WO2015005704A1

WO2015005704A1 - Apparatus and method for transmitting control channel and apparatus and method for receiving control channel in nct-based wireless communication system

Info

Publication number: WO2015005704A1
Application number: PCT/KR2014/006216
Authority: WO
Inventors: 박동현
Original assignee: 주식회사 팬택
Priority date: 2013-07-10
Filing date: 2014-07-10
Publication date: 2015-01-15
Also published as: KR20150007391A

Abstract

Provided are an apparatus and a method for transmitting a control channel, and an apparatus and a method for receiving a control channel in a NCT-based wireless communication system. A base station that transmits the control channel may comprise: a cluster configuring unit for configuring a cluster by clustering a plurality of pairs of physical resource blocks (PRBs); and a transmission unit for transmitting an enhanced physical downlink control channel (EPDCCH) to a terminal on the basis of the configured cluster.

Description

Control channel transmission device, transmission method, reception device and reception method in NCT-based wireless communication system

The present invention relates to wireless communication, and more particularly, a control considering a special subframe having a relatively small number of orthogonal frequency division multiplexing (OFDM) symbols in a wireless communication system based on a new carrier type (NCT). A channel transmitting apparatus, a transmitting method, a receiving apparatus, and a receiving method.

In a time division duplex (TDD) system, one frame may be composed of ten subframes having a length of 1 ms (millisecond), and each subframe is a downlink subframe It may consist of any one of an uplink subframe and a special subframe. Here, a subframe that is not a special subframe is called a normal subframe by distinguishing it from the special subframe. For example, a normal subframe includes a downlink subframe and an uplink subframe in a TDD system, and includes a subframe in a frequency division duplex (FDD) system. The special subframe includes a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS) field.

Meanwhile, in a wireless communication system, an extended physical downlink control channel (EPDCCH: Extended-PDCCH) may be used for the purpose of extending the capacity of the PDCCH in addition to the physical downlink control channel (PDCCH). have. EPDCCH may also be referred to as an enhanced physical downlink control channel.

Like the PDCCH, the EPDCCH may be transmitted not only in the normal subframe but also in the special subframe. However, since there is a very small number of resource elements (REs) available for transmitting the EPDCCH during the special subframe configuration, the PDSCH and the EPDCCH cannot be transmitted in the special subframe configuration. Only PDCCH can be transmitted.

Meanwhile, in the conventional multiple component carrier (CC) system using a component carrier (CC), the versatility of the physical layer is emphasized. Therefore, in the multi-component carrier system, control area redundancy and common signal overhead still exist, thereby reducing resources for the data signal, thereby causing unnecessary loss in spectral efficiency. Accordingly, new carrier types (NCTs) are being considered for efficient operation in next generation wireless communication systems.

In NCT, a reference signal (RS) for downlink control channel or channel estimation within a range that does not reduce or minimize performance as compared to legacy carrier type (LCT). Can be removed or reduced. This is to obtain the maximum data transmission efficiency. The existing carrier is distinguished from this NCT and is referred to as backward compatible carrier type (BCCT).

The NCT may include non-standalone NCT and standalone NCT. Non-standalone NCT is an NCT that may not exist in the form of a single cell and may exist in the form of a secondary serving cell (SCell) when a primary serving cell (PCell) exists. On the other hand, standalone NCT is an NCT that can exist in the form of a single cell (eg, Jussie bilcell).

In such an NCT, a CRS for demodulation except for a reference signal (TRS: Tracking RS or RCRS: Reduced CRS) used for synchronization may not be transmitted and a physical downlink control channel (PDCCH) is used. The physical HARQ indicator channel (PHICH) and the physical control format indicator channel (PCFICH) may be removed or replaced with another type of channel.

As such, since the PDCCH may not be transmitted in the NCT, the EPDCCH may be transmitted in a special subframe by using resource elements used to transmit the PDCCH in the existing LCT.

However, there may be a case where resources for EPDCCH transmission are relatively small. For example, the special subframe configuration may have a relatively small number of resource elements for EPDCCH transmission as compared to the normal subframe. In this case, there are practically many restrictions on transmitting the EPDCCH in the special subframe configuration. The same applies to the case where the number of resource elements for EPDCCH transmission is small.

Therefore, there is a need for a method that can effectively transmit EPDCCH even in a situation where there are a relatively small number of resource elements.

The present invention provides a control channel transmitting apparatus, a transmitting method, a receiving apparatus, and a receiving method in a wireless communication system.

Another technical problem of the present invention is to provide a method and apparatus that can effectively transmit and receive an EPDCCH even in a situation where there are a small number of resource elements.

According to an aspect of the present invention, a base station transmitting a control channel in a wireless communication system clusters a plurality of physical resource block (PRB) pairs (clustering) to form a cluster based on the cluster configuration unit and the configured cluster It may include a transmission unit for transmitting an Enhanced Physical Downlink Control Channel (EPDCCH) to the terminal.

In an embodiment, the cluster component may map a resource element to an enhanced resource element group (ERG) for the EPDCCH in units of clusters.

In another embodiment, the cluster configuration unit may configure the cluster by clustering a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair.

As another embodiment, the cluster configuration unit may cluster the PRB pair constituting the EPDCCH set and at least one PRB pair continuously located on a frequency from the PRB pair constituting the EPDCCH set.

In another embodiment, the cluster configuration unit may set a PRB pair indicating a start and a PRB pair indicating an end of a PRB pair constituting one EPDCCH set, respectively, and indicate the PRB pair indicating the start and the end; The cluster may be configured by clustering PRB pairs positioned between the PRB pairs.

As another embodiment, the transmitter may transmit a radio resource control (RRC) signal including information on the number of PRB pairs constituting the cluster to the terminal.

As another embodiment, the transmitter may transmit a radio resource control (RRC) signal including information indicating the location of the cluster to the terminal.

According to another aspect of the present invention, a method for transmitting a control channel by a base station in a wireless communication system comprises clustering a plurality of physical resource block (PRB) pairs to form a cluster and based on the configured cluster The method may include transmitting an Enhanced Physical Downlink Control Channel (EPDCCH) to the UE.

According to another aspect of the present invention, a terminal for receiving a control channel in a wireless communication system for receiving an RRC (Radio Resource Control) signal and the received RRC message by analyzing the received RRC message for EPDCCH (Enhanced Physical Downlink Control Channel) A data processing unit for recognizing a resource element may be included, and the EPDCCH may be transmitted based on a cluster configured by clustering a plurality of physical resource block (PRB) pairs.

According to another aspect of the present invention, a method for receiving a control channel by a terminal in a wireless communication system includes receiving an RRC (Radio Resource Control) signal and analyzing the received RRC message to generate an Enhanced Physical Downlink Control Channel (EPDCCH). Recognizing a resource element for the, and the EPDCCH may be transmitted based on a cluster configured by clustering a plurality of physical resource block (PRB) pair (pair).

According to the present invention, more efficient Extended-Physical Downlink Control Channel (EPDCCH) transmission can be supported.

According to the present invention, EPDCCH can be effectively transmitted even in a situation where there are a small number of resource elements.

1 is a block diagram illustrating a wireless communication system.

2 is a diagram illustrating an RRC parameter for setting the number of PRB pairs defined in each EPDCCH set.

3A-3E are diagrams illustrating examples of a PRB pair according to one embodiment.

4A is an exemplary diagram illustrating local transmission of an EPDCCH, and FIG. 4B is an exemplary diagram illustrating distributed transmission of an EPDCCH.

5 is a diagram illustrating an FDD frame structure.

6 is a diagram illustrating a TDD frame structure.

7 is a diagram illustrating a case in which an EPDCCH is transmitted in a special subframe.

8A to 8D are diagrams showing the configuration of a cluster according to an example of the present invention.

9A to 9F are diagrams showing the configuration of a cluster according to another example of the present invention.

10A and 10B illustrate a configuration of a cluster according to still another example of the present invention.

11A and 11D illustrate a configuration of a cluster according to still another example of the present invention.

12A to 12D are diagrams illustrating EREG mapping according to an example of the present invention.

