CN108155980B - Reception and configuration of downlink control channels - Google Patents

Abstract

The present invention relates to the reception and configuration of downlink control channels. More particularly, the present invention relates to a method and apparatus (e.g., user equipment) for receiving a downlink control channel located in a data region, and a method and apparatus (e.g., transmission/reception point) for configuring and transmitting the downlink control channel.

Description

Reception and configuration of downlink control channels

The application is a divisional application, the application number of the original application is 201380059386.7, the application date is 2013, 9 and 13, and the name of the invention is 'receiving and configuring of a downlink control channel'.

Technical Field

The present invention relates to the reception and configuration of downlink control channels. More particularly, the present invention relates to a method and apparatus (e.g., user equipment) for receiving a downlink control channel located in a data region, and a method and apparatus (e.g., transmission/reception point) for configuring and transmitting the downlink control channel.

Background

In order to efficiently use restricted resources in a wireless communication system, a control channel may be required. However, resources of the control region may correspond to system overhead, thus reducing resources of the data region available for data transmission. In a wireless communication system capable of transmitting data to multiple users, system capacity improvements may be limited due to the limited resources of a typical control region.

Therefore, in order to increase control channel resources, a method of transmitting/receiving a multi-user control channel using a space division multiplexing scheme in the data region may be required. In this case, it may be necessary to configure a search space of the user equipment so that Downlink Control Information (DCI) is received through the control channel.

Disclosure of Invention

According to at least one embodiment, a method of receiving a downlink control channel located in a data region in a User Equipment (UE) may be provided. The method may include receiving an Enhanced Physical Downlink Control Channel (EPDCCH) from a transmission/reception point through the data region of N Physical Resource Block (PRB) pairs for forming each of K EPDCCH sets in a subframe, wherein (i) the K and N are natural numbers greater than or equal to 1, (ii) each of the N PRB pairs includes 16 Enhanced Resource Element Groups (EREGs), and (iii) an Enhanced Control Channel Element (ECCE) corresponding to an EPDCCH transmission basic unit includes 4 or 8 EREGs; and decoding the EPDCCH in a corresponding EPDCCH set according to a Downlink Control Information (DCI) format in an EPDCCH UE-specific search space, wherein ECCEs associated with the decoding of the EPDCCH are defined by a function of a Radio Network Temporary Identity (RNTI) of the user equipment, an index of the subframe, an aggregation level, and a total number of ECCEs of the corresponding epddh set.

According to another embodiment, a method for configuring a downlink control channel located in a data region in a User Equipment (UE) -specific search space in a transmission/reception point may be provided. The method may include defining Enhanced Control Channel Elements (ECCEs) corresponding to basic transmission units of an Enhanced Physical Downlink Control Channel (EPDCCH) in an EPDCCH UE-specific search space, wherein (i) the EPDCCH is located in the data region of N Physical Resource Block (PRB) pairs forming each of K EPDCCH sets in a subframe, (ii) the K and N are natural numbers greater than or equal to 1, (iii) each of the N PRB pairs includes 16 Enhanced Resource Element Groups (EREGs), (iv) each of the ECCEs includes 4 or 8 EREGs, and (v) the ECCEs are defined by a function of a Radio Network Temporary Identity (RNTI) of a user equipment, an index of the subframe, an aggregation level, and a total number of ECCEs of corresponding EPDCCH sets; and transmitting the ECCEs defined in the EPDCCH UE-specific search space to the user equipment through the EPDCCH.

According to yet another embodiment, a user equipment for receiving a downlink control channel located in a data region may be provided. The user equipment may include a receiver and a control processor. The receiver may be configured to receive an Enhanced Physical Downlink Control Channel (EPDCCH) from a transmission/reception point over the data region of N Physical Resource Block (PRB) pairs forming each of K EPDCCH sets in a subframe. Where (i) the K and N are natural numbers greater than or equal to 1, (ii) each of the N PRB pairs includes 16 Enhanced Resource Element Groups (EREGs), and (iii) an Enhanced Control Channel Element (ECCE) corresponding to the EPDCCH transmission basic unit includes 4 or 8 EREGs. The control processor may be configured to decode the EPDCCH in a corresponding EPDCCH set according to a Downlink Control Information (DCI) format in an EPDCCH UE-specific search space, wherein an ECCE associated with the decoding of the EPDCCH is defined by a function of a Radio Network Temporary Identity (RNTI) of the user equipment, an index of the subframe, an aggregation level, and a total number of ECCEs of the corresponding epddh set.

