KR101901941B1

KR101901941B1 - Method for receiving downlink signal and user device, and method for transmitting downlink signal and base station

Info

Publication number: KR101901941B1
Application number: KR1020137028239A
Authority: KR
Inventors: 김학성; 서한별
Original assignee: 엘지전자 주식회사
Priority date: 2011-05-03
Filing date: 2012-05-03
Publication date: 2018-09-28
Also published as: WO2012150821A3; WO2012150821A2; KR20140031237A

Abstract

The present invention provides a method and apparatus for transmitting / receiving a control channel in a downlink subframe divided into a control domain and a data domain. In the present invention, the aggregation level of the control channel transmitted in the control domain is different from the aggregation level of the control channel transmitted in the data domain. The user equipment receives the control channel in at least one of the control region and the data region according to the aggregation level, and receives the data channel from the base station based on the control channel.

Description

TECHNICAL FIELD [0001] The present invention relates to a downlink signal receiving method and a user equipment, a downlink signal transmitting method, and a 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 a direction in which the density of nodes accessible by the user is higher. 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, the number of user equipments to which a base station should provide a service in a predetermined resource area increases, and the amount of downlink control information to be provided to each user equipment is increasing. Since the amount of radio resources available to the base station for communication with the user equipment (s) is limited, a new scheme is required for the base station to efficiently provide the downlink control information to the user equipment (s) using 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.

According to an aspect of the present invention, when a user equipment receives a downlink signal from a base station, a downlink control channel in a control region of a subframe (hereinafter referred to as a first downlink control channel Channel) and a downlink control channel (hereinafter referred to as a second downlink control channel) in the data area of the subframe; A downlink data channel is received based on the downlink control information, and 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 radio frequency (RF) unit configured to transmit or receive a radio signal when a user equipment receives a downlink signal from a base station; And a processor configured to control the RF unit, the processor comprising: 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 in a subframe according to an aggregation level of resources for transmission of control information; The control unit controls the RF unit to receive downlink control information on at least one of a downlink control channel (hereinafter, referred to as a second downlink control channel) in a data region of a subframe, and controls the downlink control channel based on the downlink control information Wherein the aggregation level of the first downlink control channel is greater than the aggregation level of the second downlink control channel.

According to another aspect of the present invention, in transmitting a downlink signal to a user equipment, a base station transmits a downlink control channel in a control region of a subframe (hereinafter referred to as a first downlink control channel) Control channel) and a downlink control channel (hereinafter referred to as a second downlink control channel) in the data area of the subframe; The downlink data channel is transmitted based on the downlink control information, and the aggregation level of the first downlink control channel is greater than the aggregation level of the second downlink control channel.

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

In one 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 different from the user equipment, and the second downlink control channel The channel may be a channel carrying 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 assigning a PDCCH to a data area of a downlink sub-frame.
FIG. 7 illustrates a wireless frame in which a normal mode and a fallback mode are set according to an embodiment of the present invention.
FIG. 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.
FIG. 9 illustrates an example of transmitting downlink control information by combining a PDCCH and an 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, apparatuses, and systems described below can be applied to various wireless multiple access systems. For convenience of explanation, it is assumed 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. Also, in the present invention, a base station (BS) is a fixed station that generally communicates with a UE and / or another BS, and exchanges various data and control information by communicating with the UE and another BS. do. The BS may be referred to as other terms such as an Advanced Base Station (ABS), a Node-B (NB), an Evolved NodeB (eNB), a Base Transceiver System (BTS), an Access Point and a Processing Server (PS).

In the present invention, the Physical Downlink Control Channel (PDCCH) / Physical Control Format Indicator CHannel / Physical Uplink Shared CHannel (PHICH) / Physical Downlink Shared CHannel (PDSCH) A set of time-frequency resources or a collection of resource elements for carrying downlink data, a Control Format Indicator / ACK / NACK / UL ACK / NACK, a Physical Uplink Control CHannel / The Physical Uplink Shared CHannel (PUSCH) is a collection of time-frequency resources or resource elements for carrying Uplink Control Information (UCI) / uplink data. In the present invention, PDCCH / PCFICH / PHICH / PDSCH / The time-frequency resource or resource element RE assigned to or belonging to the PUCCH / PUSCH is referred to as PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH RE or PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH resource, 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) .

