WO2013012151A1

WO2013012151A1 - Method and apparatus for transceiving downlink control information in a wireless communication system

Info

Publication number: WO2013012151A1
Application number: PCT/KR2012/001250
Authority: WO
Inventors: 최혜영; 한승희; 이현우; 김진민; 손혁민
Original assignee: 엘지전자 주식회사
Priority date: 2011-07-19
Filing date: 2012-02-20
Publication date: 2013-01-24

Abstract

The present invention relates to a wireless communication system. More particularly, the present invention relates to a method for receiving control information by a terminal in a wireless communication system, the method comprising the steps of: determining a search space consisting of PDCCH candidates in a downlink subframe from a base station; and attempting to encode each PDCCH candidate in the determined search space. The search space comprises: a common search space (CSS); and a terminal-specific search space (USS). The CSS is located in a first region of the subframe and the USS is located in a second region of the subframe. The first region consists of a first N-number (N <= 4) of OFDM symbols in the subframe, and the second region consists of OFDM symbols other than those of the first region in the subframe.

Description

Method and apparatus for transmitting and receiving downlink control information in wireless communication system

The following description relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting and receiving downlink control information in a wireless communication system supporting one or more serving cells.

Wireless communication systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency (SC-FDMA). division multiple access (MCD) systems and multi-carrier frequency division multiple access (MC-FDMA) systems.

An object of the present invention is to set an e-PDCCH region and to set a common search space and a cell specific search space in the PDCCH region and the e-PDCCH region.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

A first technical aspect of the present invention is a method of receiving control information from a terminal in a wireless communication system, comprising: determining a search space consisting of PDCCH candidates on a downlink subframe from a base station; And attempting to decode each of the PDCCH candidates on the determined search space, wherein the search space includes a common search space (CSS) and a terminal specific search space (USS), and the CSS includes the subframe. Located in a first region of the USS, the USS is located in a second region of the subframe, the first region consists of the first N (N <= 4) OFDM symbols in the subframe, the second region Is to provide control information receiving method consisting of OFDM symbols excluding the first region in the subframe.

According to a second aspect of the present invention, there is provided a method for transmitting control information by a base station in a wireless communication system, the method comprising: determining a search space consisting of physical downlink control channel (PDCCH) candidates on a downlink subframe; And transmitting the control information through any one of the PDCCH candidates on the search space, wherein the search space includes a common search space (CSS) and a terminal specific search space (USS), and the CSS Is located in the first region of the subframe, the USS is located in the second region of the subframe, and the first region is composed of the first N (N <= 4) OFDM symbols in the subframe, The second region is to provide a control information transmission method consisting of OFDM symbols other than the first region in the subframe.

A third technical aspect of the present invention is an apparatus for receiving control information in a wireless communication system, comprising: a receiving module; And a processor, wherein the processor determines a search space consisting of PDCCH candidates on a downlink subframe, and attempts to decode each of the PDCCH candidates on the determined search space, wherein the search space is a common search space ( CSS) and a terminal specific search space (USS), wherein the CSS is located in a first area of the subframe, the USS is located in a second area of the subframe, and the first area is in the subframe. The first N (N <= 4) OFDM symbols, and the second region consists of OFDM symbols other than the first region in the subframe, to provide an apparatus.

A fourth technical aspect of the present invention is an apparatus for transmitting control information in a wireless communication system, comprising: a transmission module; And a processor, wherein the processor determines a search space consisting of physical downlink control channel (PDCCH) candidates on a downlink subframe, and transmits the control information through one PDCCH among the PDCCH candidates on the search space. Control to transmit, wherein the search space includes a common search space (CSS) and a terminal specific search space (USS), wherein the CSS is located in a first region of the subframe, and the USS is a second region of the subframe Wherein, the first region consists of the first N (N <= 4) OFDM symbols in the subframe, and the second region consists of OFDM symbols except for the first region in the subframe. To provide a device.

In the first to fourth technical aspects of the present invention, the USS may be located on one or more subcarriers on at least one or more OFDM symbols of the second region.

In addition, the USS may be located in the first slot in the subframe.

In addition, the CSS may be located on the primary cell.

In addition, the control information received on the CSS may be one of a random access identifier (RA-RNTI), a system information identifier (SI-RNTI) or a paging identifier (P-RNTI).

According to the present invention, a signal-to-noise ratio of control information transmitted to a common search space and / or a terminal specific search space can be increased. In addition, even if the number of terminals connected to a specific base station increases significantly, there is an advantage in that the UE-specific search space can be flexibly set.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings appended hereto are for the purpose of providing an understanding of the present invention and for illustrating various embodiments of the present invention and for describing the principles of the present invention in conjunction with the description thereof.

1 is a diagram illustrating a structure of a radio frame used in a 3GPP LTE system.

FIG. 2 is a diagram illustrating a resource grid in a downlink slot.

3 is a diagram illustrating a structure of an uplink subframe.

4 is a diagram illustrating a structure of a downlink subframe.

5 is a diagram illustrating a terminal specific search space at each aggregation level.

6 is a diagram for explaining carrier aggregation.

7 is a diagram for describing cross carrier scheduling.

8 and 9 are diagrams for describing a method that can be used when exchanging scheduling information between respective base stations.

10 and 11 are diagrams illustrating time-frequency resources allocated for an e-PDCCH.

12 to 17 are diagrams illustrating an example in which a common search space and a terminal specific search space are set in a PDCCH and / or an e-PDCCH.

FIG. 18 is a view showing a process in the case described in FIG. 15.