13 is a diagram illustrating EREG mapping according to another example of the present invention.

14A and 14B are diagrams illustrating EREG mapping according to another example of the present invention.

15 is a diagram illustrating EREG mapping according to another example of the present invention.

16 is a diagram illustrating EREG mapping according to another example of the present invention.

17 is a flowchart illustrating a process of transmitting and receiving an EPDCCH between a terminal and a base station according to an embodiment of the present invention.

18 is a block diagram illustrating a terminal and a base station according to an example of the present invention.

Hereinafter, some embodiments will be described in detail with reference to the accompanying 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 embodiments of the present specification, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.

The present specification describes a communication network, and the work performed in the communication network is performed in a process of transmitting a data and controlling the network in a system (for example, a base station) that manages the communication network, or in a terminal coupled to the network. Work can be done.

According to one embodiment of the present invention, "transmitting a control channel" may be interpreted as meaning that control information is transmitted through a specific channel. Here, the control channel may be, for example, a physical downlink control channel (PDCCH), an extended PDCCH (EPDCCH: Extended-PDCCH), or a physical uplink control channel (PUCCH). Can be.

1 is a block diagram illustrating a wireless communication system. This may be a network structure of an Evolved-Universal Mobile Telecommunications System (E-UMTS). The E-UMTS system may be referred to as Long Term Evolution (LTE) or LTE-A (Advanced) system. Wireless communication systems are widely deployed to provide various communication services such as voice transmission, packet data transmission, and the like.

On the other hand, there is no limitation on the multiple access scheme applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used.

Here, 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. .

Referring to FIG. 1, a wireless communication system includes at least one base station (BS) 20 that provides a control plane and a user plane to a terminal.

The UE 10 may be fixed or mobile and may have other mobile stations, advanced MSs (AMS), user terminals (UTs), subscriber stations (SSs), wireless devices (Wireless Devices), and the like. It may be called a term.

The base station 20 generally refers to a point for communicating with the terminal 10, and includes an evolved-NodeB (eNodeB), a base transceiver system (BTS), an access point, an femto-eNB, a pico base station (e. pico-eNB), home base station (Home eNB), relay (relay), etc. may be called other terms. The base station 20 may provide at least one cell to the terminal 10. The cell may mean a geographic area where the base station 20 provides a communication service or may mean a specific frequency band. The cell may mean a downlink frequency resource and an uplink frequency resource. Alternatively, the cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource. Also, in general, when carrier aggregation (CA) is not considered, uplink and downlink frequency resources always exist in pairs in one cell.

An interface for transmitting user traffic or control traffic may be used between the base stations 20. A source base station 21 (Source BS) refers to a base station to which a radio bearer is currently set up with a terminal 10. A target base station 22 (Target BS) means that the terminal 10 disconnects the radio bearer from the source base station 21 and newly renews. It means a base station to be handed over to establish a radio bearer.

The base stations 20 may be connected to each other through an X2 interface. The X2 interface is used to send and receive messages between the base stations 20. On the other hand, the base station 20 is connected to the Evolved Packet System (EPS), more specifically the mobility management entity (MME) / Serving Gateway (S-GW) 30 through the S1 interface. The S1 interface supports a many-to-many-relation between base station 20 and MME / S-GW 30.

The PDN-GW 40 is used to provide packet data service to the MME / S-GW 30. The PDN-GW 40 varies depending on the purpose or service of communication, and the PDN-GW 40 supporting a specific service can be found using APN information.

A new carrier type (NCT) may be applied to such a wireless communication system. In NCT, for example, signals such as a physical broadcast channel (PBCH), a physical downlink control channel (PDCCH), a physical HARQ indicator channel (PHICH), and a physical control format indicator channel (PCFICH) may not be transmitted. In addition, transmission modes (TM) 1 to 8 may not be supported in NCT. That is, TM 9 or TM 10 may be supported in NCT. In the NCT, a PDSCH transmission method having a maximum of 8 layers may be supported, and downlink control information (DCI) format 1A / 2D (or 2C) may be used for PDSCH (Physical Downlink Shared CHannel) transmission on the NCT. The DCI format 1A / 2D (or 2C) may be indicated through EPDCCH on NCT or may be indicated through cross-carrier scheduling from a legacy carrier type (LCT). DCI format 0/4 may also be used for EPDCCH transmission on NCT. Since the TM 9 or TM 10 may be supported in the NCT, a CSI reference signal (CSI-RS) may be supported to support channel state information (CSI) feedback on the NCT.

Specifically, the NCT may include a non-standalone NCT and an NCT having a standalone NCT and a human mode.

Firstly, the non-standalone NCT is an NCT that cannot exist in the form of a single cell and may exist in the form of a secondary serving cell (SCell) when a primary serving cell (PCell) exists. . For example, the non-standalone NCT may be aggregated together with an existing carrier type (LCT: Legacy Carrier Type) set to SCell in a terminal configured with CA (Carrier Aggregation).

Non-standalone NCT may be classified into a synchronized carrier type and an unsynchronized carrier type. Synchronous NCT refers to an NCT that operates by referring to synchronization of another carrier (eg, a legacy carrier). In other words, the synchronous NCT may be NCT that is synchronized with other carriers in time and frequency and does not require a separate synchronization procedure in the terminal. In synchronous NCT, a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a common reference signal (CRS) may not be transmitted. This allows for overhead reduction of the CRS, PSS and SSS. In synchronous NCT, due to the overhead reduction, there may be advantages such as interference mitigation, energy saving, and improved spectral efficiency for neighboring cells. Network providers can utilize frequency bandwidth more flexibly.

Asynchronous NCT refers to an NCT capable of acquiring and operating independent synchronization regardless of other carriers (eg, legacy carriers). In the case of asynchronous NCT, PSS and SSS are transmitted in the same manner as the legacy carrier type, but CRS transmission frequency and transmission bandwidth may be small. For example, in asynchronous NCT, the CRS may be transmitted with a certain period, in which case the CRS may be called a reduced CRS or may be referred to as a tracking RS (TRS) because it may be used only for synchronization purposes. Specifically, for example, the TRS may be transmitted based on the CRS antenna port 0 with a 5 ms period on the time axis. In addition, the TRS may be transmitted in the entire system bandwidth on the frequency axis, or may be transmitted only in some system bandwidths.

Second, standalone NCT is an NCT that can exist in the form of a single cell. For example, the standalone NCT may exist in the form of a main serving cell. The standalone NCT can also be removed, as with the non-standalone NCT, but the TRS mentioned above can be transmitted. Accordingly, the existing PDCCH, PHICH, and PCFICH, which are control channels based on CRS, may be removed or replaced with another type of channel. In the standalone NCT, demodulation of the EPDCCH and PDSCH may be performed based on a demodulation reference signal (DMRS).

Hereinafter, a control channel carrying common downlink control information such as system information, paging information, and transmission power control information in a common search space (CSS) based on a DMRS is called a common EPDCCH, and a terminal specific search space ( A control channel that carries downlink control information in a USS (UE specific search space) is called a UE specific EPDCCH. Simply referred to as EPDCCH may include both a common EPDCCH and a UE specific EPDCCH.

2 is a diagram illustrating an RRC parameter for setting the number of PRB pairs defined in each EPDCCH set. Hereinafter, an EPDCCH set configuration for EPDCCH transmission will be described with reference to FIG. 2.

K EPDCCH sets may be configured in each UE (for example, 1 = K = 2), and one EPDCCH set p is defined as a group including N PRB (Physical Resource Block) pairs. . The EPDCCH set may be called an EPDCCH PRB set. Here, one PRB pair may be defined as a resource region corresponding to two slots on the time axis and one resource block on the frequency axis. Alternatively, one PRB pair may mean, for example, an area corresponding to 12 resource elements (REs) having 15 KHz subcarrier spacing in a bandwidth of 180 Khz and a normal subframe.

