KR20170037502A - Methods for transmitting and receiving downlink control information and Apparatuses thereof - Google Patents

Abstract

The present disclosure relates to a method of transmitting and receiving downlink control information and an apparatus thereof. Particularly, the present disclosure relates to a method and apparatus for configuring a UE-USS when a downlink control search space is configured for a low complexity UE category/type for a machine type communication (MTC) operation or a terminal that supports coverage enhancement. Particularly, the method for an MTC terminal to receive downlink control information may include: receiving a higher layer signaling including at least one among maximum repetition level information and offset information; calculating a location of a start subframe where the repetitive transmission of a downlink control channel starts by using a higher layer signaling; monitoring a UE-specific search space in two or more subframes including the start subframe; and repetitively receiving a downlink control channel including downlink control information through the UE-specific search space.

Description

[0001] The present invention relates to a method and apparatus for transmitting and receiving downlink control information,

The present invention relates to a method and apparatus for transmitting / receiving downlink control information. More particularly, the present invention relates to a method and apparatus for searching for a downlink control channel for a terminal supporting a low complexity UE category or a coverage enhancement operation for an MTC (Machine Type Communication) To a method and apparatus for constructing a UE-specific search space (USS).

Machine type communication (hereinafter referred to as "MTC" communication) is a type of data communication in which one or more entities represent a machine to machine communication that does not necessarily require human interaction . MTC communication that does not require human interaction refers to all communication methods in which communication is performed without human intervention in the communication process.

The MTC terminal can be installed in a place where the radio wave environment is worse than that of a general terminal. It is necessary to repeatedly transmit control information and / or data of each physical channel transmitted only in one subframe in a plurality of subframes in order for the MTC terminal to operate in a place where the propagation environment is worse than the general terminal.

On the other hand, in the case of the MTC terminal, the degree of coverage expansion required according to the radio channel environment may be different, and the number of repetitive transmissions and the transmission power may be set differently according to a plurality of coverage extension levels in one cell.

In this case, when the same UE-specific search space is set for the MTC terminal having various coverage extension levels located in one cell, inefficient use of radio resources due to repetitive transmission or the like may occur.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a method and apparatus for clearly identifying a UE-specific search space for transmitting downlink control information for an MTC terminal supporting coverage extension.

Another object of the present invention is to provide a method and apparatus for determining a position of a start subframe in which repeated transmission occurs when repeatedly transmitting downlink control information for a MTC terminal through a plurality of subframes.

According to an aspect of the present invention, there is provided a method for receiving downlink control information by a MTC (Machine Type Communication) terminal, the method comprising: receiving upper layer signaling including at least one of maximum repeat level information and offset information; Calculating a position of a start subframe in which repeated transmission of a downlink control channel starts using upper layer signaling, monitoring a terminal specific search space in two or more subframes including a start subframe, And repeatedly receiving a downlink control channel including downlink control information through a space.

According to another aspect of the present invention, there is provided a method for transmitting downlink control information in a base station, the method comprising: transmitting an upper layer signaling including at least one of maximum repeat level information and offset information to a MTC (Machine Type Communication) Determining a start subframe of a downlink control channel for the MTC terminal and repeatedly transmitting a downlink control channel including downlink control information through at least two subframes including a start subframe, ≪ / RTI >

According to another aspect of the present invention, there is provided a MTC (Machine Type Communication) terminal for receiving downlink control information, comprising: a receiver for receiving an upper layer signaling including at least one of maximum repeat level information and offset information; A controller for calculating a position of a start subframe in which repeated transmission of a control channel starts and monitoring a terminal specific search space in two or more subframes including a start subframe, The MTC terminal apparatus repeatedly receives a downlink control channel including control information.

According to another aspect of the present invention, there is provided a base station for transmitting downlink control information, comprising: a transmitter for transmitting upper layer signaling including at least one of maximum repeat level information and offset information to a MTC (Machine Type Communication) And a controller for determining a start subframe of a downlink control channel for the MTC terminal, wherein the transmitter includes: a base station for repeatedly transmitting a downlink control channel including downlink control information through two or more subframes including a start subframe; Device.

The present invention described above provides the effect of clearly confirming the UE-specific search space for transmitting the downlink control information to the MTC terminal supporting coverage extension.

Also, in the case where the downlink control information for the MTC terminal is repeatedly transmitted through a plurality of subframes, the position of the start subframe in which the repeated transmission occurs is determined to correctly recognize the repeatedly transmitted downlink control information There is an effect that can receive.

