WO2013100623A1 - Method apparatus for transmitting and receiving control information in wireless communication system - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting and receiving control information. A method of receiving control information in accordance with the present invention includes de-interleaving a received enhanced Physical Downlink Control Channel (ePDCCH) region, demodulating de-interleaved modulation symbols, and decoding the demodulated symbols, wherein subblocks mapped to ePDCCHs are de-interleaved in the de-interleaving, and the subblocks are obtained by segmenting a resource block, allocated to the ePDCCHs, in a specific number.

Description

METHOD APPARATUS FOR TRANSMITTING AND RECEIVING CONTROL INFORMATION IN WIRELESS COMMUNICATION SYSTEM

The present invention relates to wireless communication technology and, more particularly, to a method and apparatus for distributing and transmitting control channels in a data region in downlink transmission.

In a wireless communication system, channel information and system synchronization need to be obtained for effective data transmission and reception. For example, in a wireless communication system environment, fading due to path delay is generated. A receiver can restore a signal, transmitted by a sender, precisely by compensating for the distortion of the signal due to fading.

Meanwhile, in order to increase the performance and communication capacity of a wireless communication system, a method of increasing the transmission/reception efficiency of data in a specific range using a transmission/reception method using a plurality of antennas, in addition to a data transmission/reception method using one transmission antenna and one reception antenna, can be used.

As the amount of transfer rate is increased as described above, the amount of control information regarding the transmission of data is also increased. The amount of control information is increased, but control channels for transmitting the control information is limited and operated. For example, a downlink control channel is transmitted at the start part of each subframe, and it has only to be detected based on a cell-specific reference signal.

Accordingly, there is a lively discussion on how will the limited transmission region for control information be efficiently used or how will the limited transmission region be secured on a transport channel. Furthermore, if a transmission region for control information is further secured on a transport channel, how will transmission resources for the control information be allocated and mapped can be problematic.

An object of the present invention is to provide a method and apparatus for effectively transmitting downlink control information.

Another object of the present invention is to provide a method and apparatus for transmitting downlink control information in a conventional data region.

Yet another object of the present invention is to provide a method and apparatus for distributing control channels, allocated to a conventional data region, within the data region and transmitting the distributed control channels.

Further yet another object of the present invention is to provide a method and apparatus for distributing control channels, allocated to a data region, in a specific unit and transmitting the distributed control channels.

Further yet another object of the present invention is to provide a method and apparatus for defining the distribution unit of control channels, allocated to a conventional data region, according to a resource structure based on a DMRS and transmitting control information based on the defined distribution unit.

(1) An embodiment of the present invention relates to a method of receiving control information, including de-interleaving a received enhanced Physical Downlink Control Channel (ePDCCH) region, demodulating de-interleaved modulation symbols, and decoding the demodulated symbols, wherein subblocks mapped to ePDCCHs are de-interleaved in the de-interleaving, and the subblocks are obtained by segmenting a resource block, allocated to the ePDCCHs, in a specific number.

(2) In (1), the de-interleaving may be performed between a plurality of the resource blocks allocated to the ePDCCH region.

(3) In (1), the number of subblocks per resource block may be identical with the number of resource blocks allocated to transmit the ePDCCHs.

(4) In (3), the de-interleaved subblocks may be distributed over different resource blocks and received.

(5) In (1), the subblock may be obtained by segmenting the resource block, allocated to the ePDCCHs, for each Orthogonal Frequency Division Multiplexing (OFDM) symbol, and the subblock may include a resource element that does not transmit a reference signal, from among resource elements belonging to the OFDM symbol.

(6) In (5), in the de-interleaving, subblocks mapped to an identical ePDCCH, from among subblocks belonging to different resource blocks, may be de-interleaved, and the subblocks mapped to the identical ePDCCH may belong to different OFDM symbols depending on a resource block.

(7) In (1), the subblock may be obtained by segmenting the resource block, allocated to the ePDCCHs, for each subcarrier, and the subblock may include a resource element that does not transmit a reference signal, from among resource elements belonging to the subcarrier.

(8) In (7), in the de-interleaving, subblocks mapped to an identical ePDCCH, from among subblocks belonging to different resource blocks, may be de-interleaved, and the subblocks mapped to the identical ePDCCH may belong to different subcarriers depending on a resource block.

(9) Another embodiment of the present invention relates to a method of transmitting control information, including mapping enhanced Physical Downlink Control Channels (ePDCCHs) to be transmitted to a resource block and performing interleaving on the resource block to which the ePDCCHs have been mapped, wherein in the interleaving, the resource block to which the ePDCCHs have been mapped is segmented into subblocks and the subblocks are interleaved.

(10) In (9), the interleaving may be performed between a plurality of the resource blocks allocated to a region of the ePDCCHs.

(11) In (9), the number of subblocks per resource block may be identical with the number of resource blocks allocated to transmit the ePDCCHs.

(12) In (11), the subblocks may be distributed over different resource blocks and received by the interleaving.

(13) In (9), the subblocks may be obtained by segmenting the resource block, to the ePDCCHs, for each Orthogonal Frequency Division Multiplexing (OFDM) symbol, and the subblock may include a resource element that does not transmit a reference signal, from among resource elements belonging to the OFDM symbol.

(14) In (13), subblocks mapped to an identical ePDCCH may be distributed over different resource blocks through the interleaving, and the subblocks mapped to the identical ePDCCH may belong to different OFDM symbols through the interleaving.

(15) In (9), the subblock may be obtained by segmenting the resource block, allocated to the ePDCCHs, for each subcarrier, and the subblock may include a resource element that does not transmit a reference signal, from among resource elements belonging to the subcarrier.

(16) In (15), subblocks mapped to an identical ePDCCH may be distributed over different resource blocks through the interleaving, and the subblocks mapped to the identical ePDCCH may belong to different subcarriers through the interleaving.

(17) Yet another embodiment of the present invention relates to an apparatus for receiving control information, including a Radio Frequency (RF) unit configured to receive ePDCCHs and a control unit configured to obtain necessary information from the received ePDCCHs, wherein the control unit may generate modulation symbols by de-interleaving subblocks that are segmented from a resource block mapped to the ePDCCHs and are distributed and received.

(18) Further yet another embodiment of the present invention relates to an apparatus for transmitting control information, including an RF unit configured to transmit ePDCCHs, and a control unit configured to interleave a resource block to which ePDCCHs to be transmitted have been mapped, wherein the control unit may interleave the resource block to which the ePDCCHs have been mapped by segmenting the resource block into subblocks.

In accordance with the present invention, a larger amount of control information can be transmitted by sending control channels using a conventional data region.

In accordance with the present invention, a frequency gain can be increased by distributing control channels, allocated to a data region, for each subcarrier and transmitting the distributed control channels.

In accordance with the present invention, errors in transmission can be distributed and transmission efficiency can be increased by distributing and transmitting control channels allocated to a conventional data region.

In accordance with the present invention, resources can be efficiently used by defining the distribution and transmission unit of control channels so that the distribution and transmission unit is matched with a resource structure based on a DMRS.

