WO2015050339A1

WO2015050339A1 - Method for transmitting and receiving downlink control channel, and apparatus therefor

Info

Publication number: WO2015050339A1
Application number: PCT/KR2014/008995
Authority: WO
Inventors: 박규진; 최우진
Original assignee: 주식회사 케이티
Priority date: 2013-10-04
Filing date: 2014-09-26
Publication date: 2015-04-09

Abstract

The present invention relates to a method for transmitting and receiving a downlink control channel and to an apparatus therefor. The method by which a base station transmits a downlink control channel, according to one embodiment of the present invention, comprises the steps of: determining a starting subframe of a plurality of downlink subframes through which a downlink control channel is repeatedly transmitted; determining a search space consisting of a control channel element (CCE) index or indexes or an enhanced CCE (ECCE) index or indexes constituting a physical downlink control channel (PDCCH) candidate or an enhanced physical downlink control channel (EPDCCH) candidate which are repeatedly transmitted through the plurality of downlink subframes; and repeatedly transmitting the downlink control channel through the plurality of downlink subframes, on the basis of the determined starting subframe and the CCE index(es) or ECCE index(es).

Description

Method and apparatus for transmitting / receiving downlink control channel

The present invention relates to a method and apparatus for transmitting and receiving a downlink control channel, and more particularly, to a method and apparatus for transmitting a downlink control channel for a machine type communication (MTC) terminal.

Machine Type Communication (MTC) or Machine to Machine (M2M) is communication between devices and things with no or minimal human intervention. "machine" may refer to an entity that does not require direct human intervention or intervention, and "MTC" may refer to a form of data communication that includes one or more such "machines." An example of a "machine" may be a smart meter or vending machine equipped with a mobile communication module, and recently, a smartphone that automatically connects to a network and performs communication without user intervention or intervention depending on the location or situation of the user. With the advent of the portable terminal having the MTC function is also considered as a form of "machine".

The MTC terminal may be installed in a place where the radio environment is worse than that of the general terminal. Therefore, the coverage of the MTC terminal should be improved to 20dB or more compared to the coverage of the general terminal.

In order for an MTC terminal to operate in coverage improved by 20 dB or more compared with a general terminal, it is necessary to repeatedly transmit control information and / or data of each physical channel transmitted only in one subframe unit in a plurality of subframes. However, in such repeated transmission, a method of providing information on a subframe and search space to be repeatedly transmitted to the MTC terminal is required.

An object of the present invention is to provide a method and apparatus for transmitting and receiving a downlink control channel for an MTC terminal to overcome the above problems. In particular, a search space setting method for monitoring a physical downlink control channel (PDCCH) or an enhanced physical downlink control channel (EPDCCH) of an MTC terminal is proposed.

In a method for transmitting a downlink control channel by a base station according to an embodiment of the present invention, determining a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; Physical Channel Downlink Control CHannel (PDCCH) or Enhanced Physical Downlink Control CHannel (EPDCCH) candidate that is repeatedly transmitted through a frame, or Control Channel Element (CCE) index (es) or Enhanced CCE (ECCE) Index (ECCE) Determining a search space consisting of a plurality of downlink subframes; and repeating the downlink control channel through the plurality of downlink subframes based on the determined starting subframe and the CCE index (es) or ECCE index (s). Transmitting.

In another embodiment of the present invention, a method for receiving a downlink control channel by a terminal includes identifying a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted, and the plurality of downlink subframes. Control Channel Element (CCE) index or indices or ECCE (Enhanced CCE) index (s) allocated to a search space for a Physical Downlink Control CHannel (PDCCH) or Enhanced Physical Downlink Control CHannel (EPDCCH) candidate in a frame ), And based on the identified starting subframe and the CCE index (es) or ECCE index (s), monitoring is performed through the plurality of downlink subframes to repeat the downlink control channel. Receiving.

A base station transmitting a downlink control channel according to another embodiment of the present invention determines the start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted, and the plurality of downlink subframes Physical Downlink Control CHannel (PDCCH) or Enhanced Physical Downlink Control CHannel (EPDCCH) candidates that are repeatedly transmitted through a control channel element (CCE) index or indices or enhanced CCE (ECCE) index (s) A control unit for determining a search space consisting of the control unit, and repeatedly transmitting the downlink control channel through the plurality of downlink subframes based on the determined starting subframe and the CCE index (es) or ECCE index (s). It includes a transmitter.

A terminal receiving a downlink control channel according to another embodiment of the present invention identifies a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted, and in the plurality of downlink subframes. Control Channel Element (CCE) index or indices assigned to the search space for Physical Downlink Control CHannel (PDCCH) or Enhanced Physical Downlink Control CHannel (EPDCCH) candidates or Enhanced CCE (ECCE) index (s). A control unit for confirming and performing monitoring through the plurality of downlink subframes based on the identified starting subframe and the CCE index (es) or ECCE index (es) to repeatedly receive the downlink control channel. It includes a receiver.

When implementing the present invention can be implemented a method and apparatus for transmitting and receiving a downlink control channel for the MTC terminal.

1 shows an example of a wireless communication system to which an embodiment of the present invention is applied.

FIG. 2 is a diagram illustrating blind decoding of PDCCH / EPDCCH and obtaining PDSCH scheduling information.

3 illustrates four PDCCH formats.

4 is a diagram showing the number of EREGs by ECCE.

5 is a diagram for Supported EPDCCH formats.

FIG. 6 is a diagram illustrating an example of a method of blind decoding a PDCCH or an EPDCCH and receiving a PDSCH by an MTC terminal.

7 is a diagram illustrating an example of a subframe in which PDCCH / EPDCCH is repeatedly transmitted.

FIG. 8 is a diagram illustrating a process of determining, by a base station, a start subframe of repetitive transmission of scheme 1 according to an embodiment of the present invention.