1, a radio frame used in the 3GPP LTE (-A) has a length of 10ms (307200T _s), it is composed of 10 sub-frames of equal size. 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 the downlink transmission and the uplink transmission are divided by frequency, the radio frame includes only one of the downlink subframe or the uplink subframe for a predetermined frequency band operating at a predetermined carrier frequency . In the TDD mode, the downlink transmission and the uplink transmission are divided by time. Therefore, for a predetermined frequency band operating at a predetermined carrier frequency, a radio frame includes both a downlink subframe and an uplink subframe.

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 a time domain and a plurality of resource blocks (RBs) in a 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, and 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 denotes the number of OFDM symbols in the downlink slot, and N ^UL _symb denotes 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 assigned from 0 to N ^DL ^/ ^UL _RB * N ^RB _sc -1 in the frequency domain, and 1 is an index assigned 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 scheme, VRBs having the same VRB number are mapped to PRBs of 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. Therefore, distributed type VRBs having the same VRB number can 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 DL subframe is divided into a control domain and a data domain 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 usable for PDCCH transmission in a downlink subframe is referred to as a PDCCH region. The remaining OFDM symbols other than the OFDM symbol (s) used as a control region correspond to a data region to which PDSCH (Physical Downlink Shared CHancel) is allocated. Hereinafter, a resource region available for PDSCH transmission in the DL subframe is referred to as a PDSCH region. Examples of downlink control channels 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 the 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, the DCI may include 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) such as the paging information on the paging channel (PCH), the system information on the DL-SCH, the random access response sent on the PDSCH, the Tx power control instruction set for the individual UEs in the UE group, A Tx power control command, a voice over IP (VoIP) activation indication information, 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 (i.e., PDFICH and PHICH). The number of DCI formats and DCI bits is determined by the number of CCEs. For example, four DCI formats are supported, as shown in Table 3.

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 condition. For example, in the case of a PDCCH for a UE with a good downlink channel (e.g., 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. Further, the power level of the PDCCH can be adjusted in accordance with 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). Individual resources to which the PDCCH can be transmitted within the search space are referred to as PDCCH candidates. 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 transmits 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, the search space for each PDCCH format can have different sizes, 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.

The UE that detects the PDCCH by monitoring the search space at each aggregation level detects the PDCCH in the PDSCH of the downlink subframe based on the DCI carried by the detected PDCCH and transmits the PDSCH to the decoding and / PUSCH "

The BS transmits a reference signal (RS) for channel state estimation, signal demodulation, and the like, for accurate demodulation of PDCCH and / PDSCH by the UE. RS refers to a predefined signal of a particular waveform that the UE and the UE are aware of and is also referred to as a pilot.

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

RSs can be divided into a dedicated reference signal (DRS) and a common reference signal (CRS). RSs are also classified into reference signals for demodulation and reference signals for channel measurement. 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. The DMRS and the CRS may be transmitted together, but only one of them may be transmitted. However, when only the DMRS is transmitted without CRS, the DMRS transmitted using the same precoder as the data can be used only for demodulation purposes, and therefore, an RS for channel measurement must be separately provided. For example, in 3GPP LTE (-A), CSI-RS, an additional measurement RS, is transmitted to the UE (not shown) in order to allow the UE to measure channel state information. 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, the CRS REs represent the REs used by the antenna port 0 to antenna port 4 for CRS transmission. The CRS is transmitted in all downlink subframes in the cell supporting PDSCH transmission. The 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 D denote REs used for RS transmission for demodulation of the PDSCH when the BS performs PDSCH transmission over a single antenna port. Meanwhile, in FIG. 4, the UE-specific RS REs are used for RS transmission for demodulating PDSCHs through a maximum of eight antenna ports. The BS transmits the UE-specific RS in the REs when data demodulation is required, and the presence or absence of the UE-specific RS is notified to the UE by an upper layer.

5 shows an example of an uplink subframe structure used in the 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 assigned to the control region to carry UCI (uplink control information). A UCI carried by one PUCCH differs in size and usage according to the PUCCH format, and its size may vary according to the coding rate.

