminal 200 can be mapped to the R-PDCCH region without changing the design of the conventional R-PDCCH region. As a result, the base station 100 does not require a new circuit for mapping the R-PDCCH for the terminal 200, and can suppress an increase in circuit scale and an increase in test man-hours.

In the allocation example 2, as shown in FIG. 12, the R-PHICH allocation process in the case of using Normal CP is described as an example. However, for example, in the case of using Extended CP in FIG. The same can be applied. Here, the case where Normal CP is used indicates a case where a CP (Cyclic Prefix) assuming a normal delay spread (for example, about 5 μs) is given, and the case where Extended CP is used is a large delay. This shows a case where a CP with a spread (for example, about 17 μs) is given.

<Allocation example 3 (FIG. 14)>
In allocation example 3, setting section 101 of base station 100 determines an R-PHICH mapping area (R-PHICH allocation area) in the same manner as in allocation example 2. The R-PHICH allocation area set by the setting unit 101 is notified to all terminals 200 that use R-PHICH.

Also, the setting unit 101 sets the DM-RS port number used in the R-PDCCH or R-PDSCH to, for example, {7, 8} in the R-PHICH placement area. However, {7, 8, 9, 10} is notified to each terminal 200 as the DMRS port number.

Also, the transmission weight setting unit 111 sets a transmission weight (precoding weight) for the terminal 200 in which the DM-RS corresponding to the port number {7,8} (or {9,10}) is set.

The assigning unit 104 assigns an R-PHICH signal to a resource in the R-PHICH arrangement area input from the setting unit 101. Specifically, allocating section 104 transmits an R-PHICH signal (that is, an ACK / NACK signal) for each terminal 200 in which the R-PDCCH region is set, to DM in the R-PHICH arrangement region (specific RBG). -Supports port numbers {9,10} other than DM-RS port numbers {7,8} used in R-PDCCH or R-PDSCH among RS port numbers {7,8,9,10} Assign to resources

For example, FIG. 14 shows an example of PHICH allocation processing. In FIG. 14, the setting unit 101 of the base station 100 sets R-PDCCH regions for RN # 0, UE # 0, and UE # 1 as in FIG. Also, as shown in FIG. 14, setting section 101 sets the RBG including the R-PDCCH area set for UE # 0 as the R-PHICH arrangement area, as in FIG. Therefore, the R-PHICH allocation region is notified to terminal 200 (including UE # 0 and UE # 1) in which the R-PDCCH region is set.

In FIG. 14, allocating section 104 assigns R-PHICH signals for UE # 0 and UE # 1 to the DM-RS mapping position (port number {) in RBG (R-PHICH allocation area) set to UE # 0. 7,8,9,10}) of resources (R-PHICH allocation candidates) corresponding to port numbers {9,10} other than port numbers {7,8} to which DM-RS is actually mapped Assign to.

That is, in FIG. 14, in the resource corresponding to the RBG set to UE # 1 and the port number {7,8} in the RBG set to UE # 0, DM is performed in the same manner as in the conventional case (FIG. 9). -While RS is mapped, in the resource corresponding to port number {9,10} in RBG set to UE # 0 (R-PHICH placement area), R-PHICH is used instead of DM-RS Are mapped. That is, a part of the resource candidate (RE candidate) area to which the DM-RS in the R-PHICH arrangement area is mapped becomes a dedicated resource for the R-PHICH.

As an R-PHICH signal allocation method in the R-PHICH arrangement region, for example, the conventional method shown in Equation (2) may be used in the frequency domain, and R− in accordance with Equation (3) in the time domain. The OFDM symbol τ _i to which PHICH is allocated may be determined.