1 is a view for explaining a PDCCH and an EPDCCH for transmitting downlink control information.
FIG. 2 is a signal diagram illustrating a signal flow of an MTC terminal and a base station according to an exemplary embodiment of the present invention. Referring to FIG.
3 is a flowchart illustrating an operation of the MTC terminal according to another embodiment of the present invention.
4 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.
5 is a block diagram illustrating a configuration of an MTC terminal according to another embodiment of the present invention.
6 is a block diagram illustrating a base station configuration according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference numerals even though they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

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

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity 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. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, in the present specification, a base station or a cell has a comprehensive meaning indicating a part or function covered by BSC (Base Station Controller) in CDMA, Node-B in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes 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- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-Advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In a system such as LTE and LTE-A, the uplink and downlink are configured based on one carrier or carrier pair to form a standard. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

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

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or a transmission / reception point of a signal transmitted from a transmission / reception point, and the transmission / reception point itself .

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

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

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

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

1 is a view for explaining a PDCCH and an EPDCCH for transmitting downlink control information.

1, a downlink control channel (e.g., PDCCH or EPDCCH) is used as a physical control channel for transmitting downlink control information (DCI) for a UE in a 3GPP LTE / LTE- Defined.

For example, in the case of a UE connected to a certain cell, a UE-specific search space (USS) defined in the PDCCH or EPDCCH and a common search space (CSS) defined in the PDCCH are monitored do. For example, the UE may receive UE-specific downlink control information scrambled with a Cell-Radio Network Temporary Identifier (C-RNTI) of the UE and an SI-RNTI (System Information-Radio Network Temporary Identifier) Specific downlink control information scrambled with a Paging-Radio Network Temporary Identifier (P-RNTI) or a Random Access-Radio Network Temporary Identifier (RA-RNTI). Also, in the case of an LTE / LTE-Advanced terminal in an idle state, by monitoring the CSS of a cell currently camped on, scheduling information on a paging message for the corresponding terminal or system information And receive the corresponding paging message and system information based on the received scheduling information.

Specifically, for example, the UE includes scheduling information on a SIB (System Information Block) transmission resource, which is CRC-scrambled in an SI-RNTI through a CSS composed of CCE (Control Channel Element) 0 through CCE 15 of the PDCCH DCI including scheduling information for paging messages transmitted by CRC scrambling with DCI and P-RNTI and DCI including scheduling information for RAR (Random Access Response) messages transmitted by CRC scrambling with RA-RNTI As shown in FIG. In addition, monitoring for DCI format 0 / 1A scrambled with the C-RNTI of the corresponding UE including scheduling information for the PDSCH / PUSCH is also performed for the UE fallback operation.

Also, each UE performs monitoring on the UE-specific DCI scrambled with the C-RNTI of the corresponding UE including the scheduling information for the PDSCH / PUSCH through the USS defined on the PDCCH or EPDCCH.

As described with reference to FIG. 1, the conventional terminal monitors the CSS, receives the common control information, and monitors the USS to receive the UE-specific control information. However, in the case of the MTC terminal, the downlink control information can be repeatedly received through a plurality of subframes in a situation where a plurality of MTC terminals having various coverage extension levels exist in an arbitrary cell. In this case, even if the MTC terminal knows the number of repetitive transmissions (for example, repetition level), it is necessary to determine the start subframe in which the repetitive transmission starts, so that accurate downlink control information reception operation can be performed.

Accordingly, the present invention proposes a specific method and apparatus for determining the start sub-frame of the USS for the MTC terminal.

First, the MTC terminal to which the present invention can be applied will be described in detail below.

[Low complexity UE category / type for MTC operation]

As LTE networks grow, mobile operators want to minimize the number of Radio Access Terminals (RATs) to reduce network maintenance costs. However, MTC products based on the conventional GSM / GPRS network are increasing, and MTC using a low data rate is being provided at a low cost. Therefore, there is a problem that the two RATs must be operated respectively, because the LTE network is used for the general data transmission and the GSM / GPRS network is used for the MTC. Therefore, the problem of the inefficient utilization of the frequency band It causes.

To solve this problem, it is necessary to replace a cheap MTC terminal using a GSM / EGPRS network with an MTC terminal using an LTE network. To achieve this, a low complexity UE category that reflects various requirements for lowering the price of an LTE MTC terminal There is a need for the definition of / type and the need for standard techniques to support it.

In addition, about 20% of MTC terminals supporting MTC services such as smart metering are installed in a deep indoor environment such as a basement. Therefore, in order to successfully transmit MTC data, the coverage of LTE MTC terminals is compared with that of conventional LTE terminals 15 dB. Further, considering the performance reduction due to the introduction of the low complexity UE category / type for the MTC operation described above, the coverage of the LTE MTC terminal should be improved by 15 dB or more.