One or several physical uplink shared channels (PUSCHs) may be allocated to the data area of the uplink subframe to carry user data. When the UE adopts the SC-FDMA scheme for uplink transmission, it can not simultaneously transmit PUCCH and PUSCH on a single carrier in the 3GPP LTE Release 8 or Release 9 system in order to maintain single carrier characteristics. In the 3GPP LTE Release 10 system, whether or not the simultaneous transmission of PUCCH and PUSCH is supported can be indicated in an upper 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 as described above is expressed as 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.

The introduction of a new remote radio head (RRH) is being discussed to improve system performance. On the other hand, since a plurality of serving CCs can be configured in one UE under a carrier aggregation situation, a method of transmitting UL / DL grants for other CCs in a serving CC with good channel conditions is being discussed. In this way, when the CC carrying the UL / DL grant, which is the scheduling information, and the CC performing the UL / DL transmission corresponding to the UL / DL grant are different, this is referred to as cross-carrier scheduling. When the RRH technique and the cross-carrier scheduling technique 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 acts as a bottleneck in system performance. Therefore, in order to prevent the PDCCH transmission from restricting the system performance, there is a discussion to perform the PDCCH transmission using the PDSCH region of the downlink subframe.

6 shows an example of assigning a PDCCH to a data area of a downlink sub-frame.

Referring to FIG. 6, a PDCCH according to the existing 3GPP LTE standard may be allocated to the PDCCH region of the downlink sub-frame. On the other hand, the PDCCH can 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 for DMRS based UE-specific reference signal . Hereinafter, the PDCCH transmitted in the PDSCH region is referred to as an enhanced PDCCH (E-PDCCH) or an advanced PDCCH (A-PDCCH) in order to differentiate the PDCCH from the existing PDCCH transmitted in the first OFDM symbol Embodiments of the invention will now be described. The PDSCH scheduled by the E-PDCCH is also called an E-PDSCH. The latter system is referred to as a legacy system in order to distinguish between a system constituting both the PDCCH and the E-PDCCH and an existing system constituting only the PDCCH without the E-PDCCH. In embodiments of the present invention, it is assumed that the UE implemented according to the enhancement system, i. E., The enhancement UE, is configured to receive both the PDCCH and the E-PDCCH. The UE implemented to receive only the PDCCH becomes a legacy UE as compared with the UE capable of receiving the E-PDCCH.

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

As described above, the E-PDCCH has a structural feature in that control information can be transmitted somewhere in the PDSCH region by avoiding the structure in which control information is transmitted in the PDCCH region of the downlink subframe. This structural feature is constituted by a macro cell in which a communication service is provided by a macro BS and a micro cell (for example, a femtocell, a picocell, or the like) in which a communication service is provided by a micro BS having a smaller service coverage as compared to a macro BS. And may be used for the purpose of reducing mutual interference between the macrocell and the microcell in a wireless network. For example, when an MBSFN (Multimedia Broadcast Single Frequency Network) subframe having control information and RS exists in the first two OFDM symbols and an ABS (almost blank subframe) is applied to the corresponding subframe, Since only the transmission of the signal (e.g., CRS) is allowed or the downlink signal is transmitted only with very weak transmission power, the interference can be removed or mitigated in the remaining regions except for the first two OFDM symbols. It is preferable that the control information and the data are configured so that they can be transmitted in a resource region where the interference is limited. For example, a space in which an E-PDCCH may exist, i.e., a search space (SS) is designated in advance by RRC (Radio Resource Control) signaling and the UE performs blind decoding only on the SS, Allocation (i.e., DL grant), UL scheduling grant (i.e., UL grant), and the like. Further, since the search space for detecting the E-PDCCH exists in the PDSCH region, the UL / DL grant can be configured to be decoded based on the DMRS.

