KR20130020645A - Method and apparatus of allocating control channel - Google Patents

Abstract

PURPOSE: A control channel allocation method efficiently allocating control channels in a single or multiple carrier wireless communications systems and an apparatus for the same are provided to handle ambiguity or blocking in a control channel allocation process, thereby efficiently performing the blind detection of the control channel. CONSTITUTION: A terminal receives a subframe including a control area(S1110). The control area receives a CSS(Common Search Space) and at least more than one USS(UE-specific Search Space). Each SS(Search Space) includes a control channel candidate set. The terminal performs a process of determining control channel allocation in order to find a control channel which is designated for the terminal itself(S1120). The process of determining the control channel allocation includes the process of monitoring control channel candidates within the SS, considering the size of the SS obtained by a predetermined regulation, the CCE(Control Channel Element) merge level of the control channel candidate and the location of the SS. The terminal is able to perform an operation according to a designated control channel(S1130). [Reference numerals] (AA) Terminal; (BB) Terminal-specific search space is monitored on the assumption that the transfer of the control channel is restricted in at least some of the control channel candidate if the common search space and the terminal-specific search space are overlapped and a predetermined condition is corresponded; (S1110) Receiving a common search space and a terminal-specific search space; (S1120) Monitoring a control channel candidate in the common search space and the terminal-specific search space for finding a control channel designated in a terminal; (S1130) Performing an operation according to the control channel designated in the terminal

Description

Method of allocating control channel and apparatus therefor {METHOD AND APPARATUS OF ALLOCATING CONTROL CHANNEL}

The present invention relates to a wireless communication system, and more particularly, to a method for allocating a control channel and an apparatus therefor.

Wireless communication systems are widely deployed to provide various kinds of communication services such as voice and data. In general, a wireless communication system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier frequency (SC-FDMA). division multiple access) system.

It is an object of the present invention to provide a method and apparatus for efficiently allocating a control channel in a single / multi-carrier wireless communication system. Another object of the present invention is to provide a method and apparatus for solving the ambiguity / blocking that may occur in the control channel allocation. Another object of the present invention is to provide a method for efficiently performing blind detection of a control channel and an apparatus therefor. It is still another object of the present invention to provide a method and apparatus for configuring a search space to efficiently transmit a control channel.

The technical problems to be solved by the present invention are not limited to the technical problems and other technical problems which are not mentioned can be understood by those skilled in the art from the following description.

In one aspect of the present invention, a method for a terminal to determine a control channel allocation for a control channel in a wireless communication system, the method comprising: a common search space including a control channel candidate set for the control channel on a specific carrier Monitoring; And monitoring, on the particular carrier, a terminal-specific search space including a control channel candidate set for the control channel, wherein the terminal is the same RNTI (Radio) in the common search space and the terminal-specific search space. Network Temporary Identifier), when configured to monitor a plurality of control channel candidates having the same information size, the same first control channel resource, and the same control channel resource merging level, control channel candidates corresponding to the above conditions are received only in the common search space. The method is provided.

In another aspect of the present invention, a terminal configured to perform a process of determining a control channel allocation for a control channel in a wireless communication system, the terminal comprising: a radio frequency (RF) unit; And a processor, wherein the processor monitors a common search space comprising a set of control channel candidates for the control channel on a particular carrier, the terminal-specific search space comprising a control channel candidate set for the control channel; Configured to monitor on a particular carrier, the terminal having the same Radio Network Temporary Identifier (RNTI), same information size, same first control channel resource and same control channel resource merging level in the common search space and the terminal-specific search space When a plurality of control channel candidates having a configuration is set to monitor, a control channel candidate corresponding to the condition is received only in the common search space.

Preferably, for the plurality of control channel candidates, the control channel can be received only in the common search space.

Advantageously, when a control channel is detected in the plurality of control channel candidates, the control channel is considered received in the common search space.

Advantageously, monitoring the plurality of control channel candidates is performed under the assumption that the control channel can only be received in the common search space.

Preferably, the plurality of control channel candidates are scrambled with the same RNTI by a cyclic redundancy check (CRC).

Preferably, the information size is a downlink control information (DCI) payload size.

Preferably, the control channel is a physical downlink control channel (PDCCH), and the control channel candidate is a PDCCH candidate.

According to the present invention, a control channel can be efficiently allocated in a single / multi-carrier wireless communication system. In addition, it is possible to eliminate ambiguity / blocking that may occur when assigning control channels. In addition, blind detection of the control channel can be efficiently performed. In addition, the search space can be efficiently configured.

Effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.
1 illustrates a structure of a radio frame of a 3GPP system.
2 illustrates a resource grid of a downlink slot.
3 shows a structure of a downlink frame.
4 is a flowchart illustrating a configuration of a physical downlink control channel (PDCCH) in a base station.
5 illustrates a process for receiving a PDCCH at a terminal.
6 illustrates a structure of an uplink subframe.
7 illustrates a Carrier Aggregation (CA) communication system.
8 illustrates scheduling when a plurality of carriers are merged.
9 illustrates an operation of a base station / terminal in a CIF reconfiguration interval.
10 to 13 illustrate a method for eliminating ambiguity when receiving a control channel according to an embodiment of the present invention.
14 shows an example of allocating a PDCCH to a data region of a subframe.
15 illustrates an E-PDCCH (Enhanced PDCCH) and a PDSCH reception process.
16 illustrates an example of distributing search spaces (SS).
17 illustrates a case in which control channel confusion does not occur in an E-PDCCH (Enhanced Physical Downlink Control CHannel) region.
18 illustrates a method for eliminating ambiguity when receiving a control channel according to another embodiment of the present invention.
19 illustrates a base station and a terminal that can be applied to an embodiment of the present invention.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented in radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. The TDMA may be implemented in a wireless technology such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) employs OFDMA in downlink and SC-FDMA in uplink as part of Evolved UMTS (E-UMTS) using E-UTRA. LTE-A (Advanced) is an evolved version of 3GPP LTE.

For clarity of description, 3GPP LTE / LTE-A is mainly described, but the technical idea of the present invention is not limited thereto. In addition, specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

1 illustrates the structure of a radio frame.

Referring to FIG. 1, a radio frame includes 10 subframes. The subframe includes two slots in the time domain. The time for transmitting a subframe is defined as a transmission time interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. One slot has a plurality of Orthogonal Frequency Division Multiplexing (OFDM) or Single Carrier Frequency Division Multiple Access (SC-FDMA) symbols in the time domain. Since 3GPP LTE uses OFDMA in downlink and SC-FDMA in uplink, OFDM or SC-FDMA symbols represent one symbol period. A resource block (RB) is a resource allocation unit and includes a plurality of consecutive subcarriers in one slot. The structure of a radio frame is shown for illustrative purposes. Accordingly, the number of subframes included in the radio frame, the number of slots included in the subframe, and the number of symbols included in the slot may be modified in various ways.

2 illustrates a resource grid of a downlink slot.

Referring to FIG. 2, the downlink slot includes a plurality of OFDM symbols in the time domain. One downlink slot may include 7 (6) OFDM symbols, and the resource block may include 12 subcarriers in the frequency domain. Each element on the resource grid is referred to as a resource element (RE). One RB contains 12x7 (6) REs. The number NDL of RBs included in the downlink slot depends on the downlink transmission band. The structure of the uplink slot is the same as the structure of the downlink slot, and the OFDM symbol is replaced with the SC-FDMA symbol.