FIG. 1 is a flowchart schematically showing a method of configuring a PDCCH.

FIG. 2 schematically shows an example of the resource mapping of a PDCCH.

FIG. 3 is a diagram schematically illustrating an example of the transmission of an R-PDCCH.

FIG. 4 schematically shows an example of a subframe to which ePDCCHs are allocated.

FIG. 5 schematically shows an example in which ePDCCHs are distributed over and mapped to each eRB in accordance with the present invention.

FIG. 6 schematically shows eREGs defined based on OFDM symbols in accordance with the present invention.

FIG. 7 is a diagram schematically showing an example in which ePDCCHs are distributed and mapped using eREGs in accordance with the present invention.

FIG. 8 is a diagram schematically showing an example in which ePDCCHs are distributed and mapped using eREGs in accordance with the present invention.

FIG. 9 schematically shows eREGs defined based on a subcarrier in accordance with the present invention.

FIG. 10 is a diagram schematically showing an example in which ePDCCHs are distributed and mapped using eREGs in accordance with the present invention.

FIG. 11 schematically shows the structure of a subframe when there are no PDCCH and CRS like in an extension carrier or an MBSFN.

FIG. 12 schematically shows eREGs defined when an OCC having a length 2 is used in accordance with the present invention.

FIG. 13 is a flowchart schematically illustrating an operation of UE for obtaining control information from ePDCCHs in a system in accordance with the present invention.

FIG. 14 is a flowchart schematically illustrating an operation of a BS for distributing and transmitting ePDCCHs in a system to which the present invention is applied.

FIG. 15 is a block diagram schematically showing the construction of a BS in a system to which the present invention is applied.

FIG. 16 is a block diagram schematically showing the construction of UE in a system to which the present invention is applied.

Hereinafter, in this specification, the contents related to the present invention will be described in detail in connection with exemplary embodiments with reference to the accompanying drawings. It is to be noted that in assigning reference numerals to respective elements in the drawings, the same reference numerals designate the same elements throughout the drawings although the elements are shown in different drawings. Furthermore, in describing the embodiments of the present invention, a detailed description of the known functions and constructions will be omitted if it is deemed to make the gist of the present invention unnecessarily vague.

Furthermore, in this specification, a wireless communication network is described as a target, and tasks performed in the wireless communication network may be performed in a process in which a system (e.g., a base station) managing the wireless communication network controls the wireless communication network and sends data or may be performed in a terminal linked to the wireless communication network.

User Equipment (UE) may be fixed or mobile and may be called another terminology, such as a Mobile Station (MS), a Mobile Terminal (MT), a User Terminal (UT), a Subscriber Station (SS), a wireless device, a Personal Digital Assistant (PDA), a wireless modem, or a handheld device.

A Base Station (BS) commonly refers to a fixed station that communicates with UEs, and it may be called another terminology, such as an evolved-NodeB (eNB), a Base Transceiver System (BTS), or an access point.

Each BS provides communication service to a specific geographical area (commonly called a cell). The cell may be classified into a plurality of regions (called sectors). Furthermore, a plurality of transmission stages may form one cell.

In 3GPP LTE, a downlink radio frame includes 20 (#0~#19) slots. One subframe includes two slots. The time (length) taken to transmit one subframe is called a Transmission Time Interval (TTI). The length of one subframe may be, for example, 1 ms, and the length of one slot may be, for example, 0.5 ms.

One slot may include a plurality of symbols in the time domain. For example, in downlink (DL), in the case of 3GPP LTE that uses Orthogonal Frequency Division Multiple Access (OFDMA), a symbol may be an OFDM symbol. Meanwhile, an expression for the symbol period of the time domain is not limited by a multi-access method or a name.

The number of OFDM symbols included in one slot may vary depending on the length of a Cyclic Prefix (CP). For example, 1 slot may include 7 OFDM symbol in the case of a normal CP, and 1 slot may include 6 OFDM symbols in the case of an extended CP.

A Resource Block (RB) is a resource allocation unit, and it may include a plurality of subcarriers in one slot. For example, if one slot includes 7 OFDM symbols in the time domain and an RB includes 12 subcarriers in the frequency domain, one RB may include 7*12 Resource Elements (REs).

In accordance with the existing definition, a downlink subframe may be divided into a control region and a data region in the time domain. The control region may include a maximum of 4 OFDM symbols in the former part of a first slot within a subframe. The number of OFDM symbols included in the control region may be changed. Control channels, such as PDCCHs, are allocated to the control region, and data transport channels, such as PDSCHs, are allocated to the data region.

A physical control format indicator channel (PCFICH) that is transmitted in the first OFDM symbol of a subframe carries a Control Format Indicator (CIF) indicating the number of OFDM symbols (i.e., the size of the control region) used to transmit control channels within the subframe. For example, UE may receive a CIF on a PCFICH and then monitor a PDCCH. The PCFICH is transmitted through fixed PCFICH resources of the subframe without using blind decoding.

Control information transmitted through the PDCCH is called Downlink Control Information (DCI). DCI may include information on the resource allocation of a PDSCH (this is called a DL grant), the resource allocation of a PUSCH (this is called an UL grant), a set of transmission power control commands for individual UE within a specific UE group and/or the activation of a Voice over Internet Protocol (VoIP).

FIG. 1 is a flowchart schematically showing a method of configuring a PDCCH. A BS determines a PDCCH format according to DCI transmitted by UE, attaches Cyclic Redundancy Check (CRC) to the DCI, and scrambles a unique identifier (called a Radio Network Temporary Identifier (RNTI)) to the CRC depending on the owner of the PDCCH or the use of the PDCCH at step S110.

If the PDCCH is a PDCCH for specific UE, a Cell-RNTI (C-RNTI) can be masked to the CRC. If the PDCCH is a PDCCH for a paging message, a paging indication identifier, for example, a Paging-RNTI (P-RNTI) can be masked to the CRC. If the PDCCH is a PDCCH for system information, a system information identifier, a System Information-RNTI (SI-RNTI) can be masked to the CRC. In order to indicate a random access response, that is, a response to the transmission of the random access preamble of UE, a Random Access-RNTI (RA-RNTI) can be masked to the CRC.

If a C-RNTI is used, the PDCCH carries control information about specific UE (this is called UE-specific control information). If another RNTI is used, the PDCCH carries common control information (this is called cell-specific control information) received by all or a plurality of UEs within a cell.

Coded data is generated by encoding the DCI to which the CRC has been attached at step S120. Here, the encoding includes channel encoding and rate matching.

The coded data is modulated into modulation symbols at step S130. The modulation symbols are mapped to respective Resource Elements (REs) at step S140.

FIG. 2 schematically shows an example of the resource mapping of a PDCCH.

In a multi-antenna system, R0 indicates the reference signal of a first antenna, R1 indicates the reference signal of a second antenna, R2 indicates the reference signal of a third antenna, and R3 indicates the reference signal of a fourth antenna.

A control region within a subframe includes a plurality of Control Channel Elements (CCEs). The CCE is a logical allocation unit used to provide a PDCCH with a coding rate depending on the state of a radio channel, and it corresponds to a plurality of Resource Element Groups (REGs). The format of the PDCCH and the number of available bits of the PDCCH are determined by a relationship between the number of CCEs and a coding rate provided by CCEs.