Various methods such as PSD boosting, low coding rate and time domain repetition transmission in order to improve coverage while lowering the price of an LTE MTC terminal are performed for each physical channel .

For example, the requirements of the low complexity UE category / type for MTC operation are as follows.

Reduced UE bandwidth of 1.4 MHz in downlink and uplink.

 ◆ Bandwidth reduced UEs should be able to operate within any system bandwidth.

 ◆ Frequency multiplexing of bandwidth reduced UEs and non-MTC UEs should be supported.

 ◆ The UE only needs to support 1.4 MHz RF bandwidth in downlink and uplink.

■ Reduced maximum transmit power.

Reduced support for downlink transmission modes.

● further UE processing relaxations

 ◆ Reduced maximum transport block size for unicast and / or broadcast signaling.

◆ Reduced support for simultaneous reception of multiple transmissions.

 ◆ Relaxed transmit and / or receive EVM requirements including restricted modulation scheme. Reduced physical control channel processing (e.g., reduced number of blind decoding attempts).

 Reduced physical data channel processing (e.g., relaxed downlink HARQ time line or reduced number of HARQ processes).

 ◆ Reduced support for CQI / CSI reporting modes.

● Target a relative LTE coverage improvement - corresponding to 15 dB for FDD - for the UE category / type defined above and other UEs operating delay tolerant MTC applications with respect to their respective nominal coverage.

● Provide power consumption reduction for the UE category / type defined above, both in normal coverage and enhanced coverage, to target ultra-long battery life:

In the present invention, for convenience of description, an existing LTE terminal is referred to as a normal LTE terminal, and a new low complexity UE category / type satisfying a condition for an MTC operation is referred to as an MTC terminal. In addition, a normal LTE terminal or an MTC terminal supporting a coverage enhancement function or mode is referred to as a MTC terminal or a CE (coverage enhanced) terminal as needed.

[Narrowband definition ]

개의 하향링크 narrowbands 및

개의 상향링크 narrowbands가 구성된다. 여기서,

은 하향링크 자원블럭의 개수이며,

은 상향링크 자원블럭의 개수를 의미한다. In the case of the MTC terminal, transmission / reception is possible only at 1.4 MHz (i.e., 6 PRBs) through arbitrary subframes regardless of the system bandwidth. As a result, the transmission / reception band of an arbitrary MTC terminal in an arbitrary upstream / downstream subframe is defined, and 'narrowband' composed of consecutive 6 PRBs is defined as a unit for allocating the transmission / reception band.

Lt; RTI ID = 0.0 > narrowbands &

Uplink narrowbands are constructed. here,

Is the number of downlink resource blocks,

Denotes the number of uplink resource blocks.

On the other hand, in the narrowband configuration in the arbitrary system bandwidth, for the remaining RB (s) corresponding to the remainder obtained by dividing the total number of PRBs constituting the corresponding system bandwidth by six, the remaining RB (s) band edge, or center of the system band, or center of both edges and the system band, and by using PRBs other than the PRBs, six consecutive PRBs can be grouped together by increasing PRB numbers to form a narrowband.

A description will now be made of a downlink control channel (hereinafter referred to as an M-PDCCH) to which downlink control information of a MTC terminal to which the present invention is applied is transmitted.

[Physical Downlink Control / data Channel for MTC ]

PDCCH and EPDCCH are defined as downlink control channels for transmitting and receiving DCI in a conventional 3GPP LTE / LTE-Advanced Release-12 or lower system. In particular, in a system with Release-10 or lower, a UE transmits a downlink control channel through a PDCCH transmitted through first to third OFDM symbols of all downlink subframes (2 to 4 OFDM symbols when the system bandwidth is 1.4 MHz) I received.

In addition, in the 3GPP LTE / LTE-Advanced Release-11, a new downlink control channel EPDCCH is defined, and any UE receives downlink control information on the PDCCH according to the setup of the base station, It becomes possible to receive information.

Basically, in the LTE / LTE-Advanced system, the reception of the downlink control information is performed by a blind detection method by monitoring a plurality of PDCCH candidates or EPDCCH candidates of the UE. For this purpose, an arbitrary LTE / LTE-Advanced terminal monitors a Common Search Space (CSS) and a UE-specific Search Space (USS) composed of a plurality of PDCCH candidates through a PDCCH region, Lt; RTI ID = 0.0 > EPDCCH < / RTI > candidates. At this time, each PDCCH candidate or EPDCCH candidate may be composed of a set of CCE (Control Channel Element) or ECCE (Enhanced Control Channel Element) which is a basic transmission unit of PDCCH and EPDCCH, respectively. An arbitrary UE may perform a corresponding search to perform monitoring on PDCCH candidates or EPDCCH candidates having a plurality of different aggregation levels to apply link adaptation for transmission and reception of downlink control information, Spaces (CSS and USS) have been defined.