19 is a diagram illustrating a configuration of an embodiment of a base station apparatus or a terminal apparatus according to the present invention.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

In the present specification, embodiments of the present invention will be described based on a relationship between data transmission and reception between a base station and a terminal. Here, the base station has a meaning as a terminal node of the network that directly communicates with the terminal. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, it is obvious that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station may be performed by the base station or other network nodes other than the base station. A 'base station (BS)' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point (AP), and the like. In addition, in this document, the term base station may be used as a concept including a cell or a sector. On the other hand, the repeater may be replaced by terms such as Relay Node (RN), Relay Station (RS). The term “terminal” may be replaced with terms such as user equipment (UE), mobile station (MS), mobile subscriber station (MSS), and subscriber station (SS).

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802 system, 3GPP system, 3GPP LTE and LTE-Advanced (LTE-A) system and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. LTE-A (Advanced) is the evolution of 3GPP LTE. WiMAX can be described by the IEEE 802.16e standard (WirelessMAN-OFDMA Reference System) and the advanced IEEE 802.16m standard (WirelessMAN-OFDMA Advanced system). For clarity, the following description focuses on 3GPP LTE and 3GPP LTE-A systems, but the technical spirit of the present invention is not limited thereto.

무선 프레임Wireless frame

1 (a) is a diagram showing the structure of a radio frame used in the 3GPP LTE system. One radio frame includes 10 subframes, and one subframe includes two slots in the time domain. The time for transmitting one subframe is defined as a transmission time interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. One slot may include a plurality of OFDM symbols in the time domain. Since the 3GPP LTE system uses the OFDMA scheme in downlink, the OFDM symbol represents one symbol length. One symbol may be referred to as an SC-FDMA symbol or a symbol length in uplink. A resource block (RB) is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot. The structure of such a radio frame is merely exemplary. Accordingly, the number of subframes included in one radio frame, the number of slots included in one subframe, or the number of OFDM symbols included in one slot may be changed in various ways.

Figure 1 (b) illustrates the structure of a type 2 radio frame. Type 2 radio frames consist of two half frames. Each half frame consists of five subframes, a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP), and an Uplink Pilot Time Slot (UpPTS), of which one subframe consists of two slots. . DwPTS is used for initial cell search, synchronization or channel estimation at the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. The guard period is a period for removing interference generated in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

The structure of the radio frame is merely an example, and the number of subframes included in the radio frame or the number of slots included in the subframe and the number of symbols included in the slot may be variously changed.

슬롯 구조Slot structure

FIG. 2 is a diagram illustrating a resource grid in a downlink slot. One downlink slot includes seven OFDM symbols in the time domain and one resource block (RB) is shown to include 12 subcarriers in the frequency domain, but the present invention is not limited thereto. For example, one slot includes 7 OFDM symbols in the case of a general cyclic prefix (CP), but one slot may include 6 OFDM symbols in the case of an extended-CP (CP). Each element on the resource grid is called a resource element (RE). One resource block includes 12 x 7 resource elements. The number of NDLs of resource blocks included in a downlink slot depends on a downlink transmission bandwidth. The structure of the uplink slot may be the same as the structure of the downlink slot.

상향링크 서브프레임 구조UL subframe structure

3 is a diagram illustrating a structure of an uplink subframe. The uplink subframe may be divided into a control region and a data region in the frequency domain. A physical uplink control channel (PUCCH) including uplink control information is allocated to the control region. In the data area, a physical uplink shared channel (PUSCH) including user data is allocated. In order to maintain a single carrier characteristic, one UE does not simultaneously transmit a PUCCH and a PUSCH. PUCCH for one UE is allocated to an RB pair in a subframe. Resource blocks belonging to a resource block pair occupy different subcarriers for two slots. This is called a resource block pair allocated to the PUCCH is frequency-hopped at the slot boundary.

하향링크 서브프레임 구조Downlink Subframe Structure

4 is a diagram illustrating a structure of a downlink subframe. Up to three OFDM symbols at the front of the first slot in one subframe correspond to a control region to which a control channel is allocated. The remaining OFDM symbols correspond to data regions to which a physical downlink shared channel (PDSCH) is allocated. The downlink control channels used in the 3GPP LTE system include, for example, a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical HARQ indicator channel. (Physical Hybrid automatic repeat request Indicator Channel, PHICH).

The PCFICH is transmitted in the first OFDM symbol of a subframe and includes information on the number of OFDM symbols used for control channel transmission in the subframe. The PHICH includes a HARQ ACK / NACK signal as a response of uplink transmission. The PDCCH includes uplink or downlink scheduling information and power control information.

하향링크제어정보Downlink Control Information

Looking at the PDCCH in more detail, the control information transmitted through the PDCCH is called downlink control information (DCI). DCI includes uplink or downlink scheduling information or an uplink transmit power control command for a certain terminal group. The PDCCH is a resource allocation and transmission format of the downlink shared channel (DL-SCH), resource allocation information of the uplink shared channel (UL-SCH), paging information of the paging channel (PCH), system information on the DL-SCH, on the PDSCH Resource allocation of upper layer control messages such as random access responses transmitted to the network, a set of transmit power control commands for individual terminals in an arbitrary terminal group, transmission power control information, and activation of voice over IP (VoIP) And the like.

Different control information as described above has different DCI sizes. Currently, according to LTE-A (release 10), DCI formats 0, 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3, 3A, and 4 are defined. In this case, DCI formats 0, 1A, 3, and 3A are defined to have the same message size in order to reduce the number of blind decoding, which will be described later. These DCI formats are i) DCI formats 0, 4, ii) DCI formats 1, 1A, 1B, 1C, 1D, 2, used for downlink scheduling assignment depending on the purpose of the control information to be transmitted. 2A, 2B, 2C, and iii) DCI formats 3 and 3A for power control commands.