An REG may be configured by aggregating a specific number of Resource Elements (Res) and a CCE may be configured by aggregating a specific number of REGs. In order to configure one PDCCH, {1, 2, 4, 8} CCEs may be used, and each of elements within the aggregation {1, 2, 4, 8} is called a CCE aggregation level.

A control channel formed of one or more CCEs may be interleaved. A unit of interleaving may be an REG. An interleaved control channel may be subject to a cyclic shift based on a cell identifier (ID) and then mapped to physical resources. In some embodiments, the control channel may be mapped to physical resources and then interleaved.

In 3GPP LTE, blind decoding is used in order to detect a PDCCH. Blind decoding is also called blind detection. Blind decoding is a method of de-scrambling a desired ID into the CRC of a received PDCCH (this is called as a candidate PDCCH) and checking whether the received PDCCH is its own control channel or not by checking a CRC error. The PDCCH that is subject to blind detection may include an ePDCCH to be described later.

In this specification, an RE indicates the smallest frequency-time unit in which the modulation symbol of a data channel or the modulation symbol of a control channel is mapped. If M subcarriers are included on one OFDM symbol and one slot includes N OFDM symbols, one slot includes M*N REs.

Furthermore, in this specification, a 'Physical Resource Block' (PRB) indicates a unit frequency-time resource for transmitting data. One PRB includes a plurality of REs contiguous in the frequency-time domain, and a plurality of PRBs is defined within one subframe. A PRB may be the above-described RB.

Meanwhile, in order to estimate a channel or measure a channel state, a Reference Signal (RS) known to both a transmitter and a receiver is used.

A receiver can estimate a channel based on the reference signal of a received signal because it knows information on the reference signal and precisely obtain data transmitted by a transmitter by compensating for a channel value.

In general, an RS is transmitted in the form of a sequence. A Phase Shift Keying (PSK)-based computer generated sequence based on PSK may be used as an RS sequence. PSK may include, for example, Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK). Alternatively, a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence may be used as an RS sequence. The CAZAC sequence may include, for example, a Zadoff-Chu (ZC)-based sequence, a ZC sequence with cyclic extension, and a ZC sequence with truncation. Alternatively, a pseudo-random (PN) sequence may be used as the RS sequence. The PN sequence may include, for example, an m-sequence, a computer-generated sequence, a gold sequence, and a Kasami sequence. Alternatively, a cyclically shifted sequence may be used as the RS sequence.

A downlink RS includes a Cell-specific Reference Signal (CRS), a Multimedia Broadcast and multicast Single Frequency Network (MBSFN) RS, a UE-specific RS, a Positioning RS (PRS), and a Channel State Information-RS (CSI-RS).

In a multi-antenna system, REs used in the RS of one antenna are not used in the RS of another antenna in order not to give interference between antennas.

A CRS is an RS transmitted to all MSs within a cell and is used to estimate a channel. A CRS may be transmitted in all downlink subframes within a cell which supports the transmission of a PDSCH.

An MBSFN RS is an RS for providing Multimedia Broadcast Multicast Service (MBMS) and may be transmitted in a subframe assigned to transmit MBSFN. An MBSFN RS may be defined in an extended CP structure.

A PRS may be used to measure the position of UE. A PRS may be transmitted through only a resource block within a downlink subframe that has been allocated to transmit the PRS.

A CSI-RS may be used to estimate CSI. A CSI-RS is relatively sparsely disposed in the frequency domain or the time domain and may be punctured in the data region of a common subframe or an MBSFN subframe. UE may report a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), and a Rank Indicator (RI) through the estimation of CSI as occasion demands.

A UE-specific RS is an RS that is received by specific UE or specific UE group within a cell, and it may be called a demodulation RS (DMRS) because the UE-specific RS is chiefly used in the data demodulation of specific UE or specific UE group.

The position of the frequency domain and the position of the time domain within the subframe of a DMRS may be determined by a resource block allocated to transmit a PDSCH. A DMRS sequence may be determined by a UE ID, and only specific UE corresponding to a UE ID can receive a DMRS. A DMRS sequence is generated for each subframe and may be applied for each OFDM symbol.

A CRS and a DMRS may be used at the same time. For example, a CRS may be used in a region in which control information within a subframe is transmitted, and a CRS and a DMRS may be used in the remaining regions. Here, the CRS and the DMRS may be placed in different subcarriers and/or different OFDM symbols.

A BS may multiply a downlink reference signal for each cell by a predetermined sequence and transmit the downlink reference signal in order to improve the performance of channel estimation by reducing interference due to a reference signal received from a neighboring cell on the receiver side. The predetermined sequence may be any one of a PN sequence, an m-sequence, a Walsh hadamard sequence, a ZC sequence, a GCL sequence, and a CAZAC sequence. The predetermined sequence may be applied for each OFDM symbol within one subframe, and a different sequence may be applied depending on a cell ID, a subframe number, the position of an OFDM symbol, and a UE ID.

Meanwhile, in conventional 3GPP LTE, a PDCCH, that is, a downlink control signal channel, is transmitted only in the control region placed in the fore part of each subframe, and the PDCCH is detected based on a CRS. For this reason, the number of PDCCHs that can be transmitted is limited. It is difficult to sufficiently transmit a control signal using the limited PDCCH resources if a Cooperative Multi Point (CoMP) method, Multi-User-Multi-Input Multi-Output (MU-MIMO), and a Carrier Aggregation (CA) are sought to be used in order to improve the amount of data transfer and the transfer rate. In order to solve this problem, a scheme for transmitting an enhanced PDCCH (ePDCCH) in the data region based on a UE-specific DMRS may be taken into consideration.

In the case of PDCCH transmission based on a CRS, the CRS is added after each stream is precoded. Accordingly, in transmission based on a CRS, UE can recognize physical antenna ports #0 ~ #t-1 and information on the precoding has to be transmitted to the UE.

In the case of PDCCH transmission based on a DMRS, the DMRS is added before each stream is precoded. Accordingly, the DMRS is precoded along with each stream, and thus the DMRS has information on the precoding. UE can recognize virtual antenna ports, that is, streams #0 ~ #k-1. If demodulation is performed based on information included in a DMRS, it is not necessary to separately transmit information on precoding for demodulation. Here, UE uses the DMRS for the demodulation and use a CSI-RS for measurement.

In an example in which a control signal is transmitted based on a DMRS, there is a Relay-Physical Downlink Control Channel (R-PDCCH). An R-PDCCH transfers Downlink Control Information (DCI) on a relay node. For example, resources for downlink and/or uplink BS-relay data may be allocated through the R-PDCCH.

FIG. 3 is a diagram schematically illustrating an example in which an R-PDCCH is transmitted. Referring to FIG. 3, from a viewpoint of the time domain, R-PDCCHs are transmitted in the data region of a downlink subframe. From a viewpoint of the frequency domain, R-PDCCHs are transmitted in an aggregation of resource blocks that have been allocated semi-statically. From a viewpoint of latency, it is preferred that transmission regarding downlink allocation be placed in the fore part within one subframe temporally. Accordingly, in a subframe, an R-PDCCH relating to downlink allocation may be transmitted earlier than an R-PDCCH relating to an UL grant.