As shown in FIG. 2, RRC (Radio Resource Control) setting for each EPDCCH set includes information on the transmission type (distributed transmission or local transmission) of the EPDCCH, and the number (N) of PRB pairs used for the EPDCCH set. Information may be included. The EPDCCH set may consist of two, four or eight PRB pairs, respectively, and each EPDCCH set does not need to have the same N value. PRB pairs may be overlapped, partially overlapped, or not overlapped at all among different EPDCCH sets. The PRB pair in each EPDCCH set may be indicated by resourceBlockAssignment-r11 and numberPRBPairs-r11 among the parameters shown in FIG. 2.

3A to 3E, 16 Enhanced Resource Element Groups (ERREGs) are included in one PRB pair. That is, all of the EREGs belonging to one PRB pair may be represented by indices 0 to 15.

In FIG. 3A to FIG. 3E, 0, 1, 2,..., 15 indicated in each resource element indicate an index of an EREG to which each resource element belongs (or mapped). In one PRB pair,

index

0, 1, 2, ..., 15 of EREG may be indexed in ascending order for each resource element from the first subcarrier on the top along the frequency axis on the first OFDM symbol of the time axis. After the EREG indexing is completed for the frequency on the first OFDM symbol in one PRB pair, EREG indexing for each resource element may be performed from the first subcarrier from the top along the frequency axis in the OFDM symbol of the next time axis. Meanwhile, the resource element denoted by R in FIGS. 3A to 3E is a resource element used for transmission of the DMRS. Resource elements used for transmission of the DMRS may be excluded from EREG indexing.

The arrangement and number of DMRSs within a PRB pair may be different for each embodiment as shown in FIGS. 3A to 3E. For example, in FIG. 3A, since 24 resource elements are used for DMRS, 16 EREGs are created from 144 resource elements except for 24 resource elements. In this case, one EREG may include nine resource elements. However, CSI-RS or CRS may be disposed in addition to DMRS in one PRB pair. In this case, since the number of available resource elements (available RE) in the PRB pair is reduced due to the CSI-RS or CRS, the number of resource elements included in the EREG may also be reduced. In addition, since the number of available resource elements varies according to the CP type, the number of resource elements included in the EREG may also vary. In addition, since the number of available resource elements varies according to the type of subframe, the number of resource elements included in the EREG may also vary.

For example, FIG. 3A shows that 16 EREGs are formed from 144 resource elements other than 24 resource elements for DMRS among 168 resource elements in a PRB pair including a normal subframe and a normal CP.

As another example, FIG. 3B shows that 16 EREGs are formed from the remaining 128 resource elements other than the 16 resource elements for DMRS in a PRB pair including a normal subframe and an extended CP. In this case, 0 EREG includes 8 resource elements.

As another example, FIG. 3C illustrates a special subframe in a PRB pair consisting of special subframe configuration 1 (9 OFDM symbols), 2 (10 OFDM symbols), 6 (9 OFDM symbols), or 7 (10 OFDM symbols) and a normal CP. In Configurations 1 and 6 (Embodiment A), 16 EREGs are formed from 84 resource elements other than 24 resource elements for DM-RS among 108 resource elements available in downlink, and special subframe configurations 2 and 7 (Embodiment B) shows that 16 EREGs are formed from 96 resource elements except for 24 DM-RS resource elements among 120 resource elements available in downlink.

As another example, FIG. 3D illustrates a special subframe in a PRB pair consisting of special subframe configurations 3 (11 OFDM symbols), 4 (12 OFDM symbols), 8 (11 OFDM symbols), or 9 (6 OFDM symbols) and a normal CP. In Configurations 3 and 8 (Embodiment A), 16 EREGs are formed from 108 resource elements other than 24 resource elements for DM-RS among the 132 resource elements available in downlink, and a special subframe configuration 4 (implementation) In Example B), 16 EREGs are formed from 120 resource elements other than 24 resource elements for DM-RS among the 144 resource elements available for downlink, and in a special subframe configuration 9 (not shown) in downlink 16 EREGs are formed from the remaining 60 resource elements except 12 resource elements for DM-RS among the 72 available resource elements.

As another example, FIG. 3E shows a special subframe configuration 1 (8 OFDM symbols), 2 (9 OFDM symbols), 3 (10 OFDM symbols), 5 (8 OFDM symbols) or 6 (9 OFDM symbols) and extended CP. In the PRB pair, 16 EREGs are formed from 88 resource elements except for 8 DM-RS resource elements among 96 resource elements available in downlink in the special subframe configurations 1 and 5 (A). In the special subframe configurations 2 and 6 (Example B), 16 EREGs are formed from the remaining 100 resource elements except the 8 resource elements for DM-RS among the 108 resource elements available in the downlink. In the special subframe configuration 3 (not shown), 16 EREGs are formed from the remaining 112 resource elements except for 8 DM-RS resource elements among 120 resource elements available in the downlink.

As such, although the number of resource elements included in the EREG may depend on the type of the reference signal, the CP type, and the subframe type, 16, the number of EREGs included in one PRB pair, may be fixed.

In the special subframe configuration of FIGS. 3C to 3E, resource elements indicated by diagonal lines on the right side of slot 1 correspond to a guard period (GP) and an uplink pilot time slot (UpPTS). The number of Orthogonal Frequency Division Multiplexing (OFDM) symbols for a Downlink Pilot Time Slot (DwPTS) is changed depending on the special subframe configuration and the associated CP type.

The EPDCCH is transmitted based on one or more enhanced control channel elements (ECCEs). The ECCE is a basic unit through which the EPDCCH is transmitted. For example, one EPDCCH may be mapped to one ECCE, two ECCEs, four ECCEs, or eight ECCEs. Therefore, the EPDCCH for transmitting downlink control information (DCI) is transmitted in a manner of aggregation of one ECCE or a plurality of ECCEs.

One ECCE may include a plurality of EREGs. For example, the ECCE may include four EREGs or eight EREGs. Here, one EREG is a group consisting of at least one resource element.

How many EREGs are included in the ECCE may depend on the subframe type (eg, a normal subframe or a special subframe) and a CP type. For example, the ECCE may include four EREGs in normal cyclic prefix and normal subframe or

special subframe configurations

3, 4, and 8, extended CP, and normal CP and special In the

subframe configurations

1,2,6,7,9, eight EREGs may be included. That is, one ECCE may include one or more EREGs. For example, the number of EREGs included in each ECCE may be defined as shown in Table 1 below.

Table 1

Normal CP			Extended CP
Normal subframe	Special subframe configuration 3,4,8	Special Subframe Configuration 1,2,6,7,9	Normal subframe	Special Subframe Configuration 1,2,3,5,6
4		8

Referring to Table 1, N ^ECCE _{EREG which} is the number of EREGs constituting one ^ECCE is defined according to each subframe type and CP type. For example, in a PRB pair consisting of normal CP and normal subframe or normal CP and

subframe configuration

3, 4, and 8, N ^ECCE _EREG is 4, and extended CP and normal subframe or normal CP and special subframe configuration 1 N ^ECCE _EREG is 8 in a PRB pair consisting of 2,6,7,9 or extended CP and special subframe configurations _1,2,3,5,6 . Meanwhile, the number N ^RB _ECCE ^E of one _ECB per PRB pair may be determined through N ^ECCE _EREG . Here, N ^RB _ECCE = 16 / N ^ECCE _EREG . When N ^ECCE _EREG = 4, the number of _ECCEs included in one PRB pair is N ^RB _ECCE = _16/4 = 4. In addition, when N ^ECCE _EREG = 8, the number of _ECCEs included in one PRB pair N ^RB _ECCE = _16/8 = 2. Meanwhile, the number N ^EPDCCH _ECCE constituting one EPDCCH may be defined as shown in Table 2 according to the format of the EPDCCH as an example.