Even if an E-PDCCH of another cell is configured in a subframe in which a specific cell of the mutually-interfering cell includes the ABS, there is still room for unexpected interference in the PDSCH region of the subframe. In addition, a situation may occur in which the UE can not normally decode the E-PDCCH due to search space re-establishment for E-PDCCH, RRC re-configuration, and the like. In this case, designing the system to decode the PDCCH instead of the E-PDCCH to obtain the DCI required for the UE to perform communication with the network may make the radio system operation more robust. Therefore, the present invention can be applied not only to a mode in which the E-PDCCH is decoded to receive a DCI (hereinafter referred to as a normal mode), a mode in which a PDCCH is decoded and a DCI is received (hereinafter referred to as a fallback mode) We propose a working UE. For example, the UE according to the present embodiment can be configured not only to receive the PDSCH by decoding the E-PDCCH, but also to receive the PDSCH by decoding the PDCCH in a specific situation or in a specific subframe. The BS / UE can perform the PDSCH transmission / reception by the E-PDCCH in the normal mode, and switch to the fallback mode to perform PDSCH transmission / reception by the PDCCH in case of emergency.

A subframe in which the UE switches to the fallback mode and attempts PDCCH detection in the PDSCH region may be specified in advance. It is also possible to perform blind decoding on the PDCCH after a certain time period when the UE can not receive the E-PDCCH due to an abnormal channel condition. The UE may be configured to attempt to decode 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 the E-PDCCH decoding failure lasts more than N times in a designated time interval, N subframes (i.e., Time) has elapsed, a timer is activated when the E-PDCCH decoding failure starts and the timer expires, or the like can be used as the specific condition. The UE that fails to detect the E-PDCCH can obtain the necessary DCI in the designated subframe so as to be able to decode the PDCCH.

The PDSCH by the PDCCH may carry the same content as the PDSCH by the E-PDCCH, i.e., the E-PDSCH, but may be configured to carry new contents. Hereinafter, a subframe in which the UE only tries to detect the PDCCH is called a fallback subframe.

FIG. 7 illustrates a wireless 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 specified in each radio frame, or may be specified in a specific subframe every integral multiple of the radio frame. Alternatively, a subframe in which a broadcast (e.g., BCH, paging, etc.) information is transmitted or a subframe associated with broadcast information may be set as a fallback subframe. Alternatively, a subframe corresponding to a specific subframe or subframe pattern previously configured by the RRC may be set as a fallback subframe.

Referring to FIG. 7, a subframe that operates in a normal mode in which the UE decodes the E-PDCCH and receives and demodulates the PDSCH, and a fallback subframe that operates in a fallback mode in which the PDCCH is decoded and the PDSCH is received / demodulated, Lt; / RTI > In particular, the fallback subframe is a subframe that is promised to receive or not receive the E-PDCCH, and the UE decodes the PDCCH or the E-PDSCH in the corresponding subframe.

Meanwhile, the present invention proposes an embodiment in which the PDCCH transmission and the E-PDCCH transmission are properly combined according to the characteristics of the control information. FIG. 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.

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 (i.e., UE- ) May be transmitted / received on the E-PDCCH. In this case, the 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. (For example, a master information block (MIB) message, a system information block type 1 (system information block type 1), and the like) 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 may be common control information, and dynamic scheduling information , DL allocation, UL scheduling grant, etc.) and the information associated therewith can be dedicated control information. For reference, a MIB message, an SIB1 message and an SI message masked with SI-RNTI, a paging message masked with a P-RNTI, and a random access response channel (RACH) response message masked with an RA- / RTI > may be transmitted / received in space.

It is also possible that both the common search space and the dedicated search space exist as a search space for the E-PDCCH. In the common search space for the E-PDCCH (hereinafter referred to as an E-PDCCH common search space), important information shared by the UEs is transmitted / received through the E-PDCCH and dedicated search space for E-PDCCH -PDCCH dedicated search space), the above-mentioned dynamic scheduling information can be transmitted / received through the E-PDCCH. However, in the UE, in the special subframe (for example, in the subframe (SF # 0 or SF # 5) in which the subframe number is 0 or 5) in which the above-mentioned important information is transmitted / But may be configured to perform blind decoding in a common search space (hereinafter referred to as a PDCCH common search space) for the PDCCH rather than a search space to obtain the important information. It is also possible for the UE to be configured to arbitrarily heal the PDCCH in order to be able to acquire certain important information, for example, paging information, power control commands, and the like. Thus, even if blind decoding is performed in both the E-PDCCH common search space and the E-PDCCH dedicated search space for reception of the DCI, there is no change in the complexity of blind decoding for detecting the E-PDCCH.