However, unlike the conventional PDCCH / EPDCCH in which transmission is performed through a single downlink subframe, in the case of M-PDCCH, which is a downlink control channel for a MTC terminal newly defined in Release-13, Repetition is required through the downlink subframe. Accordingly, in the case of M-PDCCH, in addition to the existing set level L (L = {1,2,4,8,16,32}, L = {1,2,4,8} for PDCCH) The domain of the number of repetitive transmissions R may be added. In other words, an arbitrary M-PDCCH candidate has a set level L defined by the number of CCEs (or M-CCEs) used for the corresponding M-PDCCH transmission in a single downlink subframe, And the number of repetition times R defined by the number of link subframes. That is, an arbitrary M-PDCCH candidate can be defined as {L, R}, and each MTC terminal has a plurality of M-PDCCH candidates having L and R different from each other according to a coverage level, Can be performed.

Similarly, in transmitting and receiving a downlink data channel (PDSCH) for an MTC terminal, a PDSCH for an arbitrary MTC terminal can be repeatedly transmitted through a plurality of downlink subframes for coverage extension. To this end, the base station transmits a set of PDSCH repetition level (PDSCH repetition level) for specifying the number of repetitive transmissions of the PDSCH according to the coverage level to which the corresponding UE belongs, for each MTC terminal, using a UE-specific RRC signaling signaling, and can dynamically signal the repetition level value to be applied to the corresponding PDSCH through the DCI including the PDSCH assignment information. Here, the repetition level value to be applied to the PDSCH may be determined according to the PDSCH repetition level to be applied in the repetition level set.

In addition, a downlink radio channel for MTC terminals such as M-PDCCH and PDSCH, or a valid subframe for DL transmission capable of transmitting / receiving a downlink radio signal, is also transmitted through the MTC- specific) and broadcast to the MTC terminals in the corresponding cell. That is, the above-described M-PDCCH candidates or PDSCH transmission can be performed only through the DL valid subframe set through the corresponding MTC-SIB1.

As described above, in the case of the MTC terminal, in setting a search space for monitoring M-PDCCH candidates composed of a plurality of {L, R} sets of corresponding M-PDCCH candidates, one M- It is necessary to define the start sub-frame of the search space because it can be configured over a plurality of sub-frames. Therefore, a method for determining a starting sub-frame of a terminal specific search space (USS) for the MTC terminal will be described below. Hereinafter, the M-PDCCH for the MTC terminal can be described as a downlink control channel for ease of understanding.

FIG. 2 is a signal diagram illustrating a signal flow of an MTC terminal and a base station according to an exemplary embodiment of the present invention. Referring to FIG.

Referring to FIG. 2, the MTC terminal 200 according to an embodiment of the present invention transmits an upper layer signaling including a parameter for determining a start sub-frame from which a downlink control channel is repeatedly transmitted, 209) (S210). The upper layer signaling may be an RRC message. In addition, the parameter for determining the starting sub-frame may include at least one of a repetition level and offset information. The maximum repetition level indicates a maximum value among the repetition levels set in the MTC terminal, and the offset information may be a parameter set to be terminal-specific.

The MTC terminal 200 calculates a subframe position where repetitive transmission of the downlink control channel is started using the received parameters (S220). The MTC terminal 200 can repeatedly transmit or receive the same information through a plurality of subframes due to the limitations of coverage and power. To this end, the MTC terminal 200 is assigned a repetition level and an aggregation level, and can perform repetitive transmission and reception accordingly. Therefore, the MTC terminal 200 must know the information of the start subframe in which the repeated transmission of the downlink information starts, so that the MTC terminal 200 can correctly receive the repeatedly transmitted downlink information. To this end, the MTC terminal 200 of the present invention calculates the position of the start sub-frame in which repeated transmission starts using the maximum repeat level information and offset information received through the upper layer signaling. For example, the MTC terminal can identify a starting subframe for receiving a downlink control channel by checking a system frame index and a subframe index specified using the maximum repetition level information and offset information. To this end, a modular function may be used. The specific starting sub-frame position determining method will be described below with reference to each embodiment.

The MTC terminal 200 monitors the UE-specific search space in two or more sub-frames including the start sub-frame (S230). For example, when the location of the starting sub-frame is calculated, the MTC terminal 200 monitors the terminal-specific search space in two or more sub-frames including the corresponding starting sub-frame. The MTC terminal 200 can receive the downlink control information by detecting the downlink control channel repeatedly monitored by monitoring the terminal-specific search space (S250). The UE-specific search space may vary according to the aggregation level of the MTC terminal 200.