FIG. 9 is a diagram illustrating a process of a base station determining and signaling a start subframe of repetitive transmission according to another embodiment of the present invention.

FIG. 10 is a diagram illustrating a process of determining, by a base station, CCE / ECCE index (es) of Method 2 according to an embodiment of the present invention.

FIG. 11 illustrates a process of a base station determining and signaling a CCE / ECCE index (es) of Method 2 according to another embodiment of the present invention.

12 is a view showing an operation of a base station according to an embodiment of the present invention.

13 is a view illustrating an operation process of a terminal according to an embodiment of the present invention.

14 is a diagram illustrating a configuration of a base station according to another embodiment.

15 is a diagram illustrating a configuration of a user terminal according to another embodiment.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, in the present specification, the MTC terminal may mean a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in the present specification, the MTC terminal may mean a newly defined Release 13 low cost (or low complexity) UE category / type for performing LTE-based MTC related operations. Alternatively, in the present specification, the MTC terminal supports enhanced coverage compared to the existing LTE coverage, or UE category / type defined in the existing Release 12 or less that supports low power consumption, or newly defined Release 13 low cost (or low complexity). It may mean a UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system includes a user equipment (UE) and a base station (base station, BS, or eNB). In the present specification, a user terminal is a generic concept meaning a terminal in wireless communication. In addition, user equipment (UE) in WCDMA, LTE, and HSPA, as well as mobile station (MS) in GSM, user terminal (UT), and SS It should be interpreted as a concept that includes a subscriber station, a wireless device, and the like.

A base station 20 or a cell generally refers to a station that communicates with a user terminal, and includes a Node-B, an evolved Node-B, an Sector, and a Site. It may be called by other terms such as a base transceiver system (BTS), an access point, an access node, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, in the present specification, the base station 20 or the cell is a partial area covered by a base station controller (BSC) in CDMA, a Node-B in WCDMA, an eNB or a sector (site) in LTE / LTE-Advanced, and the like. Or, it should be interpreted as a comprehensive meaning of function, and encompasses various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range. to be.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two senses. i) the device providing the megacell, the macrocell, the microcell, the picocell, the femtocell, the small cell in relation to the wireless area, or ii) the wireless area itself. In i) all devices which provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to direct the base station. The eNB, RRH, antenna, RU, LPN, point, transmit / receive point, transmit point, receive point, and the like, according to the configuration of the radio region, become an embodiment of the base station. In ii), the base station may indicate the radio area itself to receive or transmit a signal from a viewpoint of a user terminal or a neighboring base station.

Therefore, megacells, macrocells, microcells, picocells, femtocells, small cells, RRHs, antennas, RUs, low power nodes (LPNs), points, eNBs, transmit / receive points, transmit points, and receive points are collectively referred to as base stations. do.

In the present specification, the user terminal and the base station are two transmitting and receiving entities used to implement the technology or technical idea described in this specification in a comprehensive sense and are not limited by the terms or words specifically referred to. The user terminal and the base station are two types of uplink or downlink transmitting / receiving subjects used to implement the technology or the technical idea described in the present invention, and are used in a generic sense and are not limited by the terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

There is no limitation on the multiple access scheme applied to the wireless communication system. Various multiple access techniques such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention can be applied to resource allocation in the fields of asynchronous wireless communication evolving to LTE and LTE-Advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. The present invention should not be construed as being limited or limited to a specific wireless communication field, but should be construed as including all technical fields to which the spirit of the present invention can be applied.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

In addition, in systems such as LTE and LTE-Advanced, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and the downlink include a Physical Downlink Control CHannel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control CHannel (EPDCCH), and the like. Control information is transmitted through the same control channel, and data is configured by a data channel such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

On the other hand, control information may also be transmitted using an enhanced PDCCH (EPDCCH or extended PDCCH).

In the present specification, a cell means a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

A wireless communication system to which embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-antenna transmission scheme in which two or more transmission / reception points cooperate to transmit a signal. antenna transmission system), a cooperative multi-cell communication system. The CoMP system may include at least two multiple transmission / reception points and terminals.

The multiple transmit / receive point is at least one having a base station or a macro cell (hereinafter referred to as an eNB) and a high transmission power or a low transmission power in a macro cell region, which is wired controlled by an optical cable or an optical fiber to the eNB. May be RRH.

Hereinafter, downlink refers to a communication or communication path from a multiple transmission / reception point to a terminal, and uplink means a communication or communication path from a terminal to multiple transmission / reception points. In downlink, a transmitter may be part of multiple transmission / reception points, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH may be expressed in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH.'

In addition, hereinafter, a description of transmitting (sending) or receiving a PDCCH or transmitting (sending) or receiving a signal through the PDCCH includes transmitting (sending) or receiving an EPDCCH or transmitting (sending) or receiving a signal through the EPDCCH. Can be used in the sense.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and may also be used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the portion described as the PDCCH, and the PDCCH may be applied to the portion described as the EPDCCH as an embodiment of the present invention.

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The base station or eNB 20 performs downlink transmission to the terminals 10. The eNB includes downlink control information and an uplink data channel (eg, a physical downlink shared channel (PDSCH), which is a primary physical channel for unicast transmission, and scheduling required to receive the PDSCH. For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

Referring to FIG. 1, the base station 20 transmits downlink control information (DCI) to the terminal 10 through a PDCCH / EPDCCH. The DCI may include a downlink scheduling assignment including PDSCH resource information or an uplink scheduling grant including PUSCH resource information.

That is, the base station 20 uses DCI to allocate uplink / downlink data transmission resources to the terminal 10 and transmits the same to the terminal 10 using a downlink control channel. The downlink control channel may be classified into a PDCCH and an EPDCCH according to a location of a transmission resource used for transmitting a DCI.

