WO2015050359A1

WO2015050359A1 - Method for transmitting and receiving downlink control channel, and apparatus therefor

Info

Publication number: WO2015050359A1
Application number: PCT/KR2014/009184
Authority: WO
Inventors: 박규진; 최우진
Original assignee: 주식회사 케이티
Priority date: 2013-10-04
Filing date: 2014-09-30
Publication date: 2015-04-09

Abstract

The present invention provides a method and an apparatus for limiting downlink subframes, where a control channel which is repeated arbitrary N times starts, to a subset of downlink subframes which have been set in a relevant cell, and for determining a subset of starting downlink subframes where a relevant control channel starts.

Description

Method for transmitting / receiving downlink control channel and apparatus therefor

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 repeatedly transmitting a downlink control channel in a plurality of subframes 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. On the other hand, when the PDCCH (Enhanced Downlink Control CHannel) or EPDCCH (Enhanced Physical Downlink Control CHannel) transmission for the low-cost MTC terminal, if the repetition for the corresponding channel is supported, a method for smoothly decoding the PDCCH or EPDCCH in the MTC terminal This is necessary.

An object of the present invention is to provide a method and apparatus for repeatedly transmitting a downlink control channel in a plurality of subframes in order to overcome the above problems.

According to an embodiment of the present invention, a method of transmitting a downlink control channel to a user equipment by a base station includes: determining a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; And repeatedly transmitting the downlink control channel through the plurality of downlink subframes based on the determined starting subframe.

According to another embodiment of the present invention, a method for receiving a downlink control channel from a base station by a terminal, the method comprising: determining a start subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; And repeatedly receiving the downlink control channel through the plurality of downlink subframes based on the determined starting subframe.

Another embodiment of the present invention provides a base station for transmitting a downlink control channel to a terminal, including: a control unit for determining a starting subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; And a transmitter for repeatedly transmitting the downlink control channel through the plurality of downlink subframes based on the determined starting subframe.

Another embodiment of the present invention provides a terminal for receiving a downlink control channel from a base station, comprising: a controller for determining a starting subframe of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; And a receiver configured to repeatedly receive the downlink control channel through the plurality of downlink subframes, based on the determined starting subframe.

According to the present invention described above, the downlink control channel can be repeatedly transmitted in a plurality of subframes.

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

2 is a diagram illustrating an example of a method for a general terminal to blind decode a PDCCH / EPDCCH and receive a PDSCH.

4 shows four PDCCH formats.

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

5 is a diagram for a supported EPDCCH format.

6 is a diagram illustrating an example of a method of blind decoding a PDCCH / 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.

8 is a diagram illustrating a process of repeatedly transmitting a PDCCH / EPDCCH through a plurality of subframes by a base station according to an embodiment of the present invention.

9 is a diagram illustrating a process of repeatedly transmitting a PDCCH / EPDCCH through a plurality of subframes by a base station according to another embodiment of the present invention.

FIG. 10 is a diagram illustrating a process of transmitting, by a base station, a PDCCH / EPDCCH to a mobile station through a search space according to an embodiment of the present invention.

FIG. 11 is a diagram illustrating a process of transmitting a PDCCH / EPDCCH to a user equipment through a search space by a base station according to another embodiment of the present invention.

12 is a diagram illustrating a configuration of a base station according to an embodiment of the present invention.

13 is a diagram illustrating a configuration of a terminal according to an embodiment of the present invention.

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 addition, 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.

Hereinafter, in the present specification, MTC_CSS-RNTI means an identifier for identifying MTC-only CSS.

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) 10 and a base station (Base Station, BS, or eNB) 20. 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 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, a Site, and a BTS. Other terms such as a base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell may be called.

In other words, in the present specification, a base station or a cell is a generic meaning indicating some areas or functions covered by a base station controller (BSC) in CDMA, a Node-B in WCDMA, an eNB or a sector (site) in LTE, and the like. It should be interpreted as, and it is meant to cover all the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, small cell communication range.