According to yet another embodiment, a transmission/reception point for configuring a downlink control channel located in a data region in an EPDCCH User Equipment (UE) specific search space may be provided. The transmission/reception point may include a control processor and a transmitter. The control processor may be configured to define Enhanced Control Channel Elements (ECCEs) corresponding to basic transmission units of the EPDCCH in an EPDCCH UE-specific search space. Here, (i) the EPDCCH is located in the data region of N Physical Resource Block (PRB) pairs for forming each of K EPDCCH sets in a subframe, (ii) the K and N are natural numbers greater than or equal to 1, (iii) each of the N PRB pairs includes 16 Enhanced Resource Element Groups (EREGs), (iv) each of the ECCEs includes 4 or 8 EREGs, and (v) the ECCE is defined by a function of a Radio Network Temporary Identity (RNTI) of a user equipment, an index of the subframe, an aggregation level, and a total number of ECCEs of the respective epddh set. The transmitter may be configured to transmit the ECCEs defined in the EPDCCH UE-specific search space to the user equipment over the EPDCCH.

In the case where a user equipment is configured to receive Downlink Control Information (DCI) over an Enhanced Physical Downlink Control Channel (EPDCCH) corresponding to a newly employed downlink control channel, the embodiments relate to methods and apparatus for performing blind decoding for the user equipment at each Aggregation Level (AL) in an EPDCCH set (or EPDCCH sets).

Drawings

Fig. 1 is a diagram illustrating a wireless communication system to which at least one embodiment may be applied;

fig. 2 depicts one resource block pair in case of a normal cyclic prefix (normal CP) as an example of a downlink resource structure in a Long Term Evolution (LTE) or LTE-advanced (LTE-a) system;

FIG. 3 depicts search spaces in two user devices;

figure 4 depicts two types of EPDCCH transmissions including localized EPDCCH transmissions and distributed EPDCCH transmissions;

fig. 5 depicts Resource Element (RE) mapping of Physical Resource Block (PRB) pairs indexed according to the EREG indexing process for one transmission antenna port (CRS port 0);

fig. 6 depicts RE mapping of PRB pairs indexed according to the EREG indexing process for the case of two transmission antenna ports (CRS ports 0 and 1);

fig. 7 depicts RE mapping of PRB pairs indexed according to the EREG indexing process for the case of four transmit antenna ports ( CRS ports 0,1,2, and 3);

fig. 8 is a flow chart describing a method of configuring a downlink control channel located in a data region in an EPDCCH UE-specific search space of a transmission/reception point in accordance with at least one embodiment;

fig. 9 depicts determining an ECCE start offset value in a method of configuring a downlink control channel located in a data region in an EPDCCH UE-specific search space of a transmission/reception point in accordance with at least one embodiment;

fig. 10 is a flowchart describing a method of receiving a downlink control channel located in a data region in a user equipment according to other embodiments;

FIG. 11 is a schematic diagram that depicts a base station in accordance with several embodiments;

fig. 12 is a schematic diagram depicting a user device according to several embodiments.

Detailed Description

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. In the description that follows, like elements will be designated by like reference numerals even though they are shown in different drawings. In addition, in the description of the present embodiment that follows, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present embodiment unclear.

A wireless communication system according to at least one embodiment may be widely used to provide a variety of communication services such as voice services, packet data services, and the like. The wireless communication system may include a User Equipment (UE) and at least one transmission/reception point. In this specification, the term "user equipment" or "(UE)" is used as a general concept, which includes a terminal in wireless communication. Accordingly, the user equipment should be interpreted as a concept including a Mobile Station (MS), a User Terminal (UT), a Subscriber Station (SS), and/or a wireless device in global system for mobile communication (GSM), and user equipment for use in Wideband Code Division Multiple Access (WCDMA), Long Term Evolution (LTE), and/or High Speed Packet Access (HSPA).

The transmission/reception point may indicate a station communicating with the user equipment. Such transmission/reception points may be referred to by different terms, such as a Base Station (BS), a cell, a node B, an evolved node B (enb), a sector, a site, a Base Transceiver System (BTS), an Access Point (AP), a Relay Node (RN), a Remote Radio Head (RRH), a Radio Unit (RU), and the like.

That is, in this specification, the transmission/reception point, the Base Station (BS), or the cell may be interpreted as a concept of containment indicating a part of an area or a function covered by a Base Station Controller (BSC) in Code Division Multiple Access (CDMA), an eNB or a sector (site) in a node B, LTE in WCDMA, or the like. Thus, the concept of transmission/reception points, Base Stations (BSs) and/or cells may include a wide variety of coverage areas, such as macrocells, microcells, picocells, femtocells, and the like. In addition, such concepts may include a communication range of the Relay Node (RN), the Remote Radio Head (RRH), or the Radio Unit (RU).