An R-PDCCH is used to transfer control information on a relay node. When R-PDCCHs are transmitted based on a DMRS, the R-PDCCHs are localized and transmitted. In other words, REs for transmitting one ePDCCH belong to only one RB. Furthermore, if R-PDCCHs are distributed and transmitted, the R-PDCCHs are transmitted based on a CRS. In transmitting the R-PDCCHs, interleaving of a Resource-Element Group (REG) level based on a CCE may be used. This can be considered as being identical with the distribution transmission of PDCCHs.

In the distribution transmission of PDCCHs and R-PDCCHs, an aggregation level is based on a CCE as described above and interleaving is based on an REG. Here, the REG may be defined based on a CRS.

An REG is used to define the mapping of control channels to Resource Elements (REs).

An REG may be indicated by an index pair (p', q') of the lowest index p from among all REs within a group having the same q value. A set of REs (p, q) within the REG depends on the number of Cell-specific Reference Signals (CRSs). In relation to the number of downlink resource blocks N^DL _RB, an index n_PRB specifying a PRB, and the number of subcarriers N^RB _sc within a resource block, a relationship p₀=n_PRB·N^RB _sc, 0≤n_PRB≤N^DL _RB is established.

In the first OFDM symbol of a first slot within a subframe, two REGs within a PRB (n_PRB) include REs (p, q=0). Here, p = p₀+0, p₀+1, …, p₀+5 and p=p₀+6, p₀+7, …, p₀+11.

If one or two Cell-specific Reference Signals (CRSs) are configured, in the second OFDM symbol of a first slot within a subframe, three REGs within a PRB (n_PRB) include REs (p, q=1). Here, p = p₀+0, p₀+1, …, p₀+3, p = p₀+4, p₀+5, …, p₀+7 and p=p₀+8, p₀+9, …, p₀+11.

If four CRSs are configured, in the second OFDM symbol of a first slot within a subframe, two REGs within a PRB (n_PRB) include REs (p, q=1). Here, p = p₀+0, p₀+1, …, p₀+5 and p=p₀+6, p₀+7, …, p₀+11.

In the third OFDM symbol of a first slot within a subframe, three REGs within a PRB (n_PRB) include REs (p, q=2). Here, p = p₀+0, p₀+1, …, p₀+3, p = p₀+4, p₀+5, …, p₀+7, and p=p₀+8, p₀+9, …, p₀+11.

In the case of a normal Cyclic Prefix (CP), in the fourth OFDM symbol of a first slot within a subframe, three REGs within a PRB (n_PRB) include REs (p, q=3). Here, p = p₀+0, p₀+1, …, p₀+3, p = p₀+4, p₀+5, …, p₀+7, and p=p₀+8, p₀+9, …, p₀+11.

In the case of an extended CP, in the fourth OFDM symbol of a first slot within a subframe, two REGs within a PRB (n_PRB) include REs (p, q=3). Here, p = p₀+0, p₀+1, …, p₀+5 and p=p₀+6, p₀+7, …, p₀+11.

Meanwhile, an enhanced PDCCH (ePDCCH) on which control information on UE may be taken into consideration as a control channel in which control information is transmitted in a conventional data region. ePDCCHs may also be distributed and transmitted or localized and transmitted. Unlike an R-PDCCH, an ePDCCH is used to transmit control information on UE. Both the distribution transmission and the localization transmission can be performed based on a DMRS.

Unlike in an R-PDCCH, the distribution transmission of ePDCCHs may be optimized in the structure or a PRB pair. When R-PDCCHs are distributed and transmitted, an REG to which the R-PDCCHs are mapped is defined based on a CRS structure. Accordingly, it is difficult to effectively use REs and it is also difficult for a frequency diversity to obtain a sufficient gain.

If ePDCCHs are distributed and transmitted based on a DMRS, the consumption of resources (REs) can be prevented. This is because a full match can be achieved between ePDCCHs to be transmitted and the structure or a PRB pair based on a DMRS. Furthermore, if ePDCCHs are distributed and transmitted based on a DMRS, a full gain for frequency diversity in the ePDCCH region can be obtained.

Examples in which ePDCCHs are distributed and transmitted based on a DMRS are described below.

In order to distribute and transmit ePDCCHs, interleaving may be performed on transmission resources to which the ePDCCHs have been mapped. In the prior art, a length of interleaving is fixed to 32. In the case of interleaving in accordance with the present invention, in order to match ePDCCHs with the structure or a PRB pair, a length of interleaving may be determined adaptively. In other words, the length of interleaving may be determined by the total number of PRB pairs in resource allocation. For example, if K PRB pairs are included in Resource Allocation (RA) for an ePDCCH region, the length of interleaving may become K.

A unit for performing interleaving may include the following three types.

(1) Interleaving of a bit, modulation symbol, or REG level

(2) Interleaving of a 1/N PRB pair level

(3) Interleaving based on an eREG

First, the interleaving in the level of a bit, modulation symbol, or REG is described below. In this case, it is assumed that inputs, that is, a unit of the interleaving, are d₀ ⁽ⁱ⁾, …, d_D-1 ⁽ⁱ⁾. 'd' may be a bit, a modulated symbol, or an REG, and D indicates the number of inputs.

The operation of an interleaver may be represented by an interleaving matrix. In the interleaving matrix, the number of columns is fixed to 32, and a minimum number of rows in which D≤(A*B) in a vector 'A' having elements equal to the number of rows and a vector 'B' having elements equal to the number of columns may be determined as the number of rows of the interleaving matrix.

Next, after the interleaving matrix is filled with the sequence of the inputs, interleaved results can be obtained by applying inter-column permutation.

In the present invention, each PRB pair to which ePDCCHs have been mapped may be segmented into specific resource blocks, and the segmented resource blocks may be distributed. In other words, in the present invention, ePDCCHs can be distributed and transmitted by distributing resource blocks to which the ePDCCHs have been mapped in relation to a PRB pair. Here, a method of distributing the ePDCCHs may include a method of interleaving the resource blocks to which the ePDCCHs have been mapped in a 1/N PRB level or in an eREG level. Here, the eREG may be one example of the specific resource block n which a PRB pair is segmented.

The interleaving of a 1/N PRB level and the interleaving of an eREG level in accordance with the present invention are described in detail below.

<Interleaving of a 1/N PRB pair level>

FIG. 4 schematically shows an example of a subframe to which ePDCCHs are allocated. Referring to FIG. 4, a PCFICH, a Physical HARQ Indicator Channel (PHICH), and a PDCCH are transmitted in a control region 400. ePDCCHs, together with PDSCHs, are allocated to a data region 410.