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 this specification, a cell may mean a component carrier having coverage of a signal transmitted from a base station or coverage of a signal transmitted from a base station, and the base station itself.

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 system in which two or more base stations cooperate to transmit a signal. transmission system), a cooperative multi-cell communication system. The CoMP system may include at least two multiple base stations 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 or receiving a PDCCH or transmitting or receiving a signal through the PDCCH may be used as a meaning including transmitting or receiving an EPDCCH or transmitting or receiving a signal through the EPDCCH.

That is, the 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 EPDCCH 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 20 performs downlink transmission to the terminals 10. The base station 20 is a downlink control information and uplink data channel such as a physical downlink shared channel (PDSCH), which is a main physical channel for unicast transmission, and scheduling required for reception of the PDSCH. A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in (eg, 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. If the UE checks the DCI transmitted to the UE 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 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. 3, 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 FIG. 5 for link adaptation for DCI transmission.

LTE 기반의 저가형 MTCLTE 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, a technique such as narrowband support / single RF chain / half duplex FDD / Long DRX (Discontinued Reception) may be mentioned. 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.

In order to improve coverage while lowering the LTE MTC terminal price, robust boost such as PSD (Power Spectral Density) boosting or low coding rate and time domain repetition Various methods for transmission are 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, the PDCCH / EPDCCH for transmitting scheduling control information or other downlink control information for any one terminal or terminal group is transmitted through one downlink subframe.

However, in order for the low-cost MTC terminal to support 20dB improved coverage compared to the general LTE terminal, it is necessary to repetitively transmit PDCCH or EPDCCH transmissions made in one downlink subframe unit through a plurality of downlink subframes. have. In addition, the MTC terminal also needs to perform decoding by combining PDCCHs or EPDCCHs received through the plurality of downlink subframes.

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.

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, a method for setting a PDCCH search space for an MTC terminal is defined.

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

This is made up. At this time

Level, L (where,

ECCE corresponding to 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,

Denotes a Carrier Indicator Field (CIF) value included in the DCI.) In addition,

Has the value of,

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

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

Additionally in Equation 1 above

The value is set to 9 for a common search space and determined by Equation 2 below for a UE-specific search space.

[Equation 2]

Where each

(

Has a slot number).

Meanwhile, in the case of a UE configured to receive DCI through EPDCCH in the existing 3GPP LTE / LTE-Advanced system, a set of PDCCH candidates defined to monitor for receiving downlink control information in any downlink subframe k is set. Search space for the terminal (search space),

This is made up. At this time, for EPDCCH-PRB set p,

Level L (where,

ECCE corresponding to any PDCCH candidate m with) is determined by Equation 3 below.

[Equation 3]

here

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

Has a value of and no cross-carrier scheduling is set

Has the value (only,

Has the value of,

Represents the number of EPDCCH candidates defined for the UE to monitor for the aggregation level L in EPDCCH-PRB-set p,

Denotes the number of ECCEs constituting the EPDCCH control region in EPDCCH-PRB-set p and downlink subframe k.

Additionally in Equation 3 above

The value of is determined by Equation 4 below.

[Equation 4]

Where

(

Has a slot number).

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

Accordingly, in order to determine a search space constituting any N repeated PDCCH / EPDCCH candidates m with the number of repetitions defined as N, 1) a downlink subframe index constituting the corresponding N repeated PDCCH / EPDCCH candidates is determined. 2) A search space configuration expression defining a CCE index constituting the PDCCH / EPDCCH candidate m repeated N times in each N downlink subframes may be defined.

Embodiment 1: Downlink Subframe in which PDCCH / EPDCCH Repeat for MTC UE Starts

As a first example, a method of determining a downlink subframe constituting PDCCH / EPDCCH candidate m repeated N times is proposed.