3 illustrates a structure of a downlink subframe.

Referring to FIG. 3, a maximum of 3 (4) OFDM symbols located at a first position in a first slot of a subframe corresponds to a control region to which a control channel is allocated. The remaining OFDM symbols correspond to data regions to which physical downlink shared channels (PDSCHs) are allocated. Examples of a downlink control channel used in 3GPP LTE include a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), and the like. The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols used for transmission of a control channel within the subframe. The PHICH carries an HARQ ACK / NACK (acknowledgment / negative-acknowledgment) signal in response to uplink transmission.

The control information transmitted through the PDCCH is referred to as DCI (Downlink Control Information). DCI includes resource allocation information and other control information for a terminal or a terminal group. For example, the DCI includes uplink / downlink scheduling information, an uplink transmit power control command power control command, and the like.

Control information transmitted through the PDCCH is referred to as downlink control information (DCI). The DCI format defines the formats 0, 3, 3A and 4 for the uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B and 2C for the downlink. Depending on the DCI format, the type of the information field, the number of information fields, and the number of bits of each information field are different. For example, the DCI format may include a hopping flag, an RB assignment, a modulation coding scheme (MCS), a redundancy version (RV), a new data indicator (NDI), a transmit power control (TPC) A HARQ process number, a precoding matrix indicator (PMI) confirmation, and the like. Therefore, the size (size) of the control information matched to the DCI format differs according to the DCI format. On the other hand, an arbitrary DCI format can be used for transmission of two or more types of control information. For example, DCI format 0 / 1A is used to carry DCI format 0 or DCI format 1, which are distinguished by a flag field.

The PDCCH includes a transmission format and resource allocation of a downlink shared channel (DL-SCH), resource allocation information for an uplink shared channel (UL-SCH), paging information for a paging channel (PCH), and system information on the DL-SCH. ), Resource allocation information of a higher-layer control message such as a random access response transmitted on a PDSCH, transmission power control commands for individual terminals in an arbitrary terminal group, activation of voice over IP (VoIP), and the like. . A plurality of PDCCHs may be transmitted in the control region. The terminal may monitor the plurality of PDCCHs. The PDCCH is transmitted on an aggregation of one or a plurality of consecutive CCEs (consecutive control channel elements). CCE is a logical allocation unit used to provide a PDCCH of a predetermined coding rate according to the state of a radio channel. The CCE corresponds to a plurality of resource element groups (REGs). The format of the PDCCH and the number of bits of the available PDCCH are determined according to the correlation between the number of CCEs and the code rate provided by the CCEs. The base station determines the PDCCH format according to the DCI to be transmitted to the terminal, and adds a cyclic redundancy check (CRC) to the control information. The CRC is masked with a unique identifier (referred to as a radio network temporary identifier (RNTI)) depending on the owner of the PDCCH or the intended use. If the PDCCH is for a specific terminal, a unique identifier (eg, C-RNTI (cell-RNTI)) of the terminal is masked on the CRC. As another example, if the PDCCH is for a paging message, a paging indication identifier (eg, p-RNTI (p-RNTI)) is masked in the CRC. If the PDCCH relates to system information (more specifically, a system information block (SIB) to be described later), a system information identifier (eg, a system information RNTI (SI-RNTI)) is masked to the CRC. A random access-RNTI (RA-RNTI) is masked in the CRC to indicate a random access response, which is a response to the transmission of the random access preamble of the terminal.

The PDCCH carries a message known as Downlink Control Information (DCI), and the DCI includes resource allocation and other control information for one terminal or a group of terminals. In general, a plurality of PDCCHs may be transmitted in one subframe. Each PDCCH is transmitted using one or more Control Channel Elements (CCEs), and each CCE corresponds to nine sets of four resource elements. The four resource elements are referred to as resource element groups (REGs). Four QPSK symbols are mapped to one REG. The resource element allocated to the reference signal is not included in the REG, so that the total number of REGs within a given OFDM symbol depends on the presence of a cell-specific reference signal. The REG concept (ie group-by-group mapping, each group contains four resource elements) is also used for other downlink control channels (PCFICH and PHICH). That is, REG is used as a basic resource unit of the control region. Four PDCCH formats are supported as listed in Table 1.

CCEs are numbered consecutively, and to simplify the decoding process, a PDCCH having a format consisting of n CCEs may only be started with a CCE having a number corresponding to a multiple of n. The number of CCEs used for transmission of a specific PDCCH is determined by the base station according to the channel state. For example, in case of a PDCCH for a UE having a good downlink channel (eg, adjacent to a base station), one CCE may be sufficient. However, in case of a PDCCH for a terminal having a poor channel (eg, near the cell boundary), eight CCEs may be required to obtain sufficient robustness. In addition, the power level of the PDCCH may be adjusted according to the channel state.

LTE defines a set of CCEs in which a PDCCH can be located for each UE. The CCE set in which the UE can discover its own PDCCH is referred to as a PDCCH search space, or simply a search space (SS). An individual resource to which a PDCCH can be transmitted in an SS is called a PDCCH candidate. One PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to a CCE aggregation level. The base station transmits the actual PDCCH (DCI) through any PDCCH candidate in the SS, the terminal monitors the SS to find the PDCCH (DCI). Specifically, the UE attempts blind detection (BD) for PDCCH candidates in the SS.

In LTE, the SS is sized according to the PDCCH format. In addition, UE-specific Search Space (USS) and Common Search Space (CSS) are separately defined. USS is also referred to as dedicated search space. The USS is set individually for each terminal and the CSS range is known to all terminals. USS and CSS may overlap for a given terminal. If all CCEs are already allocated for other UEs in the USS for a specific UE, since there is no remaining CCE, the BS may not find CCE resources for transmitting a PDCCH to the specific UE in the corresponding subframe. In order to minimize the possibility of the above blocking leading to the next subframe, the USS start position is changed by the UE-specific hopping sequence for each subframe. Table 2 shows the sizes of CSS and USS.

In order to keep the computational overhead according to the blind detection attempt, the UE does not search all defined DCI formats at the same time. In general, in the USS, the terminal always searches for formats 0 and 1A. Formats 0 and 1A have the same size and are separated by flags in the message. In addition, the terminal may be further required to receive another format (ie, 1, 1B or 2 depending on the PDSCH transmission mode set by the base station). In CSS, the terminal searches for formats 1A and 1C. In addition, the terminal may be configured to search for format 3 or 3A. Format 3 / 3A has the same size as format 0 / 1A and is distinguished by whether it has a CRC scrambled with a different (common) identifier. Contents of a transmission mode and a DCI format for configuring a multi-antenna technology are as follows.

