KR20140031237A - Method for receiving downlink signal and user device, and method for transmitting downlink signal and base station - Google Patents

Abstract

The present invention is provide a method and a device for transmitting and receiving a control channel in a downlink subframe divided into a control area and a data area. In the present invention, an aggregation level of the control channel that is transmitted from the control area and the aggregation level thereof that is transmitted from the data area are distinctively configured. A user device is allowed to receive the control channel from one among the control area and the data area according to the aggregation level and receive a data channel from a base station based on the control channel.

Description

Downlink signal reception method and user equipment, downlink signal transmission method and base station {METHOD FOR RECEIVING DOWNLINK SIGNAL AND USER DEVICE, AND METHOD FOR TRANSMITTING DOWNLINK SIGNAL AND BASE STATION}

The present invention relates to a wireless communication system. Specifically, the present invention relates to a method and apparatus for receiving downlink control information and a method and apparatus for transmitting downlink control information.

Various devices and technologies such as a machine-to-machine (M2M) communication and a smart phone and a tablet PC requiring a high data transmission amount are emerging and becoming popular. As a result, the amount of data required to be processed in a cellular network is increasing very rapidly. In order to satisfy such a rapidly increasing data processing demand, a carrier aggregation technique, a cognitive radio technique and the like for efficiently using more frequency bands, Multi-antenna technology and multi-base station cooperation technologies are being developed. In addition, the communication environment is evolving in the direction of increasing density of nodes that users can access from the periphery. A communication system with a high density of nodes can provide higher performance communication services to users by cooperation between nodes.

With the introduction of a new wireless communication technology, not only the number of user equipments for which a base station should provide a service in a predetermined resource area increases, but also the amount of downlink control information that each base station provides to each user equipment increases. Since the amount of radio resources available for the base station to communicate with the user equipment (s) is finite, a new scheme is needed for the base station to efficiently provide downlink control information to the user equipment (s) using the finite radio resources. .

Accordingly, the present invention provides a method and apparatus for efficiently transmitting / receiving downlink control information.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. It can be understood.

In an aspect of the present invention, when a user equipment receives a downlink signal from a base station, a downlink control channel (hereinafter, referred to as first downlink control) in a control region of a subframe according to an aggregation level of resources for transmitting control information. Receiving downlink control information on at least one of a channel) and a downlink control channel (hereinafter, referred to as a second downlink control channel) in the data region of the subframe; There is provided a downlink signal receiving method for receiving a downlink data channel based on the downlink control information, wherein an aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel.

In another aspect of the present invention, in the user equipment receiving a downlink signal from a base station, a radio frequency (RF) unit configured to transmit or receive a radio signal; And a processor configured to control the RF unit, wherein the processor is configured to control a downlink control channel (hereinafter, referred to as a first downlink control channel) in a control region of a subframe according to an aggregation level of resources for transmitting control information. The RF unit is controlled to receive downlink control information on at least one of downlink control channels (hereinafter, referred to as a second downlink control channel) in a data region of a subframe, and is based on the downlink control information. The user equipment is provided, wherein the RF unit is controlled to receive a signal, wherein an aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel.

In another aspect of the present invention, when the base station transmits a downlink signal to the user equipment, according to the aggregation level of resources for transmitting control information, a downlink control channel (hereinafter, referred to as a first downlink) in a control region of a subframe Transmitting downlink control information on at least one of a control channel) and a downlink control channel (hereinafter, referred to as a second downlink control channel) in the data region of the subframe; A downlink signal transmission method is provided based on the downlink control information, wherein an aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel.

In another aspect of the present invention, a base station transmits a downlink signal to a user equipment, comprising: a radio frequency (RF) unit configured to transmit or receive a radio signal; And a processor configured to control the RF unit, wherein the processor is configured to control a downlink control channel (hereinafter, referred to as a first downlink control channel) in a control region of a subframe according to an aggregation level of resources for transmitting control information. The RF unit is controlled to transmit downlink control information on at least one of downlink control channels (hereinafter, referred to as a second downlink control channel) in a data region of a subframe, and is based on the downlink control information. A base station is provided, wherein the RF unit is controlled to transmit a signal, wherein an aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel.

In each aspect of the present invention, the first downlink control channel may be a channel carrying common downlink control information available to both the user equipment and a user equipment other than the user equipment, and the second downlink control. The channel may be a channel that carries downlink control information specific to the user equipment.

In each aspect of the present invention, the second downlink control channel may be decoded based on a cell specific reference signal.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the present invention by those skilled in the art. And can be understood and understood.

According to the present invention, downlink control information can be efficiently transmitted / received. This increases the overall throughput of the wireless communication system.

The effects according to the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description of the invention There will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
1 shows an example of a radio frame structure used in a wireless communication system.
2 illustrates an example of a downlink / uplink (DL / UL) slot structure in a wireless communication system.
3 illustrates a DL subframe structure used in a 3GPP LTE (-A) system.
4 illustrates a reference signal used in a 3GPP LTE (-A) system.
FIG. 5 shows an example of a UL subframe structure used in the 3GPP LTE (-A) system.
6 shows an example of allocating a PDCCH to a data region of a downlink subframe.
7 illustrates a radio frame in which a normal mode and a fallback mode are set according to an embodiment of the present invention.
8 illustrates an example of transmitting downlink control information by combining a PDCCH and an E-PDCCH according to an embodiment of the present invention.
9 illustrates an example of transmitting downlink control information by combining PDCCH and E-PDCCH according to another embodiment of the present invention.
10 shows an example in which a base station performs signal transmission to a relay using a specific subframe.
11 is a diagram for explaining an example in which embodiments of the present invention are extended to relay transmission.
12 is a block diagram showing components of a transmitting apparatus 10 and a receiving apparatus 20 that perform the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details.

In addition, the techniques, devices, and systems described below may be applied to various wireless multiple access systems. For convenience of explanation, hereinafter, it will be described on the assumption that the present invention is applied to 3GPP LTE (-A). However, the technical features of the present invention are not limited thereto. For example, although the following detailed description is based on a mobile communication system that is compatible with the 3GPP LTE / LTE-A system, the mobile communication system is not limited to any other mobile communication System.

In some instances, well-known structures and devices may be omitted or may be shown in block diagram form, centering on the core functionality of each structure and device, to avoid obscuring the concepts of the present invention. In the following description, the same components are denoted by the same reference numerals throughout the specification.