The ePDCCHs may be mapped for each RB. Accordingly, resources to be used in the ePDCCHs may be allocated in an RB unit. More particularly, as described above, an RB is defined for 12 slots. The RB includes 7 OFMD symbols and 12 subcarriers in the case of a normal CP and includes 6 OFDM symbols and 12 subcarriers in the case of an extended CP. Accordingly, 1 PRB pair may be defined regarding 1 subframe. In the present embodiment illustrated in FIG. 4, the ePDCCHs may be mapped to the remaining regions 420-1, …, 420-K other than the control region 400 in K PRB pairs that have been allocated to transmit the ePDCCHs. In this specification, hereinafter "the remaining regions other than the control region in the PRB pair" is simply called an 'eRB', for convenience of description. Accordingly, "what the ePDCCHs are mapped to the remaining regions other than the control region in the PRB pair" may be represented by "what the ePDCCHs are mapped to the eRB".

Meanwhile, FIG. 4 shows an example in which an ePDCCH 1 is mapped to a second eRB 420-2, ePDCCHs are mapped to third and fourth eRBs 420-3 and 420-4, and an ePDCCH3 is mapped to a (K-1)^th eRB 420-(K-1) in the entire subframe.

In the present invention, the ePDCCHs mapped as in FIG. 4 may be distributed over an eRB. Accordingly, the ePDCCHs can be distributed and transmitted and a frequency diversity gain can be increased, thereby being capable of improving transmission efficiency.

In accordance with an embodiment, an interleaving method performed in a subblock level of an RB in order to distribute and transmit ePDCCHs is described in detail below.

(1) Segmentation of each eRB to which an ePDCCH is mapped into N subblocks

In the present embodiment, one eRB may be considered to play a role of a kind of CCE. Accordingly, in the present embodiment, an eRB may be called an enhanced CCE (eCCE). An eRB to which an ePDCCH is mapped may be segmented into N subblocks (N is an integer). A subblock SB_ij indicates a j^th subblock in an i^th eRB that has been allocated to transmit an ePDCCH (1≤i≤K, 1≤j≤N). In this specification, 'what transmission resources to which ePDCCHs have been mapped are distributed by interleaving' may be simply called 'distributed and mapped', for convenience of description.

Assuming that the number of OFDM symbols per eRB is N^PRB _SYM, each subblock includes OFDM symbols having a number that corresponds to 1/N of E^PRB _SYM. Here, N is an integer, and it may have a fixed value, such as 2, 4, …

The N value may be determined so that each subblock has an integer number of OFDM symbols. Furthermore,

After the N value is determined, the number of OFDM symbols of each subblock may be determined. For example, if a value obtained by dividing the number of OFDM symbols per subblock, that is, the number of OFDM symbols per eRB by the number of subblocks (N) is not an integer (N^PRM _SYM mod N>0), subblocks SB₁ to SB_N-1 may have '

' OFDM symbols and the last N^th subblock SB_N may have '

' OFDM symbol.

Here, N may be configured in a UE-specific manner. The N value may be configured by taking the capabilities and state of UE, a network environment, and a channel environment into consideration.

When an N value is configured so that it is identical with a K value (N=K), a full frequency gain can be obtained. Here, a case where an N value is configured so that it is identical to the number of eRBs K allocated to transmit ePDCCHs is described as an embodiment of the present invention.

(2) Assignment of the number of columns C^CC _subblock of an interleaving matrix

The number of columns of a matrix M_IL for performing interleaving may be configured as the number of subblocks. Accordingly, in the present embodiment, C^CC _subblock=K.

(3) Assignment of the number of rows R^CC _subblock of an interleaving matrix

The number of rows of a matrix M_IL for performing interleaving may be configured as the number of eRBs allocated to transmit ePDCCHs.

(4) Determination of each elements of an interleaving matrix

The matrix M_IL for performing interleaving may be expressed by a matrix of 'R^CC _subblock *C^CC _subblock'. The matrix M_IL is filled row by row in such a way to map the first subblock BS₁₁ of a first eRB to the position (1, 1) of the first row, the first column of the matrix M_IL and map the second subblock BS₁₂ of the first eRB to the position (2, 1) of the second row, the first column of the matrix M_IL. In other words, a j^th subblock B_ij of an i^th PRB pair is mapped to the elements of an i^th column (j, i) of a j^th row of the matrix M_IL.

(5) A result of interleaving using the interleaving matrix is outputted as a sequence of subblocks that are read out column by column. As a result, ePDCCHs are distributed over an ePR within the same OFDM symbol.

FIG. 5 schematically shows an example in which ePDCCHs are distributed over and mapped to each eRB in accordance with the present invention.

As shown in FIG. 5, control channels a PCFICH, a PHICH, and a PDCCH are mapped to the control region 500 of a subframe, and ePDCCHs, together with PDSCHs, are distributed over and mapped to the K eRBs 520-1, …, 520-K of a data region 510.

For example, an ePDCCH 1 may be mapped to the second subblock of each of the eRBs 520-1, …, 520-K, an ePDCCH 2 may be mapped to the third and the fourth subblocks thereof, and an ePDCCH 3 may be mapped to an (N-)^th, that is, a(K-1)^th subblock, as shown in FIG. 5.

Meanwhile, the interleaving matrix may not be configured based on eRBs to which ePDCCHs have been mapped, but a method of configuring an interleaving matrix in which the j^th subblock B_ij of an i^th PRB pair is mapped to the element of an i^th column (j, i) of the j^th row of the matrix based on sequence of common subblocks and applying an ePDCCH allocation matrix to the interleaving matrix may be used. For example, the case of FIG. 5 may be considered to be an example in which the allocation ment matrix of ePDCCH is (0 ePDCCH1 ePDCCH2 ePDCCH2 … ePDCCH3 0)^T and an interleaving matrix is applied thereto. Accordingly, a method of applying the allocation (ePDCCH_k)^{T (}k=1, 2, …, K) of a common ePDCCH to an interleaving matrix and distributing and mapping the ePDCCHs over and to each PRB pair may be taken into consideration.

<Interleaving of an eREG level>

In addition to the above-described methods, a new REG may be defined and resources to which ePDCCHs have been mapped may be distributed (or interleaved). In the present invention, a newly defined REG is called an eREG, for convenience of description.

A common REG is defined based on a CRS as described above in relation to a PDCCH. However, in order to fully match a DMRS with the structure or a PRB pair, an eREG based on the PRB pair may be newly defined.

In the present invention, one eREG may be defined every OFEM symbol. Furthermore, in the present invention, one eREG may be defined every subcarrier. An eREG defined every OFEM symbol may be easily applied to a case of Time Division Multiplexing (TDM). An eREG defined every subcarrier may be easily applied to a case of Frequency Division Multiplexing (FDM).

An eREG defined every OFEM symbol and an eREG defined every subcarrier are described below.

eREG defined based on an OFDM symbol

An eREG defined based on an OFDM symbol: one eREG includes all REs that belong to the same OFDM symbol within one PRB. Here, the RE is not mapped to a CRS and a DMRS, but is used to transmit an ePDCCH.

FIG. 6 schematically shows eREGs defined based on OFDM symbols in accordance with the present invention. As shown in FIG. 6, CRSs and DMRSs are placed within a subframe according to a pattern. OFDM symbols may include a CRS or a DMRS or may not include both a CRS and a DMRS. Accordingly, different eREGs may include a different number of REs. Here, the REs included in the eREG are not mapped to CRSs and DMRSs as described above, but ePDCCHs are mapped to REs.