Through this, the MTC terminal 200 can clearly confirm the newly started repeated transmission start subframe and monitor the UE-specific search space.

1st Example : A method of calculating a starting sub-frame using starting sub-frame period information and offset information.

A description will be given of an embodiment in which the MTC terminal calculates the period information and offset information of the start sub-frame in calculating the position of the start sub-frame.

The starting subframe of the USS for the MTC terminal may be determined by a period (denoted by Up) and an offset value (denoted by Uo). In addition, the unit of the period and the offset value may be defined in units of a subframe (1 ms) or a radio frame (10 ms), respectively. However, if the period Up and the offset value Uo are determined in units of radio frames, the first DL valid subframe of the corresponding radio frame is divided into the start of the corresponding UE-specific search space (denoted by USS) Can be defined as a subframe.

For convenience of description, Up and Uo values are determined in units of radio frames, and a system frame number (SFN) of a radio frame in which USS starts is described. However, the same method can be applied to derive the corresponding Up or Uo in units of subframes.

The DL valid subframe unit (or period) is denoted by P, and the number of DL valid subframes set in the corresponding P subframe unit is denoted by V. For example, when the corresponding DL valid subframe is configured in units of radio frames, the corresponding DL valid subframe configuration information area is composed of 10 bits of bitmap, and is composed of 10 subframes 0 through 9 constituting one radio frame The DL valid subframe may be set. In this case, the corresponding P value is 10, and if the number of the subframes set in the DL valid subframes is 5 through the bitmap of the corresponding 10 bits, the corresponding V value becomes 5. The number of valid subframes per radio frame will be described as Vr. That is, Vr = V / (P / 10) = 10V / P. However, when a DL valid subframe is allocated in units of radio frames as in the above example, Vr = V.

As an example, the period Up of the USS start sub-frame may be determined as a function of Rmax, Dmax and Vr, respectively, as described above.

For example, the USS start subframe period may be determined by the following equation (1) or (2).

[Equation 1]

&Quot; (2) "

That is, the period of the start subframe may be determined by taking the ceil function for a quotient obtained by dividing the sum of Rmax and Dmax by Vr as in Equation (1) or (2). Alternatively, the period of the starting sub-frame may be determined as a value obtained by adding the ceil function to the quotient obtained by dividing the sum of Rmax and Dmax by Vr plus the offset information Pad received from the base station. The offset information Pad can be set to be UE-specific or cell-specific and can be received from the base station through the above-described upper layer signaling. Alternatively, the offset information may be set to a predetermined value for each of the coverage level or the cell.

Equations (1) and (2) described above are only one example of determining the Up value as a function of Rmax, Dmax, and Vr, but various function expressions using Rmax, Dmax, and Vr as well as the corresponding function formula may be applied. That is, all cases in which the corresponding Up values are determined with the corresponding Rmax, Dmax, and Vr as parameters are included in the scope of the present invention. Alternatively, the starting sub-frame may be determined using at least one of Rmax, Dmax, and Vr as parameters in determining the period Up value of the USS start subframe. For example, the period of the starting sub-frame may be determined through a modulo operation using the maximum repetition level information and the offset information.

On the other hand, an Up value may be explicitly determined and received from the base station as another method of determining Up. In this case, the Up value may be set by the base station through the cell specific upper layer signaling and transmitted to the MTC terminal. The Up value may be set according to the coverage level, or a single value may be set and transmitted regardless of the coverage level It is possible. Alternatively, the Up value may be set by the base station for each MTC terminal and transmitted to each MTC terminal through the terminal-specific upper layer signaling.

In the case of the offset information, the offset information Uo may be determined by UE or by coverage level or by cell identification together with Up. When the corresponding Uo value is allocated for each UE, the corresponding Uo value may be implicitly determined as a function of the C-RNTI value and the n _RNTI of the UE. For example, the corresponding Uo value may be determined through Equation (3).

&Quot; (3) "

Uo = n _RNTI mod Up

Alternatively, the corresponding Uo value may be set for each UE through UE-specific upper layer signaling. If the corresponding Uo value is set for each coverage level or cell specific, the corresponding Uo value may be set through cell specific higher layer signaling.

When the Up and Uo values are determined by the above-described method, the position of the start subframe can be determined as a function of Up and Uo. For example, the starting subframe of the USS may be defined as the first DL valid subframe of a radio frame whose N satisfying Equation 4 is a System Frame Number (SFN).