In case of DCI format 0 used for uplink scheduling grant, a carrier indicator necessary for carrier aggregation to be described later, a flag used for distinguishing DCI formats 0 and 1A (flag for format 0 / format 1A differentiation), A frequency hopping flag indicating whether frequency hopping is used in uplink PUSCH transmission, information on resource block assignment, modulation and coding scheme to be used for PUSCH transmission, and a modulation and coding scheme. ), A new data indicator used to empty the buffer for initial transmission in relation to the HARQ process, a TPC command for scheduled for PUSCH, a cycle for demodulation reference signal (DMRS) Cyclic shift for DM RS and OCC index, UL index and channel quality information required for TDD operation r) request information (CSI request) and the like. Meanwhile, since DCI format 0 uses synchronous HARQ, it does not include a redundancy version like DCI formats related to downlink scheduling allocation. In the case of the carrier indicator, when cross carrier scheduling is not used, it is not included in the DCI format.

DCI format 4 is new in LTE-A Release 10 and is intended to support spatial multiplexing for uplink transmission in LTE-A. The DCI format 4 further includes information for spatial multiplexing as compared to the DCI format 0, and thus has a larger message size, and further includes additional control information in the control information included in the DCI format 0. That is, the DCI format 4 further includes a modulation and coding scheme for the second transport block, precoding information for multi-antenna transmission, and sounding reference signal request (SRS request) information. On the other hand, since DCI format 4 has a size larger than DCI format 0, an indicator for distinguishing DCI formats 0 and 1A is not included.

DCI formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, and 2C related to downlink scheduling allocation do not significantly support spatial multiplexing, but 1, 1A, 1B, 1C, 1D and 2, which support spatial multiplexing, It can be divided into 2A, 2B, and 2C.

DCI format 1C supports only frequency continuous allocation as a compact downlink allocation and does not include a carrier indicator and a redundant version as compared to other formats.

DCI format 1A is a format for downlink scheduling and random access procedures. This includes the carrier indicator, an indicator indicating whether downlink distributed transmission is used, PDSCH resource allocation information, modulation and coding scheme, redundancy version, HARQ processor number to inform the processor used for soft combining, HARQ In connection with the process, a new data indicator used to empty the buffer for initial transmission, a transmit power control command for the PUCCH, and an uplink index required for the TDD operation may be included.

In the case of DCI format 1, most of the control information is similar to DCI format 1A. However, compared to DCI format 1A related to continuous resource allocation, DCI format 1 supports non-contiguous resource allocation. Therefore, DCI format 1 further includes a resource allocation header, so that control signaling overhead is somewhat increased as a trade-off of increasing flexibility of resource allocation.

DCI formats 1B and 1D are common in that precoding information is further included as compared with DCI format 1. DCI format 1B includes PMI verification and DCI format 1D includes downlink power offset information. The control information included in the DCI formats 1B and 1D is mostly identical to that of the DCI format 1A.

The DCI formats 2, 2A, 2B, and 2C basically include most of the control information included in the DCI format 1A, and further include information for spatial multiplexing. This includes the modulation and coding scheme, the new data indicator and the redundancy version for the second transport block.

DCI format 2 supports closed-loop spatial multiplexing, while 2A supports open-loop spatial multiplexing. Both contain precoding information. DCI format 2B supports dual layer spatial multiplexing combined with beamforming and further includes cyclic shift information for DMRS. DCI format 2C can be understood as an extension of DCI format 2B and supports public multiplexing up to eight layers.

DCI formats 3 and 3A may be used to supplement transmission power control information included in DCI formats for uplink scheduling grant and downlink scheduling assignment, that is, to support semi-persistent scheduling. . In the case of

DCI format

3, 1 bit per terminal and 2 bit in 3A are used.

Any one of the above-described DCI formats may be transmitted through one PDCCH, and a plurality of PDCCHs may be transmitted in a control region.

PDCCH 프로세싱PDCCH Processing

In transmitting the DCI on the PDCCH, a Cyclic Redundancy Check (CRC) is attached to the DCI, and in this process, a radio network temporary identifier (RNTI) is masked. Here, the RNTI may use different RNTIs according to the purpose of transmitting the DCI. Specifically, the P-RNTI is used for a paging message related to network initiated connection establishment, the RA-RNTI is used for random access, and the SI-RNTI is used for a system information block (SIB). Can be. In the case of unicast transmission, C-RNTI, which is a unique terminal identifier, may be used. DCI with CRC is coded with a predetermined code and then adjusted to the amount of resources used for transmission through rate-matching.

In the transmission of the PDCCH as described above, when the PDCCH is mapped to the REs for efficient processing, a control channel element (CCE), which is a continuous logical allocation unit, is used. The CCE is composed of 36 REs, which corresponds to 9 units in a resource element group (REG). The number of CCEs required for a specific PDCCH depends on the DCI payload, cell bandwidth, channel coding rate, etc., which are the size of control information. In more detail, the number of CCEs for a specific PDCCH may be defined according to the PDCCH format as shown in Table 1 below.

Table 1

PDCCH Format	CCE Count	REG Count	PDCCH Bit Count
0	One	9	72
One	2	18	144
2	4	36	288
3	8	72	576

As can be seen from Table 1, the number of CCEs varies according to the PDCCH format. For example, the transmitter may use the PDCCH format 0 and then adaptively use the PDCCH format by changing the PDCCH format to 2 when the channel condition worsens. have.

블라인드 복호(Blind decoding)Blind decoding

As described above, any one of four formats may be used for the PDCCH, which is not known to the UE. Therefore, the UE needs to decode without knowing the PDCCH format, which is called blind decoding. However, since it is a heavy burden for the UE to decode all possible CCEs used for downlink for each PDCCH format, a search space is defined in consideration of the scheduler limitation and the number of decoding attempts.

That is, the search space is a set of candidate PDCCHs consisting of CCEs that the UE should attempt to decode on an aggregation level. Here, the aggregation level and the number of PDCCH candidates may be defined as shown in Table 2 below.

TABLE 2

	Navigation		PDCCH Candidates
	Set level	Size in CCE	PDCCH Candidates
Terminal specific	One	6	6
	2	12	6
	4	8	2
	8	16	2
common	4	16	4
common	8	16	2

As shown in Table 2, since four aggregation levels exist, the terminal has a plurality of search spaces according to each aggregation level.