In the present invention, a user equipment (UE) may be fixed or mobile and various devices communicating with the BS to transmit and receive user data and / or various control information. The UE may be a terminal equipment, a mobile station, a mobile terminal, a user terminal, a subscriber station, a wireless device, a personal digital assistant (PDA) modem, a handheld device, and the like. In addition, in the present invention, a base station (BS) generally refers to a fixed station for communicating with a UE and / or another BS, and communicates various data and control information by communicating with the UE and another BS. do. The BS may be referred to in other terms such as ABS (Advanced Base Station), NB (Node-B), eNB (evolved-NodeB), BTS (Base Transceiver System), Access Point (Access Point), and Processing Server (PS).

In the present invention, Physical Downlink Control CHannel (PDCCH) / Physical Control Format Indicator CHannel (PCFICH) / PHICH (Physical Hybrid automatic retransmit request Indicator CHannel) / PDSCH (Physical Downlink Shared CHannel) are respectively DCI (Downlink Control Information) / CFI ( Control Format Indicator) / Downlink ACK / NACK (ACKnowlegement / Negative ACK) / Downlink A set of time-frequency resources or a collection of resource elements that carry downlink data, or PUCCH (Physical Uplink Control CHannel) / Physical Uplink Shared CHannel (PUSCH) means a collection of time-frequency resources or a collection of resource elements that carry uplink control information (UCI) / uplink data, respectively, In the present invention, in particular, PDCCH / PCFICH / PHICH / PDSCH / Time-frequency resources or resource elements (REs) allocated to or belonging to PUCCH / PUSCH are referred to as PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH RE or PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH resources, respectively. Ta In the present invention, the expression that the user equipment transmits the PUCCH / PUSCH is used to mean that the uplink control information, the uplink data, and the random access signal are transmitted on the PUSCH / PUCCH, respectively. The expression that the BS transmits PDCCH / PCFICH / PHICH / PDSCH is used in the same sense as to transmit downlink data / control information on the PDCCH / PCFICH / PHICH / PDSCH, respectively.

In the present invention, a CRS (Cell-specific Reference Signal) / DMRS (Demodulation Reference Signal) / CSI-RS (Time State Frequency Reference) signal is allocated to CRS / DMRS / CSI-RS Or a time-frequency resource (or RE) that carries available RE or CRS / DMRS / CSI-RS. A subcarrier including a CRS / DMRS / CSI-RS RE is referred to as a CRS / DMRS / CSI-RS subcarrier, and an OFDM symbol including a CRS / DMRS / CSI-RS RE is referred to as a CRS / DMRS / .

1 shows an example of a radio frame structure used in a wireless communication system. Particularly, FIG. 1A illustrates a radio frame structure that can be used for FDD in 3GPP LTE (-A), FIG. 1B illustrates a radio frame structure that can be used for TDD in 3GPP LTE (-A) .

Referring to FIG. 1, a radio frame used in 3GPP LTE (-A) has a length of 10 ms (307200 T _s ) and consists of 10 equally sized subframes. 10 subframes within one radio frame may be assigned respective numbers. Here, T _s denotes the sampling time, and T _s = 1 / (2048 * 15 kHz). Each subframe is 1 ms long and consists of two slots. 20 slots in one radio frame can be sequentially numbered from 0 to 19. [ Each slot has a length of 0.5 ms. The time for transmitting one subframe is defined as a transmission time interval (TTI). The time resource may be classified by a radio frame number (or a radio frame index), a subframe number (also referred to as a subframe number), a slot number (or a slot index), and the like.

The radio frame may be configured differently according to the duplex mode. For example, in the FDD mode, since downlink transmission and uplink transmission are divided by frequency, a radio frame includes only one of a downlink subframe or an uplink subframe for a predetermined frequency band operating at a predetermined carrier frequency. . In the TDD mode, since downlink transmission and uplink transmission are separated by time, a radio frame includes both a downlink subframe and an uplink subframe for a predetermined frequency band operating at a predetermined carrier frequency.

Table 1 illustrates the DL-UL configuration of subframes in a radio frame in TDD mode.

In Table 1, D denotes a downlink subframe, U denotes an uplink subframe, and S denotes a special subframe. The specific subframe includes three fields of Downlink Pilot Time Slot (DwPTS), Guard Period (GP), and UpPTS (Uplink Pilot Time Slot). DwPTS is a time interval reserved for downlink transmission, and UpPTS is a time interval reserved for uplink transmission.

2 illustrates an example of a downlink / uplink (DL / UL) slot structure in a wireless communication system. In particular, FIG. 2 shows the structure of a resource grid of the 3GPP LTE (-A) system. There is one resource grid per antenna port.

Referring to FIG. 2, a slot includes a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. The OFDM symbol also means one symbol period. The resource block includes a plurality of subcarriers in the frequency domain. The OFDM symbol may be referred to as an OFDM symbol, an SC-FDM symbol, or the like according to a multiple access scheme. The number of OFDM symbols included in one slot may be variously changed according to the channel bandwidth and the length of the CP. For example, one slot includes seven OFDM symbols in the case of a normal CP, but one slot includes six OFDM symbols in the case of an extended CP. Although FIG. 2 illustrates a subframe in which one slot is composed of seven OFDM symbols for convenience of description, embodiments of the present invention may be applied to subframes having a different number of OFDM symbols in a similar manner. For reference, a resource composed of one OFDM symbol and one subcarrier is referred to as a resource element (RE) or a tone.

Referring to FIG. 2, a signal transmitted in each slot may be expressed as a resource grid consisting of N ^{DL / UL} _RB * N ^RB _sc sub-carriers and N ^{DL / UL} _symb OFDM symbols . Here, N ^DL _RB represents the number of resource blocks (RBs) in the downlink slot, and N ^UL _RB represents the number of _RBs in the uplink slot. N ^DL _RB and N ^UL _RB depend on the downlink transmission bandwidth and the uplink transmission bandwidth, respectively. Each OFDM symbol includes N ^{DL / UL} _RB * N ^RB _sc subcarriers in the frequency domain. The types of subcarriers can be divided into data subcarriers for data transmission, reference signal subcarriers for transmission of reference signals, guard bands, and null subcarriers for DC components. The null subcarrier for the DC component is a subcarrier that is left unused and is mapped to the carrier frequency (f ₀ ) in the OFDM signal generation process or the frequency up-conversion process. The carrier frequency is also referred to as the center frequency. N ^DL _symb represents the number of OFDM symbols in the downlink slot, and N ^UL _symb represents the number of OFDM symbols in the uplink slot. N ^RB _sc represents the number of sub-carriers constituting one RB. One RB is defined as N ^{DL / UL} _symb consecutive OFDM symbols in the time domain (e.g., 7) and is represented by N ^RB _sc (e.g., twelve) consecutive subcarriers in the frequency domain Is defined. Therefore, one RB consists of N ^{DL / UL} _symb * N ^RB _sc resource elements. Each resource element in the resource grid can be uniquely defined by an index pair (k, 1) in one slot. k is an index given from 0 to N ^{DL / UL} _RB * N ^RB _sc -1 in the frequency domain, and l is an index given from 0 to N ^{DL / UL} _symb -1 in the time domain.