TABLE 2

EPDCCH format	Number of ECCEs composing one EPDCCH N ^EPDCCH _ECCE
	Case a		Case b
	Local transfer	Distributed transmission	Local transfer	Distributed transmission
0	2	2	One	One
One	4	4	2	2
2	8	8	4	4
3	16	16	8	8
4	-	32	-	16

The index (ie, location) of the EREGs belonging to the ECCE may be determined by a certain rule, which may be referred to as ECCE-to-EREG mapping. There are two ECCE-to-EREG mappings: localized transmission and distributed transmission. 4A is an exemplary diagram illustrating local transmission of an EPDCCH, and FIG. 4B is an exemplary diagram illustrating distributed transmission of an EPDCCH. The EREG group constituting one ECCE in the local transmission is selected from the EREGs in one PRB pair.

For example, assume that one ECCE includes four EREGs and one EPDCCH set is configured to include four PRB pairs.

According to the local transmission, as shown in Fig. 4a, in the PRB pair # 0 ECCE # 0 = {EREG 0, EREG 4, EREG 8, EREG 12}, ECCE # 1 = {EREG 1, EREG 5, EREG 9, EREG 13} , ECCE # 2 = {EREG 2, EREG 6, EREG 10, EREG 14}, ECCE # 3 = {EREG 3, EREG 7, EREG 11, EREG 15}. The same applies to the PRB pairs # 1, # 2, and # 3. Or if one ECCE is configured to include eight EREGs, ECCE # 0 = {EREG 0, EREG 2, EREG 4, EREG 6, EREG 8, EREG 10, EREG 12, EREG 14}, ECCE # 1 = { EREG 1, EREG 3, EREG 5, EREG 7, EREG 9, EREG 11, EREG 13, EREG 15}.

On the other hand, according to distributed transmission, as shown in FIG. 4B, an EREG group constituting one ECCE is selected from EREGs of different PRB pairs. For example, ECCE # 0 = {EREG 0 of PRB pair # 0, EREG 4 of PRB pair # 1, EREG 8 of PRB pair # 2, EREG 12 of PRB pair # 3). The same applies to other ECCEs.

An EPDCCH based on local transmission may be referred to as a local EPDCCH, and an EPDCCH based on distributed transmission may be referred to as a distributed EPDCCH. The distributed EPDCCH may obtain a diversity gain, and the local EPDCCH may have a frequency selective characteristic and may be used for transmission of control information through precoding preferred for a specific terminal.

Meanwhile, the base station may transmit a plurality of EPDCCHs in one subframe, and the UE monitors at least one common EPDCCH in the common search space (CSS) or UE-specific search space (USS) in each subframe. At least one UE-specific EPDCCH may be monitored. Here, the monitoring means that the UE attempts to decode the EPDCCH according to the EPDCCH format. Monitoring may also be referred to as blind decoding.

Blind decoding demasks the cyclic redundancy check (CRC) of the received EPDCCH (this is called EPDCCH candidate) by the identifier of the common control information, checks the CRC error, and checks the CRC error for itself. This is a method of checking whether or not a control channel is used. The reason for performing blind decoding is that the UE does not know in advance which aggregation level or DCI format is used at which location in the common search space or the UE-specific search space.

Search Space (SS) may be used. The search space may be referred to as a monitoring set of ECCE for EPDCCH. The search space is divided into a common search space and a terminal specific search space. The UE monitors the EPDCCH in the corresponding search space. The common search space is a space for searching for an EPDCCH having common downlink control information such as system information, paging information, random access grant, MCCH change notification, transmission power control information, and the like. The UE-specific search space is a space for searching for an EPDCCH having downlink control information dedicated to each UE.

The common search space and the terminal specific search space may be defined differently from the start point of the search space. For example, the starting point of the common search space is fixed irrespective of the subframe, but the starting point of the terminal specific search space may be a terminal identifier (eg, a Cell-Radio Network Temporary Identifier (C-RNTI), an aggregation unit, and / Or it may vary for each subframe according to the slot number in the radio frame. When the starting point of the terminal specific search space is in the common search space, the terminal specific search space and the common search space may overlap.

In order for the UE to monitor the EPDCCH in the common search space and / or the UE-specific search space, the amount of ECCE constituting the common search space or the UE-specific search space, the aggregation level of the ECCE, and the aggregation unit The number of EPDCCH candidates or combinations thereof in accordance with the rule should be defined according to a certain rule. Such a rule is defined as an EPDCCH assignment rule. EPDCCH allocation rule is a communication protocol promised by the base station and the terminal. That is, the procedure of the base station transmitting the EPDCCH to the terminal, the number of monitoring of the terminal, etc. are determined according to the EPDCCH allocation rule.

EPDCCH allocation rules may be classified into Case 1 to Case 3, for example. The number of resource elements constituting one ECCE present in one PRB pair may be varied by various settings (eg, RS overhead, legacy control region, etc.). This is because, from a link adaptation point of view, the link performance experienced by one EPDCCH needs to be uniform regardless of other settings.

Case 1 contains: i) Normal CP and normal subframes, DCI 2 / 2A / 2B / 2C / 2D is monitored, and the number of downlink total PRB pairs in the monitored cell.

Or ii) the number of downlink total PRB pairs in the cell where the normal CP and special subframe settings 3,4,8 and DCI 2 / 2A / 2B / 2C / 2D are monitored and monitored;

Or iii) normal CP and normal subframe and DCI 1A / 1B / 1D / 1/2 / 2A / 2B / 2C / 2D / _0/4 monitored and n _EPDCCH <104, or iv) normal CP and

special Subframe settings

3, 4, 8 and DCI 1A / 1B / 1D / 1/2 / 2A / 2B / 2C / 2D / _0/4 are monitored and include n _EPDCCH <104. In this case, four ECCEs may be configured in one PRB pair.

And Case 2 includes i) an extended CP and a normal subframe and DCI 1A / 1B / 1D / 1/2 / 2B / 2C / 2D / 0/4 is monitored, or ii) a normal CP and

special subframe configuration

1, 2,6,7,9 and DCI 1A / 1B / 1D / 1/2 / 2B / 2C / 2D / 0/4 are monitored, or iii) Extended CP and

special subframe configuration

1,2,3,5 , And cases where DCI 1A / 1B / 1D / 1/2 / 2B / 2C / 2D / 0/4 are monitored. In cases other than Case 1 and Case 2, Case 3 may apply.

FIG. 5 is a diagram illustrating an FDD frame structure, and FIG. 6 is a diagram illustrating a TDD frame structure.

Referring to FIG. 5, UE-specific EPDCCH is not transmitted in a central 6PRB pair in which PBCH and PSS / SSS are transmitted in FDD. The PBCH is transmitted on the first four OFDM symbols in the second slot of FDD / TDD subframe # 0. In FDD, PSS and SSS are transmitted on the last two OFDM symbols in the first slot in subframes # 0 and # 5. In FIG. 5, the CRS indicates that the CRS is transmitted over the entire band, and does not indicate that all subcarriers in one OFDM symbol are used as the CRS.

Meanwhile, referring to FIG. 6, unlike FDD, in SDD, SSS is transmitted on the last OFDM symbol of subframe # 0 and subframe # 5, and PSS is transmitted on the third OFDM symbol of subframe # 1 and subframe # 6. do.

In TDD, each subframe may be configured of any one of a downlink subframe, an uplink subframe, and a special subframe. A subframe that is not a special subframe is called a normal subframe by distinguishing it from the special subframe. For example, the normal subframe includes a downlink subframe in the TDD, an uplink subframe, and includes a subframe in the FDD.

The special subframe includes three fields, that is, DwPTS, GP, and UpPTS, and the TDD configuration of the special subframe according to the length of each field may be defined up to nine according to the CP type as shown in Table 3 below. have.

TABLE 3

TDD Configuration of Special Subframes	Normal CP			Extended CP
	DwPTS	UpPTS		DwPTS	UpPTS
		Normal CP in uplink	CP Extended in Uplink		Normal CP in uplink	CP Extended in Uplink
0	6592Ts	2192Ts	2560Ts	7680 Ts	2192Ts	2560Ts
One	19760Ts			20480Ts
2	21952Ts			23040Ts
3	24144Ts			25600Ts
4	26336Ts			7680 Ts	4384Ts	5120Ts
5	6592Ts	4384Ts	5120Ts	20480Ts
6	19760Ts			23040Ts
7	21952Ts			12800Ts
8	24144Ts			-	-	-
9	13168Ts			-	-	-

Referring to Table 3, the TDD configuration of the special subframe may vary depending on whether the CP type is a normal CP or an extended CP. Here, Ts is a unit time indicating the size of a field on the time axis of the frame, and may be, for example, Ts = 1 / (15000 * 2048) sec.