&Quot; (4) "

N mod Up = Uo

Specifically, for example, if Up is defined by Equation (1) and Uo is determined by Equation (3), the USS start subframe for an arbitrary MTC terminal has an SFN of N that satisfies Equation (5) May be defined as the first DL valid subframe of the radio frame.

&Quot; (5) "

In other words, SFN of the radio frame including the starting sub-frame of the corresponding USS is derived by applying all combinations of the Up determination method and the Uo determination method to Equation (4) and the first DL valid subframe of the corresponding radio frame is allocated to the corresponding USS It may be calculated as a starting sub-frame.

Although the method of calculating the system frame number by extracting the start subframe period and the offset information to calculate the position of the start subframe has been described above, the position of the start subframe may be directly derived. Hereinafter, a method of directly deriving the position of the start sub-frame will be described.

Second Example : A method of calculating the position of a starting sub-frame using maximum repeat level information and offset information.

In the first embodiment, the method of using the SFN and the offset information of the radio frame in calculating the position of the starting sub-frame has been described. However, the index of the starting sub-frame may be derived directly using the parameter received through the upper layer signaling It is possible. In this case, 10 * N + n (where n is a subframe index in the corresponding SFN) can be applied instead of N, which is the SFN value in Equation (5). In determining the Up value to be applied to Equation The index of the starting sub-frame can be derived by applying Equation (2). Alternatively, unlike Equations (1) and (2), it may be determined using only the Rmax value and the offset information (Pad) value. A concrete embodiment using the maximum repetition level information and offset information will be described with reference to FIG.

3 is a flowchart illustrating an operation of the MTC terminal according to another embodiment of the present invention.

The MTC terminal according to an exemplary embodiment of the present invention includes a step of receiving an upper layer signaling including at least one of maximum repeat level information and offset information and a step of receiving a start position of a start subframe in which repeated transmission of a downlink control channel is started Monitoring a UE-specific search space in two or more sub-frames including a start sub-frame, and repeatedly receiving a DL control channel including down-link control information through a UE-specific search space .

Referring to FIG. 3, the MTC terminal may perform a step of receiving an upper layer signaling including at least one of maximum repeat level information and offset information (S300). For example, the MTC terminal can receive maximum repeat level information (e.g., Rmax) and offset information through an RRC message. The maximum repetition level information may be set to be terminal specific. In addition, the offset information may be set to UE-specific or cell-specific. The MTC terminal may receive information on the repetition level and the set level set according to the coverage level and the like, and one or more sets including the repetition level information and the set level information may be received. The highest repetition level information can be the maximum repetition level information. The maximum repetition level information may mean the maximum number of repetitive transmissions allocated to the MTC terminal or may mean the level value itself. For example, for a set of {aggregation level (L), repetition level (R)} pairs constituting M-PDCCH candidates allocated for monitoring by a MTC terminal belonging to an arbitrary coverage level, The maximum value among the values of the repetition level R constituting the set of {L, R} may be the maximum repetition level Rmax. Similarly, the maximum value of the PDSCH repetition level values included in the set of PDSCH repetition level set through the RRC signaling for the MTC terminal may be the maximum repetition level (Dmax).

In addition, the MTC terminal can calculate the position of the start subframe in which the repeated transmission of the downlink control channel starts using the upper layer signaling (S302). The starting sub-frame position may be specified by a system frame index and a sub-frame index. For example, the system frame may be determined by an index of any one of integers from 0 to 1023, and the subframe index may be determined by any one of integers from 0 to 9. [ Through this, the position of the starting service frame can be specified. The system frame may refer to a radio frame in units of 10 ms. The subframe is determined in units of 1 ms.

In addition, the MTC terminal can use the maximum repetition level information and offset information received through the higher layer signaling to calculate the position of the starting sub-frame. For example, the MTC terminal can use the product of the maximum repetition level information and the offset information. As another example, the MTC terminal may calculate the position of the starting sub-frame by calculating the period information and the offset information of the starting sub-frame. As another example, the MTC terminal may calculate the position of a starting sub-frame through a modulo operation using the product of the maximum repetition level information and offset information as a modulus factor. Modular arithmetic is sometimes referred to as conjoint arithmetic as the arithmetic method for the remainder to produce the same specific value. Specifically, the MTC terminal calculates the product of the maximum repetition level information and the offset information as a modulus factor. Using this, the MTC terminal can calculate the position of the start subframe that becomes the remaining 0 through Equation (6) below.

&Quot; (6) "

In Equation (1), T is a product of a maximum repetition level and offset information, n _f is a system frame index, and n _s means a subframe index.