Two RBs, one in each of two slots of the subframe occupying N ^RB _sc consecutive identical subcarriers in one subframe, are referred to as a pair of physical resource blocks (PRB). The two RBs constituting the PRB pair have the same PRB number (or PRB index). VRB is a kind of logical resource allocation unit introduced for resource allocation. VRB has the same size as PRB. According to the method of mapping the VRB to the PRB, the VRB is divided into a localized type VRB and a distributed type VRB. Localized type VRBs are directly mapped to PRBs so that VRB numbers (also referred to as VRB indexes) correspond directly to PRB numbers. That is, n _PRB = n _VRB . Localized type VRBs are numbered from 0 to N ^DL _VRB -1, and N ^DL _VRB = N ^DL _RB . Therefore, according to the localization mapping method, VRBs having the same VRB number are mapped to PRBs having the same PRB number in the first slot and the second slot. On the other hand, distributed type VRBs are interleaved and mapped to PRBs. Thus, VRBs of distributed type having the same VRB number may be mapped to different numbers of PRBs in the first slot. Two PRBs, which are located in two slots of a subframe and have the same VRB number, are called a VRB pair.

FIG. 3 illustrates a downlink subframe structure used in a 3GPP LTE (-A) system.

The downlink subframe is divided into a control region and a data region in the time domain. Referring to FIG. 3, a maximum of 3 (or 4) OFDM symbols located at a first position in a first slot of a subframe corresponds to a control region to which a control channel is allocated. Hereinafter, a resource region available for PDCCH transmission in a downlink subframe is called a PDCCH region. The remaining OFDM symbols other than the OFDM symbol (s) used as the control region correspond to a data region to which a Physical Downlink Shared CHance (PDSCH) is allocated. Hereinafter, a resource region available for PDSCH transmission in a downlink subframe is called a PDSCH region. Examples of a downlink control channel used in 3GPP LTE include a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), and the like. The PCFICH carries information about the number of OFDM symbols transmitted in the first OFDM symbol of the subframe and used for transmission of the control channel in the subframe. The PHICH carries an HARQ ACK / NACK (acknowledgment / negative-acknowledgment) signal in response to uplink transmission.

The control information transmitted through the PDCCH is referred to as DCI (Downlink Control Information). The DCI includes resource allocation information and other control information for the UE or UE group. For example, DCI includes a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format and resource allocation information of an uplink shared channel (UL-SCH), a paging channel paging information on (paging channel, PCH), system information on DL-SCH, resource allocation information of higher-layer control message such as random access response transmitted on PDSCH, Tx power control command set for individual UEs in UE group, Tx power control command, activation instruction information of Voice over IP (VoIP), and the like. The DCI carried by one PDCCH differs in size and usage according to the DCI format, and its size may vary according to the coding rate. Table 2 shows an example of the DCI format.

A plurality of PDCCHs may be transmitted in the PDCCH region of the downlink subframe. The UE may monitor a plurality of PDCCHs. The BS determines the DCI format according to the DCI to be transmitted to the UE, and adds a cyclic redundancy check (CRC) to the DCI. The CRC is masked (or scrambled) by an identifier (e.g., a radio network temporary identifier (RNTI)) according to the owner of the PDCCH or the purpose of use. For example, if the PDCCH is for a specific UE, the identifier (e.g., cell-RNTI (C-RNTI)) of the UE may be masked in the CRC. If the PDCCH is for a paging message, the paging identifier (e.g., paging-RNTI (P-RNTI)) may be masked to the CRC. If the PDCCH is for system information (more specifically, a system information block (SIB)), the system information RNTI (SI-RNTI) may be masked to the CRC. If the PDCCH is for a random access response, a random access-RNTI (RA-RNTI) may be masked in the CRC. CRC masking (or scrambling) includes, for example, XORing CRC and RNTI at the bit level.

The PDCCH is transmitted on an aggregation of one or more contiguous control channel elements (CCEs). The CCE is a logical allocation unit used to provide the PDCCH with a coding rate based on radio channel conditions. The CCE corresponds to a plurality of resource element groups (REG). For example, one CCE corresponds to nine REGs, and one REG corresponds to four REs. Four QPSK symbols are mapped to each REG. The resource element RE occupied by the reference signal RS is not included in the REG. Therefore, the number of REGs in a given OFDM symbol depends on the presence or absence of RS. The REG concept is also used for other downlink control channels (ie, PDFICH and PHICH). The DCI format and the number of DCI bits are determined according to the number of CCEs. For example, as shown in Table 3, four DCI formats are supported.

CCEs are numbered consecutively, and in order to simplify the decoding process, a PDCCH having a format composed of n CCEs can be started only in a CCE having a number corresponding to a multiple of n. The number of CCEs used for transmission of a specific PDCCH is determined by the BS according to the channel state. For example, in case of PDCCH for a UE having a good downlink channel (eg, adjacent to a BS), one CCE may be sufficient. However, for a PDCCH for a UE with a poor channel (e.g., near the cell boundary), eight CCEs may be required to obtain sufficient robustness. In addition, the power level of the PDCCH may be adjusted according to the channel state.

In the 3GPP LTE system, a set of CCEs in which a PDCCH can be located for each UE is defined. A set of CCEs in which a UE can discover its PDCCH is referred to as a PDCCH search space, simply a Search Space (SS). An individual resource to which a PDCCH can be transmitted in a search space is referred to as a PDCCH candidate. The collection of PDCCH candidates to be monitored by the UE is defined as a search space. One PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs depending on the CCE aggregation level. The BS sends the actual PDCCH (DCI) on any PDCCH candidate in the search space, and the UE monitors the search space to find the PDCCH (DCI). Specifically, the UE attempts blind decoding on the PDCCH candidates in the search space.

In the 3GPP LTE system, a search space for each PDCCH format may have a different size, and a dedicated search space and a common search space are defined. The dedicated search space is a UE-specific search space and is configured for each individual UE. The common search space is configured for a plurality of UEs. Table 4 illustrates the aggregation levels that define the search spaces.

By monitoring the corresponding search space at each aggregation level, the UE detecting its own PDCCH decodes and / or uplink subframes in the PDSCH region of the downlink subframe based on the DCI carried by the detected PDCCH. The PUSCH is transmitted in the data region of.