The PDCCH is transmitted in a control region established through a control format indicator (CFI). The control region is formed over the entire downlink bandwidth and consists of 1 to 4 OFDM symbols for each subframe according to the CFI setting value.

The EPDCCH is transmitted using the remaining transmission resources except for the control region in each subframe. The transmission resource used for EPDCCH transmission is allocated to a subframe predefined by upper layer signaling (for example, RRC (Radio Resource Control)) and a plurality of predefined physical resource block (PRB) pairs for each UE. Can only be used.

When transmitting DCI through the PDCCH, a basic transmission resource unit may be referred to as a control channel element (CCE). One CCE may consist of nine Resource Element Groups (REGs), and one REG may consist of four Resource Elements (REs).

When transmitting DCI through EPDCCH, the basic transmission resource unit may be referred to as ECCE (Enhanced CCE). One ECCE is composed of 4 or 8 EREGs (Enhanced REGs) according to cyclic prefix length and / or TDD configuration, and one EREG is variable depending on RE used for RS (Reference Signal) transmission. It may be composed of a plurality of RE.

The base station 20 may set the number of CCEs used to transmit one DCI through the PDCCH according to the channel condition of the terminal. This is called an aggregation level, and 1, 2, 4, or 8 CCEs may be used according to the channel condition of the UE.

In addition, the base station 20 may set the number of ECCEs used when transmitting one DCI through the EPDCCH according to the channel condition of the terminal. This is called an aggregation level, and 1, 2, 4, 8, 16, or 32 ECCEs may be used according to the channel condition of the UE.

As described above, the PDCCH / EPDCCH is composed of a plurality of CCE / ECCE, the base station can transmit a plurality of DCI to a plurality of terminals in every subframe. In this case, the UE does not separately provide CCE / ECCE allocation information (that is, CCE combining level information and CCE transmission resource location information used for one DCI transmission) necessary for the UE to receive DCI through PDCCH / EPDCCH. Therefore, the terminal performs blind decoding on the possible coupling level and the CCE / ECCE transmission resource to confirm the DCI transmitted to the terminal.

Since the UE cannot realistically blind-decode all possible CCE / ECCE combinations for each coupling level for all CCEs / ECCEs present in the PDCCH / EPDCCH, the PDCCH configured with pre-defined CCE / ECCE indices for each UE. Blind decoding is performed only on a candidate / EPDCCH candidate. The CCE index / ECCE index constituting the PDCCH candidate / EPDCCH candidate for each coupling level may be defined as a function of a coupling level, a value of a Radio Network Temporary Identifier (RNTI), and a slot number (or subframe number). The UE may perform blind decoding only on a limited number of PDCCH candidates / EPDCCH candidates at each coupling level in every subframe.

As an example, FIG. 2 illustrates a method of blind decoding a PDCCH / EPDCCH by a general terminal and receiving a PDSCH. Referring to FIG. 2, the UE attempts blind decoding of the PDCCH / EPDCCH with respect to the PDCCH candidate / EPDCCH candidate. A cyclic redundancy check (CRC) is added to the DCI, and the UE checks the CRC to confirm the DCI transmitted to the DCI. When checking the DCI transmitted to itself as a result of the CRC check, the UE acquires downlink scheduling information included in the DCI and decodes the PDSCH using downlink data transmission resources in the same subframe as the subframe in which the DCI is transmitted. do.

2 illustrates blind decoding PDCCH / EPDCCH and obtaining PDSCH scheduling information. In a manner similar to that of FIG. 2, PUSCH scheduling information may also be obtained by blind decoding PDCCH / EPDCCH.

In the conventional 3GPP LTE / LTE-Advanced system, a PDCCH defined in a Rel-10 or lower system and an EPDCCH newly defined in a Rel-11 system are used as a downlink control information (DCI) transmission channel for a UE. .

3 illustrates four PDCCH formats. In the case of the PDCCH, four PDCCH formats as shown in FIG. 3 are transmitted for link adaptation according to downlink radio channel quality and DCI size of the UE. In FIG. 4, the number of CCEs represents an aggregation level.

4 is a diagram showing the number of EREGs by ECCE. In Figure 4

The value of (Number of EREGs per ECCE) is determined according to the characteristics of the subframe, and in the case of the normal cyclic prefix, it is a normal subframe or a special subframe of 3, 4, and 8 settings. Special subframe,

configuration

3, 4, 8) is 4. On the other hand, in the case of an extended cyclic prefix, a normal subframe or a special subframe of 1, 2, 3, 5, and 6 configuration (Special subframe,

configuration

1, 2, 3, 5, 6) ) Is 8.

5 is a diagram for Supported EPDCCH formats. In FIG. 5, it is divided into case A and case B, and is divided into five types according to localized transmission and distributed transmission, respectively.

That is, in the case of EPDCCH, five EPDCCH formats are transmitted according to FIGS. 4 and 5 for link adaptation for DCI transmission.

[LTE 기반의 저가형 MTC][LTE-based low-cost MTC]

As LTE networks proliferate, mobile operators want to minimize the number of Radio Access Terminals (RATs) to reduce network maintenance costs. However, MTC products based on conventional GSM / GPRS networks are increasing, and MTCs using low data rates can be provided at low cost. Therefore, since the mobile operators use the LTE network for general data transmission and the GSM / GPRS network for the MTC, there is a problem of operating two RATs, which are inefficient use of the frequency band. It becomes burden on profit.

In order to solve such a problem, the cheap MTC terminal using the GSM / EGPRS network should be replaced with the MTC terminal using the LTE network, for this purpose, various requirements for reducing the price of the LTE MTC terminal has been proposed.