Transmission Mode

Transmission mode 1: Transmission from a single base station antenna port

● Transmission mode 2: Transmit diversity

Transmission mode 3: Open-loop spatial multiplexing

Transmission Mode 4: Closed-loop spatial multiplexing

● Transmission Mode 5: Multi-user MIMO

● Transmission Mode 6: Closed-loop rank-1 precoding

Transmission mode 7: Transmission using UE-specific reference signals

DCI format

Format 0: Resource grants for the PUSCH transmissions (uplink)

Format 1: Resource assignments for single codeword PDSCH transmissions (transmission modes 1, 2 and 7)

Format 1A: Compact signaling of resource assignments for single codeword PDSCH (all modes)

Format 1B: Compact resource assignments for PDSCH using rank-1 closed loop precoding (mode 6)

Format 1C: Very compact resource assignments for PDSCH (e.g. paging / broadcast system information)

Format 1D: Compact resource assignments for PDSCH using multi-user MIMO (mode 5)

Format 2: Resource assignments for PDSCH for closed-loop MIMO operation (mode 4)

Format 2A: Resource assignments for PDSCH for open-loop MIMO operation (mode 3)

Format 3 / 3A: Power control commands for PUCCH and PUSCH with 2-bit / 1-bit power adjustments

4 is a flowchart illustrating the configuration of a PDCCH at a base station.

Referring to FIG. 4, the base station generates control information according to the DCI format. The base station can select one of a plurality of DCI formats (DCI formats 1, 2, ..., N) according to control information to be sent to the terminal. In step S410, a cyclic redundancy check (CRC) for error detection is attached to control information generated according to each DCI format. In the CRC, an identifier (eg, Radio Network Temporary Identifier) (RNTI) is masked according to the owner or purpose of the PDCCH. In other words, the PDCCH is CRC scrambled with an identifier (eg, RNTI).

Table 3 shows examples of identifiers masked on the PDCCH.

When C-RNTI, Temporary C-RNTI, or Semi-Persistent Scheduling (SPS) C-RNTI is used, the PDCCH carries control information for a specific UE. If other RNTIs are used, the PDCCH is received by all UEs in the cell. Carries common control information. In operation S420, channel coding is performed on the control information added with the CRC to generate coded data. In step S430, rate matching is performed according to a CCE aggregation level allocated to the PDCCH format. In step S440, modulated coded data is generated. The modulation symbols constituting one PDCCH may have one of 1, 2, 4, and 8 CCE aggregation levels. In step S450, modulation symbols are mapped to the physical resource elements RE (CCE to RE mapping).

5 illustrates a process for receiving a PDCCH at a terminal.

Referring to FIG. 5, in step S510, the UE demaps a physical resource element to CCE. In step S520, the UE demodulates each CCE aggregation level because it does not know which CCE aggregation level it should receive the PDCCH. In step S530, the terminal performs rate dematching on the demodulated data. The terminal performs rate-matching on each DCI format (or DCI payload size) because it does not know which DCI format (or DCI payload size) it should receive control information. In operation S540, channel decoding is performed on the rate dematched data according to a code rate, and a CRC is checked to detect whether an error occurs. If no error occurs, the UE detects its own PDCCH. If an error occurs, the UE continuously performs blind detection for another CCE aggregation level or another DCI format (or DCI payload size). In step S550, the UE detecting its own PDCCH removes the CRC from the decoded data and obtains control information.

A plurality of PDCCHs for a plurality of terminals may be transmitted in a control region of the same subframe. The base station does not provide the terminal with information about where the corresponding PDCCH is in the control region. Accordingly, the UE monitors a set of PDCCH candidates in a subframe and finds its own PDCCH. Here, monitoring includes attempting to decode each of the PDCCH candidates according to the DCI format and the CCE merging level (hereinafter, blind detection (BD)). Through the BD, the UE simultaneously performs identification of the PDCCH transmitted to it and decryption of control information transmitted through the corresponding PDCCH. For example, when de-masking the PDCCH with C-RNTI, if there is no CRC error, the UE detects its own PDCCH.

On the other hand, in order to reduce the BD overhead, the number of DCI formats is smaller than the type of control information transmitted using the PDCCH. The DCI format includes a plurality of different information fields. Depending on the DCI format, the type of the information field, the number of information fields, and the number of bits of each information field are different. In addition, the size of the control information matched to the DCI format differs according to the DCI format. Any DCI format can be used for transmission of two or more kinds of control information.

Table 4 shows an example of control information transmitted by DCI format 0. The bit size of each information field below is only an example, and does not limit the bit size of the field.

The flag field is an information field for distinguishing between format 0 and format 1A. That is, DCI formats 0 and 1A have the same payload size and are distinguished by flag fields. The resource block allocation and hopping resource allocation fields may have different bit sizes according to a hopping PUSCH or a non-hopping PUSCH. The _RB Allocation and Hopping Resource Allocation field for the non-hopping PUSCH provides the ceiling [log ₂ (N ^UL _RB (N ^UL _RB +1) / 2)] bits to the resource allocation of the first slot in the uplink subframe. . Here, N ^UL _RB is the number of resource blocks included in an uplink slot and depends on an uplink transmission bandwidth set in a cell. Therefore, the payload size of DCI format 0 may vary depending on the uplink bandwidth. DCI format 1A includes an information field for PDSCH allocation, and the payload size of DCI format 1A may also vary according to downlink bandwidth. DCI format 1A provides reference information bit size for DCI format 0. Therefore, if the number of information bits of DCI format 0 is less than the number of information bits of DCI format 1A, '0' is added to DCI format 0 until the payload size of DCI format 0 is equal to the payload size of DCI format 1A. Is added. The added '0' is filled in the padding field of the DCI format.

6 illustrates a structure of an uplink subframe used in LTE.

Referring to FIG. 6, an uplink subframe includes a plurality of slots (eg, two). The slot may include different numbers of SC-FDMA symbols according to a cyclic prefix (CP) length. For example, in case of a normal CP, a slot may include 7 SC-FDMA symbols. The UL subframe is divided into a data region and a control region in the frequency domain. The data area includes a PUSCH and is used to transmit a data signal such as voice. The control region includes a PUCCH and is used to transmit control information. The PUCCH includes RB pairs (eg, m = 0, 1, 2, 3) located at both ends of the data region on the frequency axis and hops to the slot boundary. The control information includes HARQ ACK / NACK, Channel Quality Information (CQI), Precoding Matrix Indicator (PMI), Rank Indication (RI), and the like.

7 illustrates a Carrier Aggregation (CA) communication system.

Referring to FIG. 7, a plurality of uplink / downlink component carriers (CCs) may be collected to support a wider uplink / downlink bandwidth. The term “component carrier (CC)” may be replaced with other equivalent terms (eg, carrier, cell, etc.). Each of the CCs may be adjacent or non-adjacent to each other in the frequency domain. The bandwidth of each component carrier can be determined independently. Asymmetrical carrier aggregation in which the number of UL CCs and the number of DL CCs are different is also possible. Meanwhile, the control information may be set to be transmitted and received only through a specific CC. This particular CC may be referred to as the primary CC (or anchor CC) and the remaining CCs may be referred to as the secondary CC.

When cross-carrier scheduling (or cross-CC scheduling) is applied, the PDCCH for downlink allocation may be transmitted on DL CC # 0, and the corresponding PDSCH may be transmitted on DL CC # 2. For cross-CC scheduling, the introduction of a carrier indicator field (CIF) may be considered. The presence or absence of the CIF in the PDCCH may be set in a semi-static and terminal-specific (or terminal group-specific) manner by higher layer signaling (eg, RRC signaling). The baseline of PDCCH transmission is summarized as follows.