Even when the eREG is used, transmission resources mapped to ePDCCHs can be distributed. In this case, the ePDCCHs may be mapped for each eREG.

Here, the distribution of the resources mapped to the ePDCCH may be performed by an interleaver or may be performed through randomization for simply permutating eREGs. In this specification, 'interleaving' includes 'randomization', such as permutation, unless otherwise defined, for convenience of description.

In the present embodiment, distribution by permutation is described as an example of interleaving.

A method of distributing and mapping ePDCCHs by permutation is described below:

(1) Permutation is performed between eRBs to which ePDCCHs have been mapped for each OFDM symbol.

It is assumed that a k ^th eRB, an eREG corresponding to a l ^th OFDM symbol within a subframe are an eREG (k, l). Here, 1≤k≤K (K is the number of PRB pairs within the subframe), 1≤l≤14 in the case of a normal CP, and 1≤l≤12 in the case of an extended CP.

If an eREG defined based on an OFDM symbol is used, permutation is performed on each eRB in relation to one OFDM symbol. Accordingly, in relation to a fixed l value, permutation is performed while changing the k value.

(2) More particularly, in relation to l=1, k' (i.e., k'= (k+P _l ) mod K (here, P _l is a randomization/permutation factor)) is calculated and the eREG (k, l) is allocated to an eREG (k', l).

(3) After k' is calculated, the k value is increased by 1 (k=k+1).

(4) (2) and (3) are repeated until k=K.

(5) While increasing an l value (e.g., l=l+1), (2) to (4) are repeated until l=14 in the case of a normal CP and l=12 in the case of an extended CP.

Here, it is to be noted that the l value is not changed in the randomization (permutation) process. That is, eREG randomization is performed within the same OFDM symbol.

FIG. 7 is a diagram schematically showing an example in which ePDCCHs are distributed and mapped using eREGs in accordance with the present invention. In FIG. 7, a PCFICH, a PHICH, and a PDCCH are mapped to a control region 700, and PDSCHs and ePDCCHs are mapped to a data region 710. In FIG. 7, the ePDCCHs are finally distributed over and mapped to eRBs 720-1, …, 720-K within the same OFDM symbol. In FIG. 7, the number of ODEM symbols, that is, the number of eREGs L within a PRB pair, is 14 in the case of a normal CP and 12 in the case of an extended CP.

A distribution pattern may be determined according to a randomization factor P _l . For example, an ePDCCH may be mapped to an i^th eRB in an x^th OFDM symbol and may be placed in an (i+j)^th eRB in a y^th OFDM symbol (x, y, i, and j are integers, x,y≤14 in a normal CP, and x,y≤12 in an extended CP). Furthermore, i+j≤K. The reason why a mapping position in each OFDM symbol is different may be the results of permutation according to a P _l value.

FIG. 8 is a diagram schematically showing an example in which ePDCCHs are distributed and mapped using eREGs in accordance with the present invention. FIG. 8 shows an example of the distribution and mapping of ePDCCHs when a P _l value is set as l and k'= (k+l) by applying a cyclic shift. If two ePDCCH: ePDCCHs 1 and ePDCCHs 2 are distributed over and mapped to eRBs 810-1, …, 810-K, each of the ePDCCHs is mapped while moving by one OFDM symbol for each eRB.

eREG defined based on a subcarrier

An eREG defined based on a subcarrier: one eREG includes all REs that belong to the same subcarrier within an eRB. Here, the RE is not mapped to a CRS and a DMRS, but an ePDCCH is mapped to REs.

FIG. 9 schematically shows eREGs defined based on a subcarrier in accordance with the present invention. As shown in FIG. 9, CRSs and DMRSs are placed according to a pattern within a subframe. Subcarriers may include CRSs or DMRSs and may not include both a CRS and a DMRS. Accordingly, different eREGs may include a different number of REs. Here, REs included in an eREG are not mapped to CRSs and DMRSs as described above, but are REs that may be used to transmit ePDCCHs.

Even when eREGs are used, ePDCCHs may be distributed over and mapped to transmission resources. In this case, the ePDCCHs may be mapped for each eREG.

Here, the distribution and mapping of the ePDCCHs may be performed by an interleaver and may be performed through randomization for permuting the eREGs simply. In this specification, 'interleaving' includes randomization unless otherwise described, for convenience of description.

In the present embodiment, the distribution and mapping of the ePDCCHs by permutation are described as one example of interleaving for the distribution and transmission of the ePDCCHs.

A method of distributing and mapping the ePDCCHs by permutation is as follows:

(1) Permutation is performed between eRBs for each subcarrier.

It is assumed that a k ^th eRB, an eREG corresponding to a l ^th subcarrier within the subframe are an eREG (k, l). Here, k is 1≤k≤K (K is the number of PRB pairs within the subframe), and 1≤l≤12.

If an eREG defined based on a subcarrier is used, permutation is performed on each eRB and an eREG in which a corresponding ePDCCH is placed in a corresponding eRB is determined. Accordingly, l is determined in relation to a fixed k value.

(2) More particularly, in relation to k =1, l' (i.e., l'= (l+P _k ) mod 12 (P _k is a randomization/permutation factor)) is calculated and the eREG (k, l) is allocated to an eREG (k, l').

(3) After l' is calculated, a l value is increased by 1 (l= l+1).

(4) (2) and (3) are repeated until l=12.

(5) While increasing the k value (k=k+1), (2) to (4) are repeated until k=12.

It is to be noted that in the randomization/permutation process, the k value is not changed. That is, eREG randomization is performed within the same eRB.

FIG. 10 is a diagram schematically showing an example in which ePDCCHs are distributed and mapped using eREGs in accordance with the present invention. In FIG. 10, a PCFICH, a PHICH, and a PDCCH may be mapped to a control region 1000, and PDSCHs and ePDCCHs may be mapped to a data region 1010. eRBs are defined for each subcarrier.

In FIG. 10, the distribution pattern of the ePDCCHs may be determined according to a randomization factor P _k . For example, within one subframe, an ePDCCH placed in an x^th eREG (subcarrier) in an i^th eRB may be placed in a y^th eREG in a K^th OFDM symbol according to the randomization factor P _k (x, y, and i are integers, x,y≤≤12, i≤K).

eREG without CRS

In the case of an extension carrier or a Multimedia Broadcast Single Frequency Network (MBSFN), a PDCCH and a CRS do not exist. Accordingly, in this case, a full DMRS-based eREG may be defined.

FIG. 11 schematically shows the structure of a subframe when there are no PDCCH and CRS like in an extension carrier or an MBSFN.

Referring to FIG. 11, what OFDM symbol may include 6 REs and what OFDM symbol may include 12 REs according to a pattern of a DMRS.