Meanwhile, the uplink-downlink configuration in TDD is shown in Table 4 below.

Table 4

Uplink-Downlink Configuration

Period of Uplink-Down Link Transition Point

Subframe number

0

One

2

3

4

5

6

7

8

9

0

5 ms

D

S

U

D

S

U

One

5 ms

D

S

U

D

S

U

D

2

5 ms

D

S

U

D

S

U

D

3

10 ms

D

S

U

D

4

10 ms

D

S

U

D

5

10 ms

D

S

U

D

6

5 ms

D

S

U

D

S

U

D

In Table 4, D represents a downlink subframe, U represents an uplink subframe, and S represents a special subframe.

As an example, if EPDCCH is transmitted in (normal CP + special subframe configuration # 0, # 5) and (extended CP + special subframe configuration # 0, # 4, # 7), a resource element for EPDCCH transmission as shown in FIG. Mapping is possible. FIG. 7 illustrates a mapping of possible resource elements for EPDCCH transmission in normal CP and special subframe configurations # 0 and # 5. However, as shown in FIG. 7, PDSCH and / or EPDCCH are transmitted in the special subframe configuration because the number of resource elements available for one ECCE or EREG in one PRB pair is very small. It may not be possible, or only PDCCH may be transmittable.

In addition, in the TDD, in the case of subframe numbers # 1 and # 6, a resource element for PSS transmission is required within a central 6PRB pair. Accordingly, the number of resource elements available for transmission of EPDCCH per PRB pair according to a special subframe configuration and CP type is shown in Table 5 below.

Table 5

CP type	Normal CP		Extended CP
Subframe type	Sp	0	Sp 5	Sp 0	Sp 4	Sp 7
DwPTS Length (Symbol)	3	3	3	3	5
Number of available support elements when PSS is included DMRS (AP7-10 with time moving using symbol # 0, 1)	12	12	16	16	40
Number of available support elements when PSS is included DMRS (AP7-8 with time moving using symbol # 0, 1)	18	18	16	16	40
The number of available support elements if PSS is not included.DMRS (AP 7-10 with time moving using symbol # 0, 1)	24	24	28	28	52
DMRS (AP 7-8 with time moving using symbol # 0, 1)	30	30	28	28	52

In Table 5, Sp x represents a special subframe configuration, and AP represents an antenna port. The number of resource elements for DMRS is assumed to be 12 when using AP 7-10 in a PRB pair, and 6 (normal CP) or 8 (extended CP) when using only AP 7-8. Of course, different assumptions can be made about the number of resource elements for different numbers of DMRSs.

As such, since the number of resource elements available for EPDCCH transmission in the corresponding subframe configuration is very small, very high aggregation units are forced to maintain EPDCCH link performance. This means that the number of UEs that can be scheduled by the base station (ie, EPDCCH capacity) can be reduced. Therefore, a method for reducing the influence on the capacity of resources available for EPDCCH transmission is required.

8A to 8D are views showing the configuration of a cluster according to an example of the present invention, and FIGS. 9A to 9F are views showing the configuration of a cluster according to another example of the present invention, and FIGS. 10A and 10B are views of the present invention. It is a figure which shows the structure of the cluster which concerns on another example. 11A and 11D are diagrams illustrating a configuration of a cluster according to still another example of the present invention.

The base station according to the present invention can form a cluster by clustering a plurality of PRB pairs to support more efficient EPDCCH transmission on the NCT. The EPDCCH may be transmitted to the terminal based on the configured cluster. To this end, the base station according to the present invention may map resource elements to EREGs for EPDCCH in cluster units. This may have the same meaning as numbering resource elements constituting one EREG in cluster units and numbering EREGs constituting one ECCE in cluster units. Numbering does not limit local and distributed transmissions.

First embodiment

As a first embodiment, the base station according to the present invention is a first PRB pair from the first PRB pair constituting one EPDCCH set as shown in Figures 8a to 8e at least one second PRB pair adjacent on the frequency You can configure a cluster by clustering with. For example, when there are PRB pairs A and B constituting an EPDCCH set, cluster 1 including a PRB pair A and cluster 2 including a PRB pair B may be configured. At this time, the number X (eg, 2, 4, or 8) of PRB pairs constituting one cluster may be RRC signaled through the EPDCCH set configuration. Specifically, the base station includes the X value in the EPDCCH set configuration including the information (for example, resourceBlockAssignment-r11) for the PRB pair constituting one EPDCCH set as shown in FIG. Information about the pair may be transmitted to the terminal.

For example, when the number N of PRB pairs constituting one EPDCCH set is 2 and the number X of PRB pairs constituting one cluster is 2, the existing signaling is P0 (for example, PRB pair # 0). Although P1 (eg, PRB pair # 10) is indicated, according to the present invention, cluster # 0 = {P0, P1} and cluster # 1 = {P10, P11} may be indicated as an X = 2 value is additionally signaled. have. If X is any value, then cluster # 0 = {P0, P0 + 1, ..., P0 + (X-1)}, and cluster # 1 = {P10, P10 + 1, ..., P10 + (X -1)}. Through this method, the combinations shown in Table 6 can be made. However, the combination of the clusters in the present embodiment is not limited to the following values.

Table 6

Combination	N	X	Number of PRB Pairs Required	Number of clusters
0	2	2	4	2
One	2	4	8	2
2	2	8	16	2
3	4	2	8	4
4	4	4	16	4
5	4	8	32	4
6	8	2	16	8
7	8	4	32	8
8	8	8	64	8

Referring to Table 6, the number of clusters is equal to the number N of PRB pairs constituting one EPDCCH. That is, clusters may be configured as many as the number of PRB pairs constituting the EPDCCH.

At this time, the base station may prevent the settings for the PRB pairs constituting the N clusters from overlapping each other.

8A illustrates an example in which the number N of PRB pairs constituting one EPDCCH set is 4 and the number X of PRB pairs constituting one cluster is 2.

8B illustrates an example in which the number N of PRB pairs constituting one EPDCCH set is 2 and the number X of PRB pairs constituting one cluster is 4.

8C illustrates an example in which the number N of PRB pairs constituting one EPDCCH set is 4 and the number X of PRB pairs constituting one cluster is 4.

8D illustrates an example in which the number N of PRB pairs constituting one EPDCCH set is 2 and the number X of PRB pairs constituting one cluster is 8.

Second embodiment

As a second embodiment, the base station according to the present invention may configure a plurality of PRB pairs constituting one EPDCCH set, and may be configured such that each PRB pair is a start or end of a unique cluster. The base station may configure a cluster by clustering consecutive PRB pairs positioned between a PRB pair indicating a start for a specific cluster and a PRB pair indicating an end for the specific cluster on a frequency. The beginning and end of the cluster may be implicitly indicated by signaling (eg, resourceBlockAssignment-r11) indicating a PRB pair belonging to the EPDCCH set.

For example, when the plurality of PRB pairs N constituting one EPDCCH set are four (P0, P1, P2, P3), P0 (for example, PRB pair # 0) and P1 (for example, PRB pair) Four PRB pairs of # 3), P2 (eg, PRB pair # 8), and P3 (eg, PRB pair # 11) are indicated by conventional signaling. The terminal recognizes P0 and P1 as the start and end of cluster # 0, respectively, and recognizes P2 and P3 as the start and end of cluster # 1, respectively. The terminal may interpret the cluster # 0 = {P0, P0 + 1, ..., P1} and the cluster # 1 = {P2, P2 + 1, ..., P3}. Through this method, the combinations shown in Table 7 can be made. However, the combination of the clusters in the present embodiment is not limited to the following values.