■ CIF disabled: PDCCH on DL CC allocates PDSCH resources on the same DL CC or PUSCH resources on one linked UL CC

● No CIF

LTE PDCCH structure (same encoding, same CCE-based resource mapping) and same as DCI format

■ CIF enabled: A PDCCH on a DL CC can allocate PDSCH or PUSCH resources on a specific DL / UL CC among a plurality of merged DL / UL CCs using the CIF.

Extended LTE DCI format with CIF

CIF (if set) is a fixed x-bit field (eg x = 3)

-CIF (if set) position is fixed regardless of DCI format size

Reuse LTE PDCCH structure (same coding, same CCE-based resource mapping)

If the CIF exists, the base station may allocate the PDCCH monitoring DL CC set to reduce the BD complexity of the terminal side. The PDCCH monitoring DL CC set includes one or more DL CCs as part of the merged total DL CCs, and the UE performs detection / decoding of the PDCCH only on the corresponding DL CCs. That is, when the base station schedules PDSCH / PUSCH to the UE, the PDCCH is transmitted only through the PDCCH monitoring DL CC set. The PDCCH monitoring DL CC set may be configured in a UE-specific, UE-group-specific or cell-specific manner. The term “PDCCH monitoring DL CC” may be replaced with equivalent terms such as a monitoring carrier, a monitoring cell, and the like. In addition, the CC merged for the terminal may be replaced with equivalent terms such as a serving CC, a serving carrier, a serving cell, and the like.

8 illustrates scheduling when a plurality of carriers are merged. Assume that three DL CCs are merged. Assume that DL CC A is set to PDCCH monitoring DL CC. DL CC A to C may be referred to as a serving CC, a serving carrier, a serving cell, and the like. When the CIF is disabled, each DL CC may transmit only the PDCCH scheduling its PDSCH without the CIF according to the LTE PDCCH rule. On the other hand, when CIF is enabled by UE-specific (or UE-group-specific or cell-specific) higher layer signaling, DL CC A (monitoring DL CC) uses the CIF to schedule PDSCH of DL CC A. In addition to the PDCCH, the PDCCH scheduling the PDSCH of another CC may be transmitted. In this case, PDCCH is not transmitted in DL CC B / C that is not configured as PDCCH monitoring DL CC. Accordingly, the DL CC A (monitoring DL CC) should include both the PDCCH search space associated with DL CC A, the PDCCH search space associated with DL CC B, and the PDCCH search space associated with DL CC C. In this specification, it is assumed that the PDCCH search space is defined for each carrier.

As described above, LTE-A considers the use of CIF in the PDCCH for cross-CC scheduling. Whether to use CIF (ie, support for cross-CC scheduling mode or non-cross-CC scheduling mode) and switching between modes may be semi-static / terminal-specifically configured through RRC signaling, and the corresponding RRC signaling process may be configured. After coarse, the UE can recognize whether CIF is used in the PDCCH to be scheduled to it.

9 illustrates an operation of a base station / terminal in a CIF reconfiguration interval. The figure assumes a situation in which CIF off is reconfigured from CIF off.

9, an RRC command (eg, “RRCConnectionReconfigutation” command) for setting whether to use CIF in a PDCCH (ie, CIF ON / OFF) for a corresponding UE, that is, delivering a CIF reconfiguration message to a corresponding UE. ) Is transmitted to the terminal (S902). The terminal delivers the received RRC command to its RRC layer. The RRC layer of the UE transmits an RRC response (eg, an “RRCConnectionReconfigurationComplete” message) for transmitting the CIF reconfiguration complete message to the base station in response to the RRC command received from the base station (S904).

On the other hand, since the timing at which the CIF reconfiguration (ie, CIF on / off) starts to be applied in the RRC signaling period 910 may be different between the base station and the terminal, it malfunctions in the PDCCH transmission of the base station and the reception / decoding process of the terminal. This is likely to occur. In other words, there is a possibility that the base station and the UE differently recognize whether to use the CIF for the same PDCCH at a specific time point within the RRC signaling period 910. For example, while the base station transmits the PDCCH without the CIF, the terminal may receive / decode the corresponding PDCCH assuming the use of the CIF. In addition, although the base station transmits the PDCCH by inserting the CIF, the terminal may receive / decode the corresponding PDCCH without assuming the use of the CIF. This malfunction not only causes unnecessary overhead in PDCCH transmission / reception between the base station and the terminal but also increases scheduling time delay.

In addition, in the conventional LTE, the UE transmits a periodic SRS (Sounding Reference Signal) to inform the base station of uplink channel information, and information for this is set through RRC signaling. However, LTE-A may set a method for dynamically triggering aperiodic SRS transmission for each CC through a DCI format set in the USS for the purpose of adaptive uplink channel measurement. In addition, in LTE-A, a method of increasing the number of bits of the aperiodic CSI request field in the DCI format set in the USS has been considered in order to obtain richer downlink channel information in the CC merging situation. Therefore, PRCCH-related malfunctions similar to those described above may also be caused when RRC reconfiguration for aperiodic SRS configuration and RRC reconfiguration for CC aggregation (single CC => multiple CC, or multiple CC => single CC). . That is, the base station and the UE may recognize differently whether the aperiodic SRS request field is used or the aperiodic CSI request field size for the same PDCCH at a specific time point in the RRC signaling period.

Embodiment: A method for eliminating ambiguity of detected control channels

In LTE-A, when a cross-CC scheduling operation is applied when a plurality of CCs are merged, CIF is included in PDCCH transmitted through USS, but CIF is not included in PDCCH transmitted through CSS. In the case of CSS, this is to prevent an additional BD increase for the DCI format size added due to coexistence with existing LTE terminals and use of CIF. When a plurality of CCs are merged, the USS is configured for each CC. On the other hand, the payload size of a specific DCI format (for convenience, DCI format A) without a CIF set in CSS on one CC (e.g., DL PCC) of a specific DCI format (for convenience, DCI format B) with CIF set in USS The same case as the payload size may occur. Here, the payload size of the DCI format may or may not include a CRC size according to the definition, and may simply be referred to as a DCI format size. The payload size of the DCI format may vary depending on the frequency band of the CC, etc. The DCI format A and the DCI format B may be the same format or different formats. For convenience, the above-described DCI format A / B is referred to as equal size DCI format between SSs, or simply same size DCI format, same size DCI. DCI format A and DCI format B have different field configurations (eg, CIF). Preferably, the present invention may be limited to the case where the CRC is masked (or scrambled) using the same RNTI (eg, C-RNTI). On the other hand, when CSS and USS overlap and the UE succeeds in decoding the same size DCI format in the overlap region, the UE distinguishes through which SS the detected PDCCH is received, that is, PDCCH with CIF or PDCCH without CIF. You may not be able to (Situation # 1).