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

8, the PDCCH transmission and the E-PDCCH transmission are classified by the aggregation level instead of being divided by the common search space and the dedicated search space. That is, according to the present embodiment, different aggregation levels are used for PDCCH transmission and E-PDCCH transmission.

For example, referring to Table 4, a PDCCH candidate of a sub aggregation level (e.g., CCE aggregation level 1 or 2) has a higher aggregation level (e. G., CCE aggregation level 4 8) PDCCH candidates have relatively many resources. Accordingly, the present invention proposes that the E-PDCCH is configured to be transmitted / received in the PDSCH region with a lower aggregation level, and the PDCCH is configured to be transmitted / received in the PDCCH region with a higher aggregation level. In other words, a DCI requiring a high aggregation level is transmitted / received in the PDCCH region, and a DCI not requiring a high aggregation level can 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 as being transmitted at aggregation level 1 or 2, And the E-PDCCH can be monitored only at the aggregation level 1 and the 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 search space is high, the PDCCH can be transmitted / received in the search space, . According to the present embodiment, when the E-PDCCH is transmitted with a lower aggregation level, there is an advantage that more E-PDCCHs can be transmitted / received on the same resource region.

The E-PDCCH carrying the DL grant or the UL grant can be divided into slot units. In other words, one E-PDCCH can occupy only one PRB of the two PRBs constituting the 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.

Relay refers to an extension of the service area of the BS or a device and / or a branch installed in the shadow area and smoothly performing the service of the BS. 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 MBSFN (Multimedia Broadcast Single Frequency Network) subframe from a BS to a relay.

In the case of an in-band relay mode operating in the same frequency band as a BS-relay link (ie, backhaul link) and a relay-UE link (ie, relay access link), the relay transmits a signal The transmitter and the receiver of the relay cause interference with each other. In order to solve the interference problem, the relay can be configured not to communicate with the 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 an arbitrary subframe is signaled as an MBSFN subframe, the UE detects a downlink signal only in the PDCCH region of the corresponding subframe, so that the relay can construct a backhaul link using the PDSCH region of the corresponding subframe. The relay may transmit a signal from a BS in a specific subframe (e.g., MBSFN subframe), and may 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, the relay may be configured to receive the E-PDCCH upon receiving the R-PDCCH. The R-PDCCH is a collection of time-frequency resources that carry control information that the BS provides to the relay. In current 3GPP LTE systems, the R-PDCCH is allocated within one slot range. That is, the R-PDCCH of the current 3GPP LTE system occupies only one PRB out of the two PRBs constituting the PRB pair. However, the E-PDCCH of the present invention may occupy only one PRB or occupy all two PRBs. On the other hand, according to one embodiment of the present invention, although the R-PDCCH may carry a DL / UL grant, an E-PDCCH transmitted / received in a specific search space (e.g., common or dedicated search space) (See the embodiment of FIG. 8), and the E-PDCCH transmitted / received on the aggregation of a predetermined number of CCEs according to a specific aggregation level (see the embodiment of FIG. 9). Referring to FIG. 11, the downlink control information provided by the BS to the relay may be transmitted on the R-PDCCH and / or the E-PDCCH. At this time, the control information carried by the R-PDCCH and the control information carried by the E-PDCCH can 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 via the R-PDCCH, and dedicated control information for a specific relay or relay group may be transmitted / received via the E-PDCCH.

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

The above-described embodiments of the present invention have been mainly described by taking as an example the case where the E-PDCCH carries a DL grant, which is scheduling information for the PDSCH. However, the E-PDCCH can also be applied to carrying a DCI other than a DL grant. For example, the E-PDCCH may carry the UL grant. In this case, the UE that detects the E-PDCCH transmits the uplink subframe associated with the detected downlink subframe (for example, And a UL sub-frame after the number of sub-frames).

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 provided 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 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 the 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 (where N _t is a positive integer) transmit antennas.