In order to support the low-cost LTE MTC terminal, there may be mentioned, for example, technologies such as narrowband support / single RF chain / half duplex FDD / long discontinued reception (DRX). However, the above methods, which are considered to lower the price, may reduce the performance of the MTC terminal compared to the conventional LTE terminal.

In addition, since about 20% of MTC terminals supporting MTC services such as smart metering are installed in a 'deep indoor' environment such as a basement, for successful MTC data transmission, the coverage of the LTE MTC terminal is conventional LTE terminal. It should be improved by about 20dB compared to the coverage of. In addition, if the performance reduction due to the specification change is further considered, the coverage of the LTE MTC terminal should be improved by 20 dB or more.

As described above, various methods for robust transmission such as PSD boosting or low coding rate and time domain repetition are used to improve coverage while lowering the LTE MTC terminal price. This is considered for each physical channel. The requirements of the LTE-based low-cost MTC terminal is as follows.

1) The data transmission rate must satisfy the data transmission rate provided by the minimum EGPRS-based MTC terminal, that is, downlink 118.4kbps, uplink 59.2kbps.

2) Frequency efficiency should be improved significantly compared to GSM / EGPRS MTC terminal.

3) The service area provided shall not be smaller than that provided by the GSM / EGPRS MTC terminal.

4) Power consumption should not be greater than GSM / EGPRS MTC terminal.

5) Legacy LTE terminal and LTE MTC terminal should be available in the same frequency.

6) Reuse existing LTE / SAE networks.

7) Optimization is performed not only in the FDD mode but also in the TDD mode.

8) Low cost LTE MTC terminal should support limited mobility and low power consumption module.

In the existing LTE / LTE-Advanced system, PDCCH / EPDCCH for transmission of scheduling control information or other downlink control information for any one terminal or terminal group is transmitted through one downlink subframe.

However, in order to support 20dB enhanced coverage of a low-cost MTC terminal compared to a general LTE terminal, PDCCH or EPDCCH transmission, which was performed in one downlink subframe unit, is repeatedly transmitted through a plurality of downlink subframes and corresponding MTC. The UE also needs to perform decoding by combining PDCCHs or EPDCCHs received through the plurality of downlink subframes. As such, when repetition for a corresponding channel is supported when transmitting a PDCCH or EPDCCH for a low-cost MTC terminal, it is necessary to define a PDCCH / EPDCCH format for performing PDCCH / EPDCCH decoding in the corresponding MTC terminal.

In the example of FIG. 6, the base station repeatedly transmits one DCI through four subframes of SF # 0 (Subframe Number # 0) to SF # 3 in consideration of a channel condition of the UE. In addition, the base station repeatedly transmits the same data through four subframes of SF # 3 to SF # 6 in consideration of the channel condition of the terminal. When the CRC check succeeds as a result of blind decoding by soft combining the received values of the DCIs transmitted from SF # 0 to SF # 3, the UE checks scheduling information of the PDSCH included in the DCI. The terminal performs decoding by soft combining the received values of the data transmitted in SF # 3 to SF # 6.

As described above, when repetition for a corresponding channel is supported when transmitting a PDCCH or EPDCCH for a low-cost MTC terminal, in order to successfully decode the corresponding MTC terminal, a definition of a search space including the repetition number and repetition is required.

In the present invention, to define a PDCCH / EPDCCH search space configuration method for the MTC terminal. In more detail, N repeated PDCCH / EPDCCH candidates, corresponding PDCCH / EPDCCH candidates in each of the N DL subframe (s) in a method of determining DL subframe (s) for the configuration of m, m A method and apparatus for setting up a search space constituting the allocated CCE / ECCE index (es) (indexes or indices) are described.

In case of a UE configured to receive DCI through PDCCH in an existing 3GPP LTE / LTE-Advanced system, a set of PDCCH candidates defined to be monitored for receiving downlink control information in any downlink subframe k Search space for the terminal,

This is made up. At this time

Aggregation level, L (where,

Any PDCCH candidate m with) is determined by Equation 1 below.

[Equation 1]

here

Has a value of and cross-carrier scheduling is set,

If cross carrier scheduling is not set,

Has the value of. (only,

Means CIF (Carrier Indicator Field) value included in the DCI)

Has the value of,

Denotes the number of PDCCH candidates defined for the UE to monitor for the coupling level, L,

Denotes the number of CCEs constituting the PDCCH control region in the corresponding DL subframe k.

Additionally in Equation 1 above

The value is determined by Equation 2 below.

[Equation 2]

Where each

(

Has a value of slot number.

However, in case of the MTC terminal, the corresponding PDCCH is not transmitted through a single downlink subframe, but N downlink subframes are defined according to the number of PDCCH repetitions or the definition of a new PDCCH format for the MTC terminal. Since it can be repeatedly transmitted through, it is necessary to extend the corresponding search space to the downlink subframe domain.

Accordingly, a method of determining a search space constituting an N repeated PDCCH candidate, m, in which the number of repetitions is defined as N. In Method 1, a DL subframe index constituting a corresponding N repeated PDCCH candidate ( (Index or indices), and in scheme 2, a search space configuration expression defining a CCE index (es) (index or indices) constituting a corresponding N repeated PDCCH candidate and m in each N DL subframes. Can be defined. Likewise, in the case of EPDCCH, Method 1 and Method 2 described below may be equally applied. In this case, PDCCH may be changed to EPDCCH, and CCE may be changed to ECCE.

In the example of FIG. 7, a method of determining a downlink subframe constituting N repeated PDCCH / EPDCCH candidates m based on the joint level L, the downlink subframe k _{start in} which N repeated PDCCH / EPDCCH transmissions are started. _{, n} is determined, and PDCCH / EPDCCH is N consecutive downlink subframes from the downlink subframe SF # k _{start, n} , that is, SF # k _{start, n} to SF # (k _{start, n} + N-1 May be repeated N times.