On the other hand, in addition to information indicating a control channel (PDCCH or R-PDCCH) mapped from the base station 100 to a transmission area set for each terminal 200, the terminal 200 adds an R-PHICH arrangement area (specific RBG). And DM-RS port numbers {7, 8, 9, 10} are notified. When the R-PDCCH region is set as the downlink control information transmission region, the PHICH reception unit 209 of the terminal 200 maps the DM-RS in the R-PHICH arrangement region (specific RBG) as in the base station 100. Port number applied to the actual DM-RS is identified as {7,8} among the resources (port numbers {7,8,9,10}). Then, the PHICH receiving unit 209 transfers the R for the own device to the resource corresponding to the port number {9, 10} other than the port number {7, 8} applied to the DM-RS in the R-PHICH arrangement area. -Determine that the PHICH signal is assigned. Also, as with the base station 100, the PHICH receiving unit 209 identifies the resource to which the R-PHICH signal for the own device is allocated in the R-PHICH arrangement area, for example, according to the equations (2) and (3). To do.

As described above, in the allocation example 3, the base station 100 determines a part of the DM-RS mapping rules in the resource area other than the R-PHICH arrangement area (FIG. 9) and the R-PHICH in the R-PHICH arrangement area. And the same mapping rule. In addition, the base station 100 separately notifies the terminal 200 in which the R-PDCCH region is set, information on the RBG that is the R-PHICH placement region. As a result, terminal 200 regards a part of DM-RS resources in the R-PHICH allocation area as resources to which R-PHICH is allocated. That is, in the allocation example 3, in the R-PHICH allocation region, DM-RS resource candidates in the prior art (FIG. 9) are divided into DM-RS resources and R-PHICH resources.

Here, allocation example 2 (FIG. 12) is compared with allocation example 3 (FIG. 14). In allocation example 2 (FIG. 12), all resources corresponding to DM-RSs in the R-PHICH allocation region are R-PHICH allocation candidates. Therefore, UE # 1 using the RBG set in the R-PHICH arrangement area cannot use DM-RS. On the other hand, in allocation example 3 (FIG. 14), only a part of resources corresponding to DM-RSs in the R-PHICH allocation area are R-PHICH allocation candidates, and the remaining resources are the same as those in the conventional (FIG. 9). Similarly, it becomes a resource for DM-RS. Therefore, the UE # 1 using the RBG set in the R-PHICH arrangement area can use DM-RS. Therefore, the allocation example 3 can improve the flexibility of setting the reference signal as compared with the allocation example 2.

Further, in the base station 100, as in the allocation example 2, the signals (DM-RS and R-) are allocated to some of the conventional DM-RS resource candidates depending on whether or not the R-PHICH allocation area is used. Although the PHICH signal is switched, the REG excluding resources in the R-PDCCH region, that is, resources to which the reference signal is mapped remains unchanged.

Therefore, in the allocation example 3, the base station 100 can map the R-PDCCH for the terminal 200 without changing the conventional R-PDCCH mapping design (FIG. 9). That is, R-PHICH for terminal 200 can be mapped to the R-PDCCH region without changing the design of the conventional R-PDCCH region. Thereby, in the base station 100, as in the allocation example 2, a new circuit for mapping the R-PDCCH for the terminal 200 becomes unnecessary, and an increase in circuit scale and an increase in test man-hours can be suppressed.

In allocation example 3, the port number actually used for DM-RS is {7,8}, but the port number actually used for DM-RS is {9,10}, and R-PHICH is used. {7,8} may be used as the port number. That is, base station 100 sets DM-RS port numbers and R-PHICH port numbers as appropriate, and terminal 200 may determine the location of each signal in accordance with the settings of base station 100. Also, in the allocation example 3, the DM-RS port number is {7, 8, 9, 10}, but the DM-RS port number is not limited to these.

<Allocation example 4 (FIG. 15)>
In the allocation example 4, R-PHICH allocation processing in the MBSFN subframe will be described. In subframes other than MBSFN subframes (referred to as non MBSFN subframes), for example, as shown in FIG. 9, CRS and DM-RS are used in the R-PDCCH region, and CRS is always used in each subframe. Sent. On the other hand, in the MBSFN subframe (particularly when the MBSFN subframe is used individually), CRS is not used in the R-PDCCH region, and only DM-RS is used.