In addition, when only one CC is allocated in LTE-A or when a non-cross-CC scheduling operation is applied when multiple CCs are merged, CIF is used for both the PDCCH transmitted through the USS and the PDCCH transmitted through the CSS. It is considered not to do it. At this time, aperiodic SRS request field setting for each CC, aperiodic CSI request field setting in a CC merging situation, or for other reasons, a specific DCI format without CIF set in CSS on one CC (eg, DL PCC) (for convenience, DCI A case may occur in which the payload size of format C) and the payload size of a specific DCI format (DCI format D for convenience) without the CIF set are the same. The DCI format C / D has the same total payload size but different fields in the DCI format or different sizes for the same field. Similar to the above, DCI format C / D may be referred to as equal size DCI format between SSs, or simply equal size DCI format, same size DCI. Preferably, the present invention may be limited to the case where the same size DCI formats are CRC masked (or scrambled) using the same RNTI. For convenience, unless otherwise stated herein, the same size DCI format assumes that the CRC has been masked (or scrambled) with the same RNTI. On the other hand, when CSS and USS overlap, and the UE succeeds in decoding the same size DCI format in the overlap region, the UE knows through which SS the detected PDCCH is received, that is, the field configuration of the DCI format transmitted through the corresponding PDCCH. However, it may not be possible to determine exactly what the field size is (Situation # 2).

That is, when a single CC or a plurality of CCs are configured, confusion may occur between a DCI format (hereinafter referred to as CSS-DCI) set in CSS and a DCI format (hereinafter referred to as USS-DCI) set in USS from the terminal point of view. Hereinafter, various methods for solving the above-mentioned problems are proposed. The scheme according to the invention comprises, for example, a control channel allocation scheme and a processing scheme.

In order to solve the above problem of situation # 1 / # 2, CSS and USS are configured on one CC, CSS-DCI and USS-DCI have the same payload size but the fields in the DCI format When differently configured or having different sizes for the same field, it is proposed to transmit / receive only CSS-DCI among DCI formats having the same payload size at least in the overlap region of CSS and USS. Here, in CSS-DCI and USS-DCI, a field configuration / field size of DCI information may vary due to a CIF field, an aperiodic SRS request field, or an aperiodic CSI request field. This scheme may be limited to the case where the CRC is masked (or scrambled) using the same RNTI (eg, C-RNTI, SPS-RNTI) that the CSS-DCI and the USS-DCI are the same. In addition, the present scheme allows or recognizes only CSS-DCI transmission for the entire overlap region of CSS and USS, or PDCCH candidate for CSS-DCI and PDCCH candidate for USS-DCI are configured with the same starting CCE in the overlap region. In this case, only the CSS-DCI transmission can be allowed / recognized.

According to the present scheme, the UE recognizes the DCI format detected in the overlap region as CSS-DCI for the same payload size DCI formats at the overlap time point (eg, subframe n). As an equivalent process, when the UE monitors the DCI format having the same payload size in the CSS and the USS, it may be assumed that only the CSS-DCI is transmitted in the overlap region. The reason for the high priority of CSS-DCI is that the fields constituting the CSS-DCI are not changed before and after the RRC reconfiguration, so that there is an overlap between SSs in the RRC reconfiguration (eg, CIF reconfiguration, aperiodic SRS reconfiguration, CC merge reconfiguration). This is because the terminal malfunction can be prevented.

10 shows an example in which a network device (eg, a base station) transmits a control channel.

Referring to FIG. 10, the base station configures one or more USSs with the CSS (S1010). Each SS includes a set of control channel candidates, and the USS is configured for each CC. The SS may be configured by the process of determining the control channel assignment. The control channel includes a PDCCH and the control channel candidate includes a PDCCH candidate. By the process of determining the control channel (eg, PDCCH) allocation, the SS size (eg, the number of CCEs), the CCE aggregation level of the PDCCH candidates, the position of the SS, and the like may be determined. CSS and USS can overlap. In this example, it is assumed that CSS-DCI and USS-DCI have the same payload size, and fields in the DCI format are configured differently or have different sizes for the same field. One control information format may be set per DL CC or UL CC, and two or more control information formats may be set per DL CC or UL CC. The SS may also be configured with a DL / UL common control information format such as LTE's DCI format 0 / 1A. The SS configuration method may follow the PDCCH SS configuration method of the existing LTE. However, parameters (eg, hashing pattern, location, size, etc.) related to SS for each CC may be obtained by combining CIF values and parameters related to PDCCH SS of the existing LTE.

Thereafter, the base station transmits a control channel for a specific terminal through at least one of the CSS and one or more USS (S1020). In this example, CSS and one or more USSs are transmitted through the control region of the same subframe on the same DL CC (eg, DL PCC). Specifically, the CSS and one or more USSs are transmitted through the control region (ie, up to three (4) consecutive OFDM symbols specified by the PCFICH) within the subframe (see FIG. 3). The control channel (or control information) may carry identification information for indicating the corresponding terminal. The identification information includes an RNTI, for example C-RNTI, SPS-RNTI, and the like. The control channel (or control information) may be scrambled using the identification information. For example, the base station may transmit the CRC scrambled PDCCH to the UE by the C-RNTI. In this example, it is assumed that control channels transmitted in CSS and USS are scrambled with the same RNTI.

On the other hand, there may be a case of confusion of the control channel (or control information) between the CSS and the USS. Cases of confusion of control channels include cases where CSS and USS overlap. In addition, the possibility of confusion of the control channel includes a case where the control channel candidates in the CSS and the USS have the same DCI format size (in other words, the DCI payload size), and preferably the control channel candidates of the CSS and the USS. May also be limited to cases having the same identifier (eg, RNTI) and / or the same first CCE resource. In this case, according to the present scheme, the USS may restrict transmission of a control channel (or DCI) in at least some control channel candidates.

For example, if there is a possibility of confusion of the control channel between the CSS and the USS, transmission of the control channel (or DCI) may be dropped on at least some control channel candidates of the USS. The region in which transmission of the control channel (or DCI) is restricted may be the entire USS, an overlap region on the USS, or a region of some of them (or a control channel resource (eg, CCE) corresponding to the above-described region). According to an embodiment, transmission control of a control channel (or DCI) may be performed in the process of allocating control channel resources to the DCI or may be performed in the actual transmission step of the control channel (or DCI). Further, depending on the implementation, transmission restriction of the control channel (or DCI) may be achieved through puncturing (or nulling) (some kind of rate matching) before resource mapping or puncturing (or nulling) after resource mapping. In summary, in this scheme, the transmission of the control channel (or DCI) is restricted because the control channel candidates to be monitored in the CSS and USS have the same size DCI format, or preferably also the same identifier (eg, RNTI) and / or Or it may be the case configured to have the same starting resource (eg, starting CCE).

11 illustrates an example in which a UE processes a control channel (eg, PDCCH). Since the process of FIG. 11 corresponds to the process of FIG. 10, a detailed description will be described with reference to FIG. 10.

Referring to FIG. 11, the terminal receives a subframe including a control region (S1110). The control region receives CSS and one or more USSs. Each SS includes a set of control channel candidates. In this example, it is assumed that CSS-DCI and USS-DCI have the same payload size, and fields in the DCI format are configured differently or have different sizes for the same field. Thereafter, the terminal performs a process of determining a control channel (eg, PDCCH) allocation in order to find a control channel assigned thereto (S1120). The process of determining the control channel allocation includes monitoring the control channel candidates in the SS in consideration of the SS size (eg, the number of CCEs) obtained by the predetermined rule, the CCE merging level of the control channel candidate, the SS position, and the like. The monitoring process includes blind detection of each control channel candidate. Thereafter, the terminal may perform an operation (eg, PDSCH reception, PUSCH transmission, transmission power control, etc.) according to a control channel assigned to the terminal (S1130).