TABLE 7

Combination	N	Number of PRB pairs per cluster	Number of clusters
0	2	Determined by PRB pairs indicating start and end, depending on configuration	One
One	2	Determined by PRB pairs indicating start and end, depending on configuration	One
2	4	Determined by PRB pairs indicating start and end, depending on configuration	2
3	4	Determined by PRB pairs indicating start and end, depending on configuration	2
4	8	Determined by PRB pairs indicating start and end, depending on configuration	4
5	8	Determined by PRB pairs indicating start and end, depending on configuration	4

In Table 7, the number of clusters is equal to 1/2 of the number N of PRB pairs constituting one EPDCCH set. At this time, the base station may prevent the settings for the PRB pairs constituting the N / 2 clusters from overlapping each other.

9A and 9C, for example, a case where the number N of PRB pairs constituting one EPDCCH set is 8 is illustrated, and the number N of PRB pairs constituting one EPDCCH set is 4 in FIGS. 9B and 9D. The case is shown. In FIG. 9A, one cluster is formed of only two PRB pairs as PRB pairs indicating a start and an end for one cluster are continuously positioned on a frequency. In FIG. 9C, a start and end for one cluster is illustrated. It is shown that one cluster consists of four PRB pairs as there are two PRB pairs on the frequency between the PRB pairs indicating the end. Similarly, in the case of FIG. 9B, one cluster is composed of four PRB pairs as two PRB pairs exist in frequency between PRB pairs indicating a start and an end for one cluster, and in the case of FIG. 9D. It is shown that one cluster consists of eight PRB pairs as there are six PRB pairs on the frequency between the PRB pairs indicating the start and the end for.

9E and 9F illustrate, for example, a case in which the number N of PRB pairs constituting one EPDCCH set is two.

In the case of FIG. 9E, one cluster is composed of eight PRB pairs as there are six PRB pairs in frequency between the PRB pairs indicating the start and the end for one cluster, and FIG. 9F shows the start for one cluster. It is shown that one cluster consists of four PRB pairs as two PRB pairs exist on the frequency between the PRB pairs indicating the end and the end.

Third embodiment

As a third embodiment, the base station according to the present invention clusters at least one PRB pair adjacent to the frequency from the PRB pair constituting one EPDCCH set with the PRB pair constituting the EPDCCH like the first embodiment. And configure the EPDCCH transmission using the configured cluster. However, in this case, unlike the first embodiment, a predetermined value between the base station and the terminal may be used as an X value which is the number of PRB pairs constituting one cluster. In this case, additional RRC signaling between the base station and the terminal is not required. In the case of the second embodiment, like the first embodiment, the cluster may be configured as shown in FIGS. 8A to 8D according to a predetermined value between the base station and the terminal.

Fourth embodiment

As a fourth embodiment, the base station according to the present invention may add information for indicating a cluster in the EPDCCH set configuration and transmit the information to the terminal. Here, the number X of PRB pairs constituting one cluster may be included in the EPDCCH set configuration or may be predetermined between the base station and the terminal. The numbering of the clusters may be performed according to the number of PRB pairs sequentially determined from low frequency on the entire bandwidth as in the numbering of conventional PRB pairs.

For example, the number of clusters can be indicated by including numberCluster- {n2, n4, n8} in the EPDCCH set configuration, and the location of the cluster can be indicated by including clusterAssignment in the EPDCCH set configuration. That is, the units constituting the EPDCCH set are clusters, not PRB pairs. The location of the cluster may be determined through RRC signaling including the EPDCCH set configuration and r in Equation 1 below.

Equation 1

here,

Is

,

And

Is the number of PRB pairs constituting one cluster,

Denotes the number of clusters constituting one EPDCCH set, and p denotes an EPDCCH set index. Meanwhile,

Silver unique label

Extended binomial coefficient from.

In FIG. 10A, for example, two clusters constitute one EPDCCH set and four PRB pairs constitute one cluster. In FIG. 10B, two clusters constitute one EPDCCH set and two A case where a PRB pair constitutes one cluster is shown.

Fifth Embodiment

The fifth embodiment may also perform numbering for one EREG on a cluster basis. However, in this case, the base station may signal so that PRB pairs constituting one cluster may be scattered without being mapped to consecutive PRB pairs.

To this end, the base station RRC signaling the number N (eg, 2, 4, or 8) of PRB pairs constituting a cluster through the EPDCCH set configuration, while signaling for an existing PRB pair in the EPDCCH set configuration. (Eg, resourceBlockAssignment-r11) may be signaled in association with the cluster ID. That is, by linking the cluster ID (IDentifier) for each signaling for the existing PRB pair it can be explicitly indicated which PRB pair each cluster includes. At this time, the number of clusters may also be signaled. For example, the resourceBlockAssignment value in the EPDCCH set configuration may be indicated as follows for each cluster. resourceBlockAssignment-r11 BIT STRING (SIZE (4..38)) for cluster # 0, ..., resourceBlockAssignment-r11 BIT STRING (SIZE (4..38)) for cluster # N-1

E.g. When the number N of PRB pairs constituting one cluster is 2 and the number of cluster IDs is 2 (# 0, # 1), the corresponding PRB pair may be configured according to the N value set for each cluster. In this case, since cluster ID # 0 has N equals 2, P0 (e.g., PRB pair # 0) and P1 (e.g., PRB pair # 10) are directed to the existing signaling and cluster ID # 1 indicates N = 2. Instructs P2 and P3 as the basis. Therefore, cluster # 0 may be composed of {P0, P1} and cluster # 1 may be composed of {P2, P3}. Through this method, a combination as shown in Table 8 or Table 9 can be made. However, the combination of the clusters in the present embodiment is not limited to the following values. Only some of these may also be used.

Table 8

Combination	N	Number of clusters	Number of PRB Pairs Required
0	2	2	4
One	2	4	8
2	4	2	8
3	4	4	16
4	8	2	16
5	8	4	32

Table 9

Combination	N	Number of clusters	Number of PRB Pairs Required
0	2	2	4
One	2	4	8
2	2	8	16
3	4	2	8
4	4	4	16
5	4	8	32
6	8	2	16
7	8	4	32
8	8	8	64

In Tables 8 and 9, the number of clusters may be indicated separately or predetermined between the base station and the terminal. Depending on the number of clusters, a cluster ID may also be indicated.

For example, FIG. 11A illustrates a case where the number N of PRB pairs constituting one cluster is 2 and the number of clusters constituting one EPDCCH set is 2, and FIG. 11B illustrates a case of the PRB pairs constituting one cluster. A case where the number N is 4 and the number of clusters constituting one EPDCCH set is 2 is illustrated. Meanwhile, FIG. 11C illustrates a case where the number N of PRB pairs constituting one cluster is 4 and the number of clusters constituting one EPDCCH is 4, and the number N of PRB pairs constituting one cluster is illustrated in FIG. 11D. The case where this is 8 and the number of clusters constituting one EPDCCH is 2 is shown. As described above, according to the present embodiment, a PRB pair constituting one cluster may be continuously mapped or scattered on a frequency by using a cluster ID.

In the above, a method of configuring a cluster by a base station and signaling a cluster configuration has been described. When the EPDCCH is transmitted on a cluster, the basic unit of transmission is ECCE, and the ECCE consists of an EREG. However, as the cluster concept is introduced, the EREG needs to be newly defined at the cluster level. Hereinafter, a method of mapping each EREG to a cluster will be described.

12A to 12D are diagrams illustrating EREG mapping according to an example of the present invention, and FIG. 13 is a diagram illustrating EREG mapping according to another example of the present invention, and FIGS. 14A, 14B, 15, and 16 are examples of the present invention. A diagram illustrating EREG mapping according to another example.

The base station according to the present invention may number the EREG for EPDCCH transmission from 0-15 in cluster units in a special subframe. EREG numbering excludes resource elements (AP 7-10 in normal CP or AP 7-8 in extended CP) for DMRS. The resource elements numbered with index i become the resource elements constituting the EREG index i. The resource element is included in an EREG allocated for EPDCCH transmission. However, the resource element is not included in the PBCH or PRB pair used for synchronization signal transmission. In addition, the resource element is not used for transmission of the UE-specific reference signal or the CSI reference signal. The number of resource elements satisfying these conditions per one cluster may be determined as shown in Table 10 below according to the subframe configuration and the CP type.