Specifically, the setting unit 101 of the base station 100 determines a region (R-PHICH placement region) for mapping R-PHICH in the same manner as in allocation example 2. The R-PHICH allocation area set by the setting unit 101 is notified to all terminals 200 that use R-PHICH.

The assigning unit 104 assigns an R-PHICH signal to a resource in the R-PHICH arrangement area input from the setting unit 101. Specifically, allocating section 104 sets resources (RE) and R-PDCCH areas corresponding to CRS mapping positions (RE candidates) in the R-PHICH arrangement area in the non-MBSFN subframe in the MBSFN subframe. An R-PHICH signal (that is, an ACK / NACK signal) for each terminal 200 is assigned.

For example, FIG. 15 shows an example of PHICH allocation processing in the MBSFN subframe. In FIG. 15, the setting unit 101 of the base station 100 sets the R-PDCCH region for RN # 0, UE # 0, and UE # 1 as in FIG. Also, as shown in FIG. 15, setting section 101 sets the RBG including the R-PDCCH area set for UE # 0 in the R-PHICH arrangement area, as in FIG. Therefore, the R-PHICH allocation region is notified to terminal 200 (including UE # 0 and UE # 1) in which the R-PDCCH region is set.

In FIG. 15, allocating section 104 includes R-PHICH signals for UE # 0 and UE # 1 in the RBG (R-PHICH arrangement area in non MBSFN subframe (FIG. 9)) set to UE # 0. The resource is assigned to one of the resources (R-PHICH placement candidates) corresponding to the CRS mapping position.

That is, in the R-PHICH arrangement area of the MBSFN subframe shown in FIG.
A resource candidate (RE candidate) to which a CRS is mapped in the MBSFN subframe is a dedicated resource for the R-PHICH.

As a method for mapping R-PHICH in the R-PHICH arrangement region, for example, the conventional method shown in Equation (2) may be used in the frequency domain, and in the time domain, R-PHICH may be used according to Equation (3). it may determine the OFDM symbol tau _i to assign.

On the other hand, in addition to information indicating a control channel (PDCCH or R-PDCCH) mapped from the base station 100 to a transmission area set for each terminal 200, the terminal 200 adds an R-PHICH arrangement area (specific RBG). Information indicating is notified. When the R-PDCCH region is set as the downlink control information transmission region, the PHICH reception unit 209 of the terminal 200 has the same MBSFN subframe in the R-PHICH arrangement region in the non MBSFN subframe as in the base station 100. It is determined that the R-PHICH signal for the own device is assigned to the resource corresponding to the resource to which the CRS is mapped. Also, as with the base station 100, the PHICH receiving unit 209 identifies the resource to which the R-PHICH signal for the own device is allocated in the R-PHICH arrangement area, for example, according to the equations (2) and (3). To do.

Thus, in the allocation example 4, the base station 100 shares the CRS mapping rule (FIG. 9) in the non-MBSFN subframe and the R-PHICH mapping rule in the R-PHICH allocation area of the MBSFN subframe. And Also, base station 100 separately notifies terminal 200 in which the R-PDCCH region is set, information on RBGs that are R-PHICH allocation regions of MBSFN subframes. Thereby, terminal 200 regards the resource for CRS in the R-PHICH arrangement area of the MBSFN subframe as a resource to which R-PHICH is allocated. Thereby, base station 100 can allocate an R-PHICH signal to a resource based on the conventional R-PDCCH mapping design even in the R-PHICH arrangement region of the MBSFN subframe.

Note that the base station 100 and the terminal 200 may operate in the same manner as in any of the allocation examples 1 to 3 in the non MBSFN subframe.