Accordingly, if there is no CRS as in the example of FIG. 11, the number of REs included in an eREG may be specified when defining the eREG based on an OFDM symbol. For example, (1) the eREG may be defined so that it includes 3 REs, and (2) the eREG may be defined so that it includes 6 REs. Furthermore, (3) like in the case where an eREG is defined based on OFDM symbol, an eREG may be defined so that it includes all REs belonging to one OFDM symbol.

If an eREG is defined so that it includes 3 REs as in the definition (1), 4 eREGs exist in an ODFM symbol without a DMRS and 2 eREGs exist in an OFDM symbol with a DMRS in FIG. 11.

If an eREG is defined so that it includes 6 REs as in the definition (2), 2 eREGs exist in an ODFM symbol without a DMRS and 1 eREG exists in an OFDM symbol with a DMRS in FIG. 11.

If an REG is defined for each OFDM symbol as in the definition (3), 14 eREGs exist in FIG. 11. FIG. 11 relates to a normal CP, and 12 eREGs exist in the case of an extended CP.

ePDCCHs may be mapped to a defined eREG as described above, and the defined eREG may be randomized between eRBs within the same OFDM symbol. For example, if the number of eREGs belonging to an OFDM symbol within one eRB is two or more as in the definition (1) or the definition (2), a method described in the randomization of eREGs defined based on a subcarrier may be used. Furthermore, if the number of eREGs belonging to an OFDM symbol within one eRB is 1 as in the definition (3), a randomization method of randomizing eREGs defined based on an OFDM symbol may be used.

Orthogonal Cover Code (OCC) for distribution transmission

In the distribution and transmission of ePDCCHs, some ePDCCHs may share the same PRB pair. For example, a Code Division Multiplexing (CDM) method may be applied using an OCC. The OCC means a code that has orthogonality and that is applicable to a sequence. In general, different sequences may be used in order to distinguish a plurality of channels from one another, but a plurality of channels may be distinguished from one another using an OCC. Accordingly, if an OCC is used, a multiplexing capacity can be increased.

If the length of an OCC is 2, two ePDCCHs can share the same PRB pair and two MSs can receive the ePDCCHs using the same PRB pair. If the length of an OCC is n, n ePDCCHs share the same PRB pair, and n MSs can receive the ePDCCHs using the same PRB pair.

FIG. 12 schematically shows eREGs defined when an OCC having a length 2 is used in accordance with the present invention. An eREG-based CDM method is described below with reference to FIG. 12:

(1) CDM in the frequency domain between different subcarriers within a PRB pair

This scheme may be matched with an eREG based on a subcarrier. Since each PRB includes 12 subcarriers, a spreading factor may become 2, 4, 6, or 12.

An OCC having a length 2 may be used by taking the symmetry of a PRB pair into consideration. That is, as shown in FIG. 12, the first part of the OCC may be allocated to a PRB of an upper half, and the second part of the OCC may be allocated to the PRB of a lower half. Accordingly, in relation to a first user terminal, 1 is allocated to the first part of the OCC as a code and 1 is allocated to the second part of the OCC as a code ([1, 1]) and in relation to a second user terminal, 1 is allocated to the first part of the OCC as a code and -1 is allocated to the second part of the OCC as a code ([1, -1]) so that the two user terminals use the same PRB.

If a different spreading factor (the length of an OCC) 4, 6, or 12 is applied, some REs may be muted.

(2) CDM in the time domain between different OFDM symbols within a PRB pair

If there is no PDCCH region because an extension carrier is applied, unlike in the case of FIG. 12, the first part of an OCC having a length 2 may be allocated to the former PRB (i.e., the former slot of a subframe) and the second part of the OCC having the length 2 may be allocated to the latter PRB (i.e., the latter slot of the subframe).

Accordingly, even in this case, two user terminals can receive ePDCCHs using the same PRB. In this case, if the number of DMRS antenna ports is 2, 4 DMRS antenna ports in which some REs are muted may be assumed when mapping the ePDCCHs.

FIG. 13 is a flowchart schematically illustrating an operation of UE for obtaining control information from ePDCCHs in a system in accordance with the present invention.

Referring to FIG. 13, when a signal is received through a physical channel, the UE performs de-interleaving in an ePDCCH region at step S1310. In this specification, as described above, interleaving includes randomization unless otherwise described. Furthermore, in this specification, de-interleaving은 de-randomization unless otherwise described. The UE can combine interleaved or distributed ePDCCHs through the de-interleaving.

The assumption of the de-interleaving performed by the UE is performed in reverse order of the above-described interleaving process. Information on the interleaving, for example, information on an interleaving matrix or information on a permutation factor, may be transferred to the UE in advance.

If a PRB pair (eRB) to which the ePDCCHs have been mapped is segmented into N subblocks and interleaved, the UE performs corresponding de-interleaving. Furthermore, if an eRB to which the ePDCCHs have been mapped has been interleaved based on an eREG, the UE may perform de-interleaving according to an interleaving method that has been performed.

The UE demodulates symbols at step S1320.

The UE decodes the demodulated symbols at step S1330.

The UE performs blind detection on the ePDCCHs based on a search space in relation to the decoded symbols at step S1340. The blind detection is also called blind decoding. The blind detection is a method of demasking a desired identifier to the CRC of a received physical control channel and checking whether the physical control channel is its own physical control channel or not by checking a CRC error. Here, the physical control channel may include an ePDCCH.

Since a plurality of physical control channels can be transmitted within one subframe, the UE monitors a plurality of physical control channels every subframe. Here, the term 'monitoring' refers to a UE's attempt to decode a target physical control channel according to the format of the physical control channel.

In order to reduce a burden due to a blind search, a search space may be used. The search space is divided into a common search space and a UE-specific search space. The common search space is a space for searching for a physical control channel having common control information. The common search space includes 16 CCEs having CCE indices 0~15 and supports a physical control channel having a CCE aggregation level of {4, 8}. The UE-specific search space supports a physical control channel having a CCE aggregation level of {1, 2, 4, 8}.

FIG. 14 is a flowchart schematically illustrating an operation of a BS for distributing and transmitting ePDCCHs in a system to which the present invention is applied.

Referring to FIG. 14, the BS encodes symbols to be transmitted at step S1410. As described with reference to FIG. 1, if control information is sought to be transmitted, the BS adds CRS to the control information, scrambles the control information, and encodes the control information. The BS may encode control information to be transmitted on an ePDCCH.

The BS modulates the encoded symbols at step S1420. The BS may map the control information to the transmission resources of a data region that have been allocated to the ePDCCHs.

The BS interleaves the transmission resources mapped to the ePDCCHs at step S1430. Here, the BS may segment a PRB pair (eRB) on which the ePDCCHs are transmitted into N blocks and then interleave the transmission resources or may define an eREG and perform interleaving based on the defined eREG.

An interleaving method performed by the BS has been described above.

The BS may distribute the interleaved resources over the ePDCCHs and transmit them at step S1440.

FIG. 15 is a block diagram schematically showing the construction of a BS in a system to which the present invention is applied. Referring to FIG. 15, the BS 1500 includes a control unit 1510, memory 1520, and an RF unit 1530.

The BS can transmit and receive necessary data through the RF unit 1530. The RF unit 1530 includes a plurality of antennas and can supports Multi-Input Multi-Output (MIMO).