Particularly, in the present invention, a downlink subframe in which the corresponding PDCCH / EPDCCH repetition is started for any N repeated PDCCH / EPDCCH candidate m is limited to a subset of downlink subframes configured in the corresponding cell, and corresponding PDCCH / We propose a method for determining a starting DL subframe subset in which EPDCCH repetition is started.

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.

Referring to FIG. 8, the downlink subframe k _{start, n} at which the start of the corresponding PDCCH / EPDCCH repetition is performed in the terminal 10 and the base station 20 is determined by the number N of the corresponding PDCCH / EPDCCH repetitions and / or the coupling level L. It may be determined (S810).

As one embodiment of this

May be determined as a value satisfying Equation 5 below.

[Equation 5]

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

Denotes a slot number. However, the mod value of Equation 5 may be defined to have an arbitrary natural value smaller than N, not 0, and the value is defined as a fixed value or UE-specific for MTC terminal. Or, it may be set through cell-specific Radio Resource Control (RRC) signaling or may be determined as a function of C-RNTI of the corresponding MTC terminal. In addition, the α value may have any natural value.

Alternatively, as shown in Equation 6 below, the coupling level L may also define the corresponding DL subframe (s) as a parameter of the determination equation. The β value may also have any natural value.

[Equation 6]

Equations

5 and 6 above are only embodiments for determining a downlink subframe in which the corresponding PDCCH / EPDCCH repetition is performed as a function of the number of repetitions N or a function of the number of repetitions N and the coupling level L, but the present invention is not limited thereto. Rather, other types of equations for determining a downlink subframe as a function of N or a function of N and L may be included in the scope of the present invention.

In addition, the base station 20 may repeatedly transmit the PDCCH / EPDCCH to the UE through the N subframes determined as described above (S820).

Referring to FIG. 9, as another method of determining a downlink subframe index k _{start, n at} which a corresponding PDCCH / EPDCCH transmission is started to define a downlink subframe constituting N repeated PDCCH / EPDCCH candidates m; The base station 20 directly sets the corresponding start subframe index value according to the number of repetitions N (S910), and performs the cell-specific or UE-specific higher layer signaling (S910). It may be transmitted to each MTC terminal through higher layer signaling (S920).

As an example of a method of setting a start downlink subframe index k _{start, n} for monitoring N repeated PDCCH / EPDCCH candidate m based on the higher layer signaling, the corresponding N times repeated PDCCH for a downlink subframe of a certain period The starting downlink subframe index for monitoring the / EPDCCH candidate m may be set in a bitmap manner to be signaled.

Subframe offset value k _start, off for k _{start, n} as another method of starting downlink subframe index k _{start, n} for monitoring N repeated PDCCH / EPDCCH candidate m based on the upper layer signaling And period P may be set to signal it. In this case, the start downlink subframe for transmitting the N times repeated PDCCH / EPDCCH may be defined repeatedly with a P subframe period based on the corresponding k _{start and offset} . However, the downlink subframe index k _{start, n} may be set to a separate value according to the PDCCH / EPDCCH repetition number N value defined to be monitored by the corresponding MTC terminal, or one regardless of the repetition number N value. The downlink subframe index k _{start, n} is set and can be commonly applied to all the repetition times.

As another method for defining a downlink subframe constituting the N repeated PDCCH / EPDCCH candidates m, the N downlink subframe index constituting the corresponding N repeated PDCCH / EPDCCH candidates m is selected from the base station. Each MTC terminal may be configured directly through cell-specific or UE-specific higher layer signaling. In this case, the corresponding N downlink subframes may be allocated discontinuously, and for this purpose, N downlink subframes having a constant period P may be defined. In this case, the corresponding N downlink subframes include all DL subframes in the corresponding period P (the number of downlink subframes in the case of FDD may be P, and the number of corresponding downlink subframes may be smaller than P in the case of TDD). It can be allocated in a bitmap manner, but does not limit the specific signaling scheme for allocating the corresponding N downlink subframes.