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 (where N _r is a positive integer) reception antenna, and the RF unit 23 performs frequency down conversion on each of the signals received through the reception antenna -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 composed of a combination of more than one physical antenna element. The signal transmitted from each antenna can not be further decomposed by the receiving apparatus 20. [ A reference signal (RS) transmitted in response to a corresponding antenna defines an 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 processor of the BS (hereinafter referred to as a BS processor) may assign 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 of the present invention not only operates in the normal mode of decoding the E-PDCCH and receiving the DCI, but also can operate in the fallback mode of decoding the PDCCH and receiving the DCI. The UE processor of the present invention can be configured not only to receive the PDSCH by decoding the E-PDCCH, but also to receive the PDSCH by decoding the PDCCH in a specific situation or in a specific subframe.

The BS processor may control an RF unit (hereinafter, referred to as a BS RF unit) of the BS to set a fallback sub-frame in which the UE should operate in a fallback mode, and to transmit information indicating the fallback sub-frame to the UE. The BS processor may set the fallback subframe in each radio frame unit or a multiple of a radio frame. Instead of configuring the fallback sub-frame by the BS processor, it may be assumed that a specific sub-frame, for example, a sub-frame to which broadcast information is transmitted is a fallback sub-frame. The UE processor may be configured to operate in a fallback mode in a subframe configured with a fallback subframe, but the UE processor according to another embodiment of the present invention may perform decoding of a PDCCH instead of an E-PDCCH if a specific condition is satisfied Lt; / RTI > For example, if the E-PDCCH reception quality falls below a threshold value and the E-PDCCH decoding failure lasts more than N times in a designated time interval, N subframes (i.e., Time) has elapsed, a timer is activated when the E-PDCCH decoding failure starts and the timer expires, or the like can be used as the specific condition. The UE processor that fails to detect the E-PDCCH can obtain the required DCI in the designated subframe so as to be able to decode the PDCCH.

The BS processor can use the PDCCH and the E-PDCCH in appropriate combination 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) over the PDCCH, and to control the BS RF unit to transmit dedicated control information over a E-PDCCH to a specific UE have. In this case, the UE processor controls the UE's RF unit (hereinafter, UE RF unit) to perform blind decoding in the common search space in order to acquire common control information, and acquires dedicated control information, i.e. UE- It is possible to control the UE RF unit 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 a search space for the E-PDCCH. The BS processor controls the BS RF unit to transmit the E-PDCCH carrying important information shared by the UEs in the E-PDCCH common search space and transmits the E-PDCCH carrying the dynamic scheduling information in the dedicated E-PDCCH search space To control the BS RF unit. The UE processor controls the UE RF unit to detect the E-PDCCH carrying the important information in the resource area designated as the E-PDCCH common search space, and in the resource area indicated as the E-PDCCH dedicated search space, the dynamic scheduling information E-PDCCH < / RTI > The BS processor may control the BS RF unit to transmit the important information through the PDCCH in the PDCCH common search area within the PDCCH area of the predetermined specific subframe. The UE processor can control the UE RF unit to perform blind decoding in the PDCCH common search area in the PDCCH area of the special subframe to detect the PDCCH.

The E-PDCCH transmission and the PDCCH transmission may be classified based on the CCE aggregation level instead of the common search space and the dedicated search space. The BS processor can control the BS RF unit to transmit on a collection of a small number of resources according to the sub-aggregation level and the PDCCH to transmit on a collection of many resources according to the higher aggregation level. The UE processor monitors the E-PDCCH with an aggregation level below a predetermined value and monitors the PDCCH with 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 PDCCH To be transmitted over four CCEs or eight CCEs. The UE processor can perform blind decoding in the search space by assuming that the E-PDCCH occupies one CCE for detection of the E-PDCCH, performs blind decoding in the search space, and occupies two CCEs. The UE processor may perform blind decoding in the search space by assuming that the PDCCH occupies 4 CCEs for detection of the PDCCH and perform blind decoding in the search space and occupy 8 CCEs.