On the other hand, there may be a case of confusion of the control channel (or control information) between the CSS and the USS. Cases of confusion of control channels include cases where CSS and USS overlap. In addition, the possibility of confusion of control channels includes the case where control channel candidates in CSS and USS have the same DCI format size (in other words, DCI payload size), preferably control channel candidates in both SSs. May also be limited to cases having the same identifier (eg, RNTI) and / or the same first CCE resource. In this case, according to the present scheme, the UE assumes that transmission of a control channel (or DCI) is limited in at least some control channel candidates in the USS. The terminal may perform the process of determining the control channel allocation, more specifically, the monitoring under this assumption. In other words, the UE may perform monitoring under the assumption that the control channel (or DCI) may be transmitted only in CSS in an area where transmission control of the control channel (or DCI) is limited. The region in which control channel (or DCI) transmission is restricted may be the entire USS, an overlap region on the USS, or a region of some of them (or a control channel resource (eg, CCE) corresponding to the above-described region). In summary, it is assumed in this scheme that transmission control of the control channel (or DCI) is assumed that the control channel candidates to be monitored in the CSS and USS have the same size DCI format, or preferably also the same identifier (eg RNTI) and And / or configured to have the same starting resource (eg, starting CCE).

According to the present scheme, according to the implementation example, the terminal may search only the CSS-DCI in the region in which there is a transmission restriction of the control channel (or DCI). For example, the UE may search only one of the same size DCI formats in a specific SS region at a specific time. In other words, when the DCI format sizes set in the two SSs are the same, the UE may not perform monitoring / BD for the same size DCI format set in the USS for a specific SS region at a specific time point. In addition, according to the embodiment, after the terminal monitors both the CSS and the USS according to a conventional procedure, when the control channel (eg, PDCCH) is detected in a region where transmission of the control channel (or DCI) is restricted, the corresponding PDCCH is You can think of it as being received from CSS.

Transmission of the same size DCI format in the USS may be limited as follows.

1) Applies only to overlapped USS area when two SS overlap occurs

The base station does not transmit the USS-DCI only when the overlap between the CSS and the USS occurs and only for the overlap area. 12A illustrates an SS configuration according to the present scheme. Therefore, the terminal considers that the control channel is transmitted only through the CSS in the overlap region. That is, when the control channel is detected in the overlap region, the terminal may consider that the control channel is received in the CSS. According to an embodiment, the UE may receive / decode (BD) only for the same size DCI formats at that time, for the USS-DCI only through the CSS-DCI through the overlap region and the USS except the overlap region. have. That is, the terminal may not monitor the control channel candidate for the USS-DCI in the overlap region. Alternatively, the terminal monitors all control channel candidates for CSS-DCI and USS-DCI in the overlap region, but considers the CSS-DCI when the control channel is detected. The present method can minimize the reduction in scheduling flexibility in the USS by enabling the USS-DCI allocation to the USS except the overlap region.

Preferably, the present scheme provides that control channel candidates of CSS and USS in the overlap region have the same DCI (payload) size, have the same RNTI (eg CRC scrambled), and the same starting resource (eg CCE). Only when configured in the USS, it is possible to limit the transmission of the control channel in the USS. 12b illustrates an SS configuration according to the present scheme.

2) Applied to entire USS area when overlap between two SS

The base station does not transmit the USS-DCI for the entire USS region only when the overlap between the CSS and the USS occurs. Therefore, when overlap occurs, the UE considers that the control channel is transmitted only through CSS in the overlap area. That is, when the control channel is detected in the overlap region, the terminal may consider that the control channel is received in the CSS. According to the embodiment, the UE cannot receive / decode (BD) for the USS-DCI through the entire USS for the same size DCI formats at that time and receive / decode (BD) only for the CSS-DCI in the overlap region. You can do Alternatively, the terminal monitors all control channel candidates for CSS-DCI and USS-DCI in the overlap region, but considers the CSS-DCI when the control channel is detected. In the case of the present method, the scheduling flexibility in the USS is further reduced, but the complexity of distinguishing the overlapping and non-overlapping areas can be reduced.

Preferably, the scheme should only be configured to monitor control channel candidates having the same DCI (payload) size, the same RNTI (e.g. CRC scrambled), and the same starting resource (e.g. CCE) in CSS and USS. In this case, transmission of control channel candidates may be restricted in the entire USS.

Next, in a method specific to situation # 2, the payload sizes of CSS-DCI and USS-DCI are different for CSS and USS configured on one CC in a non-cross-CC scheduling situation without using CIF. If the same fields in the DCI format are configured differently or have different sizes for the same field, a scheme of reconfiguring the CSS-DCI field to be identical to the USS-DCI field is proposed. That is, when the above condition is satisfied, it may be allowed to perform an aperiodic SRS request and an aperiodic CSI request for a plurality of CCs through the CSS-DCI. Alternatively, if the above conditions are met, certain fields that may cause ambiguity between CSS-DCI and USS-DCI in the overlap region of CSS and USS (eg, aperiodic SRS request field, aperiodic CSI request field, It is proposed to set all of the values of the flag field indicating whether to allocate a discontinuous PUSCH resource to 0 (that is, disable the corresponding field function) or ignore the corresponding field. The two methods described above have control channel candidates (eg, PDCCH candidates) having the same size DCI format having the same RNTI (eg, C-RNTI) (CRC masked (or scrambled) with RNTI) and / or having the same starting resource ( Yes, it may be applied only when configured to have a starting CCE).

In the 3GPP LTE / LTE-A system, the FDD DL carrier and TDD DL subframes are used to transmit PDCCH, PHICH, PCFICH, etc., which are physical channels for transmitting various control information, as described in FIG. The remaining OFDM symbols are used for PDSCH transmission. The number of symbols used for control channel transmission in each subframe is transmitted to the UE either dynamically via a physical channel such as PCFICH or semi-static through RRC signaling. The n value may be set from 1 symbol up to 4 symbols according to subframe characteristics and system characteristics (FDD / TDD, system band, etc.). On the other hand, PDCCH, which is a physical channel for transmitting DL / UL scheduling and various control information in the existing LTE system, has limitations such as transmission through limited OFDM symbols. Therefore, the introduction of enhanced PDCCH (E-PDCCH), which is more freely multiplexed with PDSCH and FDM / TDM scheme, is considered.

14 shows an example of allocating a downlink physical channel to a subframe.

Referring to FIG. 14, a PDCCH (for convenience, legacy PDCCH) according to existing LTE / LTE-A may be allocated to a control region (see FIG. 3) of a subframe. In the figure, the L-PDCCH region means a region to which a legacy PDCCH can be allocated. According to the context, the L-PDCCH region may mean a control region, a control channel resource region (ie, a CCE resource) to which a PDCCH can be actually allocated in the control region, or a PDCCH search space. Meanwhile, a PDCCH may be additionally allocated in a data region (eg, a resource region for PDSCH, see FIG. 3). The PDCCH allocated to the data region is called an E-PDCCH. The figure shows a case where one E-PDCCH exists in one slot. However, as an example, the E-PDCCH may exist in subframe units (ie, over two slots).