The BS transmits a reference signal (RS) for estimation of channel state, demodulation of a signal, and the like, for accurate demodulation of the PDCCH and / PDSCH by the UE. RS refers to a signal of a predetermined waveform, which is defined by a UE and a UE known to each other, also called a pilot.

4 illustrates an RS used in a 3GPP LTE (-A) system. In particular, FIG. 4 (a) shows the positions of RS resources in a subframe having a general CP, and FIG. 4 (b) shows the positions of RS resources in a subframe having an extended CP.

RSs can be broadly classified into a dedicated reference signal (DRS) and a common reference signal (CRS). RSs may be classified into demodulation reference signals and channel measurement reference signals. CRS and DRS are also referred to as cell-specific RS and demodulation RS (DMRS), respectively. In addition, the DMRS is also referred to as a UE-specific RS. DMRS and CRS may be transmitted together, but only one of them may be transmitted. However, when only the DMRS is transmitted without the CRS, the DMRS transmitted by applying the same precoder as the data may be used only for the purpose of demodulation, and thus RS for channel measurement should be separately provided. For example, in 3GPP LTE (-A), in order to enable the UE to measure channel state information, an additional measurement RS, CSI-RS, is transmitted to the UE (not shown). The CSI-RS is transmitted every predetermined transmission period consisting of a plurality of subframes, unlike the CRS transmitted for each subframe, based on the fact that the channel state is not relatively varied with time.

In FIG. 4, CRS REs represent REs that antenna port 0 to antenna port 4 uses for CRS transmission. The CRS is transmitted in all downlink subframes in a cell supporting PDSCH transmission. CRS can be used for both demodulation and measurement purposes and is shared by all user equipment in the cell. The CRS sequence is transmitted on all antenna ports regardless of the number of layers.

In FIG. 4, REs denoted by D represent REs used for RS transmission for demodulation of the PDSCH when the BS performs PDSCH transmission through a single antenna port. Meanwhile, in FIG. 4, UE-specific RS REs are used for RS transmission for demodulation of PDSCH through up to eight antenna ports. The BS transmits a UE-specific RS in REs when data demodulation is needed, and the presence or absence of the UE-specific RS is notified to the UE by a higher layer.

5 shows an example of an uplink subframe structure used in a 3GPP LTE (-A) system.

Referring to FIG. 5, the uplink subframe may be divided into a control domain and a data domain in the frequency domain. One or several physical uplink control channels (PUCCHs) may be allocated to the control region to carry uplink control information (UCI). The UCI carried by one PUCCH is different in size and use according to the PUCCH format, and may vary in size according to a coding rate.

One or several physical uplink shared channels (PUSCHs) may be allocated to a data region of an uplink subframe to carry user data. When the UE adopts the SC-FDMA scheme for uplink transmission, in order to maintain a single carrier characteristic, in the 3GPP LTE release 8 or release 9 system, PUCCH and PUSCH cannot be simultaneously transmitted on one carrier. In 3GPP LTE Release 10 system, whether to support simultaneous transmission of PUCCH and PUSCH may be indicated in a higher layer.

In the uplink subframe, subcarriers far away from the direct current (DC) subcarrier are used as a control region. In other words, subcarriers located at both ends of the uplink transmission bandwidth are allocated to transmission of uplink control information. The DC subcarrier is a component that is left unused for signal transmission and is mapped to the carrier frequency f ₀ in the frequency up conversion process. In one subframe, a PUCCH for one UE is allocated to an RB pair belonging to resources operating at a single carrier frequency, and RBs belonging to the RB pair occupy different subcarriers in two slots. The PUCCH allocated in this way is expressed as that the RB pair allocated to the PUCCH is frequency hopped at the slot boundary. However, when frequency hopping is not applied, the RB pairs occupy the same subcarrier.

In order to improve the performance of the system, the introduction of a new remote radio head (RRH) is being discussed. Meanwhile, since a plurality of serving CCs may be configured in one UE under a carrier aggregation situation, a method of transmitting a UL / DL grant for another CC in a channel CC having a good channel situation is discussed. As such, when the CC carrying the UL / DL grant, which is scheduling information, and the CC on which the UL / DL transmission corresponding to the UL / DL grant is performed, this is called cross-carrier scheduling. When the RRH technique, the cross-carrier scheduling technique, and the like are introduced, the amount of PDCCH to be transmitted by the BS is gradually increased. However, since the size of the control region in which the PDCCH can be transmitted is the same as before, the PDCCH transmission serves as a bottleneck of system performance. Therefore, in order to prevent PDCCH transmission from limiting system performance, there is a discussion to perform PDCCH transmission using a PDSCH region of a downlink subframe.

6 shows an example of allocating a PDCCH to a data region of a downlink subframe.

Referring to FIG. 6, a PDCCH according to the existing 3GPP LTE standard may be allocated to a PDCCH region of a downlink subframe. Meanwhile, the PDCCH may be additionally allocated using some resources of the PDSCH region. When the PDCCH is transmitted in the PDSCH region, the PDCCH can be used not only for CRS-based transmit diversity or spatial multiplexing transmission but also to operate based on the UE-specific reference signal DMRS. Can be. Hereinafter, the PDCCH transmitted in the PDSCH region is referred to as an enhanced PDCCH (E-PDCCH) or an advanced PDCCH (A-PDCCH) to distinguish it from the existing PDCCH transmitted in the first OFDM symbol (s) of the downlink subframe. Embodiments of the invention will be described. PDSCH scheduled by E-PDCCH is also called E-PDSCH. In addition, the latter system is referred to as a legacy system in order to distinguish between a system configuring both the PDCCH and the E-PDCCH and an existing system configuring only the PDCCH without the E-PDCCH. In embodiments of the present invention, it is assumed that a UE implemented according to an enhancement system, in other words an enhancement UE, is configured to receive both a PDCCH and an E-PDCCH. A UE implemented to receive only a PDCCH becomes a legacy UE when compared to a UE capable of receiving an E-PDCCH.

Referring to FIG. 6, frequency and time resources to which the E-PDCCH is mapped may be variously set. For example, the E-PDCCH may be configured from the fourth symbol to the last symbol of the downlink subframe, or may be configured only in the first slot or in the second slot. In addition, the location of the DL / UL grant carried by the E-PDCCH may also be configured in various ways. However, in order to prevent occurrence of interference between the E-PDCCH and the existing PDCCH, the E-PDCCH resource may not overlap with the existing PDCCH resource.