Therefore, in the allocation example 4, the base station 100 can map the R-PDCCH for the terminal 200 even in the MBSFN subframe without changing the conventional R-PDCCH mapping design. That is, base station 100 can map R-PHICH for terminal 200 to the R-PDCCH region without changing the design of the conventional R-PDCCH region regardless of the type of subframe. As a result, a new circuit for mapping the R-PDCCH for the terminal 200 becomes unnecessary, and an increase in circuit scale and an increase in the number of test steps can be suppressed.

The R-PHICH allocation examples 1 to 4 have been described above.

In this way, the base station 100 gives the downlink control information (PDCCH signal) to each terminal 200 in consideration of the status of each terminal 200, for example, whether the PDCCH region is receiving interference in HetNet. Determine whether to transmit in the R-PDCCH region. Furthermore, when transmitting downlink control information in the R-PDCCH region, the base station 100 determines CRS or DM-RS as a reference signal to be used. Furthermore, the base station 100 sets a dedicated resource area (assignment example 1) or a reference signal mapping position (DM-RS or CRS, assignment examples 2 to 4) as a resource to which R-PHICH is assigned.

Specifically, according to the present embodiment, an RBG composed of a plurality of REs includes an RE candidate to which a reference signal (DM-RS or CRS) is mapped and a reference signal (DM-RS or CRS). R-PDCCH region composed of REs excluding RE candidates to be mapped. In the base station 100, the transmission region setting unit 131 assigns an R-PDCCH region to which R-PDCCH is mapped to a plurality of REs. The determination unit 132 sets a specific RBG (R-PHICH arrangement region) from among a plurality of RBGs each including the R-PDCCH region set for each terminal 200. ) And assigning section 104 sets the ACK / NACK signal for each terminal 200 in which the R-PDCCH region is set as the RE candidate for the reference signal in the specific RBG. Shed Ri.

In this way, R-PHICH for terminal 200 can be mapped only by switching the allocation target of the resource (RE) to which the reference signal is mapped in a specific RBG. The influence on the mapping design of the resource to which the reference signal is mapped by the PHICH mapping, that is, the resource constituting the R-PDCCH region can be suppressed.

That is, according to the present embodiment, it is possible to map the R-PHICH for the terminal to the R-PDCCH region without changing the design of the conventional R-PDCCH region. This avoids an increase in circuit for new R-PDCCH mapping in the base station and terminal, and further avoids an increase in test items.

Also, by assigning the R-PHICH signal for terminals to the R-PDCCH region, it is possible to prevent a decrease in throughput due to interference in the PDCCH region. Specifically, as described above, among the signals transmitted in the PDCCH region (maximum 3 OFDM symbols), PCFICH and PHICH in which the transmission region (OFDM symbol) is limited are used even if the interference station (MeNB in FIG. 4A) is CRS. Even if signals other than those are not sent (muting), interference by CRS (maximum 2 OFDM symbols) is reliably received in a wide range. On the other hand, as in this embodiment, by transmitting a PHICH signal for the terminal also in the R-PDCCH region, in the R-PDCCH region, first, a signal corresponding to the PCFICH signal in the PDCCH region is unnecessary. Become. This is because the start position of the R-PDCCH region is fixed, and the start position of the R-PDSCH region from slot 0 (1st slot) is notified to semi-static. Furthermore, since the PHICH signal is transmitted at a location where the DM-RS in the R-PDCCH region is mapped, that is, at a resource where no CRS is allocated, interference due to CRS can be avoided. Also, in an MBSFN subframe in which CRS is not transmitted, interference due to CRS can be avoided by transmitting a PHICH signal at the CRS mapping position of the own cell where CRS is not transmitted reliably in other cells. This is because the CRS is transmitted at a unique position for each cell and the mapping position of the CRS is different for each cell. Therefore, by assigning the PHICH signal to the CRS mapping position of the own cell, interference from other cells is reliably received. This is because there is not.