In this specification, the user equipment and the transmission/reception point may be two transmission/reception bodies having inclusive meanings for embodying the technological and technical concepts disclosed herein, and may not be limited to specific terms or words. In addition, the user equipment and the transmission/reception point may be uplink or downlink transmission/reception bodies having inclusive meanings for embodying the disclosed technological and technical concepts related to the present embodiment, and may not be limited to specific terms or words. Here, Uplink (UL) transmission/reception is a scheme of transmitting data from a user equipment to a transmission/reception point. Alternatively, Downlink (DL) transmission/reception is a scheme of transmitting data from the transmission/reception point to the user equipment.

The wireless communication system may use a variety of multiple access schemes such as CDMA, Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA, and/or others. However, such a multiple access scheme is not limited thereto. At least one embodiment may be applied to resource allocation in the field of asynchronous wireless communication evolving into LTE and LTE-advanced (LTE-a) through GSM, WCDMA, and HSP, and in the field of synchronous wireless communication evolving into CDMA, CDMA-2000, and UMB. The present embodiment should not be construed as limited or restricted to a particular field of wireless communication, and should be construed to include all technical fields to which the spirit of the present embodiment can be applied.

In the case of uplink transmission and downlink transmission, at least one of time division multiplexing (TDD) and frequency division multiplexing (FDD) may be used. Here, the TDD may perform the uplink/downlink transmission using different times.

In a corresponding standard-compliant LTE or LTE-a system, one uplink and/or one downlink may be formed on a carrier or pair of carriers basis. In the uplink and/or downlink case, control information may be transmitted over such control channels as a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator Channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a Physical Uplink Control Channel (PUCCH), and/or others. Data may be transmitted over such data channels as a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Shared Channel (PUSCH), and/or others. In this specification, PDCCH may be a concept including EPDCCH.

In this specification, the term "cell" may denote one of a signal transmitted by a transmission point or a transmission/reception point, a component carrier having a coverage, and a coverage of the transmission/reception point. Here, the term "transmission/reception point" may mean one of a transmission point at which a signal is transmitted, a reception point at which a signal is received, and a combination thereof (i.e., transmission/reception point).

In this specification, the term "HARQ ACK/NACK" is an abbreviation of hybrid automatic repeat request (HARQ) Acknowledgement (ACK)/Negative Acknowledgement (NACK), and may be referred to as a hybrid-ARQ acknowledgement or hybrid ACK/NACK signal. The channel state information CSI may mean a channel state information report such as Rank Indication (RI), Precoding Matrix Indication (PMI), and Channel Quality Indication (CQI).

Fig. 1 is a diagram illustrating a wireless communication system to which at least one embodiment may be applied.

Referring to fig. 1, the wireless communication system 100 may be one of a coordinated multi-point transmission/reception (CoMP) system, a multi-antenna coordinated transmission system, and a multi-cell coordinated communication system. Here, the CoMP system may transmit signals through cooperation between a plurality of transmission/reception points. A wireless communication system 100, such as a CoMP system, may include a plurality of transmission/reception points 110 and 112 and at least one User Equipment (UE)120 or 122.

As shown in the figure, the transmission/reception point may be one of a first transmission/reception point (e.g., eNB 110) and a second transmission/reception point (e.g., RRH 112). Here, the first transmission/reception point (e.g., eNB 110) may be a base station or a macro cell (or macro node). The second transmission/reception point (e.g., RRH 112) may be at least one pico cell wired to the first transmission/reception point (e.g., eNB 110) by fiber optic cable or fiber. Additionally, the second transmission/reception point (e.g., RRH 112) may have a high transmission power or a low transmission power within the macrocell region. The first and second transmission/reception points (e.g., eNB 110 and RRH 112) may have the same cell Identification (ID) or different cell identifications.

Hereinafter, Downlink (DL) may represent a communication or communication path from transmission/reception points 110 and 112 to user equipment 120. The Uplink (UL) may represent the communication or communication path from user equipment 120 to transmission/reception points 110 and 112. In the downlink, the transmitter may be part of transmission/reception points 110 and 112 and the receiver may be part of user equipment 120 and 122. In the uplink, the transmitter may be part of the user equipment 120 and the receiver may be part of the transmission/reception points 110 and 112.

Hereinafter, a case where a signal is transmitted or received through such a channel as PUCCH, PUSCH, PDCCH, and/or PDSCH may be referred to as the expression "transmitting or receiving PUCCH, PUSCH, PDCCH, and/or PDSCH".

The first transmission/reception point (e.g., eNB 110) corresponding to one of the transmission/reception points (e.g., 110 and 112) may perform downlink transmission to the user equipments 120 and 122. The first transmission/reception point (e.g., eNB 110) may transmit a PDSCH corresponding to the primary physical channel for unicast transmission. In addition, the first transmission/reception point (e.g., eNB 110) may transmit PDCCH for transmitting downlink control information, such as scheduling information required for receiving PDSCH, and scheduling grant information for uplink data channel (e.g., PUSCH) transmission. Hereinafter, "transmitting or receiving a signal through a channel" may be referred to as the expression "transmitting or receiving a channel".