In addition, as shown in Table 2, the search space may be divided into a terminal specific search space and a common search space. The UE specific search space (USS) is for specific UEs, and each UE monitors the UE specific search space (attempting to decode a PDCCH candidate set according to a possible DCI format) and is masked on the PDCCH. The RNTI and CRC may be checked to obtain control information if valid.

The common search space (CSS) is for a case where a plurality of terminals or all terminals need to receive a PDCCH such as dynamic scheduling or paging message for system information. However, CSS may be used for a specific terminal for resource management. In addition, CSS may overlap with a terminal specific search space. The control information for the plurality of terminals may be masked by any one of a random access identifier (RA-RNTI), a system information identifier (SI-RNTI), or a paging identifier (P-RNTI).

The search space may be specifically determined by Equation 1 below.

Equation 1

here,

Is the aggregation level,

Is a variable determined by RNTI and subframe number k,

Is the number of PDCCH candidates when carrier aggregation is applied

If not,

as

And

Is the number of PDCCH candidates,

Is the total number of CCEs of the control region in the kth subframe,

Is a factor that specifies an individual CCE in each PDCCH candidate in the PDCCH.

to be. For common navigation space

Is always determined to be zero.

5 shows a terminal specific search space (shading part) at each aggregation level that can be defined according to Equation (1). Carrier merge is not used here.

Is illustrated as 32 for convenience of explanation.

(A), (b), (c), and (d) of FIG. 5 illustrate the case of

aggregation levels

1, 2, 4, and 8, respectively, and numbers represent CCE numbers. In FIG. 5, the start CCE of the search space at each aggregation level is determined by the RNTI and the subframe number k, as described above.

Can be determined differently for each set level.

Is always determined as a multiple of the aggregation level. In the description below,

Is assumed to be CCE number 18 by way of example. From the start CCE, the UE attempts decoding sequentially in units of CCEs determined according to a corresponding aggregation level. For example, in (b) of FIG. 5, the UE attempts to decode the two CCE units according to the aggregation level from the CCE number 4 which is the starting CCE.

As described above, the UE attempts to decode the search space, and the number of decoding attempts is determined by a transmission mode determined through DCI format and RRC signaling. In case carrier aggregation is not applied, the UE should consider two DCI sizes (DCI format 0 / 1A / 3 / 3A and DCI format 1C) for each of six PDCCH candidates for a common search space. Decryption attempt is necessary. For the UE-specific search space, a maximum of 32 decoding attempts are required because two DCI sizes are considered for the number of PDCCH candidates (6 + 6 + 2 + 2 = 16). Therefore, up to 44 decoding attempts are required when carrier aggregation is not applied.

On the other hand, when carrier aggregation is applied, since the UE-specific search space and the decoding for DCI format 4 are added as many as downlink resources (component carriers), the maximum number of decoding is further increased.

반송파 병합(Carrier Aggregation)Carrier Aggregation

6 is a diagram for explaining carrier aggregation. Prior to describing carrier aggregation, a concept of a cell introduced to manage radio resources in LTE-A will be described first. A cell may be understood as a combination of downlink resources and uplink resources. Here, the uplink resource is not an essential element, and thus, the cell may be composed of only the downlink resource or the downlink resource and the uplink resource. However, this is the definition in the current LTE-A Release 10 and vice versa, that is, the cell may be made up of uplink resources alone. The downlink resource may be referred to as a downlink component carrier (DL CC) and the uplink resource may be referred to as an uplink component carrier (UL CC). The DL CC and the UL CC may be represented by a carrier frequency, and the carrier frequency means a center frequency in a corresponding cell.

A cell may be classified into a primary cell (PCell) operating at a primary frequency and a secondary cell (SCell) operating at a secondary frequency. PCell and SCell may be collectively referred to as a serving cell. In the PCell, the terminal may perform an initial connection establishment (initial connection establishment) process, or the cell indicated in the connection reset process or handover process may be a PCell. That is, the PCell may be understood as a cell that is the center of control in a carrier aggregation environment to be described later. The UE may receive and transmit a PUCCH in its PCell. The SCell is configurable after the RRC connection establishment is made and can be used to provide additional radio resources. In the carrier aggregation environment, the remaining serving cells except the PCell may be viewed as SCells. In the RRC_CONNECTED state, but the UE is not configured carrier aggregation or does not support carrier aggregation, there is only one serving cell consisting of a PCell. On the other hand, in the case of a terminal in the RRC_CONNECTED state and the carrier aggregation is configured, one or more serving cells exist, and all the serving cells include the PCell and the entire SCell. For a terminal supporting carrier aggregation, after the initial security activation process is initiated, the network may configure one or more SCells in addition to the PCell initially configured in the connection establishment process.

Hereinafter, carrier aggregation will be described with reference to FIG. 6. Carrier aggregation is a technology introduced in LTE-A to use a wider frequency band to meet the increasing demand for high data rates. Carrier aggregation may be defined as an aggregation of two or more component carriers (CCs) having different carrier frequencies. Referring to FIG. 6, FIG. 6 (a) shows a subframe when one CC is used in the existing LTE system, and FIG. 6 (b) shows a subframe when carrier aggregation is used. In FIG. 6B, three CCs of 20 MHz are used to support a total bandwidth of 60 MHz. Here, each CC may be continuous or may be non-continuous.

The terminal may simultaneously receive and monitor downlink data through a plurality of DL CCs. The linkage between each DL CC and UL CC may be indicated by system information. The DL CC / UL CC link may be fixed in the system or configured semi-statically. In addition, even if the entire system band is composed of N CCs, the frequency band that a specific UE can monitor / receive may be limited to M (<N) CCs. Various parameters for carrier aggregation may be set in a cell-specific, UE group-specific or UE-specific manner.