Scheme 1: starting DL subframe of PDCCH / EPDCCH repetition for MTC UEs

First, a method of determining DL subframe (s) constituting N repeated PDCCH candidates, m, will be proposed.

A method for determining a coupling level, L-based N repeated PDCCH candidates, and DL subframe (s) constituting m, the DL subframe in which N repeated PDCCH transmissions are started, k _{start, n} is defined, and accordingly _, N repeated PDCCH transmissions are performed through consecutive DL DL subframes from DL subframe #k _{start, n} to DL subframe # (k _{start, n} + N-1). can do.

In this case, the downlink subframe k _{start, n} at which the _start of the corresponding PDCCH repetition is performed may be determined by the number N of the corresponding PDCCH repetitions.

May be determined as a value satisfying Equation 3 below.

[Equation 3]

Where M represents a System Frame Number (SFN) value.

Indicates the slot number. However, the mod value of Equation 3 may be defined to have any natural value smaller than N, not 0. Alternatively, as shown in Equation 4 below, the coupling level and L may also define the corresponding DL subframe (s) as a parameter of the determination equation.

[Equation 4]

Equations

3 and 4 above are merely an embodiment for determining DL subframe (s) in which the corresponding PDCCH repetition is performed as a function of the number of repetitions, a function of N or the number of repetitions N and L, but is not limited thereto. Other forms of determining the DL subframe (s) as a function of or as a function of N and L may be included within the scope of the present invention.

As another method of determining N repeated PDCCH candidates, DL subframe index at which the corresponding PDCCH transmission to define DL subframe (s) constituting m, and k _{start, n} are repeated. According to the N value, the corresponding start subframe index value may be set directly and transmitted to each MTC terminal through cell specific or UE-specific higher layer signaling. Can be. N repeating PDCCH candidate based on the upper layer signaling, starting DL subframe index for monitoring m, k _{start, n} as an example of setting method, as in the existing EPDCCH monitoring subframe configuration method, A starting DL subframe index for monitoring the corresponding N repeated PDCCH candidates and m for a DL subframe of a period may be set and signaled in a bitmap manner.

As another method for defining the N repeated PDCCH candidates and DL subframe (s) constituting m, the N repeated PDCCH candidates and N DL subframe index (s) constituting m are cell-specific at the base station. Through direct or terminal specific higher layer signaling, each MTC terminal may be configured directly. In this case, the corresponding N DL subframe (s) may be allocated discontinuously, and for this purpose, N DL subframe (s) having a constant period P may be defined. In this case, the N DL subframe (s) is a bitmap scheme for all DL subframes in the corresponding period P (the number of DL subframes may be P in the case of FDD and may be smaller than P in the case of TDD). It may be allocated as, but there is no restriction on a specific signaling scheme for allocating corresponding N DL subframe (s).

방안 2: N 반복되는 PDCCH/EPDCCH를 위한 검색 공간 설정(Search space configuration for N repeated PDCCH/EPDCCH)Scheme 2: Search space configuration for N repeated PDCCH / EPDCCH

Following the DL subframe (s) determination method for configuring the N repeated PDCCH candidate, m, CCE index (s) (index) allocated for the corresponding PDCCH candidate, m in each of the N DL subframe (s) Or we propose a method of setting up the search space that constitutes indices.

Equation 1 may be applied as a first method of determining a search space constituting a corresponding N-repeatable PDCCH candidate, m in each DL subframe (s). That is, accordingly, N repeated PDCCH candidates for any MTC terminal, a search space set in each DL subframe (s) for m, {

} May be determined as in Equation 5 below.

[Equation 5]

As another method of determining a search space constituting a corresponding N repeated PDCCH candidate, m in each DL subframe (s), the following equation 6 and N are added as parameters to modify the MTC terminal for the MTC terminal.

} Can be defined.

[Equation 6]

However, Equation 6 above is only one embodiment of the search space determination formula including the number of repetitions and N as a parameter, but the form of the search space setting formula including the N is not limited thereto. That is, in defining the corresponding search space setting expression, another type of search space setting expression using the corresponding N value as a parameter may be included in the scope of the present invention.

DL subframe #k _start , which is a DL subframe in which the N repeated PDCCH transmission is started as another method for determining a corresponding N repeated PDCCH candidate in each DL subframe (s), m. _The CCE index (es) defined in _{, n may be used} to define the CCE index (s) allocated in a subsequent downlink subframe. That is, when N PDCCH repetitions are performed in N consecutive downlink subframes from downlink subframe k _{start, n} to downlink subframe k _{start, n} + N−1 for DCI transmission for an arbitrary MTC terminal. CCEs allocated in each subsequent N-1 downlink subframes from downlink subframe k _{start, n} +1 to k _{start, n} + N-1 for N repeated PDCCH transmissions The index (es) may be defined to use the same CCE index (s) as the CCE index (es) used for transmission of the corresponding PDCCH in k _{start, n} , which is the first downlink subframe. That is, according to Equation 5 or Equation 6, the N repeated candidate, the CCE index (es) in the first DL subframe #k _{start, n} constituting m,

The CCE index (es) constituting the corresponding N repeated PDCCH candidates, m, in DL subframes # (k _{start, n} +1) to DL subframes # (k _{start, n} + N-1) are determined accordingly. Degree

Can be defined to follow.