In wireless communication, one radio frame may include 10 subframes, and one subframe may include two slots. The radio frame may have a length of 10ms, and the subframe may have a length of 1.0 ms. Typically, a basic unit of data transmission may be a subframe, and downlink or uplink scheduling may be performed on a subframe unit. In case of a normal Cyclic Prefix (CP), one slot may include 7 OFDM symbols in the time domain. In case of an extended Cyclic Prefix (CP), one slot may include 6 OFDM symbols in the time domain.

For example, the frequency domain in wireless communication may be formed on subcarrier units having an interval of 15 kHz.

In downlink, time-frequency resources may be determined in Resource Block (RB) units. A Resource Block (RB) may be composed of one slot in a time axis and 180kHz (12 subcarriers) in a frequency axis. A resource element consisting of one subcarrier (corresponding to two slots) in the time axis and 12 subcarriers in the frequency axis may be referred to as a Resource Block Pair (RBP). The total number of resource blocks may vary depending on the system bandwidth. A Physical Resource Block (PRB) pair including a PRB in a first slot and a PRB in a second slot having the same PRB index may correspond to a resource allocation basic unit in one downlink subframe. In this specification, the PRB pair may be simply referred to as a PRB. The Resource Element (RE) may be composed of one OFDM symbol in the time axis and one subcarrier in the frequency axis. One Resource Block Pair (RBP) may include 14x12 resource elements (in the case of a normal CP) or 12x12 resource elements (in the case of an extended CP).

Fig. 2 depicts one resource block pair in the case of a normal cyclic prefix (normal CP) as an example of a downlink resource structure in a Long Term Evolution (LTE) or LTE-advanced (LTE-a) system.

Referring to fig. 2, in case of a normal Cyclic Prefix (CP), one Resource Block Pair (RBP) may include 14 OFDM symbols ( l 0,1 … 13) and 12 subcarriers (k 0 … 11). In the embodiment shown in fig. 2, one Resource Block Pair (RBP) may include 14 OFDM symbols. Of the 14 OFDM symbols, the first 3 OFDM symbols (l ═ 0-2) may correspond to a control region 210 allocated for a control channel such as a Physical Control Format Indicator Channel (PCFICH), a physical hybrid ARQ indicator channel (PHICH), a Physical Downlink Control Channel (PDCCH), and the like. The remaining OFDM symbols (l — 3-13) may correspond to a data region 220 allocated for a data channel such as a Physical Downlink Shared Channel (PDSCH). Although 3 OFDM symbols are allocated for the control region 210 in fig. 2, 1 to 4 OFDM symbols may be allocated for the control region 210 according to various embodiments. Information on the size of the control region 210 may be transferred through the PCFICH. Here, the size information may be set to the number of OFDM symbols.

The PDCCH may be transmitted through the entire system bandwidth. The PDSCH may be transmitted on a resource block basis. The user equipment may identify a corresponding PDCCH (i.e., a PDCCH allocated to the user equipment) and enter a micro sleep mode when there is no data (i.e., data for the user) in the corresponding PDCCH. Therefore, it is possible to reduce the power consumption of the user equipment in the data area 220.

Referring to fig. 2, a reference signal may be mapped to a specific resource element of a downlink. That is, a common reference signal (or cell-specific reference signal, hereinafter, referred to as CRS)230, demodulation reference signals (DM-RSs) (or user-specific reference signals) 232 and 234, a channel state information reference signal (CSI-RS), and the like may be transmitted through a downlink. In fig. 2, only the CRS 230 and DM- RSs 232 and 234 are illustrated for convenience of description.

The CRS 230 in the control region 210 may be used to perform channel estimation for PDCCH decoding. The CRS 230 in the data region 220 may be used for downlink channel measurements. Channel estimation for data decoding of the data region 220 may be performed using the DM-RSs 232 and/or 234. The DM- RSs 232 and 234 may be multiplexed using orthogonal codes as reference signals for multiple layers. For example, in the case of 4-layer transmission, 2 different reference signals for each reference signal group may be multiplexed by applying a length-2 orthogonal code to 2 consecutive reference signal resource elements in the time axis. In the case of 8-layer transmission, 4 different reference signals for each reference signal group may be multiplexed by applying a length-4 orthogonal code to 4 reference signal resource elements distributed in the time axis.

In case of layer 1 or layer 2 transmission, since the reference signal of each layer may be transmitted using only one DM-RS group (i.e., DM-RS group 1(232)), another DM-RS group (i.e., DM-RS group 2(234)) may be used for data transmission. The DM-RS corresponding to each layer may be precoded according to a precoding schedule applied to each layer and transmitted to the user equipment. Accordingly, the receiving side (i.e., user equipment) can perform data decoding without precoding information applied to the transmitting side (i.e., base station).