크로스 반송파 스케줄링(cross carrier scheduling)Cross carrier scheduling

7 is a diagram for describing cross carrier scheduling. Cross-carrier scheduling means, for example, including all downlink scheduling allocation information of another DL CC in a control region of one DL CC among a plurality of serving cells, or a DL CC of any one of a plurality of serving cells. This means that the uplink scheduling grant information for the plurality of UL CCs linked with the DL CC is included in the control region of the UE. 7 is a diagram illustrating a case where cross carrier scheduling is applied. As a premise of description, a carrier indicator field (CIF) will be described first, and FIG. 7 will be described.

As described above, the CIF may be included or not included in the DCI format transmitted through the PDCCH, and when included, it indicates that the cross carrier scheduling is applied. When cross carrier scheduling is not applied, downlink scheduling allocation information is valid on a DL CC through which current downlink scheduling allocation information is transmitted. The uplink scheduling grant is also valid for one UL CC linked with the DL CC through which the downlink scheduling assignment information is transmitted.

When cross carrier scheduling is applied, the CIF indicates a CC related to downlink scheduling allocation information transmitted through a PDCCH in one DL CC. For example, referring to FIG. 7, downlink allocation information about DL CC B and DL CC C, that is, information about PDSCH resources, is transmitted through a PDCCH in a control region on DL CC A. The UE monitors the DL CC A to know the CC corresponding to the resource region of the PDSCH through the CIF.

e-PDCCHe-PDCCH

Although control information included in the above-described DCI formats has been described mainly for transmission through a PDCCH defined in LTE / LTE-A, the downlink control channel other than the PDCCH, for example, e-PDCCH (enhanced PDCCH) Application is possible. The e-PDCCH is an enhanced version of the PDCCH that can be discussed in LTE-A Release 11. The background of the introduction is as follows.

In a cellular network-based wireless communication system, there is interference between homogeneous networks or heterogeneous networks of the same type. The influence of such interference may affect not only the data channel but also the control channel. In the LTE / LTE-A system, in order to alleviate inter-cell interference, a cell causing interference interferes with a specific subframe (s) of an Almost blank subframe (ABS) (eg, a basic downlink signal (eg, a cell-specific reference signal)). Subframes in which only transmission of 0 or very weak power is performed), thereby reducing interference with neighboring cells or using the inter-base station scheduling information to each cell allocated to the terminal at the cell edge. It may be set to orthogonal the frequency domain of. However, the control channel (PDCCH, PCFICH, PHICH) may need to be transmitted in all subframes, there is a problem that it is difficult to avoid interference because it is allocated and transmitted in the entire downlink bandwidth.

FIG. 8 is a technique that can be used when exchanging scheduling information between base stations, and shows a technique of allocating PDSCH in orthogonal frequency domains to terminals at a cell edge to mitigate interference. However, as described above, the PDCCH has a problem that the interference cannot be mitigated due to the transmission of the entire downlink bandwidth. For example, since the time-frequency region in which the PDCCH is transmitted from eNB1 to UE1 and the time-frequency region in which the PDCCH is transmitted from eNB2 to UE2 overlap, the PDCCH transmissions for each of UE1 and UE2 interfere with each other. Give and receive.

In addition, as illustrated in FIG. 9, the PUCCH or the PUSCH transmitted by the UE1 may act as an interference to the PDCCH or the PDSCH that the adjacent UE2 should receive. In this case, if the scheduling information is exchanged between base stations, interference on the PDSCH can be avoided by allocating terminals to the orthogonal frequency domain, but the PDCCH is affected by the interference by the PUCCH or the PUSCH transmitted by the UE1.

For this reason, the introduction of an e-PDCCH different from the current PDCCH has been discussed. Of course, the e-PDCCH has not only interference, but also has the purpose of effectively supporting CoMP (Coordinated Multipoint Transmission) and MU-MIMO (Multiuser-Multi input Multi Output).

e-PDCCH 영역의 설정e-PDCCH area setting

10 and 11 illustrate examples of time-frequency resources allocated for an e-PDCCH. The time-frequency resource for the e-PDCCH is in the subframe indicated by the time-frequency resource region (eg, indicated by PCIFCH) for the PDCCH in the existing LTE / LTE-A system as in FIG. 10 (a). The first slot may be allocated to a time-frequency resource region excluding up to four OFDM symbols from the beginning). That is, the PDCCH and the e-PDCCH may be distinguished on the time axis. In this case, when two or more OFDM symbols for the e-PDCCH are formed, the OFDM symbols may be continuous or discontinuous.

Alternatively, as shown in FIG. 10 (b), time excluding a time-frequency resource region (eg, up to four OFDM symbols from the beginning in the first slot in a subframe) in the existing LTE / LTE-A system In the frequency resource region, time-frequency resources for the e-PDCCH may be allocated in a frequency division multiplexing (FDM) scheme. That is, different e-PDCCHs may be distinguished on the frequency axis. For example, the e-PDCCH may be allocated to a predetermined number of subcarriers for the entire OFDM symbol except for the resource region for the PDCCH in the subframe.

FIG. 10 (c) shows that time-frequency resources for the e-PDCCH are allocated in a time division multiplexing (TDM) scheme. In FIG. 10 (c), each e-PDCCH divided by a time axis may be multiplexed for each UE.

Subsequently, the time-frequency resource region for the PDCCH shown in FIGS. 10B and 10C may be allocated only on one slot as shown in FIG. 11. That is, referring to FIG. 11 (a), a time-frequency resource region (eg, indicated by PCIFCH) for a PDCCH in an existing LTE / LTE-A system in a first slot of a subframe is indicated by a first in a subframe. E-PDCCH may be allocated to the time-frequency resource region excluding the maximum 4 OFDM symbols from the first slot in the first slot by the FDM scheme. Alternatively, as shown in FIG. 11B, the e-PDCCH may be allocated in the TDM scheme on the remaining time-frequency resource region of the first slot except for the time-frequency resource region for the PDCCH.