As such, the E-PDCCH has a structural feature in which the control information may be transmitted somewhere in the PDSCH region, deviating from the structure in which the control information should be transmitted in the PDCCH region of the downlink subframe. This structural feature consists of a macro cell in which communication service is provided by a macro BS and a micro cell (eg, femto cell, pico cell, etc.) in which communication service is provided by a micro BS having a smaller service coverage than the macro BS. It may be used for the purpose of reducing mutual interference between the macro cell and the micro cell in a wireless network. For example, if a multimedia broadcast single frequency network (MBSFN) subframe in which control information and RS exist in the first two OFDM symbols is configured, and an ABS (almost blank subframe) is applied to the corresponding subframe, a specific downlink in the ABS Since only the transmission of a signal (eg, CRS) is allowed or the downlink signal is transmitted only at a very weak transmission power, interference may be removed or mitigated in the remaining areas except for the first two OFDM symbols. It is preferable that the control information and data are configured to be transmitted in the resource region where interference is limited. For example, a space in which an E-PDCCH may exist, that is, a search space (SS), is previously designated by RRC (Radio Resource Control) signaling or the like, and the UE performs blind decoding only on the corresponding SS to perform DL decoding. Decoding (ie, DL grant), UL scheduling grant (ie, UL grant), and the like can be decoded. Furthermore, since the search space for detecting the E-PDCCH exists in the PDSCH region, the UL / DL grant may be configured to be decoded based on the DMRS.

Even if the E-PDCCH of another cell is configured in a subframe in which a specific cell constitutes an ABS among cells that may interfere with each other, there is still room for unexpected interference in the PDSCH region of the subframe. In addition, due to discovery space reconfiguration and RRC reconfiguration for the E-PDCCH, a situation in which the UE cannot normally decode the E-PDCCH may occur. In such a case, designing the system to decode the PDCCH instead of the E-PDCCH so that the UE can obtain the DCI necessary to perform communication with the network can make the radio system operation more robust. Therefore, the present invention not only operates in a mode for receiving DCI by decoding the E-PDCCH (hereinafter, the normal mode), but also in a mode for receiving DCI by decoding the PDCCH (hereinafter, referred to as a fallback mode). We propose a working UE. For example, the UE according to the present embodiment may not only receive the PDSCH by decoding the E-PDCCH but also may be configured to receive the PDSCH by decoding the PDCCH in a specific situation or a specific subframe. In general, the BS / UE may perform PDSCH transmission / reception on the E-PDCCH in a normal mode, and then switch to the fallback mode to perform PDSCH transmission / reception on the PDCCH in case of emergency.

The subframe in which the UE switches to the fallback mode and attempts to detect the PDCCH in the PDSCH region may be predefined. If the UE cannot receive the E-PDCCH due to an abnormal channel situation, it is possible to perform blind decoding on the PDCCH after that. The UE may be configured to attempt decoding of the PDCCH instead of the E-PDCCH if certain conditions are met. For example, if the E-PDCCH reception quality falls below a threshold value, and if the E-PDCCH decoding failure persists more than N times in a specified time interval, N subframes (i.e., since the E-PDCCH decoding failure starts). Time), a timer is started when the E-PDCCH decoding failure starts, and the timer expires, etc. can be used as the specific condition. The UE that fails to detect the E-PDCCH may obtain the required DCI in the designated subframe so as to decode the PDCCH.

The PDSCH on the PDCCH may carry the same contents as the PDSCH on the E-PDCCH, that is, the E-PDSCH, but may be configured to carry new contents. Hereinafter, a subframe in which the UE attempts only detection of the PDCCH is called a fallback subframe.

7 illustrates a radio frame in which a normal mode and a fallback mode are set according to an embodiment of the present invention.

The fallback subframe may be designated in each radio frame or a specific subframe every integer multiple of the radio frame. Alternatively, a subframe in which broadcast (eg, BCH, paging, etc.) information is transmitted or a subframe associated with the broadcast information may be set as a fallback subframe. Alternatively, a subframe corresponding to a specific subframe or subframe pattern previously configured by RRC may be set as a fallback subframe.

Referring to FIG. 7, a radio frame includes a subframe operating in a general mode in which the UE decodes an E-PDCCH to receive / demodulate a PDSCH, and a fallback subframe operating in a fallback mode in which a PDCCH is decoded to receive / demodulate a PDSCH. Can be set. In particular, the fallback subframe is a subframe promised to be difficult or not to receive the E-PDCCH, and the UE decodes the PDSCH or the E-PDSCH by decoding the PDCCH in the corresponding subframe.

Meanwhile, the present invention proposes an embodiment in which PDCCH transmission and E-PDCCH transmission are appropriately combined and operated according to the characteristics of control information. 8 illustrates an example of transmitting downlink control information by combining a PDCCH and an E-PDCCH according to an embodiment of the present invention.

Referring to FIG. 8, for example, common control information that a plurality of UEs should attempt to decode in common is transmitted / received on a PDCCH, and dedicated control information for a specific UE or UE group (ie, UE-specific control information). ) May be transmitted / received on the E-PDCCH. In this case, common control information carried by the PDCCH may not be transmitted / received on the E-PDCCH. It can be seen that the E-PDCCH is not transmitted in the common search space but only in the dedicated search space. Change and update information of important information such as system information or cell selection / reselection information, other broadcast information (for example, a master information block (MIB) message, system information block type 1) 1, SIB1) message, system information (SI) message, a message defined to be transmitted in a common search space according to the 3GPP LTE-A system, etc. may be common control information, and dynamic scheduling information (for example, , DL allocation, UL scheduling grant, etc.) and related information may be dedicated control information. For reference, a MIB message, SIB1 message, and SI message masked with SI-RNTI, a paging message masked with P-RNTI, and a random access response channel (RACH) response message masked with RA-RNTI are commonly searched. Can be transmitted / received in space

It is also possible that both the common search space and the dedicated search space exist as search spaces for the E-PDCCH. In the common search space for the E-PDCCH (hereinafter referred to as the E-PDCCH common search space), important information shared by several UEs is transmitted / received through the E-PDCCH, and a dedicated search space for the E-PDCCH (hereinafter referred to as E In the dedicated search space (PDCCH), the aforementioned dynamic scheduling information may be transmitted / received through the E-PDCCH. However, the UE is common in E-PDCCH in a special subframe (for example, a subframe whose subframe number is 0 or 5 (SF # 0 or SF # 5)) in which the aforementioned critical information is transmitted / received. It may be configured to perform blind decoding in a common search space (hereinafter, PDCCH common search space) for the PDCCH and not the search space to obtain the important information. In addition, in order to be able to obtain certain important information, for example, paging information, power control command, etc., the UE may be configured to arbitrarily listen to the PDCCH. As such, even when blind decoding is performed in both the E-PDCCH common search space and the E-PDCCH dedicated search space for DCI reception, there is no change in the complexity of blind decoding for detecting the E-PDCCH.