In the allocation examples 2 to 4, among the resources (CSI-RS resource candidates) in which the CSI-RS can be allocated in the R-PHICH allocation area set by the setting unit 101 of the base station 100, the CSI-RS is R-PHICH may be mapped to resources that are not actually mapped. FIG. 16 shows an example of R-PHICH mapping. In FIG. 16, among resources corresponding to the mapping position of CSR-RS, which resource is allocated as a resource for CSI-RS is notified by RRC signaling. In FIG. 16, it is notified that a resource surrounded by a dotted line (resource for CSI-RS in slot 0) is allocated to the CSI-RS, and among the resources surrounded by the dotted line, Assume that the resource used for CSI-RS is a resource corresponding to the port number {0, 1}. In this case, the remaining resources (port numbers {2 to 7}) among the resources surrounded by the dotted line shown in FIG. 16 can be used as R-PHICH resources.

Further, in the present embodiment, base station 100 and terminal 200 may operate by fixing any one of the allocation examples 1 to 4, and select and operate allocation examples 1 to 4 as appropriate. May be.

[Other embodiments]
(1) In the above embodiment, the case where the R-PHICH mapping position is set over the entire subframe (slot 0 and slot 1) has been described. However, the present invention is not limited to this, and for example, the R-PHICH mapping position As an alternative, only slot 0 (1st slot) may be set. Alternatively, allocating section 104 of base station 100 transmits an ACK / NACK signal to a resource candidate at an earlier time in the time domain among reference signal resource candidates (RE candidates) in the R-PHICH arrangement region (specific RBG). May be assigned. By doing so, the terminal 200 can determine whether or not there is a need for retransmission earlier, so that the processing flexibility due to securing more time for preparation of uplink data (the processing is completed earlier and remains). Can improve the performance of the upstream data by entering the sleep process in order to reduce power consumption, or by supporting more complicated processes.

(2) The expression “DCI format common to all terminals” in the above embodiment can be read as “DCI format independent of transmission mode”.

(3) In each of the above embodiments, DCI 0 / 1A has been described as “a DCI format common to all terminals”. However, the present invention is not limited to this, and any format may be used as long as it does not depend on the terminal transmission mode. .
Moreover, formats other than DCI 0A, 0B, 1, 1B, 1D, 2, 2A may be used as DCI depending on the transmission mode.
Further, continuous band allocation transmission may be included as an uplink or downlink transmission mode. In the terminal set with this transmission mode, the DCI depending on the transmission mode is DCI 0 (uplink) and DCI 1A (downlink), respectively. In this case, since the DCI format common to all terminals and the transmission mode-dependent format are the same, the UE-SS may perform blind decoding for one format each on the uplink and downlink. When the uplink and downlink transmission modes are both continuous band allocation (in the case of DCI 0 / 1A), the terminal performs blind decoding on one type of DCI format for both uplink and downlink. That's fine.
By setting DCI 0 / 1A to be a transmission mode-dependent DCI with a wider search space, the base station can be used for a terminal to which a PDCCH is assigned only by DCI 0 / 1A because the channel condition is originally poor. Since allocation control information of DCI 0 / 1A can be allocated to CCEs in a wider search space, an increase in the block rate (CCE block rate) for the terminal can be prevented.

(4) The CCE and R-CCE described in the above embodiment are logical resources. When CCEs and R-CCEs are allocated to actual physical time / frequency resources, CCEs are distributed over the entire band, and R-CCEs are distributed within a specific RB. Arranged. Further, the effects of the present invention can be obtained in the same manner even with other arrangement methods.

(5) Although the above embodiments have been described as an antenna, the present invention can be similarly applied to an antenna port.

An antenna port refers to a logical antenna composed of one or more physical antennas. That is, the antenna port does not necessarily indicate one physical antenna, but may indicate an array antenna composed of a plurality of antennas.

For example, in 3GPP LTE, it is not specified how many physical antennas an antenna port is composed of, but it is specified as a minimum unit in which a base station can transmit different reference signals (Reference signal).

Also, the antenna port may be defined as a minimum unit for multiplying the weight of a precoding vector (Precoding vector).