In order to efficiently use the restricted resources in the wireless communication system, a control channel may be required. However, the resources of the control region 210 may correspond to system overhead and thus reduce the resources of the data region 220 available for data transmission. In an OFDM-based LTE system, one Resource Block Pair (RBP) may include 14 or 12 OFDM symbols. Of the OFDM symbols, a maximum of 3 OFDM symbols may be used for the control region 210, and the remaining OFDM symbols may be used for the data region 220. Meanwhile, in an LTE-a system capable of transmitting data to multiple users, system capability enhancement may be limited due to limited resources of a typical control area (i.e., 210). Therefore, in order to increase control channel resources, it may be necessary to consider a method of transmitting/receiving a multi-user control channel, such as using a space division multiplexing scheme in the data region 220. In other words, the method may transmit/receive the control channel in the data region 220. For example, the control channel transmitted in the data region 220 may be referred to as an enhanced PDCCH or an enhanced PDCCH, but is not limited thereto.

As described above, in a typical (or existing) 3GPP LTE/LTE-a rel-8/9/10 system, in order to receive downlink DCI, all user equipments rely on PDCCH transmitted through the first one, two or three OFDM symbols (in case of system bandwidth greater than 10 PRB) or four OFDM symbols (in case of system bandwidth less than or equal to 10 PRB) in the downlink subframe. The basic unit of PDCCH transmission for a given user equipment may be a Control Channel Element (CCE). Here, one CCE may include 9 Resource Element Groups (REGs). One REG may include 4 consecutive Resource Elements (REs) in the frequency axis. Especially, 4 consecutive Resource Elements (REs) of one REG may be selected among the remaining Resource Elements (REs) not including Resource Elements (REs) transmitting different physical channels (e.g., PCFICH/PHICH) and physical signals (e.g., CRS) in the PDCCH region of the corresponding downlink subframe.

To perform EPDCCH resource mapping for a given user equipment, enhanced REGs (eregs) or enhanced CCEs (ecces) corresponding to the REGs or CCEs of a typical PDCCH may be employed or defined in the EPDCCH.

As described above, in a typical (or existing) 3GPP LTE/LTE-a rel-8/9/10 system, in order to receive downlink DCI, all user equipments perform blind decoding of the PDCCH transmitted through the first one, two or three OFDM symbols (in case of system bandwidth greater than 10 PRB) or the first two, three or four OFDM symbols (in case of system bandwidth less than or equal to 10 PRB) in a downlink subframe. In this case, in order to provide sufficient processing time for PDSCH reception of the user equipment and to reduce energy consumption of the user equipment, blind decoding may be performed in the restricted search space as many times as the number of blind decodings restricted per Aggregation Level (AL) based on the corresponding DCI format determined according to the PDSCH/PUSCH transmission mode. That is, the blind decoding is not performed based on the Aggregation Level (AL) and DCI format in the entire PDCCH region.

Fig. 3 depicts search spaces in two user devices.

Referring to fig. 3, a given user equipment according to 3GPP LTE/LTE-a rel-8/9/10 may perform a limited number of blind decodings according to Aggregation Levels (ALs) in a Common Search Space (CSS) region and a user-specific search space (USS) region (or referred to herein as a terminal-specific search space region) in a PDCCH transmitted over a downlink subframe. Here, the CSS region is generally configured for all user equipments in a cell to which the corresponding user equipment belongs. The USS area is configured by user equipment only.

The respective PDCCH region may be divided into Control Channel Elements (CCEs) corresponding to resource allocation basic units for DCI transmission. PDCCHs for a given user equipment may be defined to be transmitted over 1,2, 4, or 8 CCEs according to an aggregation level. In addition, the given user equipment may perform blind decoding. The Transmission Mode (TM) that relies on the DCI formats associated with the blind decoding of the given user equipment (e.g., DCI format 1/1B/1D/2/2A/2B/2C for the downlink and DCI format 4 for the uplink) may be determined based on the PDSCH Transmission Mode (TM) and the PUSCH Transmission Mode (TM). Here, the PDSCH TM and the PUSCH TM may be configured by higher layer signaling according to the capabilities of a transmission/reception point and a user equipment (e.g., the number of Tx/Rx antennas per transmission/reception point and/or per user equipment) and a channel state between the user equipment and the transmission/reception point. Thus, blind decoding in the given user equipment may be performed in the UE-specific search space (USS) as many times as the number of blind decodes determined per Aggregation Level (AL) according to the respective TM depending on the DCI format and/or the backup DCI format, such as DCI format 0/1 a. Here, the USS may be determined by a function of a cell radio network temporary identity (C-RNTI), a slot index, and an aggregation level associated with the given user equipment, as defined by equation 1 below.