However, the e-PDCCH region illustrated in FIGS. 10 and 11 is exemplary and may be determined in various ways such as allocating by a combination of TDM and FDM. In other words, the region to which the e-PDCCH is allocated may be set to a region that is distinguished from the existing PDCCH and / or another e-PDCCH from one or more time resources or frequency resources.

Meanwhile, the e-PDCCH region illustrated in FIGS. 10 and 11 may be notified to the UE in various ways as follows. i) by radio resource control (RRC) signaling or configuration, ii) when the use of the e-PDCCH is configured by RRC signaling or configuration, the specific format of the PDCCH predetermined by RRC signaling or configuration or Iii) If the use of the e-PDCCH is configured by RRC signaling or configuration, the resource region of the e-PDCCH can be known through a specific field of PHICH or PCFICH.

CSS 및 USS 설정CSS and USS settings

Hereinafter, in the existing LTE / LTE-A system, for the control region (first region) and the non-first data region (second region), which are up to four OFDM symbols indicated by the PCFICH on a subframe, CSS and Describes the various ways in which the USS is defined. When CSS and / or USS is configured in the second region, all or part of the above-described e-PDCCH region may be used. In the following descriptions, the DCI formats used in the CSS and the USS may be used as they are in the above-described LTE / LTE-A system, or may be appropriately modified as necessary. In addition, hereinafter, the e-PDCCH region will be described with reference to the one illustrated in FIG. 10 (b) for convenience of description, but the conventional e-PDCCH region shown in FIGS. Note that this may be an area that knowledgeable ones can easily derive.

12 is a diagram illustrating that CSS and USS are set in a second region. FIG. 12A illustrates a case where cross carrier scheduling is not applied and FIG. 12B illustrates cross carrier scheduling applied. Referring to FIG. 12A, it can be seen that both CSS and USS are set in the e-PDCCH region of the second region. Accordingly, a terminal configured to use e-PDCCH by RRC signaling or configuration may perform monitoring for CSS and USS only in the e-PDCCH region without monitoring the PDCCH. In more detail, the UE may attempt blind decoding on four PDCCH candidates of aggregation level 4 and two PDCCH candidates of aggregation level 8 with respect to CSS on the e-PDCCH. In addition, the UE may attempt blind decoding on the number of

PDCCH candidates

6, 6, 2, and 2 corresponding to each of

aggregation levels

1, 2, 4, and 8 in the USS of the e-PDCCH. Since both CSS and USS are set in the e-PDCCH region, CSS and USS may overlap each other. That is, in the case of FIG. 12 (a), the discussion about blind decoding in the existing LTE / LTE-A may be applied as it is except that the PDCCH region is changed to the e-PDCCH region.

Or, in the case of FIG. 12 (a), three e-PDCCH regions 1201-1203 are shown, which are separated on frequency, and each e-PDCCH region 1201-1203 represents a specific terminal or a group of terminals. It may be for. In other words, the e-PDCCH is multiplexed in frequency with respect to a specific UE or a set of UEs. For example, the first e-PDCCH 1201 is a UE e (or UE group A) and a second e-PDCCH. 1202 may be assigned to UE B (or UE group B), and the third e-PDCCH 1203 may be allocated to UE C (or UE group C). UE A (or UE group A) may monitor the CSS and USS in the first e-PDCCH 1201. In this case, however, the terminal A (or terminal group A) cannot monitor other than the first e-PDCCH region 1201 (the terminal A (or terminal group A) is the second and third e-PDCCH (1202, 1203) ) Region is an e-PDCCH region), the DCI common to the UE A (or UE group A) and the UE B (or UE group B) is the CSS of the first e-PDCCH 1201 region and the base station. There is a need to send duplicated CSS in the second e-PDCCH 1202 region. For example, this may be the case of system information (SI). The main parts of the SI that are not transmitted over the broadcast channel are transmitted over the DL-SCH indicated by the PDCCH masked with the SI-RNTI, which is the SI A (or UE group A) and the UE B. (Or UE group B), the base station needs to transmit in both the CSS of the first e-PDCCH region 1201 and the CSS of the second e-PDCCH region 1202.

In FIG. 12B, cross carrier scheduling is applied. The e-PDCCH is transmitted on the DL CC0 which is the primary cell, and the PDSCH indicated by the first e-PDCCH is present in the DL CC0 and the PDSCH indicated by the second e-PDCCH is present in the DL CC1. If the DCI transmitted on the e-PDCCH contains uplink grant information of

formats

0 and 4, the PUSCH indicated by the first e-PDCCH is the UL CC0 linked to the DL CC0 and the PUSCH indicated by the second e-PDCCH. May be UL CCx (x is indicated by CIF) (not shown).

13 illustrates that CSS and USS are located in the second region, but CSS and USS are separately set in the e-PDCCH region in the second region. In FIG. 13A, the CSS is a search space that is not multiplexed with respect to a specific terminal or a set of terminals, and each USS may be a search space that is multiplexed with respect to a specific terminal or a set of terminals. In other words, the UEs in the cell decode some regions 1311 to 1313 as CSS in the e-PDCCH regions 1301 + 1311, 1302 + 1312, and 1303 + 1313 for each UE, and the e-PDCCH regions allocated only to them. Is decoded for a portion of (e.g., 1301). For example, referring to the terminal A, the terminal A should attempt blind decoding for the CSS (1311-1313) and the USS (1301). FIG. 13 (b) shows that cross-carrier scheduling is applied in the case of FIG. 13 (a), indicating that the PDSCH resource of the DL CC1 is indicated by the CFI of the DCI transmitted on the e-PDCCH on the primary cell DL CC0. Can be. In the case of FIG. 13, even though each e-PDCCH is allocated to each UE, the CSS is common to each UE, so that signaling overhead can be reduced because the DCI for CSS is not duplicated. have.