In addition, the base station 20 may repeatedly transmit PDCCH / EPDCCH to the terminal through N subframes configured as described above and the configuration information transmitted to the terminal through higher layer signaling (S930).

In addition, while the above schemes focus on PDCCH repetition, it is clear that the same concept can be applied to EPDCCH repetition. However, when a DCI for an arbitrary MTC terminal is configured to be transmitted through an EPDCCH, in applying the above method, a downlink subframe as a target is limited to an EPDCCH monitoring subframe included in a corresponding EPDCCH configuration RRC signaling. Can be. That is, according to the above-described schemes, the definition of the start downlink subframe of the EPDCCH repetition and the N downlink subframes in which the EPDCCH repetition including the same is performed may be defined by applying the above method in the corresponding EPDCCH monitoring subframes. have.

Example 2 Search Space Configuration for N Repeated PDCCH / EPDCCH

Following the downlink subframe determination method for the configuration of the above-described N times repeated PDCCH / EPDCCH candidate m, a search for configuring the CCE / ECCE index allocated for the corresponding PDCCH / EPDCCH candidate m in each N downlink subframes. Suggest ways to set up space.

Referring to FIG. 10, the base station 20 and the terminal 10 determine a PDCCH or EPDCCH search space for each downlink subframe (S1010).

As the first method of determining a search space constituting the corresponding N times repeated PDCCH candidate m in each downlink subframe, the existing equation (1) may be applied. That is, according to this, a search space {configured in each downlink subframe for N repeated PDCCH candidates m for an arbitrary MTC terminal {

} May be determined as in Equation 1.

Alternatively, as another method of determining a search space constituting the corresponding N times repeated PDCCH candidate m in each downlink subframe, Equation 7 and N below are added as parameters to the modified {

} Can be defined.

[Equation 7]

However, Equation 7 above is only one embodiment of the search space determination equation including the number of repetitions N as a parameter, and 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.

Meanwhile, it is possible to apply the existing equation (3) as the first method of determining the search space constituting the corresponding N repeated EPDCCH candidate m in each downlink subframe. That is, according to the search space is set in each downlink subframe for the N repeated PDCCH candidate m for any MTC terminal {

} May be determined as in Equation 3.

Alternatively, as another method of determining a search space constituting a corresponding N repeated PDCCH candidate m in each downlink subframe, Equation 8 and N below are added as parameters to the modified {

} Can be defined.

[Equation 8]

However, Equation (8) above is only one embodiment of the search space determination formula including the repetition number 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.

The base station 20 transmits downlink control information to the terminal 10 through the determined search space (S1020).

Referring to FIG. 11, the base station 20 and the terminal 10 identify a PDCCH or EPDCCH search space based on a specific subframe (for example, a starting subframe) among downlink subframes in which PDCCH or EPDCCH is repeatedly transmitted. Determine (S1110).

As another method of determining a search space constituting the corresponding N times repeated PDCCH / EPDCCH candidate m in each downlink subframe _, by the CCE / ECCE index defined in the downlink subframe #k _{start, n} A CCE / ECCE index allocated in a subsequent downlink subframe may be defined. That is, N PDCCH / EPDCCH 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. In this case, CCE / ECCE allocated in each subsequent N-1 downlink subframes from downlink subframe k _{start, n} +1 to k _{start, n} + N-1 for transmission of the corresponding N times repeated PDCCH / EPDCCH. The index may be defined to use the same CCE / ECCE index used for transmitting the corresponding PDCCH in k _{start, n} , which is the first downlink subframe. That is, in case of PDCCH, the CCE index in the first downlink subframe #k _{start, n} constituting the candidate m repeated N times according to Equation 1 or Equation 7 above.

The CCE index constituting the corresponding PDCCH candidate m repeated N times in downlink subframe # (k _{start, n} +1) to downlink subframe # (k _{start, n} + N-1) is determined accordingly.