[ equation 1]

Here, i is 1, …, L-1 and M' is M + M^(L)·n_CI·n_CIDenotes a carrier indicator field value, and M is 0^(L)-1·M^(L)Indicating the number of PDCCH candidates monitored in a given space. L denotes Aggregation Level (AL), and L ∈ {1, 2, 4, 8} in UE-specific search space.

In addition, Y_k＝(A·Y_k-1) mod D, where a is 29827, D is 65537, and

indicating the number of slots in the radio frame.

Thus, a given user equipment according to 3GPP LTE/LTE-a rel-8/9/10 may perform blind decoding for DCI formats configured to be received by the user equipment. Here, the blind decoding may be performed on each of the aggregation levels 1,2, 4, and 8 in a respective UE-specific search space (USS), i.e., the USS for the given user equipment. In particular, the blind decoding may be performed 6, 2 or 2 times according to the aggregation level 1,2, 4 or 8. That is, the blind decoding may be performed 16 times for each of PDSCH TMs that depend on DCI formats and spare DCI formats, and thus up to 32 times in total. Meanwhile, in case that a given user equipment is configured as PUSCH Transmission Mode (TM)2, blind decoding may be further performed 16 times for DCI format 4. Thus, in this case, the blind decoding may be performed up to 48 times in total.

In case the user equipment is configured to receive DCI via a newly employed (or defined) EPDCCH in 3GPP LTE/LTE-a rel-11, blind decoding may be defined to be performed in the EPDCCH USS (i.e. the UE-specific search space of the EPDCCH) in place of the original PDCCH USS (i.e. the UE-specific search space of the original PDCCH) in the EPDCCH-monitored downlink subframe. In addition, in this case, K (K ≧ 1) EPDCCH sets may be determined by higher layer RRC signaling along with the downlink subframe configuration monitored for the EPDCCH as the EPDCCH USS for the respective user equipment (i.e., the user equipment configured to receive DCI over the respective EPDCCH) as described above. Here, the maximum value of K may be one of 2, 3, 4, and 6. Each EPDCCH set may include a PRB-group (e.g., N PRBs, where N is a natural number greater than or equal to 1 and less than or equal to the number of PRBs associated with the downlink bandwidth).

In addition, each EPDCCH set may be determined as one of a distributed type and a localized type and signaled according to the determined type.

The EPDCCH set may correspond to a localized type or a distributed type according to an EPDCCH transmission type. The above N may be 2, 4 or 8 for both localized type and distributed type, and is not limited thereto.

Fig. 4 depicts two types of EPDCCH transmissions including localized EPDCCH transmissions and distributed EPDCCH transmissions.

EPDCCH may be transmitted through a corresponding PDSCH region. In this case, the transmission type of the EPDCCH may correspond to localized EPDCCH transmission and distributed EPDCCH transmission as shown in fig. 4a and 4 b. Accordingly, an ECCE structure and the number of Resource Elements (REs) forming one ECCE may be different according to each EPDCCH transmission type. Alternatively, the ECCE structure and the number of Resource Elements (REs) per ECCE may be the same regardless of EPDCCH transmission similarity.

The localized EPDCCH transmission as shown in fig. 4a may illustrate that an ECCE is located and transmitted in one resource block pair (e.g., one PRB pair). The distributed EPDCCH transmission as shown in fig. 4b may illustrate that one ECCE is located and transmitted in at least two resource block pairs (e.g., at least two PRB pairs).

Meanwhile, K (K is more than or equal to 1) EPDCCH sets can be allocated to one user equipment. In this case, since each EPDCCH set is of a distributed type or a localized type, one user equipment may be allocated K_LLocalized EPDCCH set and K_DA set of distributed EPDCCH. I.e. K_LAnd K_DMay be K (K)_L+K_DK). In other words, K EPDCCH sets (or one set) may be classified as (i) K_LA localized EPDCCH set (or set) and (ii) K_DA set (or one set) of distributed EPDCCH. Here, K_LAnd K_DSatisfy K ═ K_L+K_D。

However, regardless of N, K, K described above_LAnd K_DHow the total number of blind decodings of the user equipment can be determined to be the same as in the typical (or legacy) system. Accordingly, in case of configuring K EPDCCH sets for a given EPDCCH user equipment, the number of blind decodings per Aggregation Level (AL) to be performed in each EPDCCH set by the respective user equipment may be determined. In addition, the size of the search space required for each respective Aggregation Level (AL) may be determined according to the number of blind decodes for each Aggregation Level (AL) in the respective EPDCCH set.