As another method of determining a search space constituting a corresponding N repeated PDCCH candidate and m in each DL subframe (s), the UE performs CCE index (es) constituting PDCCH candidate (s) for each repetition level. It can be set semi-static via specific or cell specific RRC signaling. In this case, each coupling level, L and repetition levels, CCE starting offset values for each _N , and CCE _{L, N} may be signaled. That is, if the number of repetitions of the corresponding PDCCH for an arbitrary coupling level L-based PDCCH transmission is N, and the number of N repeated PDCCH monitoring candidates is C, the corresponding N repeated candidate, m The first N repeating PDCCH candidates in the first DL subframe #k _{start, n} to Dl subframe # (k _{start, n} + N-1) are configured by CCE _{L, N} to CCE _{L, N} + L-1, respectively. The second CCE is composed of CCE _{L, N} + L ~ CCE _{L, N} + 2L-1, and the C-th N repeated PDCCH candidate is CCE _{L, N} + (C-1) L ~ CCE. _{L, N} + CL-1. Search Space Setting Method of the Invention The above N value may be applied regardless of any value, and the DL subframe index setting method for the N repeated PDCCH candidates and m and the CCE configuration method in each DL subframe. In the application of the present invention, the combination is not limited and may be included in the scope of the present invention even when the proposed methods are applied to each other independently.

In addition, even if the DCI for the MTC terminal is transmitted through the EPDCCH, that is, it is apparent that the contents proposed in the present invention can be applied to a method of configuring an N repeated EPDCCH candidate. Therefore, the above-described

methods

1 and 2 of the present invention have been described based on the PDCCH for convenience of understanding, and the same method may be applied to the EPDCCH. In this case, PDCCH should be understood as EPDCCH and CCE will be understood as ECCE.

As shown in Equation 3 or Equation 4 of Scheme 1, the base station 20 and the terminal 10 may be configured to perform a repetition number N, an aggregation level L, and a slot number n _s . Use one or more of them. That is, the start subframe of the repeated transmission may be checked by a function using at least one of N, L, and n _s as parameters (S810). Thereafter, the base station 20 repeatedly transmits the PDCCH / EPDCCH to the terminal 10 in the checked start subframe, and the terminal 10 receives it (S820).

FIG. 9 illustrates, in another embodiment of the first method, that the base station 20 sets a repetitive start subframe (S910), and transmits information on the start subframe to the UE using higher layer signaling (S920). As a result, the terminal 10 can identify which subframe is a subframe in which repetitive transmission is started, and then the base station 20 repeatedly transmits PDCCH / EPDCCH to the terminal 10 in the identified starting subframe. The terminal 10 receives this (S930).

In FIG. 10, the base station 20 may calculate the search space of the PDCCH / EPDCCH to be repeatedly transmitted by using a repetition number N and an aggregation level as shown in Equation 5 or Equation 6. That is, the base station 20 and the terminal 10 determine the PDCCH / EPDCCH search space of the start subframe of the repeated transmission as a function of the number of repetitions (N) and / or the combined level (L) in a predetermined manner ( In step S1010, the base station 20 repeatedly transmits the PDCCH / EPDCCH to the terminal 10 in the checked start subframe, and the terminal 10 receives the received signal (S1020).

In FIG. 11, the base station 20 sets CCEs / ECCEs of subframes to be repeatedly transmitted (S1110), and transmits information on these CCEs / ECCEs to the terminal 10 through higher layer signaling (S1120). As a result, since the terminal 10 secures information on the CCE / ECCE to be monitored, the base station 20 repeatedly transmits the PDCCH / EPDCCH to the terminal 10 in the checked start subframe, and the terminal ( 10) receives it (S1130).

An embodiment of the present invention may be configured by selecting and combining the method 1 of FIGS. 8 and 9 and the method 2 of FIGS. 10 and 11, respectively.

Following N repeated PDCCH / EPDCCH candidates, DL subframe (s) for determining m, corresponding PDCCH / EPDCCH candidates in each N DL subframe (s), A method and apparatus for setting a search space for configuring the CCE index (es) or ECCE index (es) allocated for m will be described.

The base station shows a process of transmitting a downlink control channel to the terminal. The base station determines the start subframe of the plurality of downlink subframes in which the downlink control channel is repeatedly transmitted (S1210). The base station determines a search space composed of CCE index (es) or ECCE index (es) constituting a PDCCH or EPDCCH candidate repeatedly transmitted through the plurality of downlink subframes (S1220). The base station repeatedly transmits the downlink control channel through the plurality of downlink subframes based on the determined starting subframe and the CCE index (es) or ECCE index (s) (S1230).

When applying the method 1 of FIG. 8, the step S1210 may include calculating using any one or more of the repetition number N, the aggregation level L, and the slot number n _s . do. This may be preceded by the process of determining the equation or the application method in advance with respect to the terminal using the equation (3) or (4). When applying the method 1 of FIG. 9, the step S1210 further includes setting a subframe index of the start subframe to the terminal through higher layer signaling.

When applying the method 2 of FIG. 10, the step S1220 includes each downlink subframe or slot index where the repeated transmission is performed, the total number of CCEs or ECCEs configured in each downlink subframe, RNTI of the UE, and repeated transmission. It can be calculated using the number N and / or the coupling level L. This may be preceded by the process of determining the equation or the application method in advance with respect to the terminal using the equation (5) or (6). When applying the method 2 of FIG. 11, the step S1220 is a higher layer of information on CCE index (es) or ECCE index (s) allocated to a search space for PDCCH or EPDCCH candidates in the plurality of downlink subframes. The terminal may be configured through high layer signaling.

Higher layer signaling may be one of cell specific higher layer signaling or terminal specific higher layer signaling as described above.

A terminal shows a process of receiving a downlink control channel from a base station. The terminal checks the start subframe of the plurality of downlink subframes in which the downlink control channel is repeatedly transmitted (S1310). In operation S1320, the UE identifies CCE index (es) or ECCE index (s) allocated to a search space for PDCCH or EPDCCH candidates in the plurality of downlink subframes. Confirmation of the S1310 and S1320 may be performed at the same time or at a time interval. Thereafter, the UE repeatedly monitors the downlink control channel by performing monitoring through the plurality of downlink subframes based on the identified starting subframe and the CCE index (es) or ECCE index (s) (S1330). ).