9 illustrates an example of transmitting downlink control information by combining PDCCH and E-PDCCH according to another embodiment of the present invention.

Unlike in the embodiment of FIG. 8, in the embodiment of FIG. 9, PDCCH transmission and E-PDCCH transmission are distinguished by the aggregation level instead of the common search space and the dedicated search space. That is, according to this embodiment, different aggregation levels are used for PDCCH transmission and E-PDCCH transmission.

For example, referring to Table 4, PDCCH candidates of a lower aggregation level (eg, CCE aggregation level 1 or 2) do not have much resources, while higher aggregation levels (eg, CCE aggregation level 4 or The PDCCH candidate of 8) has a relatively large amount of resources. Accordingly, the present invention proposes that the E-PDCCH is configured to be transmitted / received in the PDSCH region at a lower aggregation level, and the PDCCH is configured to be transmitted / received in the PDCCH region at a higher aggregation level. In other words, DCI requiring high aggregation level may be transmitted / received in the PDCCH region, and DCI not requiring high aggregation level may be transmitted / received in the PDSCH region. For example, assuming that the PDCCH is transmitted at aggregation level 4 or 8, and the E-PDCCH is defined to be transmitted at aggregation level 1 or 2, the UE is a PDCCH only at aggregation level 4 and aggregation level 8 in the search space in the PDCCH region. The E-PDCCH needs to be monitored only at aggregation level 1 and aggregation level 2 in the search space in the PDSCH region.

According to the present embodiment, even in the case of a dedicated search space, if the aggregation level of the corresponding search space is high, the PDCCH may be transmitted / received in the search space, which is different from the embodiment of FIG. 8. There is. According to this embodiment, when the E-PDCCH is transmitted at a lower aggregation level, more E-PDCCHs may be transmitted / received on the same resource region.

The E-PDCCH carrying the DL grant or the UL grant may be divided into slot units. In other words, one E-PDCCH may occupy only one PRB out of two PRBs constituting a PRB pair. Alternatively, one E-PDCCH may be configured to occupy the entire PRB pair.

The above-described embodiments of the present invention can be applied to transmission / reception between the BS and the relay. 10 shows an example in which a base station performs signal transmission to a relay using a specific subframe.

The relay means an extension of the service area of the BS or installed in a shaded area to smoothly service the BS and / or a branch. Relays can be called by other terms such as RN (Relay Node), RS (Relay Station). From the point of view of the UE, the relay is part of the radio access network and acts like a BS, with a few exceptions. A BS that transmits a signal to or receives a signal from the relay is referred to as a donor BS. The relay is connected wirelessly to the donor BS. From the perspective of the BS, the relay behaves like a UE except for some exceptions (e. G., The downlink control information is transmitted on the R-PDCCH rather than the PDCCH). Thus, the relay includes both the physical layer entity used for communication with the UE and the physical layer entity used for communication with the donor BS. The transmission from the BS to the relay, hereinafter referred to as BS-to-RN transmission, occurs in the downlink subframe, and transmission from the relay to the BS, hereinafter referred to as RN-to-BS transmission, occurs in the uplink subframe. Meanwhile, the BS-to-RN transmission and the RN-to-BS transmission occur in the downlink frequency band, and the RN-to-BS transmission and the UE-to-RN transmission occur in the uplink frequency band. In the present invention, a relay or a UE may communicate with a network to which the one or more BSs belong via one or more BSs.

In particular, FIG. 10 illustrates communication using a general subframe from a relay to a UE and communication using a multimedia broadcast single frequency network (MBSFN) subframe from a BS to a relay.

In in-band relay mode operating in the same frequency band as the BS-relay link (i.e. backhaul link) and the relay-UE link (i.e. relay access link), the relay receives signals from the BS and sends signals to the UE. In the case of vice versa or vice versa, the transmitter and receiver of the relay cause interference with each other. In order to solve the interference problem, the relay may be configured not to communicate with UEs in a time interval in which the relay receives data from the BS. The time interval in which the UEs do not expect any relay transmission, i.e., the transmission gap, can be generated by constructing the MBSFN subframe. That is, the relay or BS may set an arbitrary subframe as an MBSFN subframe and set a backhaul link in the MBSFN subframe (fake MBSFN method). When any subframe is signaled to be an MBSFN subframe, since the UE detects a downlink signal only in the PDCCH region of the subframe, the relay may configure a backhaul link using the PDSCH region of the subframe. The relay may receive a signal from the BS in a specific subframe (eg, MBSFN subframe) and transmit data received from the BS to the UE in another subframe.

11 is a diagram for explaining an example in which embodiments of the present invention are extended to relay transmission.

Referring to FIG. 11, for example, a relay may be configured to receive an E-PDCCH while receiving an R-PDCCH. R-PDCCH means a collection of time-frequency resources carrying control information provided to the relay by the BS. In current 3GPP LTE systems, the R-PDCCH is allocated within one slot range. That is, the current R-PDCCH of the 3GPP LTE system occupies only one PRB of the two PRBs constituting the PRB pair. However, the E-PDCCH of the present invention may occupy only one PRB or may occupy both PRBs. Meanwhile, although the R-PDCCH may carry a DL / UL grant, according to an embodiment of the present invention, an E-PDCCH transmitted / received in a specific search space (for example, a common or dedicated search space) may be carried. (See the embodiment of FIG. 8), the E-PDCCH transmitted / received on the aggregation of a predetermined number of CCEs according to a specific aggregation level may carry (see the embodiment of FIG. 9). Referring to FIG. 11, downlink control information provided to a relay by a BS may be transmitted through an R-PDCCH and / or an E-PDCCH. In this case, the control information carried by the R-PDCCH and the control information carried by the E-PDCCH may be classified according to the characteristics of the control information. For example, common control information shared by a plurality of relays may be transmitted / received through an R-PDCCH, and dedicated control information for a specific relay or relay group may be transmitted / received through an E-PDCCH.

The BS may continuously allocate the E-PDCCH to a specific RB (for example, six RBs located at the center of the frequency bandwidth) to configure a common search space and may use the E-PDCCH to transmit broadcast information. . The E-PDCCH in the common search space may be decoded based on the CRS and / or DMRS. In this case, however, UE-specific beam-forming or precoding is not applied to CRS / DMRS. However, it is possible for UE-group specific precoding to be applied to CRS / DMRS so that CRS or DMRS can be shared among specific UEs. Although the CRS is generally transmitted over all downlink RBs, the CRS of the present invention may be configured to be transmitted only in specific RBs corresponding to a common search space. When the E-PDCCH is transmitted based on the DMRS, the DMRS for the E-PDCCH may be restricted to be used only for decoding of the E-PDCCH in limited RB (s).