Can be defined to follow. In case of EPDCCH, the ECCE index in the first downlink subframe #k _{start, n} constituting the corresponding N repeated candidate m by Equation 3 or Equation 8 above.

The ECCE index constituting the corresponding N repeated EPDCCH candidates m in downlink subframe # (k _{start, n} +1) to downlink subframe # (k _{start, n} + N-1) is determined accordingly.

Can be defined to follow.

In addition, the base station 20 transmits downlink control information to the terminal 10 through the determined search space (S1120).

Search Space Setting Method of the Invention The above N value may be applied regardless of the value, and the downlink subframe index setting method for the N times repeated PDCCH / EPDCCH candidate m and each downlink subframe In applying the CCE / ECCE method of the configuration is not limited to the combination, and may be included in the scope of the present invention even if the proposed method is applied independently of each other. 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 the method of configuring the N times repeated EPDCCH candidate.

Referring to FIG. 12, the base station 1200 may include a controller 1210, a transmitter 1220, and a receiver 1230.

The controller 1210 may control the overall operation of the base station 1200. In particular, the controller 1210 performs a downlink subframe in which a corresponding PDCCH / EPDCCH transmission is repeatedly performed for a PDCCH / EPDCCH candidate m repeatedly transmitted N times to perform the above-described embodiments. It may be limited to a subset of all downlink subframes set in. For example, the controller 1210 may limit a start subframe of a downlink subframe in which PDCCH / EPDCCH transmission is repeatedly performed to a subset of a downlink subframe set in a corresponding cell. For example, the starting subframe may include at least one of the number N of the plurality of downlink subframes in which PDCCH / EPDCCH is repeatedly transmitted, the coupling level L of the downlink control information, and the identifier (eg, C-RNTI) of the UE. It can be determined based on.

The transmitter 1220 and the receiver 1230 may be used to transmit and receive signals, messages, data, and the like, necessary to perform the above-described embodiment. In particular, the transmitter 1220 may repeatedly transmit PDCCH / EPDCCH through a plurality of downlink subframes determined by the controller 1210.

In some embodiments, the transmitter 1220 may transmit information on a plurality of downlink subframes in which PDCCH / EPDCCH is repeatedly transmitted to the terminal through higher layer signaling. The information on the plurality of downlink subframes in which PDCCH / EPDCCH is repeatedly transmitted may include information about the start subframe of the plurality of downlink subframes or information on each of the plurality of downlink subframes. The higher layer signaling may be higher layer signaling specific to the terminal or higher layer signaling specific to the cell.

13 is a diagram illustrating a configuration of a base station according to an embodiment of the present invention.

Referring to FIG. 13, the terminal 1300 may include a controller 1310, a transmitter 1320, and a receiver 1330.

The controller 1310 may control the overall operation of the terminal 1300. In particular, the control unit 1310 performs a downlink subframe in which a corresponding PDCCH / EPDCCH transmission is repeatedly performed for a PDCCH / EPDCCH candidate m repeatedly transmitted N times in order to perform the aforementioned embodiments. It may be limited to a subset of all downlink subframes set in. For example, the controller 1310 may limit a start subframe of a downlink subframe in which PDCCH / EPDCCH transmission is repeatedly performed to a subset of a downlink subframe set in a corresponding cell. For example, the starting subframe may include at least one of the number N of the plurality of downlink subframes in which PDCCH / EPDCCH is repeatedly transmitted, the coupling level L of the downlink control information, and the identifier (eg, C-RNTI) of the UE. It can be determined based on.

The transmitter 1320 and the receiver 1330 may be used to transmit and receive signals, messages, data, and the like necessary for performing the above-described embodiment with the base station. In particular, the receiver 1330 may repeatedly receive the PDCCH / EPDCCH through a plurality of downlink subframes determined by the controller 1310.