In case of applying the method 1 of FIG. 8, the confirmation method of S1310 may be performed by the terminal using one or more of the repetition number N, the aggregation level L, and the slot number n _s . The index of the starting subframe may be calculated. This may be preceded by a process of determining an equation or an application scheme with the base station in advance with respect to the use of

Equations

3 or 4. When applying the method 1 of FIG. 9, the checking method of S1310 further includes receiving a subframe index of the starting subframe from the base station through higher layer signaling.

In the case of applying the method 2 of FIG. 10, in order to implement the identification scheme of S1320, the UE may determine each downlink subframe or slot index in which the repetitive transmission is performed and the total CCE or ECCE configured in each downlink subframe. It can be calculated using the number, the RNTI of the terminal, the number of repetitive transmissions N and / or the coupling level L. This may be preceded by the process of determining the equation or the application method in advance with the base station for using the equation (5) or (6). In case of applying the method 2 of FIG. 11, in order to implement the identification scheme of S1320, the UE performs CCE index (es) or ECCE index (s) allocated to a search space for PDCCH or EPDCCH candidates in the plurality of downlink subframes. ) Can be received from the base station through high layer signaling.

Referring to FIG. 14, the base station 1400 according to another embodiment includes a controller 1410, a transmitter 1420, and a receiver 1430.

The control unit 1410 is a downlink control channel transmission method for a machine type communication (MTC) terminal in a 3GPP LTE / LTE-A system required to carry out the above-described present invention. To control the overall operation of the base station.

The transmitter 1420 and the receiver 1430 are used to transmit and receive signals, messages, and data necessary for carrying out the above-described present invention.

In more detail, the base station 1400 transmits a downlink control channel, and for this purpose, the controller 1410 determines a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted and A search space consisting of CCE index (es) or ECCE index (s) constituting a PDCCH or EPDCCH candidate repeatedly transmitted through a downlink subframe is determined. In addition, the transmitter 1420 repeatedly transmits the downlink control channel through the plurality of downlink subframes based on the determined start subframe and the CCE index (es) or ECCE index (es).

In the case of applying the method 1 of FIG. 8, the controller 1410 starts using the at least one of the repetition number N, the aggregation level L, and the slot number n _s . The subframe may be determined. This may be preceded by the process of determining the equation or the application method in advance with respect to the terminal using the equation (3) or (4). When applying the method 1 of FIG. 9, the controller 1410 may control the transmitter 1420 to set the subframe index of the start subframe to the terminal through higher layer signaling.

When applying the method 2 of FIG. 10, the controller 1410 may include each downlink subframe or slot index for which the repetitive transmission is performed, the total number of CCEs or ECCEs configured in each downlink subframe, RNTI of the UE, The CCE index (es) or ECCE index (s) may be determined using the number of repetitive transmissions N and / or the coupling level L. This may be preceded by the process of determining the equation or the application method in advance with respect to the terminal using the equation (5) or (6). When applying the method 2 of FIG. 11, the controller 1410 may provide information on CCE index (es) or ECCE index (s) allocated to a search space for PDCCH or EPDCCH candidates in the plurality of downlink subframes. The transmitter 1420 may be controlled to be set to the terminal through higher layer signaling.

Referring to FIG. 15, a user terminal 1500 according to another embodiment includes a receiver 1530, a controller 1510, and a transmitter 1520.

The receiver 1530 receives downlink control information, data, and a message from a base station through a corresponding channel.

Also, the control unit 1510 sets up a search space for PDCCH monitoring of an MTC terminal in a downlink control channel transmission method for a machine type communication (MTC) terminal in a 3GPP LTE / LTE-A system required to perform the above-described present invention. Control the overall operation of the terminal according to.

The transmitter 1520 transmits uplink control information, data, and a message to a base station through a corresponding channel.

In more detail, the terminal 1500 receives a downlink control channel, and the controller 1510 identifies a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted, and the plurality of downlink control channels. In the downlink subframe, the CCE index (es) or ECCE index (s) allocated to the search space for PDCCH or EPDCCH candidates are identified.

In the case of applying the method 1 of FIG. 8, the controller 1510 starts using the at least one of the repetition number N, the aggregation level L, and the slot number n _s . You can check the subframe. This may be preceded by a process of determining an equation or an application scheme with the base station in advance with respect to the use of

Equations

3 or 4. When applying the method 1 of FIG. 9, the controller 1510 may control the receiver 1530 such that the receiver 1530 receives the subframe index of the start subframe from the base station through higher layer signaling.

When applying the method 2 of FIG. 10, the control unit 1510 may include each downlink subframe or slot index for which the repetitive transmission is performed, the total number of CCEs or ECCEs configured in each downlink subframe, RNTI of the UE, The CCE index (es) or ECCE index (s) may be calculated using the number of repetitive transmissions N and / or the coupling level L. This may be preceded by the process of determining the equation or the application method in advance with the base station for using the equation (5) or (6). When applying the method 2 of FIG. 11, the controller 1510 allocates a search space for PDCCH or EPDCCH candidates in the plurality of downlink subframes to identify the CCE index (es) or ECCE index (es). The receiver 1530 may control the CCE index (es) or ECCE index (es) to be received from the base station through higher layer signaling.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATIONCROSS-REFERENCE TO RELATED APPLICATION

This patent application is filed with Korea Patent Application No. 10-2013-0118593 filed in Korea on October 04, 2013 and Patent Application No. 10-2013-0142479 filed in Korea on November 21, 2013 and June 2014 Patent Application No. 10-2014-0067128 filed with Korea on 02 February claims priority under US Patent Act Article 119 (a) (35 USC § 119 (a)), all of which are hereby incorporated by reference. Incorporated into the application. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims

In the method for the base station transmits a downlink control channel,

Determining a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted;

Physical Channel Downlink Control CHannel (PDCCH) or Enhanced Physical Downlink Control CHannel (EPDCCH) candidate that is repeatedly transmitted through the plurality of downlink subframes. Determining a search space consisting of (Enhanced CCE) index (es); And

And repeatedly transmitting the downlink control channel on the plurality of downlink subframes based on the determined starting subframe and CCE index (es) or ECCE index (s).
The method of claim 1,

The determining of the starting subframe may be performed using any one or more of the repetition number N, the aggregation level L, and the slot number n s .
The method of claim 1,

The determining of the starting subframe further includes setting a subframe index of the starting subframe to the terminal through higher layer signaling.
The method of claim 1,

Determining a search space consisting of the CCE index (es) or ECCE index (es)

Calculated by using each downlink subframe or slot index for the repeated transmission, the total number of CCEs or ECCEs configured in each downlink subframe, the RNTI of the terminal, the number of repeated transmissions N and / or the combined level L Characterized in that the method.
The method of claim 1,

Determining a search space consisting of the CCE index (es) or ECCE index (es)

And setting information on a CCE index (es) or ECCE index (s) allocated to a search space for a PDCCH or EPDCCH candidate in the plurality of downlink subframes to a UE through higher layer signaling.
In a method for receiving a downlink control channel by the terminal,

Identifying a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted;

Control Channel Element (CCE) index or indices allocated to a search space for a Physical Downlink Control CHannel (PDCCH) or Enhanced Physical Downlink Control CHannel (EPDCCH) candidate in the plurality of downlink subframes; Identifying Enhanced CCE) index (es); And

Based on the identified starting subframe and the CCE index (es) or ECCE index (s), performing monitoring through the plurality of downlink subframes and repeatedly receiving the downlink control channel. .
The method of claim 6,

The determining of the starting subframe may be performed using any one or more of the repetition number N, an aggregation level L, and a slot number n s .
The method of claim 6,

Identifying the starting subframe further includes receiving a subframe index of the starting subframe from a base station via higher layer signaling.
The method of claim 6,

Identifying the CCE index (es) or ECCE index (s)

Calculated by using each downlink subframe or slot index for the repeated transmission, the total number of CCEs or ECCEs configured in each downlink subframe, the RNTI of the terminal, the number of repeated transmissions N and / or the combined level L Method comprising the steps.
The method of claim 6,

Identifying the CCE index (es) or ECCE index (s)

And receiving information from a base station through higher layer signaling on CCE index (es) or ECCE index (s) allocated to a search space for a PDCCH or EPDCCH candidate in the plurality of downlink subframes.
The method of claim 6,

In the step of repeatedly receiving the downlink control channel by performing monitoring through the plurality of downlink subframes,

Monitoring the same physical downlink control channel (PDCCH) or enhanced physical downlink control channel (EPDCCH) candidate within a repetition window repeatedly received through the plurality of downlink subframes.
A base station transmitting a downlink control channel,

The start subframe of the plurality of downlink subframes in which the downlink control channel is repeatedly transmitted is determined, and the physical downlink control channel (PDCCH) or enhanced physical downlink (EPDCCH) is repeatedly transmitted through the plurality of downlink subframes. A control unit for determining a search space consisting of Control Channel Element (CCE) index (es) or Enhanced CCE (ECCE) index (s) constituting a Control CHannel candidate; And

And a transmitter for repeatedly transmitting the downlink control channel through the plurality of downlink subframes based on the determined starting subframe and the CCE index (es) or ECCE index (s).
The method of claim 12,

The controller determines the start subframe using any one or more of the repetition transmission number N, the aggregation level (L), the slot number (slot number) n s .
The method of claim 12,

And the control unit controls the transmitter to set the subframe index of the start subframe to the terminal through higher layer signaling.
The method of claim 12,

The control unit uses each downlink subframe or slot index for which the repetitive transmission is performed, the total number of CCEs or ECCEs configured in each downlink subframe, the RNTI of the UE, the number of repetitive transmissions N, and / or the combined level L. And control so that a search space consisting of the CCE index (es) or ECCE index (s) is determined.
The method of claim 12,

The controller is configured to configure information on a search space consisting of a CCE index (es) or ECCE index (s) allocated to a search space for a PDCCH or EPDCCH candidate in the plurality of downlink subframes through higher layer signaling. And a base station for controlling the transmitter.
In a terminal for receiving a downlink control channel,

Identify a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; and identify a physical downlink control channel (PDCCH) or an enhanced physical downlink control channel (EPDCCH) candidate in the plurality of downlink subframes A control unit for identifying a control channel element (CCE) index (es) or enhanced CCE (ECCE) index (s) allocated to a search space for the control space; And

A terminal including a receiver for repeatedly receiving the downlink control channel by monitoring through the plurality of downlink subframes based on the identified starting subframe and the CCE index (s) or ECCE index (s). .
The method of claim 17,

The control terminal is characterized in that to determine the starting sub-frame by using the number of iterative transfer times (repetition) N, bonding level (aggregation Level) L, slot number (slot number) n s one or more of.
The method of claim 17,

The control unit uses each downlink subframe or slot index for which the repetitive transmission is performed, the total number of CCEs or ECCEs configured in each downlink subframe, the RNTI of the UE, the number of repetitive transmissions N, and / or the combined level L. To calculate the CCE index (es) or ECCE index (s).
The method of claim 17,

The control unit may assign a CCE index (es) or ECCE index (s) allocated to a search space for PDCCH or EPDCCH candidates in the plurality of downlink subframes to identify the CCE index (es) or ECCE index (s). And controlling the receiver to receive information about the information from the base station through higher layer signaling.