Table 10

CP type	Normal CP		Extended CP
Subframe type	Sp	0	Sp 5	Sp 0	Sp 4	Sp 7
DwPTS Length (Symbol)	3	3	3	3	5
Number of available support elements when PSS is included DMRS (AP7-10 with time moving using symbol # 0, 1)	12 * X	12 * X	16 * X	16 * X	40 * X
Number of available support elements when PSS is included DMRS (AP7-8 with time moving using symbol # 0, 1)	18 * X	18 * X	16 * X	16 * X	40 * X
The number of available support elements if PSS is not included.DMRS (AP 7-10 with time moving using symbol # 0, 1)	24 * X	24 * X	28 * X	28 * X	52 * X
DMRS (AP 7-8 with time moving using symbol # 0, 1)	30 * X	30 * X	28 * X	28 * X	52 * X

In Table 10, the Sp number (e.g. Sp0) represents a special subframe configuration, the AP represents an antenna port, and X represents the number of PRB pairs included in one cluster. The number of resource elements in Table 10 is a value determined according to resource elements for DMRS and PSS. In addition, there may be additional overhead (eg, ZP / NZP, CSI-RS, CRS or TRS, etc.).

For example, FIG. 12A illustrates DMRS of 72 total resource elements when there are no PSSs in the normal CP and special

subframe configuration #

0, 24 resource elements for DMRS, and one cluster is composed of two PRB pairs. 16 EREGs are formed from the remaining 48 resource elements except 24 resource elements.

As another example, FIG. 12B illustrates a case in which a PSS is present in a normal CP and special

subframe configuration #

0, 24 resource elements for DMRS, and one cluster is composed of two PRB pairs. 16 EREGs are formed from the remaining 36 resource elements except 24 resource elements and 12 resource elements for the PSS.

As another example, FIG. 12C illustrates that in the case of the normal CP and the special subframe configuration # 0, when there is no PSS, there are 12 resource elements for DMRS, and one cluster is composed of two PRB pairs. 16 EREGs are formed from the remaining 60 resource elements except 12 resource elements.

As another example, FIG. 12D illustrates a DMRS of 72 total resource elements when a PSS exists in a normal CP and special

subframe configuration #

0, 12 resource elements for DMRS, and one cluster consists of two PRB pairs. 16 EREGs are formed from the remaining 48 resource elements except 12 resource elements for 12 and 12 resource elements for PSS.

As another example, FIG. 13 shows DMRSs among 144 resource elements when PSS does not exist in the normal CP and special

subframe configuration #

0, 48 resource elements for DMRS, and one cluster is composed of four PRB pairs. 16 EREGs are formed from the remaining 96 resource elements except for 48 resource elements. Although the numbering for the EREG is omitted in FIG. 13, it may be performed in the same manner as in FIGS. 12A to 12D.

As another example, FIG. 14A illustrates DMRS of 72 resource elements in the case where there is no PSS in the extended CP and special subframe configuration # 0, 16 resource elements for DMRS, and one cluster is composed of two PRB pairs. 16 EREGs are formed from the remaining 56 resource elements except 16 resource elements.

As another example, FIG. 14B illustrates DMRS of 72 total resource elements when PSS exists in extended CP and special subframe configuration # 0, 16 resource elements for DMRS, and one cluster is composed of two PRB pairs. 16 EREGs are formed from the remaining 44 resource elements except for 16 resource elements and 12 resource elements for the PSS.

As another example, FIG. 15 illustrates DMRS of 120 resource elements in the case where there is no PSS in the extended CP and special subframe configuration # 7, 16 resource elements for DMRS, and one cluster is composed of two PRB pairs. 16 EREGs are formed from the remaining 104 resource elements except 16 resource elements.

Meanwhile, FIG. 16 illustrates EREG numbering when PRB pairs constituting a cluster may be scattered without being mapped to consecutive PRB pairs. In this case, the PRB pairs constituting one cluster may be numbered in units of clusters as in the case of consecutive mapping.

Referring to FIG. 17, the base station configures a cluster by clustering a plurality of PRB pairs (S1710). For example, the base station may configure a cluster for EPDCCH transmission by clustering a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair. Specifically, the base station may configure a cluster by clustering at least one PRB pair continuously positioned on a frequency from the PRB pair constituting the EPDCCH set and the PRB pair constituting the EPDCCH set.

Meanwhile, as another example, the base station sets a PRB pair indicating the start of the cluster and a PRB pair indicating the end of the cluster among PRB pairs constituting one EPDCCH set, and sets the PRB pair indicating the start and the PRB pair indicating the end, respectively. The cluster may be configured by clustering PRB pairs located in between. Here, the base station may map resource elements to EREGs in cluster units.

Meanwhile, as another example, the base station may configure a cluster by individually selecting a PRB pair included in each cluster.

On the other hand, the base station may perform the RRC signaling with the terminal (S1720). At this time, the base station may, for example, transmit an RRC message including information on the number of PRB pairs constituting the cluster and / or an RRC message including information indicating the location of the cluster to the terminal. For example, an example of the RRC message may be defined as shown in the following table.

Table 11

EPDCCH-SetConfig-r11 :: = SEQUENCE {

epdcch-SetIdentity-r11 EPDCCH-SetIdentity-r11,

epdcch-TransmissionType-r11 ENUMERATED {localised, distributed},

numberPRBPairs-r11 ENUMERATED {n2, n4, n8},

resourceBlockAssignment-r11 BITSTRING (SIZE (4..38)),

dmrs-ScramblingSequenceInt-r11 INTEGER (0..503),

pucch-ResourceStatOffset INTEGER (0..2047),

re-MappingQCLConfigList-Id INTEGER (1..4)

numberPRBPairsOfCluster INTEGER (1… 2)

Referring to Table 11, numberPRBPairsOfCluster is information on the number X of PRB pairs constituting the cluster, and may have a value of 1-4, which is merely an example.

Alternatively, another example of the RRC message may be defined as shown in the following table.

Table 12

EPDCCH-SetConfig-r11 :: = SEQUENCE {

epdcch-SetIdentity-r11 EPDCCH-SetIdentity-r11,

epdcch-TransmissionType-r11 ENUMERATED {localised, distributed},

numberPRBPairs-r11 ENUMERATED {n2, n4, n8},

resourceBlockAssignment-r11 BITSTRING (SIZE (4..38)),

dmrs-ScramblingSequenceInt-r11 INTEGER (0..503),

pucch-ResourceStatOffset INTEGER (0..2047),

re-MappingQCLConfigList-Id INTEGER (1..4)

numberOfCluster ENUMERATED {n2, n4, n8}

clusterAssignment BITSTRING (SIZE (4..38)),

Referring to Table 12, numberOfCluster is the number of clusters, which may be one of 2, 4, and 8, which is merely an example. In addition, clusterAssignment is information indicating the position of the cluster and may have a length of 4 to 38 bits, but this is only an example.

Or for example, another example of the RRC message may be defined as shown in the following table.

Table 13

EPDCCH-SetConfig-r11 :: = SEQUENCE {

epdcch-SetIdentity-r11 EPDCCH-SetIdentity-r11,

epdcch-TransmissionType-r11 ENUMERATED {localised, distributed},

numberPRBPairs-r11 ENUMERATED {n2, n4, n8},

resourceBlockAssignment-r11 BITSTRING (SIZE (4..38)),

dmrs-ScramblingSequenceInt-r11 INTEGER (0..503),

pucch-ResourceStatOffset INTEGER (0..2047),

re-MappingQCLConfigList-Id INTEGER (1..4)

resourceBlockAssignment-r11 BIT STRING (SIZE (4..38)) for cluster # 0

resourceBlockAssignment-r11 BIT STRING (SIZE (4..38)) for cluster # N-1

When the terminal receives the RRC message from the base station, it can recognize the resource element for the EPDCCH by analyzing the received RRC message (S1730).