FIG. 14 illustrates another example in which the CSS 1411 and the USS 1401-1403 are set separately in the second region. For example, assuming a specific terminal A, the terminal A performs blind decoding on the CSS set in the e-PDCCH 1411 region, and the e-PDCCH 1401 allocated to itself by RRC signaling or configuration. It is possible to perform blind decoding on the USS in the region. In this case, the terminal A does not perform blind decoding on the first region. FIG. 14 (b) shows that cross carrier scheduling is applied to FIG. 14 (a). In the case of FIG. 14, even though each e-PDCCH 1401-1403 is allocated to each UE, since the CSS 1411 is common to each UE, the overhead of signaling DCI for CSS is not necessary. Can be reduced.

15 shows that CSS is set in the first region and USS is set in the second region. In detail, as shown in FIG. 15A, each of the e-PDCCHs 1501-1503 is set to USS for different terminals, and a part of the first region 1511 is set to CSS for a plurality of terminals. Can be.

In this case, the effect due to the introduction of e-PDCCH can be reduced. Specifically, for example, a random access response is masked with the RA-RNTI (CRC scrambling) is transmitted from the base station, which is sent to the CSS. When the e-PDCCH is applied, since the UE attempting initial access to the network has not been assigned a C-RNTI, the USS may not exist because the UE-specific RRC configuration cannot be received. In addition, even if C-RNTI and USS exist, when performing a non-contention based PRACH that does not require contention for synchronization update, scheduling request, reconfiguration, etc. In some cases, the UE may transmit a masked random access response in RA-RNTI without knowing which terminal the received random access preamble is. Such a signal is preferably transmitted via CSS. In addition, reconfiguration ambiguity is applied by applying the same CSS in an ambiguity interval that may occur at various resets (e.g., activation (or true) and release (or false) of the e-PDCCH). It is possible to prevent).

FIG. 15 (b) illustrates that cross carrier scheduling is applied in the case of FIG. 15 (a), and in each case of FIG. 15, there is an advantage in that the DCI for the CSS in FIG. 13 does not need to be repeatedly transmitted.

FIG. 16 shows that a USS is set in a first region and CSS is set in a second region in a subframe. In FIG. 16 (a), the UE may perform blind decoding on CSS on the e-PDCCH and blind decoding on USS in the first region. FIG. 16 (b) shows that cross carrier scheduling is applied in the case of FIG. 16 (a). That is, the UE which decodes the USS in the PDCCH region of the primary cell DL CC0 may know the PDSCH of the DL CC0 and the PDSCH on the DL CC1 through the CIF.

17 illustrates that only USS is set in the second region. FIG. 17A illustrates a case where cross carrier scheduling is not applied and FIG. 17B illustrates a case where cross carrier scheduling is applied. In FIGS. 17A and 17B, the USS is multiplexed in an e-PDCCH region for each UE, and CSS is not defined. Therefore, in this example, all DCI formats (eg, DCI format 1A masked with RA-RNTI, SI-RNTI, P-RNTI, etc.) transmitted in CSS in the existing LTE / LTE-A system are transmitted to USS. On the premise.

12 to 17, the CSS or USS set in the e-PDCCH region of the second region may increase the received signal-to-noise ratio (SNR) compared to using the PDCCH of the first region in the existing LTE / LTE-A system. There is an advantage. In other words, since the e-PDCCH may be transmitted like a PDSCH, beamforming may be performed using a cell-specific reference signal (CRS) or a terminal-specific reference signal (DMRS), which may improve SNR. Can be. For example, in FIG. 15, CSS is set to the PDCCH in the first region and USS is set to the e-PDCCH regions in the second region. Beamforming may be applied to DCI transmitted to the USS as in the case of PDSCH. It is possible to ensure more reliable reception than the DCI transmitted to the.

12 to 15 and 17, it can be seen that the USS is set in the e-PDCCH region in the second region. In this case, the existing LTE / LTE- in which the control region is limited to 1 to 4 OFDM symbols in a subframe. Compared with the A system, even if the number of terminals that need to transmit control information from a specific base station increases significantly, it can be flexibly coped with.

FIG. 18 is a view showing a process in the case described in FIG. 15. Referring to FIG. 18, the control information may be processed in the process of CRC addition (S1811, S1821), coding with convolutional code (S1812, S1822), rate matching (S1813, S1823), and CCE mapping (S1814, S1824). Can be. In particular, when the CSS is located on the first area and the USS is located on the second area as shown in FIG. 15, when the control information is masked by any one of RA-RNTI, SI-RNTI, P-RNTI, and the like (S1811). When mapped to the CCE on the first region and masked by the C-RNTI (S1821), the CCE on the second region may be mapped.

기지국 장치 및 단말 장치Base station device and terminal device

19 is a diagram illustrating the configuration of a base station apparatus and a terminal apparatus according to the present invention.

Referring to FIG. 19, the base station apparatus 1910 according to the present invention may include a receiving module 1911, a transmitting module 1912, a processor 1913, a memory 1914, and a plurality of antennas 1915. The plurality of antennas 1915 means a base station apparatus supporting MIMO transmission and reception. The receiving module 1911 may receive various signals, data, and information on uplink from the terminal. The transmission module 1912 may transmit various signals, data, and information on a downlink to the terminal. The processor 1913 may control the overall operation of the base station apparatus 1910.

The base station apparatus 1910 according to an embodiment of the present invention may be configured to transmit control information for uplink multi-antenna transmission. The processor 1913 of the base station apparatus may be configured to transmit the DCI through the PDCCH through the transmission module 1912. Further, the processor 1913 determines a search space consisting of PDCCH candidates on a downlink subframe, and attempts to decode each of the PDCCH candidates on the determined search space, wherein the search space is a common search space (CSS). And a UE specific search space (USS), wherein the CSS is located in a first area of the subframe, the USS is located in a second area of the subframe, and the first area is the first N in the subframe. N <= 4 OFDM symbols, and the second region may include OFDM symbols except for the first region in the subframe.