In some embodiments, the receiver 1330 may receive information on a plurality of downlink subframes in which PDCCH / EPDCCH is repeatedly transmitted from the base station through higher layer signaling. The information on the plurality of downlink subframes in which PDCCH / EPDCCH is repeatedly transmitted may include information about the start subframe of the plurality of downlink subframes or information on each of the plurality of downlink subframes. The higher layer signaling may be higher layer signaling specific to the terminal or higher layer signaling specific to the cell.

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 Korean Patent Application No. 10-2013-0118593 filed with Korea on October 04, 2013 and Patent Application No. 10-2013-0142474 filed with Korea on November 21, 2013 and March 2014. Priority is claimed to Korean Patent Application No. 10-2014-0026752 filed to Korea on the 06th in accordance with US Patent Law 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 transmitting a downlink control channel to the terminal by the base station,

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

Based on the determined starting subframe, repeatedly transmitting the downlink control channel on the plurality of downlink subframes.
The method of claim 1,

The starting subframe is a subset of the entire downlink subframe.
The method of claim 1,

The starting subframe is determined based on at least one of the number of the plurality of subframes, the combined level of downlink control information, and the identifier of the terminal.
The method of claim 1,

And transmitting the information on the starting subframe to the terminal through higher layer signaling specific to the terminal or higher layer signaling specific to the cell.
The method of claim 1,

And transmitting information on the plurality of subframes to the terminal through higher layer signaling specific to the terminal or higher layer signaling specific to the cell.
In a method for receiving a downlink control channel from a base station,

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

Based on the determined starting subframe, repeatedly receiving the downlink control channel through the plurality of downlink subframes.
The method of claim 6,

The starting subframe is a subset of the entire downlink subframe.
The method of claim 6,

The starting subframe is determined based on at least one of the number of the plurality of subframes, the combined level of downlink control information, and the identifier of the terminal.
The method of claim 6,

The determining may further include receiving information on the starting subframe from the base station through higher layer signaling specific to a terminal or higher layer signaling specific to a cell.
The method of claim 6,

The determining may further include receiving information on the plurality of subframes from the base station through higher layer signaling specific to a terminal or higher layer signaling specific to a cell.
In the base station for transmitting a downlink control channel to the terminal,

A controller configured to determine start subframes of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; And

And a transmitter for repeatedly transmitting the downlink control channel through the plurality of downlink subframes based on the determined starting subframe.
The method of claim 11,

The starting subframe is a subset of the entire downlink subframe.
The method of claim 11,

The starting subframe is determined based on at least one of the number of the plurality of subframes, the combined level of downlink control information, and the identifier of the terminal.
The method of claim 11,

The transmitter, the base station, characterized in that further transmitting to the terminal via the higher layer signaling specified in the terminal or the higher layer signaling specified in the terminal.
The method of claim 11,

The transmitter, the base station, characterized in that for transmitting the information on the plurality of sub-frames to the terminal via higher layer signaling specific to the terminal or higher layer signaling specific to the cell.
In a terminal receiving a downlink control channel from a base station,

A controller configured to determine start subframes of a plurality of downlink subframes in which the downlink control channel is repeatedly transmitted; And

And a receiver configured to repeatedly receive the downlink control channel through the plurality of downlink subframes based on the determined starting subframe.
The method of claim 16,

The starting subframe is a subset of the entire downlink subframe.
The method of claim 16,

The starting subframe is determined based on at least one of the number of the plurality of subframes, the combined level of downlink control information, and the identifier of the terminal.
The method of claim 16,

The receiving unit further receives information on the start subframe from the base station through higher layer signaling specified in a terminal or higher layer signaling specified in a cell,

The controller determines the start subframe based on the information on the start subframe.
The method of claim 16,

The receiver further receives information on the plurality of subframes from the base station through higher layer signaling specified in a terminal or higher layer signaling specified in a cell,

The control unit, characterized in that for determining the start subframe based on the information on the plurality of subframes.