Then, when the base station transmits the EPDCCH to the terminal based on the cluster (S1740), the terminal may receive the EPDCCH based on the resource element for the recognized EPDCCH (S1750).

18 is a block diagram illustrating a base station and a terminal according to an example of the present invention.

Referring to FIG. 18, the base station 1700 includes a base station processor 1710, a transmitter 1720, and a receiver 1730. The base station processor 1710 may include a cluster configuration unit 1711 and a data processing unit 1712.

The cluster configuration unit 1711 configures a cluster by clustering a plurality of PRB pairs. In addition, the resource element may be mapped to the EREG for the EPDCCH on a cluster basis.

For example, the cluster configuration unit 1711 may configure a cluster by clustering a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair. In detail, the cluster configuration unit 17110 may configure a cluster by clustering at least one PRB pair continuously positioned on a frequency from the PRB pair constituting the EPDCCH set and the PRB pair constituting the EPDCCH set. Meanwhile, the cluster configuration unit 1711 sets PRB pairs indicating the start and PRB pairs indicating the end of the PRB pairs constituting one EPDCCH set, respectively, and is located between the PRB pair indicating the start and the PRB pair indicating the end. A cluster may be formed by clustering PRB pairs.

The data processor 1712 may generate a DCI to be sent to the terminal 1800, and may add a CRC for error detection to the DCI. The data processor 2872 may generate the encoded data by performing channel coding on the control information to which the CRC is added.

The transmitter 1720 transmits an RRC message to the terminal 1800. The EPDCCH is transmitted to the terminal 1800 based on the cluster configured by the cluster configuration unit 1710. In this case, the RRC message may include information on the number of PRB pairs constituting the cluster and / or information indicating the location of the cluster.

The receiver 1730 may receive the uplink data from the terminal 1800.

The terminal 1800 includes a receiver 1810, a terminal processor 1820, and a transmitter 1830. The terminal processor 1820 may include a monitoring controller 1821 and a data processor 1822.

The receiving unit 1810 receives the RRC message from the base station 1700 and receives the EPDCCH, while monitoring the EPDCCH received by the control of the monitoring control unit 1821. The EPDCCH may be transmitted based on a cluster configured by clustering a plurality of PRB pairs. For example, the cluster may be configured by clustering a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair, or indicating a PRB pair and an end indicating one of the PRB pairs constituting one EPDCCH set. PRB pairs may be set respectively, and the PRB pairs located between the PRB pair indicating the start and the PRB pair indicating the end may be configured by clustering. Resource elements may be mapped in units of clusters in the EREG for the EPDCCH.

Meanwhile, the process of monitoring the EPDCCH by the receiver 1810 may include demapping resource elements of the EPDCCH into modulation symbols based on a predetermined EPDCCH allocation rule, demodulation process of extracting the modulation symbols into encoded data, and encoding. A decoding process may be performed to decode the data and extract the DCI, a demasking process to the CRC added to the DCI, and an error detection process to detect an error. In addition, the receiver 1810 may perform monitoring of the EPDCCH based on a predetermined EPDCCH allocation rule between the terminal 1800 and the base station 1700.

The monitoring controller 1821 controls the receiver 1810 to monitor the EPDCCH candidates according to each aggregation unit, and transmits the DCI obtained as a result of decoding the EPDCCH from the receiver 1810 to the data processor 1822.

The data processor 1822 recognizes a resource element for the EPDCCH by analyzing the RRC message received from the receiver 1810. Then, the DCI received from the monitoring controller 1821 is analyzed, and the terminal 1800 is controlled to perform a control operation indicated by the DCI. In this case, the RRC message may include at least one of information on the number of PRB pairs constituting the cluster and information indicating the location of the cluster.

The transmitter 1830 transmits uplink data generated by the data processor 1822 to the base station 1700.

All of the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

Although the present invention has been described above with reference to the embodiments, it will be apparent to those skilled in the art that the present invention may be modified and changed in various ways without departing from the spirit and scope of the present invention. I can understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

Claims

In the base station for transmitting a control channel in a wireless communication system,

A cluster configuration unit constituting a cluster by clustering a plurality of physical resource block (PRB) pairs; And

Transmitter for transmitting an Enhanced Physical Downlink Control Channel (EPDCCH) to the terminal based on the configured cluster

Base station comprising a.
The method of claim 1,

The cluster component,

And mapping resource elements to an enhanced resource element group (ERG) for the EPDCCH in units of clusters.
The method of claim 1,

The cluster component,

And configuring the cluster by clustering a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair.
The method of claim 3,

The cluster component,

And configuring the cluster by clustering the PRB pair constituting the EPDCCH set and at least one PRB pair continuously positioned on a frequency from the PRB pair.
The method of claim 1,

The cluster component,

Among the PRB pairs constituting one EPDCCH set, a PRB pair indicating a start and a PRB pair indicating an end are respectively set, and a PRB pair indicating a start, a PRB pair indicating the end, and a PRB pair indicating a start are respectively set. And configuring the cluster by clustering PRB pairs positioned between the PRB pairs indicating the end.
The method of claim 1,

The transmission unit,

The base station, characterized in that for transmitting a radio resource control (RRC) message containing information on the number of PRB pairs constituting the cluster to the terminal.
The method of claim 1,

The transmission unit,

And a radio resource control (RRC) message including information indicating the location of the cluster to the terminal.
A control channel transmission method by a base station in a wireless communication system,

Clustering a plurality of physical resource block (PRB) pairs to configure a cluster; And

Transmitting an Enhanced Physical Downlink Control Channel (EPDCCH) to the terminal based on the configured cluster;

Control channel transmission method comprising a.
The method of claim 8,

And mapping the resource elements to an enhanced resource element group (ERG) for the EPDCCH in units of clusters.
The method of claim 8,

The step of configuring the cluster,

And configuring the cluster by clustering a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair.
The method of claim 10,

The step of configuring the cluster,

And configuring the cluster by clustering the PRB pair constituting the EPDCCH set and at least one PRB pair consecutively located on a frequency from the PRB pair.
The method of claim 8,

The step of configuring the cluster,

Setting a PRB pair indicating a start and a PRB pair indicating an end among PRB pairs constituting one EPDCCH set; And

Clustering the PRB pairs positioned between the PRB pair indicating the start and the PRB pair indicating the end, and the PRB pair indicating the start and the PRB pair indicating the end to configure the cluster;

Control channel transmission method comprising a.
The method of claim 8,

And transmitting a radio resource control (RRC) message including information on the number of PRB pairs constituting the cluster to the terminal.
The method of claim 8,

And transmitting a radio resource control (RRC) message including information indicating the location of the cluster to the terminal.
A terminal for receiving a control channel in a wireless communication system,

Receiving unit for receiving an RRC (Radio Resource Control) message; And

Data processing unit for recognizing the resource elements for the Enhanced Physical Downlink Control Channel (EPDCCH) by analyzing the received RRC message

Including,

The receiver receives the EPDCCH based on the recognized resource elements,

The EPDCCH is,

Terminal based on a cluster configured by a plurality of physical resource block (PRB) pairs (clustering).
The method of claim 15,

In the Enhanced Resource Element Group (ERG) for the EPDCCH,

And the resource elements are mapped in units of clusters.
The method of claim 15,

The cluster is,

And a PRB pair constituting one EPDCCH set and at least one PRB pair adjacent to the PRB pair are configured by clustering.
The method of claim 17,

The cluster is,

And a PRB pair constituting the EPDCCH set and at least one PRB pair continuously positioned on a frequency from the PRB pair constituting the EPDCCH set.
The method of claim 15,

The cluster is,

Among the PRB pairs constituting one EPDCCH set, a PRB pair indicating a start and a PRB pair indicating an end are respectively set, a PRB pair indicating the start and a PRB pair indicating the end, a PRB pair indicating the start, and And a PRB pair located between the PRB pairs indicating the end is configured by clustering.
The method of claim 15,

The RRC message is,

And at least one of information on the number of PRB pairs constituting the cluster and information indicating a location of the cluster.