Hereinafter, a method of allocating and operating resources for a downlink control channel using a data region (eg, PDSCH) of a subframe will be described with reference to the drawings. For convenience, the following description is described based on the relationship between the base station and the terminal, but the present invention can be applied equally or similarly to the base station relay or the relay terminal. Therefore, in the following description, the base station terminal may be replaced with a base station relay or a relay terminal. In terms of signal reception, the relay and the terminal may be generalized to the receiving end. When the relay operates as a receiver, the E-PDCCH may be replaced with a relay-PDCCH (R-PDCCH).

First, the E-PDCCH will be described in more detail. E-PDCCH carries DCI. For example, the E-PDCCH may carry downlink scheduling information and uplink scheduling information. E-PDCCH / PDSCH process and E-PDCCH / PUSCH process are the same / similar to the process according to the L-PDCCH. That is, the terminal may receive the E-PDCCH and may receive data / control information through a PDSCH corresponding to the E-PDCCH. In addition, the UE may receive the E-PDCCH and transmit data / control information through a PUSCH corresponding to the E-PDCCH. E-PDCCH transmission processing (eg, channel encoding, interleaving, multiplexing, etc.) may be performed using processing defined in existing LTE (see FIGS. 4 to 5) to the extent possible, and may be modified as necessary.

On the other hand, the existing LTE is taking a scheme of pre-reserving the PDCCH candidate region (PDCCH SS) in the control region and transmitting the PDCCH of a specific terminal to a portion thereof. Accordingly, the UE may obtain its own PDCCH in the PDCCH SS through blind detection. Similarly, the E-PDCCH may also be transmitted over some or all of the pre-reserved resources.

15 illustrates a process of resource allocation and E-PDCCH reception for an E-PDCCH.

Referring to FIG. 15, the base station transmits E-PDCCH resource allocation (RA) information to the terminal (S1510). The E-PDCCH RA information may include RB (or Virtual Resource Block (VRB)) allocation information. RB allocation information may be given in units of RBs or in units of resource block groups (RBGs). RBGs comprise two or more consecutive RBs. The E-PDCCH RA information may be transmitted using higher layer (eg, RRC) signaling. Here, the E-PDCCH RA information is used to pre-reserve the E-PDCCH resource (area). Thereafter, the base station transmits the E-PDCCH to the terminal (S1520). The E-PDCCH may be transmitted in some or all regions of the reserved E-PDCCH resources (eg, M RBs) in step S1510. Accordingly, the UE monitors a resource (region) in which the E-PDCCH can be transmitted (hereinafter, E-PDCCH SS, simply SS) (S1530). The E-PDCCH SS may be given as part of the RB set allocated in step S1510. Here, monitoring includes blindly detecting a plurality of E-PDCCH candidates in the SS.

When E-PDCCH is introduced, PDCCH SS (ie, CSS and USS) for control channel detection may be operated in three ways as follows according to control overhead and / or L-PDCCH interference. 16 shows the following scheme.

Case 0: Both CSS and USS are configured on L-PDCCH region

Case 1: CSS is configured on the L-PDCCH region, USS is configured on the E-PDCCH region

Case 2: Both CSS and USS are configured on the E-PDCCH region

Case 0 is a conventional operation and may be suitable when both the control overhead and the L-PDCCH interference effects are relatively small. Case 1 has a low L-PDCCH interference but a large control overhead, and further improves transmission performance for a UE-specific PDCCH through, for example, multi-antenna transmission and / or UE-specific DeModulation Reference Signal (DMRS) operation. May be useful for the purpose. Case 2 may be suitable when the L-PDCCH interference effect and / or control overhead is relatively large. In case 0/2, since CSS and USS are transmitted through the same resource region (that is, L-PDCCH region or E-PDCCH region), there may exist a control channel confusion problem due to overlap between CSS and USS. Here, in case 0, control channel confusion may be resolved by using the method described with reference to FIGS. 10 to 13.

Hereinafter, a case of solving the control channel confusion in Case 2 is proposed. Since the basic proposal is similar to the method described with reference to FIGS. 10 to 13, the details described with reference to FIGS. 10 to 13 may be referred to.

In case 2, CSS and USS for one UE are configured in the E-PDCCH region on the same CC, and the CSS-DCI and USS-DCI have the same payload size but the fields in the DCI format are configured differently or the same. When the fields have different sizes, it is proposed to transmit / receive only CSS-DCI among DCI formats having the same payload size at least in the overlap region of CSS and USS. Here, in CSS-DCI and USS-DCI, a field configuration / field size of DCI information may vary due to a CIF field, an aperiodic SRS request field, or an aperiodic CSI request field. This scheme uses the same RNTI (e.g. C-RNTI, SPS-RNTI) to mask the CRC using the same CSS-DCI (or PDDCH candidate for CSS-DCI) and USS-DCI (or PDDCH candidate for CSS-DCI). (Or scrambled) where applicable. In addition, the present scheme may allow / recognize only CSS-DCI transmission for the entire overlap region of CSS and USS, or the PDCCH candidate for CSS-DCI and the PDCCH candidate for USS-DCI may have the same starting CCE (or, Only a corresponding control channel resource unit (designed specifically for the E-PDCCH) may be allowed / recognized only for the corresponding CSS-DCI transmission.

Unlike the method described with reference to FIGS. 10 to 13, the confusion resolution scheme for the E-PDCCH may further consider the CCE (or corresponding minimum control channel resource unit (designed specifically for the E-PDCCH)) merging level. Can be. In the case of the existing L-PDCCH, since a repeating DCI codeword is mapped to the CCE due to the circular buffer characteristic of the base station, the UE detects the blind at a CCE aggregation level lower than the corresponding CCE aggregation level. The case where the corresponding DCI is detected may occur. As a result, the UE cannot know the actual CCE aggregation level applied to the DCI. In the case of the L-PDCCH, since the UE only needs to receive the PDCCH indicated to the SS in the corresponding SS, even if the CCE aggregation level is not known correctly, problems such as resource waste do not occur. However, in the case of the E-PDCCH, since the E-PDCCH and the PDSCH for the same UE may be multiplexed together in the data region, when the resource merging level (eg, the CCE merging level) of the E-PDCCH is not known correctly, the E-PDCCH and the PDSCH are not known. It can result in wasted resources that cannot be used for either purpose. In particular, when the E-PDCCH and the PDSCH for one UE are multiplexed in the same RB or RB pair, an unclear CCE merging level may cause an error in the PDSCH decoding process.

Therefore, in the case of introducing the E-PDCCH structure, in order to maximize the resource usage efficiency of the existing data region, the DCI codeword is appropriately applied so that the encoding / decoding result for the same DCI codeword is matched between the base station and the UE in view of the CCE aggregation level. You can consider mapping it as: Through this, the UE correctly grasps the CCE merging level of the DCI and, in particular, when the E-PDCCH and the PDSCH are multiplexed in the same RB or RB pair, the scheduled / transmitted E-PDCCH and PDSCH regions Can be distinguished exactly.