The memory 1520 can store pieces of information necessary for the operation of the BS. For example, the memory 1520 may store information on resources allocated to ePDCCHs and information on interleaving.

The control unit 1510 embodies the functions, processes and/or method proposed in this specification. The control unit 1510 can configure control information and map the control information to resources. The control information configured by the control unit 1510 includes information transmitted on ePDCCHs. The control unit 1510 may encode the control information that is transmitted on the ePDCCHs, modulate the control information, map the control information to the resources allocated to the ePDCCHs, and interleave the resources so that the ePDCCHs are distributed and transmitted.

The control unit 1510 may include a distribution and mapping module 1540 and a control information configuration module 1550. The control information configuration module 1550 can configure information to be transmitted on a PDCCH and an ePDCCH. The configured information may be transmitted on a control channel according to a Downlink Control Information (DCI) format.

The distribution and mapping module 1540 may encode and modulate control information, map the control information to transmission resources, and interleave the transmission resources. A detailed method regarding the interleaving of ePDCCHs has been described above.

FIG. 16 is a block diagram schematically showing the construction of UE in a system to which the present invention is applied. Referring to FIG. 16, the UE 1600 includes a control unit 1610, an RF unit 1620, and memory 1630.

The UE can transmit and receive necessary data through the RF unit 1620. The RF unit 1620 can include a plurality of antennas and support MIMO based on the plurality of antennas.

The memory 1630 can store pieces of information necessary for the operation of the UE. For example, the memory 1630 can receive information on the interleaving of ePDCCHs in advance and store the received information.

The control unit 1610 embodies the functions, processes and/or method proposed in this specification. The control unit 1610 can de-interleave received data and demodulate and decode the de-interleaved data. The control unit 1620 may perform the de-interleaving in a reverse direction to an interleaving method performed by a BS. The control unit 1620 can obtain control information transmitted on an ePDCCH by performing blind detection on the ePDCCH in relation to decoded symbols.

The control unit 1610 may include a channel detection module 1640 and a control information processing module 1650. The channel detection module 1640 can detect an ePDCCH by performing blind detection, and the control information processing module 1650 processes information transmitted on the detected ePDCCH.

In the above exemplary systems, although the methods have been described on the basis of the flowcharts using a series of the steps or blocks, the present invention is not limited to the sequence of the steps, and some of the steps may be performed in order different from that of the remaining steps or may be performed simultaneously with the remaining steps. Furthermore, those skilled in the art will understand that the steps shown in the flowcharts are not exclusive and they may include other steps or one or more steps of the flowchart may be deleted without affecting the scope of the present invention.

The above embodiments include various aspects of examples. Although all possible combinations for describing the various aspects may not be described, those skilled in the art may appreciate that other combinations are possible. Accordingly, the present invention should be construed as including all other replacements, modifications, and changes which fall within the scope of the claims.

Claims (18)

1. A method of receiving control information, comprising:

   de-interleaving a received enhanced Physical Downlink Control Channel (ePDCCH) region;

   demodulating de-interleaved modulation symbols; and

   decoding the demodulated symbols,

   wherein subblocks mapped to the ePDCCH are de-interleaved in the de-interleaving step, and the subblocks are obtained by segmenting a resource block, allocated to the ePDCCHs, in a specific number.
2. The method of claim 1, wherein the de-interleaving is performed between a plurality of the resource blocks allocated to the ePDCCH region.
3. The method of claim 1, wherein a number of subblocks per resource block is identical with a number of resource blocks allocated to transmit the ePDCCHs.
4. The method of claim 3, wherein the de-interleaved subblocks are distributed over different resource blocks and received.
5. The method of claim 1, wherein:

   the subblock is obtained by segmenting the resource block, allocated to the ePDCCHs, for each Orthogonal Frequency Division Multiplexing (OFDM) symbol, and

   the subblock comprises a resource element that does not transmit a reference signal, from among resource elements belonging to the OFDM symbol.
6. The method of claim 5, wherein:

   in the de-interleaving, subblocks mapped to an identical ePDCCH, from among subblocks belonging to different resource blocks, are de-interleaved, and

   the subblocks mapped to the identical ePDCCH belong to different OFDM symbols depending on a resource block.
7. The method of claim 1, wherein:

   the subblock is obtained by segmenting the resource block, allocated to the ePDCCHs, for each subcarrier, and

   the subblock comprises a resource element that does not transmit a reference signal, from among resource elements belonging to the subcarrier.
8. The method of claim 7, wherein:

   in the de-interleaving, subblocks mapped to an identical ePDCCH, from among subblocks belonging to different resource blocks, are de-interleaved, and

   the subblocks mapped to the identical ePDCCH belong to different subcarriers depending on a resource block.
9. A method of transmitting control information, comprising:

   mapping enhanced Physical Downlink Control Channels (ePDCCHs) to be transmitted to a resource block; and

   performing interleaving on the resource block to which the ePDCCHs have been mapped,

   wherein in the interleaving, the resource block to which the ePDCCHs have been mapped is segmented into subblocks and the subblocks are interleaved.
10. The method of claim 9, wherein the interleaving is performed between a plurality of the resource blocks allocated to a region of the ePDCCHs.
11. The method of claim 9, wherein a number of subblocks per resource block is identical with a number of resource blocks allocated to transmit the ePDCCHs.
12. The method of claim 11, wherein the subblocks are distributed over different resource blocks and received by the interleaving.
13. The method of claim 9, wherein:

    the subblocks is obtained by segmenting the resource block, allocated to the ePDCCHs, for each Orthogonal Frequency Division Multiplexing (OFDM) symbol, and

    the subblock comprises a resource element that does not transmit a reference signal, from among resource elements belonging to the OFDM symbol.
14. The method of claim 13, wherein:

    subblocks mapped to an identical ePDCCH are distributed over different resource blocks through the interleaving, and

    the subblocks mapped to the identical ePDCCH belong to different OFDM symbols through the interleaving.
15. The method of claim 9, wherein:

    the subblock is obtained by segmenting the resource block, allocated to the ePDCCHs, for each subcarrier, and

    the subblock comprises a resource element that does not transmit a reference signal, from among resource elements belonging to the subcarrier.
16. The method of claim 15, wherein:

    subblocks mapped to an identical ePDCCH are distributed over different resource blocks through the interleaving, and

    the subblocks mapped to the identical ePDCCH belong to different subcarriers through the interleaving.
17. An apparatus for receiving control information, comprising:

    a Radio Frequency (RF) unit configured to receive ePDCCHs; and

    a control unit configured to obtain necessary information from the received ePDCCHs,

    wherein the control unit generates modulation symbols by de-interleaving subblocks that are segmented from a resource block mapped to the ePDCCHs and are distributed and received.
18. An apparatus for transmitting control information, comprising:

    a Radio Frequency (RF) unit configured to transmit ePDCCHs; and

    a control unit configured to interleave a resource block to which ePDCCHs to be transmitted have been mapped,

    wherein the control unit interleaves the resource block to which the ePDCCHs have been mapped by segmenting the resource block into subblocks.

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