The BS processor may be configured such that the PDSCH by the PDCCH and the PDSCH by the E-PDCCH carry the same contents, 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 PDCCH and / or the E-PDCCH transmitted according to the above-described embodiment of the present invention, and transmits the PDSCH to the PDSCH of the corresponding subframe according to the detected PDCCH and / Lt; RTI ID = 0.0 > UE < / RTI >

The embodiments of the present invention described above can be extended to relays. A relay processor (hereinafter referred to as a relay processor) can control a relay RF unit (hereinafter, relay RF unit) to receive an R-PDCCH as well as a relay RF unit to receive an E-PDCCH. The BS processor may control the BS RF unit to transmit the DL / UL grant for the relay on the R-PDCCH, but may control the BS RF unit to transmit the E-PDCCH carrying the DL / UL grant in a particular search space, And control the BS RF unit to transmit to the aggregation level. The relay processor may control the relay RF unit to detect the R-PDCCH for acquisition of the DL / UL grant or 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 the UE-group-specific precoded DMRS without UE-specific beam-forming or precoding It is possible to decode it.

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

When the user equipment receives the downlink signal from the base station,
Attempts to decode the first downlink control channel in the control region of the subframe using the aggregation level belonging to the first control channel element (CCE) aggregation level set, Level in a data area of the subframe to receive downlink control information on at least one of the first downlink control channel and the second downlink control channel; And
Receiving a downlink data channel in the data area based on the downlink control information,
Wherein the subframe is divided into the control region including leading OFDM symbols in the time domain and the data region including remaining OFDM symbols,
Wherein each aggregation level of the first CCE aggregation level set is greater than each aggregation level of the second CCE aggregation level set,
And receiving the downlink signal.

The method according to claim 1,
Wherein the first downlink control channel carries common downlink control information available for both the user equipment and a user equipment different from the user equipment and the second downlink control channel carries downlink control information specific to the user equipment Carrying,
And receiving the downlink signal.

The method according to claim 1,
The second downlink control channel is configured in an OFDM symbol belonging to a first slot in the data area and a last OFDM symbol of the subframe in the time domain and in some resource blocks in the frequency domain, And decoded based on the device specific reference signal,
And receiving the downlink signal.

When 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
A processor configured to control the RF unit, the processor comprising:
Attempts to decode the first downlink control channel in the control region of the subframe using the aggregation level belonging to the first control channel element (CCE) aggregation level set, Level control channel on the first downlink control channel and the second downlink control channel on the second downlink control channel in the data area of the subframe using the level information, Control the unit, and
And control the RF unit to receive a downlink data channel in the data area based on the downlink control information,
Wherein the subframe is divided into the control region including leading OFDM symbols in the time domain and the data region including remaining OFDM symbols,
Wherein each aggregation level of the first CCE aggregation level set is greater than each aggregation level of the second CCE aggregation level set,
User device.

5. The method of claim 4,
Wherein the first downlink control channel carries common downlink control information available for both the user equipment and a user equipment different from 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 second downlink control channel is configured in an OFDM symbol belonging to a first slot in the data area and a last OFDM symbol of the subframe in the time domain and in some resource blocks in the frequency domain, And decoded based on the device specific reference signal,
User device.

When a base station transmits a downlink signal to a user equipment,
Attempts to decode the first downlink control channel in the control region of the subframe using the aggregation level belonging to the first control channel element (CCE) aggregation level set, Level in a data area of the subframe to transmit downlink control information on at least one of the first downlink control channel and the second downlink control channel; And
Transmitting a downlink data channel in the data area based on the downlink control information,
Wherein the subframe is divided into the control region including leading OFDM symbols in the time domain and the data region including remaining OFDM symbols,
Wherein each aggregation level of the first CCE aggregation level set is greater than each aggregation level of the second CCE aggregation level set,
Downlink signal transmission method.

When a base station transmits a downlink signal to a user equipment,
A radio frequency (RF) unit configured to transmit or receive a radio signal; And
A processor configured to control the RF unit, the processor comprising:
Attempts to decode the first downlink control channel in the control region of the subframe using the aggregation level belonging to the first control channel element (CCE) aggregation level set, Level to decode the second downlink control channel in the data area of the subframe and to transmit the downlink control information on at least one of the first downlink control channel and the second downlink control channel Controlling the RF unit, and
And to control the RF unit to transmit a downlink data channel in the data area based on the downlink control information,
Wherein the subframe is divided into the control region including leading OFDM symbols in the time domain and the data region including remaining OFDM symbols,
Wherein each aggregation level of the first CCE aggregation level set is greater than each aggregation level of the second CCE aggregation level set,
Base station.