Accordingly, the MTC terminal can obtain the T value using the parameter received through the upper layer signaling, and calculate the system frame index and the subframe index at which the modulo operation value becomes zero.

Alternatively, the MTC terminal may separately calculate the period information and the offset information of the starting subframe to calculate the starting subframe position. This content will be described later as a separate embodiment.

Meanwhile, the MTC terminal may perform a step of monitoring the UE-specific search space in two or more sub-frames including the start sub-frame (S304). When the position of the start sub-frame is determined, the UE-specific search space is monitored in a plurality of sub-frames including the position of the start sub-frame. In the case of the MTC terminal, downlink information may be repeatedly transmitted through a plurality of subframes for coverage extension. Accordingly, the MTC terminal monitors the terminal-specific search space in a plurality of subframes. The UE-specific search space monitored by the MTC terminal may vary according to the aggregation level. The aggregation level and the number of subframes to be monitored by the MTC terminal may be set to be terminal specific. For example, the base station may allocate one or more sets of information, including aggregation level and repetition level, to the UE. The MTC terminal can monitor the UE-specific search space using the set information allocated to the UE. In this case, the information calculated in step S302 may be used for the start sub-frame. Alternatively, the base station may dynamically transmit information indicating a specific set of set information allocated to the MTC terminal to the MTC terminal to set the aggregation level and the repetition level to be used by the MTC terminal. On the other hand, when a plurality of pieces of set information are allocated, information having the largest repetition level included in each of the plurality of sets of information may become the repetition level.

In step S306, the MTC terminal repeatedly receives the downlink control channel including the downlink control information through the UE-specific search space. The MTC terminal repeatedly receives the downlink control channel through the UE-specific search space monitored in a plurality of subframes and decodes the downlink control information included in the downlink control channel. Herein, the downlink control channel means an M-PDCCH defined for the MTC terminal.

Although the MTC terminal has described the monitoring of the UE-specific search space in the above description, the same contents can be applied to the common search space of a specific type. For example, in the case of calculating the starting sub-frame positions of the type 0 and type 2 common search spaces, the same contents as in FIG. 3 can also be applied.

4 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.

4, in a method for transmitting downlink control information, a base station transmits a higher layer signaling including at least one of maximum repeat level information and offset information to an MTC (Machine Type Communication) terminal (S400). The base station can set and transmit the repetition level and the aggregation level pair set for each MTC terminal. The base station may also transmit the offset information used to determine the repeated transmission start sub-frame. The maximum repetition level may mean a max value among the repetition levels. The maximum repetition level information may mean the maximum repetition number of transmissions according to the level value itself or the level value.

In step S402, the base station determines a start subframe of a downlink control channel for the MTC terminal using higher layer signaling. The base station can calculate the position of the starting subframe by using the maximum repetition level information and the offset information for an arbitrary MTC terminal. The position of the starting subframe may be specified by a system frame index and a subframe index as in the second embodiment. Or the position of the start subframe may be determined by the start subframe period information and the offset information as in the first embodiment.

Specifically, the base station can calculate the position of the starting sub-frame by using the product of the maximum repetition level information and the offset information. For example, the base station can calculate the product of the maximum repetition level information and the offset information through a modular arithmetic operation using a modulus factor as shown in Equation (6).

In step S404, the base station repeatedly transmits a downlink control channel including downlink control information through two or more subframes including a start subframe. The base station can repeatedly transmit the downlink control information to the MTC terminal through the terminal-specific search space of the calculated starting subframe. Repetitive transmission may be performed through a plurality of subframes, and the number of repetitive transmissions may be determined by the repetitive transmission level set for each MTC terminal.

The MTC terminal and the base station configuration capable of performing all of the embodiments of the present invention described above will be described again with reference to the drawings.

5 is a block diagram illustrating a configuration of an MTC terminal according to another embodiment of the present invention.

5, the MTC terminal 500 according to another embodiment of the present invention includes a receiver 530 for receiving upper layer signaling including at least one of maximum repeat level information and offset information, and a downlink And a controller 510 for calculating the position of the start sub-frame at which the repeated transmission of the control channel starts and monitoring the UE-specific search space in two or more sub-frames including the start sub-frame. The position of the start subframe may be calculated by period information and offset information, or may be specified by a system frame index and a subframe index.

Also, the receiver 530 can repeatedly receive the downlink control channel including the downlink control information through the UE-specific search space. In addition, the receiving unit 530 receives downlink information, data, and messages from the base station through the corresponding channel.

The control unit 510 controls the overall operation of the MTC terminal 500 according to the determination of the start sub-frame of the USS for the MTC terminal required to perform the above-described present invention. In addition, the controller 510 checks the maximum repeat level information from the set level and repeat level pair set received from the base station, and calculates the position of the start sub-frame through a modulo operation using the product of the maximum repeat level information and the offset information have. Also, the controller 510 can monitor the USS in a plurality of sub-frames from the calculated start sub-frame position.