The above-described embodiments of the present invention are mainly described by taking the case where the E-PDCCH carries a DL grant which is scheduling information for the PDSCH. However, the E-PDCCH may be applied even when carrying a DCI other than the DL grant. For example, the E-PDCCH may carry a UL grant, in which case, the UE detecting the E-PDCCH may be an uplink subframe (eg, a predetermined subframe) associated with a downlink subframe in which the E-PDCCH is detected. Uplink subframes after the number of subframes) may be configured to transmit a PUSCH according to the UL grant.

12 is a block diagram showing components of a transmitting apparatus 10 and a receiving apparatus 20 that perform the present invention.

The transmitting apparatus 10 and the receiving apparatus 20 may include RF (Radio Frequency) units 13 and 23 capable of transmitting or receiving radio signals carrying information and / or data, signals, messages, (12, 22) for storing various information related to communication, a RF unit (13, 23) and a memory (12, 22) And a processor 11, 21, respectively, configured to control the memory 12, 22 and / or the RF unit 13, 23 to perform at least one of the embodiments of the present invention described above.

The memories 12 and 22 may store a program for processing and controlling the processors 11 and 21, and may temporarily store the input / output information. The memories 12 and 22 can be utilized as buffers.

Processors 11 and 21 typically control the overall operation of the various modules within the transmitting or receiving device. In particular, the processors 11 and 21 may perform various control functions to perform the present invention. The processors 11 and 21 may also be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, or the like. The processors 11 and 21 may be implemented by hardware or firmware, software, or a combination thereof. When implementing the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays) may be included in the processor. Meanwhile, when the present invention is implemented using firmware or software, firmware or software may be configured to include a module, a procedure, or a function for performing the functions or operations of the present invention. The firmware or software may be contained within the processors 11, 21 or may be stored in the memories 12, 22 and driven by the processors 11,

The processor 11 of the transmission apparatus 10 performs predetermined coding and modulation on signals and / or data scheduled to be transmitted from the scheduler connected to the processor 11 or the processor 11, And transmits it to the RF unit 13. For example, the processor 11 converts a data stream to be transmitted into K layers through demultiplexing, channel coding, scrambling, modulation, and the like. The encoded data stream is also referred to as a code word and is equivalent to a transport block that is a data block provided by the MAC layer. One transport block (TB) is encoded into one codeword, and each codeword is transmitted to a receiving device in the form of one or more layers. The RF unit 13 for frequency up-conversion may include an oscillator. The RF unit 13 may include N _t transmit antennas, where N _t is a positive integer.

The signal processing procedure of the receiving apparatus 20 is configured in reverse to the signal processing procedure of the transmitting apparatus 10. [ Under the control of the processor 21, the RF unit 23 of the receiving device 20 receives the radio signal transmitted by the transmitting device 10. The RF unit 23 may include N _r reception antennas (N _r is a positive integer), and the RF unit 23 performs frequency down conversion on each of the signals received through the reception antennas. -convert) Restore to baseband signal. The RF unit 23 may include an oscillator for frequency down conversion. The processor 21 may perform decoding and demodulation of the radio signal received through the reception antenna to recover data that the transmission apparatus 10 originally intended to transmit.

The RF units 13 and 23 have one or more antennas. The antenna may transmit signals processed by the RF units 13 and 23 to the outside under the control of the processors 11 and 21 or receive radio signals from the outside and transmit the signals processed by the RF unit 13 , 23). Antennas are sometimes referred to as antenna ports. Each antenna may correspond to one physical antenna or may be configured by a combination of more than one physical antenna elements. The signal transmitted from each antenna can not be further decomposed by the receiving apparatus 20. [ A reference signal (RS) transmitted in response to the antenna defines the antenna viewed from the perspective of the receiving apparatus 20 and indicates whether the channel is a single radio channel from one physical antenna, Enables the receiving device 20 to channel estimate for the antenna regardless of whether it is a composite channel from a plurality of physical antenna elements. That is, the antenna is defined such that a channel carrying a symbol on the antenna can be derived from the channel through which another symbol on the same antenna is transmitted. In case of an RF unit supporting a multi-input multi-output (MIMO) function for transmitting and receiving data using a plurality of antennas, it can be connected to two or more antennas.

In the embodiments of the present invention, the UE operates as the transmitting apparatus 10 in the uplink and operates as the receiving apparatus 20 in the downlink. In the embodiments of the present invention, the BS operates as the receiving apparatus 20 in the uplink and operates as the transmitting apparatus 10 in the downlink.

A BS processor (hereinafter, referred to as a BS processor) may allocate a PDCCH according to the existing 3GPP LTE standard to a PDCCH region of a downlink subframe and allocate an E-PDCCH to a PDSCH region according to an embodiment of the present invention.

The UE processor (hereinafter, referred to as a UE processor) of the present invention may operate not only in the normal mode of receiving the DCI by decoding the E-PDCCH, but also in the fallback mode of receiving the DCI by decoding the PDCCH. The UE processor of the present invention may not only receive the PDSCH by decoding the E-PDCCH but also may be configured to receive the PDSCH by decoding the PDCCH in a specific situation or a specific subframe.

The BS processor may control the RF unit (hereinafter, referred to as a BS RF unit) of the BS to set up a fallback subframe in which the UE should operate in the fallback mode and transmit information indicating the fallback subframe to the UE. The BS processor may set the fallback subframe in each radio frame unit or an integer multiple of the radio frame. Instead of the fallback subframe being configured by the BS processor, a specific subframe, for example, a subframe through which broadcast information is transmitted, may be defined as a fallback subframe. Although the UE processor may be configured as a fallback subframe or configured to operate the UE in a fallback mode in a predetermined subframe, the UE processor according to another embodiment of the present invention decodes the PDCCH instead of the E-PDCCH when a specific condition is satisfied. Can be configured to attempt. For example, if the E-PDCCH reception quality falls below a threshold value, and if the E-PDCCH decoding failure persists more than N times in a specified time interval, N subframes (i.e., since the E-PDCCH decoding failure starts). Time), a timer is started when the E-PDCCH decoding failure starts, and the timer expires, etc. can be used as the specific condition. The UE processor that fails to detect the E-PDCCH may obtain the required DCI in the designated subframe so as to decode the PDCCH.

The BS processor may appropriately combine the PDCCH and the E-PDCCH according to the characteristics of the control information. For example, the BS processor may control the BS RF unit to transmit common control information to the UE (s) via the PDCCH, and control the BS RF unit to transmit dedicated control information to a specific UE via the E-PDCCH. have. In this case, the UE processor controls the RF unit (hereinafter referred to as UE RF unit) of the UE to perform blind decoding in the common search space to obtain common control information, and acquires dedicated control information, that is, UE-specific control information. In order to do so, the UE RF unit may be controlled to perform blind decoding in a dedicated search space.