In a typical wireless communication system, the search space size associated with blind decoding for each Aggregation Level (AL) may be determined according to the number of blind decodes. That is, in case of PDCCH Aggregation Level (AL)1, blind decoding is defined to be performed 6 times, and thus 6 CCEs are configured for a UE-specific search space (USS) of the PDCCH Aggregation Level (AL) 1. Likewise, USSs for PDCCH Aggregation Levels (AL)2, 4, and 8 are determined in the same manner. More specifically, in the case of PDCCH AL 2, blind decoding is defined as being performed 6 times, and thus the USS for PDCCH AL 2 is configured with 12(═ 2 × 6) CCEs. In the case of PDCCH AL 4 and PDCCH AL 8, each respective blind decoding is defined to be performed 2 times, and thus 8 CCEs and 16 CCEs are configured for the USS of PDCCH AL 4 and PDCCH AL 8, respectively.

However, the size of the EPDCCH set may very likely be determined to be larger than the search space size typically required for each Aggregation Level (AL). Therefore, in case the size of an EPDCCH set is larger than a search space size determined based on the number of blind decodes per Aggregation Level (AL) to be performed in a respective EPDCCH aggregation, it may be necessary to define a search space configuration per Aggregation Level (AL) in the respective EPDCCH aggregation.

In the case where a user equipment is configured to receive Downlink Control Information (DCI) over an EPDCCH corresponding to a newly employed downlink control channel, the present embodiments may provide methods and apparatus for performing blind decoding for each Aggregation Level (AL) of the user equipment in a corresponding EPDCCH set (or EPDCCH sets). In particular, the present embodiments may provide methods and apparatuses for configuring a search space for each Aggregation Level (AL) to be monitored by a corresponding user equipment in each EPDCCH set configured for the corresponding user equipment.

As described above, in case a given user equipment is configured to receive Downlink Control Information (DCI) over EPDCCH, K (K ≧ 1) EPDCCH sets (or one set) may be configured for the user equipment. In this case, each EPDCCH set may include PRB-groups (i.e., N PRBs). In addition, in case of each EPDCCH set, a type of the corresponding EPDCCH set may be determined as a distributed type or a localized type. In other words, K EPDCCH sets (or one set) configured for EPDCCH user equipment may be configured with (i) K_LA localized EPDCCH set (or set) and (ii) K_DA set (or one set) of distributed EPDCCH. Here, the EPDCCH user equipment represents user equipment to which EPDCCH is applied. K_LAnd K_DSatisfy K ═ K_L+K_D。

Regardless of subframe type, Cyclic Prefix (CP) length, and the presence of other physical signals, one PRB included in each localized or distributed EPDCCH set may be configured with a total of 16 EREGs (e.g., EREG #0 through EREG #15) in the corresponding PRB pair.

In the case of the newly defined EREG/ECCE, a total of 16 EREGs (e.g., EREG #0 to EREG #15) may be included in one PRB pair per EPDCCH set. Specifically, regardless of (i) frame structure type, (ii) subframe configuration, (iii) Cyclic Prefix (CP) length, (iv) size of the legacy PDCCH control region, and/or (v) whether there are other reference signals (e.g., CRS, CSI-RS, PRS, etc.) that do not include DM-RS, the one PRB pair may include a total of 16 EREGs.

More specifically, in case of a normal Cyclic Prefix (CP), one PRB-pair in a certain EPDCCH set may include a total of 168 Resource Elements (REs) (e.g., 12 × 14 ═ 168 REs). In this case, EREG indexing may be performed on the remaining Resource Elements (REs), such as 144 REs, of the 24 Resource Elements (REs) excluding the DM-RS from the 168 Resource Elements (REs). That is, the EREG indexing may be performed using 16 numbers (e.g., 0,1,2 … 15) according to a frequency first scheme (i.e., a frequency first and time later manner). Accordingly, the respective Resource Elements (REs) may be numbered (i.e., indexed) from 0 to 15. Similarly, in case of an extended Cyclic Prefix (CP), one PRB-pair in a certain EPDCCH set may include a total of 144 Resource Elements (REs) (e.g., 12 × 12 ═ 144 REs). In this case, EREG indexing may be performed for remaining Resource Elements (REs), such as 128 REs, that do not include 16 Resource Elements (REs) for the DM-RS from among the 144 Resource Elements (REs). That is, the EREG indexing may be performed using 16 numbers (e.g., 0,1,2 … 15) according to a frequency first scheme (i.e., a frequency first and time later manner). Accordingly, the respective Resource Elements (REs) may be numbered (i.e., indexed) from 0 to 15.

In a downlink subframe corresponding to a normal Cyclic Prefix (CP) (normal DL subframe), embodiments associated with an EREG indexing procedure for one PRB pair in a certain EPDCCH set will be described in connection with fig. 5 to 7. In fig. 5 to 7, the abnormal polyline portion without numbers may represent Resource Elements (REs) for DS-RS, and the abnormal polyline portion or the lattice pattern portion with numbers may represent Resource Elements (REs) for CRS transmission.