In addition, the processor 1913 of the base station apparatus 1910 performs a function of processing information received by the base station apparatus 1910, information to be transmitted to the outside, and the memory 1914 stores arithmetic processing information for a predetermined time. And may be replaced by a component such as a buffer (not shown).

Referring to FIG. 19, the terminal device 1920 according to the present invention may include a reception module 1921, a transmission module 1922, a processor 1913, a memory 1924, and a plurality of antennas 1925. The plurality of antennas 1925 refers to a terminal device that supports MIMO transmission and reception. The receiving module 1921 may receive various signals, data, and information on a downlink from the base station. The transmission module 1922 may transmit various signals, data, and information on the uplink to the base station. The processor 1923 may control operations of the entire terminal device 1920.

The terminal device 1920 according to an embodiment of the present invention may be configured to perform uplink multi-antenna transmission. The processor 1923 of the terminal device may be configured to receive the PDCCH through the receiving module 1921. In addition, the processor 1913 determines a search space consisting of physical downlink control channel (PDCCH) candidates on a downlink subframe, and transmits the control information through any one PDCCH among the PDCCH candidates in the search space. The search space includes a common search space (CSS) and a terminal specific search space (USS), wherein the CSS is located in a first area of the subframe, and the USS is located in a second area of the subframe. The first region may consist of the first N (N <= 4) OFDM symbols in the subframe, and the second region may consist of OFDM symbols except for the first region in the subframe.

In addition, the processor 1923 of the terminal device 1920 performs a function of processing the information received by the terminal device 1920, information to be transmitted to the outside, and the memory 1924 for a predetermined time. And may be replaced by a component such as a buffer (not shown).

Specific configurations of the base station apparatus and the terminal apparatus as described above may be implemented so that the above-described matters described in various embodiments of the present invention may be independently applied or two or more embodiments may be applied at the same time. Omit.

In addition, in the description of FIG. 19, the description of the base station apparatus 1910 may be equally applicable to a relay apparatus as a downlink transmitting entity or an uplink receiving entity, and the description of the terminal device 1920 may include downlink reception. The same may be applied to the relay apparatus as a subject or an uplink transmission subject.

Embodiments of the present invention described above may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For implementation in hardware, a method according to embodiments of the present invention may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). It may be implemented by field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable those skilled in the art to implement and practice the invention. Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will understand that various modifications and changes can be made without departing from the scope of the present invention. For example, those skilled in the art can use each of the configurations described in the above-described embodiments in combination with each other. Thus, 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.

The invention can be embodied in other specific forms without departing from the spirit and essential features of the invention. Accordingly, the above detailed description should not be interpreted as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention. 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. In addition, the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship or may be incorporated as new claims by post-application correction.

Embodiments of the present invention as described above may be applied to various mobile communication systems.

Claims

In a method of receiving control information by a terminal in a wireless communication system,

Determining a search space consisting of PDCCH candidates on a downlink subframe from the base station; And

Attempting to decode each of the PDCCH candidates on the determined search space

Including;

The search space includes a common search space (CSS) and a terminal specific search space (USS),

The CSS is located in a first area of the subframe, and the USS is located in a second area of the subframe,

The first region consists of the first N (N <= 4) OFDM symbols in the subframe, and the second region consists of OFDM symbols except for the first region in the subframe. .
The method of claim 1,

The USS is located on at least one subcarrier on at least one or more OFDM symbols of the second region.
The method of claim 2,

The USS is located in the first slot in the subframe, control information receiving method.
The method of claim 1,

The CSS is located on the primary cell, control information receiving method.
The method of claim 1,

The control information received on the CSS is any one of a random access identifier (RA-RNTI), a system information identifier (SI-RNTI) or a paging identifier (P-RNTI) masked.
In a method for transmitting control information from a base station in a wireless communication system,

Determining a search space consisting of physical downlink control channel (PDCCH) candidates on a downlink subframe; And

Transmitting the control information via any one of the PDCCH candidates in the search space

Including;

The search space includes a common search space (CSS) and a terminal specific search space (USS),

The CSS is located in a first area of the subframe, and the USS is located in a second area of the subframe,

The first region consists of the first N (N <= 4) OFDM symbols in the subframe, and the second region consists of OFDM symbols except for the first region in the subframe. .
The method of claim 6,

The USS is located on at least one subcarrier on at least one or more OFDM symbols of the second region.
The method of claim 6,

The USSS is located in the first slot in the subframe, control information transmission method.
The method of claim 8,

The CSS is located on the primary cell, control information transmission method.
The method of claim 6,

Control information transmission method of any one of a random access identifier (RA-RNTI), a system information identifier (SI-RNTI) or a paging identifier (P-RNTI) is masked in the control information received on the CSS.
An apparatus for receiving control information in a wireless communication system,

A receiving module; And

Includes a processor,

The processor determines a search space consisting of PDCCH candidates on a downlink subframe, and attempts to decode each of the PDCCH candidates on the determined search space, wherein the search space is a common search space (CSS) and a UE-specific search. Space USS, wherein the CSS is located in a first area of the subframe, the USS is located in a second area of the subframe, and the first area is the first N (N <) in the subframe. = 4) OFDM symbol, wherein the second region consists of OFDM symbols except for the first region in the subframe.
An apparatus for transmitting control information in a wireless communication system,

Transmission module; And

Includes a processor,

The processor determines a search space consisting of physical downlink control channel (PDCCH) candidates on a downlink subframe, and controls to transmit the control information through any one PDCCH among the PDCCH candidates on the search space. The search space includes a common search space (CSS) and a terminal specific search space (USS), wherein the CSS is located in a first area of the subframe, and the USS is located in a second area of the subframe. One region consists of the first N (N <= 4) OFDM symbols in the subframe, and the second region consists of OFDM symbols except for the first region in the subframe.