It is also possible that both the common search space and the dedicated search space exist as search spaces for the E-PDCCH. The BS processor controls the BS RF unit to transmit an E-PDCCH carrying important information shared by multiple UEs in the E-PDCCH common search space, and transmits an E-PDCCH carrying dynamic scheduling information in the E-PDCCH dedicated search space. The BS RF unit can be controlled to The UE processor controls the UE RF unit to detect the E-PDCCH carrying the important information in the resource region indicated by the E-PDCCH common search space and the dynamic scheduling information in the resource region indicated by the E-PDCCH dedicated search space. It is possible to obtain an E-PDCCH carrying. The BS processor may control the BS RF unit to transmit the important information through the PDCCH in the PDCCH common search region within the PDCCH region of the predetermined special subframe. The UE processor may detect the PDCCH by controlling the UE RF unit to perform blind decoding in the PDCCH common search region within the PDCCH region of the special subframe.

E-PDCCH transmission and PDCCH transmission may be classified based on the CCE aggregation level instead of being divided into a common search space and a dedicated search space. The BS processor may control the BS RF unit so that the E-PDCCH transmits on a small collection of resources according to the lower aggregation level, and the PDCCH transmits on a collection of many resources according to the higher aggregation level. The UE processor monitors the E-PDCCH at an aggregation level below a predetermined value, and monitors the PDCCH at an aggregation level greater than the predetermined value. For example, if aggregation level 1 or 2 is used for E-PDCCH transmission and aggregation level 4 or 8 is used for PDCCH transmission, the BS processor transmits one E-PDCCH on one CCE or two CCEs, and the PDCCH Control the BS RF unit to transmit on 4 CCEs or 8 CCEs. The UE processor may perform blind decoding in the search space on the assumption that the E-PDCCH occupies one CCE for detection of the E-PDCCH, and may perform blind decoding in the search space on the assumption that the E-PDCCH occupies two CCEs. The UE processor may perform blind decoding in the search space on the assumption that the PDCCH occupies four CCEs for detection of the PDCCH, and may perform blind decoding in the search space on the assumption that the PDCCH occupies eight CCEs.

The BS processor may be configured to carry the same contents of the PDSCH on the PDCCH and the PDSCH on the E-PDCCH, but may also be configured to carry new contents. The BS processor of the present invention controls the BS RF unit to transmit the PDSCH according to the DL grant carried by the PDCCH and / or the E-PDCCH to the UE in the PDSCH region of the downlink subframe. The UE processor controls the UE RF unit to detect the transmitted PDCCH and / or the E-PDCCH according to the embodiment of the present invention described above, and transmits the PDSCH according to the detected PDCCH and / or the E-PDCCH according to the PDSCH of the corresponding subframe. The UE RF unit may be controlled to receive in the area.

Embodiments of the present invention described above may be extended to a relay. The processor of the relay (hereinafter referred to as a relay processor) may control the relay RF unit to receive the E-PDCCH as well as control the RF unit (hereinafter referred to as a relay RF unit) of the relay to receive the R-PDCCH. The BS processor may control the BS RF unit to transmit the DL / UL grant for the relay on the R-PDCCH, but control or predetermined the BS RF unit to transmit the E-PDCCH carrying the DL / UL grant in a specific search space. The BS RF unit can be controlled to transmit at an aggregation level. The relay processor may control the relay RF unit to detect the R-PDCCH for obtaining the DL / UL grant, and may control the relay RF unit to detect the E-PDCCH. The relay processor or the UE processor decodes the E-PDCCH based on the CRS, or the E-PDCCH based on the DMRS or UE-group specific precoded DMRS without UE-specific beam-forming or precoding. It can be decoded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the invention disclosed herein has been presented to enable any person skilled in the art to make and use the present invention. While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the following claims It can be understood that Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Embodiments of the present invention may be used in a wireless communication system, such as a base station, a relay or a user equipment, or any other equipment.

Claims (8)

In the user equipment receives the downlink signal from the base station,
According to the aggregation level of resources for transmitting control information, a downlink control channel (hereinafter referred to as a first downlink control channel) in a control region of a subframe and a downlink control channel (hereinafter referred to as a second downlink) in a data region of the subframe Receiving downlink control information on at least one of the link control channels);
Receiving a downlink data channel based on the downlink control information;
An aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel,
Downlink signal receiving method. The method of claim 1,
The first downlink control channel carries common downlink control information available to both the user equipment and the user equipment other than the user equipment, and the second downlink control channel carries downlink control information specific to the user equipment. Carrying,
Downlink signal receiving method. The method of claim 1,
Decoding the second downlink control channel based on a cell specific reference signal;
Downlink signal receiving method. In the user equipment receives the downlink signal from the base station,
A radio frequency (RF) unit configured to transmit or receive a radio signal; And
And a processor configured to control the RF unit,
The processor determines a downlink control channel (hereinafter, referred to as a first downlink control channel) in a control region of a subframe and a downlink control channel (hereinafter, referred to as: Controlling the RF unit to receive downlink control information on at least one of a second downlink control channel), and control the RF unit to receive a downlink data channel based on the downlink control information;
An aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel,
User device. 5. The method of claim 4,
The first downlink control channel carries common downlink control information available to both the user equipment and the user equipment other than the user equipment, and the second downlink control channel carries downlink control information specific to the user equipment. Carrying,
User device. 5. The method of claim 4,
The processor is configured to decode the second downlink control channel based on a cell specific reference signal;
User device. In the base station transmits the downlink signal to the user equipment,
According to the aggregation level of resources for transmitting control information, a downlink control channel (hereinafter referred to as a first downlink control channel) in a control region of a subframe and a downlink control channel (hereinafter referred to as a second downlink) in a data region of the subframe Transmitting downlink control information on at least one of a link control channel);
Transmitting a downlink data channel based on the downlink control information;
An aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel,
Downlink signal transmission method. In the base station transmits the downlink signal to the user equipment,
A radio frequency (RF) unit configured to transmit or receive a radio signal; And
And a processor configured to control the RF unit,
The processor determines a downlink control channel (hereinafter, referred to as a first downlink control channel) in a control region of a subframe and a downlink control channel (hereinafter, referred to as: Controlling the RF unit to transmit downlink control information on at least one of a second downlink control channel), and controlling the RF unit to transmit a downlink data channel based on the downlink control information;
An aggregation level of the first downlink control channel is greater than an aggregation level of the second downlink control channel,
Base station.

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