Meanwhile, the transmitter 520 transmits uplink control information, data, and messages to the base station through the corresponding channel.

6 is a block diagram illustrating a base station configuration according to another embodiment of the present invention.

6, a BS 600 for transmitting downlink control information includes a transmitter 620 for transmitting upper layer signaling including at least one of maximum repeat level information and offset information to an MTC (Machine Type Communication) terminal, And a controller 610 for determining a start sub-frame of a downlink control channel for the MTC terminal using upper layer signaling.

Also, the transmitter 620 may repeatedly transmit the downlink control channel including the downlink control information through two or more subframes including the starting subframe.

The controller 610 may generate the maximum repetition level information from the set level and the repetition level pair set and may calculate the position of the starting sub frame through a modulo operation using the product of the maximum repetition level information and the offset information. In addition, the control unit 610 controls the overall operation of the base station 600 in determining the start sub-frame of the USS for the MTC terminal required to perform the above-described present invention.

The transmitting unit 620 and the receiving unit 630 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the MTC terminal.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and some of the standard documents is added to or contained in the scope of the present invention, as falling within the scope of the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (20)

A method of receiving downlink control information by a MTC (Machine Type Communication)
Receiving an upper layer signaling including at least one of a maximum repeat level information and an offset information;
Calculating a position of a start subframe in which repeated transmission of a downlink control channel starts using the upper layer signaling;
Monitoring a UE-specific search space in two or more sub-frames including the starting sub-frame; And
And repeatedly receiving the downlink control channel including downlink control information through the UE-specific search space. The method according to claim 1,
The position of the start sub-
A system frame index and a subframe index. The method according to claim 1,
The position of the start sub-
The maximum repetition level information and the offset information. The method of claim 3,
The position of the start sub-
The maximum repetition level information and the offset information. The method according to claim 1,
The position of the start sub-
And calculating the product of the maximum repetition level information and the offset information through modular arithmetic with a modulus factor. A method for a base station to transmit downlink control information,
Transmitting an upper layer signaling including at least one of maximum repeat level information and offset information to a MTC (Machine Type Communication) terminal;
Determining a starting subframe of a downlink control channel for the MTC terminal using the higher layer signaling; And
And repeatedly transmitting the downlink control channel including downlink control information through at least two subframes including the starting subframe. The method according to claim 6,
The position of the start sub-
A system frame index and a subframe index. The method according to claim 6,
The position of the start sub-
The maximum repetition level information and the offset information. 9. The method of claim 8,
The position of the start sub-
The maximum repetition level information and the offset information. The method according to claim 6,
The position of the start sub-
And calculating the product of the maximum repetition level information and the offset information through modular arithmetic with a modulus factor. A MTC (Machine Type Communication) terminal for receiving downlink control information,
A receiving unit receiving an upper layer signaling including at least one of a maximum repeat level information and an offset information; And
A position of a start subframe in which repeated transmission of a downlink control channel starts using the upper layer signaling is calculated,
And a controller for monitoring a UE-specific search space in two or more subframes including the start subframe,
The receiver may further comprise:
Wherein the MTC terminal repeatedly receives the downlink control channel including the downlink control information through the UE-specific search space. 12. The method of claim 11,
The position of the start sub-
A system frame index and a subframe index. 12. The method of claim 11,
The position of the start sub-
The maximum repetition level information and the offset information. 14. The method of claim 13,
The position of the start sub-
The maximum repetition level information and the offset information. 12. The method of claim 11,
The position of the start sub-
And calculating the product of the maximum repetition level information and the offset information through a modular arithmetic operation as a modulus factor. A base station for transmitting downlink control information,
A transmitter for transmitting upper layer signaling including at least one of maximum repeat level information and offset information to a MTC (Machine Type Communication) terminal; And
And a controller for determining a starting sub-frame of a downlink control channel for the MTC terminal using the higher layer signaling,
The transmitter may further comprise:
And repeatedly transmits the downlink control channel including downlink control information through at least two subframes including the starting subframe. 17. The method of claim 16,
The position of the start sub-
A system frame index and a subframe index. 17. The method of claim 16,
The position of the start sub-
The maximum repetition level information and the offset information. 19. The method of claim 18,
The position of the start sub-
The maximum repetition level information and the offset information. 17. The method of claim 16,
The position of the start sub-
And calculating a product of the maximum repetition level information and the offset information through a modular arithmetic operation as a modulus factor.

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