(6) Although cases have been described with the above embodiments as examples where the present invention is configured by hardware, the present invention can also be realized by software in conjunction with hardware.

(7) 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 a part or all of them. Although referred to as LSI here, it may be referred to as 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 implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of progress in semiconductor technology or other derived technology, it is naturally possible to integrate functional blocks using this technology. Biotechnology can be applied.

The disclosures of the specification, drawings and abstract included in the Japanese application of Japanese Patent Application No. 2011-010676 filed on Jan. 21, 2011 are all incorporated herein by reference.

The present invention is useful for mobile communication systems.

DESCRIPTION OF SYMBOLS 100 Base station 101 Setting part 102 Selection part 103 PHICH generation part 104,109 Allocation part 105 Control part 106 Search space setting part 107 PDCCH generation part 108,110,112 Encoding / modulation part 111 Transmission weight setting part 113 Multiplexer 114, 216 IFFT section 115, 217 CP addition section 116, 218 Transmission RF section 117, 201 Antenna 118, 202 Reception RF section 119, 203 CP removal section 120, 204 FFT section 121 Extraction section 122 IDFT section 123 Data reception section 124 ACK / NACK Receiving unit 200 Terminal 205 Separating unit 206 Setting information receiving unit 207 PDCCH receiving unit 208 PDSCH receiving unit 209 PHICH receiving unit 210, 211 Modulating unit 212 Buffer 213 Switching unit 214 DFT unit 215 Mappings section

Claims (8)

A means for setting a resource region to which a control channel is mapped for each terminal in a resource group unit composed of a plurality of resource elements, wherein the resource group includes a resource element candidate to which a reference signal is mapped, and the resource A setting unit including the resource region including resource elements excluding element candidates;
Determining means for determining a specific resource group from among a plurality of resource groups each including the resource region set in each terminal;
Allocating means for allocating a response signal for each terminal in which the resource area is set to resource element candidates in the specific resource group;
A base station. The reference signal is a first reference signal that can be received by all terminals, and a second reference signal for each terminal,
In the first subframe in which the first reference signal and the second reference signal are used in the resource group, the allocating unit sends the response signal to the second resource in the specific resource group. Assign to reference signal resource element candidates,
The base station according to claim 1. The assigning means assigns the response signal to a part of resource element candidates of the second reference signal in the specific resource group.
The base station according to claim 2. In the second subframe in which only the second reference signal is used in the resource group, the allocating means further transmits the response signal in the specific resource group in the first subframe. Assigning to resource elements corresponding to resource element candidates of the first reference signal;
The base station according to claim 2. The assigning means assigns the response signal to a resource element candidate at an earlier time in the time domain among resource element candidates in the specific resource group.
The base station according to claim 1. A control channel mapped to a resource area set in a resource group unit composed of a plurality of resource elements is received and determined from a plurality of resource groups each including the resource area set for each terminal. Means for receiving information indicating a specific resource group, wherein the resource group includes a resource element candidate to which a reference signal is mapped and the resource region including resource elements excluding the resource element candidate. , Receiving means,
Identifying means for identifying any of the resource element candidates in the specific resource group as a mapping position of a response signal for the own device;
A terminal comprising: A resource region to which a control channel is mapped is set for each terminal in a resource group unit including a plurality of resource elements, and the resource group excludes a resource element candidate to which a reference signal is mapped and the resource element candidate. Including the resource area composed of resource elements,
A specific resource group is determined from a plurality of resource groups each including the resource region set in each terminal,
A response signal for each terminal in which the resource area is set is assigned to resource element candidates in the specific resource group.
Transmission method. A control channel mapped to a resource area set in a resource group unit composed of a plurality of resource elements is received and determined from a plurality of resource groups each including the resource area set for each terminal. Information indicating a specific resource group, the resource group includes a resource element candidate to which a reference signal is mapped, and the resource region configured by resource elements excluding the resource element candidate,
One of resource element candidates in the specific resource group is specified as a mapping position of a response signal for the own device.
Reception method.

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