As described above, when the detected CCE merge level of the DCI can be distinguished by the UE, if the CCE merge levels of the CSS-DCI and the USS-DCI are different from each other, channel confusion does not occur.

17 exemplifies a case in which control channel confusion does not occur in the E-PDCCH region. FIG. 17 (a) shows a starting CCE (or corresponding minimum control channel resource unit (designed specifically for E-PDCCH)) in which the PDCCH candidate for the CSS-DCI and the PDCCH candidate for the USS-DCI are the same in the overlap region. Illustrates the case consisting of. However, since CSS has a CCE merge level of 4 (L = 4) and USS has a CCE merge level of 2, control channel confusion does not occur in the overlap region of CSS and USS. In contrast, FIG. 17B illustrates a case where the CCE merging levels of the CSS and the USS are the same (L = 4). However, CSS-DCI and USS-DCI are not confused in the overlap region because the PDCCH candidate for the CSS-DCI and the PDCCH candidate for the USS-DCI have different starting CCEs in the overlap region.

Therefore, if the UE can clearly distinguish the CCE aggregation level of DCI, the scheme for resolving the E-PDCCH confusion is additionally the CCE aggregation level of the E-PDCCH candidate for CSS-DCI and the E-PDCCH candidate for USS-DCI. It may be applied when the CCE merging level is the same. 18 illustrates a control channel transmission / reception process according to the present scheme. Referring to FIG. 18, for example, when CSS and USS for the same UE are configured in an E-PDCCH region on the same CC (eg, DL PCC), an E-PDCCH candidate satisfying the following condition is transmitted only through CSS. Can be received Equivalently, if the UE is configured to monitor an E-PDCCH candidate that satisfies the following conditions in CSS and USS, the UE assumes that the E-PDCCH candidate is received only through CSS (eg, monitoring) )can do.

E-PDCCH candidates with the same payload size

E-PDCCH candidates with CRC masked (or scrambled) with the same RNTI (eg C-RNTI, SPS-RNTI)

E-PDCCH candidates with the same starting CCE (or corresponding minimum control channel resource unit (designed specifically for the E-PDCCH)).

E-PDCCH candidates with the same CCE (or corresponding minimum control channel resource unit (designed specifically for E-PDCCH)) merge level

According to the present scheme, the UE recognizes the DCI format detected in the overlap region as CSS-DCI for the same payload size DCI formats at the overlap time point (eg, subframe n). As an equivalent process, when the UE monitors the DCI format having the same payload size in the CSS and the USS, it may be assumed that only the CSS-DCI is transmitted in the overlap region. The reason for the high priority of CSS-DCI is that the fields constituting the CSS-DCI are not changed before and after the RRC reconfiguration, so that there is an overlap between SSs in the RRC reconfiguration (eg, CIF reconfiguration, aperiodic SRS reconfiguration, CC merge reconfiguration). This is because the terminal malfunction can be prevented.

Although the above description has been described under the assumption that the CCE merging level is divided for the E-PDCCH, it may be preferable that the CCE merging level is also divided for the L-PDCCH. Therefore, when the CCE aggregation level of the L-PDCCH can also be clearly distinguished by the UE, the CCE aggregation level may be further considered in the control channel confusion scheme of FIGS. 10 to 13.

19 illustrates a base station and a terminal that can be applied to an embodiment of the present invention.

Referring to FIG. 19, a wireless communication system includes a base station (BS) 110 and a terminal (UE) 120. Base station 110 includes a processor 112, a memory 114, and a radio frequency (RF) unit 116. The processor 112 may be configured to implement the procedures and / or methods suggested by the present invention. The memory 114 is connected to the processor 112 and stores various information related to the operation of the processor 112. The RF unit 116 is coupled to the processor 112 and transmits and / or receives wireless signals. The terminal 120 includes a processor 122, a memory 124 and an RF unit 126. The processor 122 may be configured to implement the procedures and / or methods proposed by the present invention. The memory 124 is connected with the processor 122 and stores various information related to the operation of the processor 122. The RF unit 126 is coupled to the processor 122 and transmits and / or receives radio signals. The base station 110 and / or the terminal 120 may have a single antenna or multiple antennas.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is clear that the claims that are not expressly cited in the claims may be combined to form an embodiment or be included in a new claim by an amendment after the application.

In this document, the embodiments of the present invention have been mainly described with reference to the data transmission / reception relationship between the terminal and the base station. The specific operation described herein as being performed by the base station may be performed by its upper node, in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A base station may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. In addition, the terminal may be replaced with terms such as a user equipment (UE), a mobile station (MS), a mobile subscriber station (MSS), and the like.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, an embodiment of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) field programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit of the invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

The present invention can be used in a wireless communication device such as a terminal, a relay, a base station, and the like.

Claims (14)

In the method of the terminal in the wireless communication system to perform the process of determining the control channel allocation for the control channel,
Monitoring a common search space comprising a set of control channel candidates for the control channel on a particular carrier; And
Monitoring on the particular carrier a terminal-specific search space comprising a set of control channel candidates for the control channel,
The terminal selects a plurality of control channel candidates having the same Radio Network Temporary Identifier (RNTI), the same information size, the same first control channel resource, and the same control channel resource merging level in the common search space and the terminal-specific search space. And when set to monitor, control channel candidates corresponding to the condition are received only in the common search space. The method of claim 1,
And for the plurality of control channel candidates, the control channel can be received only in the common search space. The method of claim 1,
If a control channel is detected in the plurality of control channel candidates, the control channel is considered to have been received in the common search space. The method of claim 1,
Monitoring the plurality of control channel candidates is performed under the assumption that the control channel can only be received in the common search space. The method of claim 1,
Wherein the plurality of control channel candidates are scrambled with a cyclic redundancy check (CRC) with the same RNTI. The method of claim 1,
And the information size is a downlink control information (DCI) payload size. The method of claim 1,
Wherein the control channel is a Physical Downlink Control Channel (PDCCH) and the control channel candidate is a PDCCH candidate. A terminal configured to perform a process of determining a control channel allocation for a control channel in a wireless communication system,
A radio frequency (RF) unit; And
Includes a processor,
The processor is configured to monitor a common search space including a control channel candidate set for the control channel on a specific carrier and to monitor a terminal-specific search space including the control channel candidate set for the control channel on the specific carrier. Become,
The terminal selects a plurality of control channel candidates having the same Radio Network Temporary Identifier (RNTI), the same information size, the same first control channel resource, and the same control channel resource merging level in the common search space and the terminal-specific search space. When set to monitor, the control channel candidate corresponding to the condition is received only in the common search space. 9. The method of claim 8,
The control channel can be received only in the common search space only for the plurality of control channel candidates. 9. The method of claim 8,
And when a control channel is detected in the plurality of control channel candidates, the control channel is received in the common search space. 9. The method of claim 8,
Monitoring the plurality of control channel candidates is performed under the assumption that the control channel can only be received in the common search space. 9. The method of claim 8,
The control channel candidate is a terminal in which a cyclic redundancy check (CRC) is scrambled with the same RNTI. 9. The method of claim 8,
The information size is a terminal downlink control information (DCI) payload size. 9. The method of claim 8,
The control channel is a physical downlink control channel (PDCCH), the control channel candidate is a PDCCH candidate terminal.

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