Fig. 5 depicts Resource Element (RE) mapping of Physical Resource Block (PRB) pairs indexed according to the EREG indexing procedure in case of one transmission antenna port (CRS port 0). Fig. 6 depicts RE mapping of PRB pairs indexed according to the EREG indexing procedure in the case of two transmission antenna ports (CRS ports 0 and 1). Fig. 7 depicts RE mapping of PRB pairs indexed according to the EREG indexing process for the case of four transmit antenna ports ( CRS ports 0,1,2, and 3).

Referring to fig. 5-7, EREGs may be numbered (i.e., indexed) from 0 to 15 according to a frequency-first scheme (i.e., frequency-first and then time-later). In the embodiments shown in fig. 5-7, indexing may be performed without a symbol-based cyclic offset. More specifically, as shown in fig. 5, after the Resource Element (RE) indicated by 500 in the first symbol is indexed to 11 (i.e., index 11), the RE indicated by 510 in the second symbol is continuously indexed to 12 (i.e., index 12). Here, the RE (510) indexed to 12 (i.e., the RE (510) corresponding to the next round) is not adjacent to the RE (500) indexed to 11. In the same manner, after the RE indicated by 520 in the second symbol is indexed to 7 (i.e., index 7), the RE indicated by 530 in the third symbol is continuously indexed to 8 (i.e., index 8). Here, the RE (530) indexed to 8 (i.e., the RE (530) corresponding to the next round) is not adjacent to the RE (520) indexed to 7.

In fig. 5 to 7, REs having the same index may be grouped into one EREG. Therefore, in the case of one PRB pair, a total of 16 EREGs (e.g., EREG #0 to EREG #15) may be allocated. Fig. 5-7 describe embodiments associated with PRB pairs with normal CPs. That is, one PRB pair having the normal CP may include a total of 16 EREGs. Similarly, even in the case of one PRB pair with an extended CP, a total of 16 EREGs (e.g., EREG #0 to EREG #15) may be allocated. That is, one PRB pair having the extended CP may include a total of 16 EREGs.

Each ECCE corresponding to an EPDCCH transmission basic unit may include M EREGs according to a subframe type and a CP length. More specifically, the M value may be determined as follows.

In at least one embodiment, the M value may be determined to be 4 (M-4) in case of (i) a normal subframe having a normal CP and (ii) a special subframe having a special subframe configuration of 3, 4 or 8 and a normal CP. In other words, in this case, if 16 EREGs are included in one PRB pair, a total of 4 ECCEs may be configured because each ECCE is composed of 4 EREGs.

In other embodiments, the M value may be determined to be 8 (M-8) in the case of (i) a normal subframe having an extended CP, and (ii) a special subframe having a special subframe configuration of 1,2, 6, 7, or 9 and a normal CP, and (iii) a special subframe having a special subframe configuration of 1,2, 3, 5, or 6 and an extended CP. In other words, in this case, if 16 EREGs are included in one PRB pair, a total of 2 ECCEs may be configured because each ECCE consists of 8 EREGs.

Thus, one EPDCCH set formed for a given user equipment may be configured with (i)2N ECCEs (in case one ECCE consists of 8 EREGs) or (ii)4N ECCEs (in case one ECCE consists of 4 EREGs) according to the PRB size (i.e., N values, such as the value of a PRB) associated with one EPDCCH set, downlink subframe type, Cyclic Prefix (CP) length, etc.

Additionally, the user equipment may be configured to monitor EPDCCH. For when the number of REs for a possible EPDCCH transmission is less than a threshold value (X)_thresh) Normal subframe and normal CP when and for when the number of REs for possible EPDCCH transmission is less than a threshold value (X)_thresh) (hereinafter referred to as example 1) with special subframe configuration 3, 4 or 8 and normal CP, the localized EPDCCH set may be defined to support aggregation levels 2, 4, 8, and 16, and the distributed EPDCCH may be defined to support aggregation levels 2, 4, 8, 16, and 32.

Otherwise (hereinafter referred to as example 2), the localized EPDCCH set may be defined to support aggregation levels 1,2, 4, and 8, and the distributed EPDCCH may be defined to support aggregation levels 1,2, 4, 8, and 16.

As described above, regardless of (i) the number of EPDCCH sets (K) configured for the respective user equipment, (ii) each respective EPDCCH set type, and (iii) the aggregation level supported in the respective EPDCCH set, the total number of blind decoding attempts performed in the respective user equipment may need to be the same as in typical (or existing) user equipment. Therefore, the total number of blind decoding attempts performed in the respective user equipments according to the above-described PUSCH Transmission Mode (TM) may need to be 32 or 48.

The present embodiments may provide methods and apparatus for determining a search space for blind decoding of a given user equipment in EPDCCH aggregation configured for the given user equipment according to an EPDCCH design criterion. More specifically, the present embodiments may provide methods and apparatus for determining a search space in which to perform blind decoding by the given user equipment on a per aggregation level basis. In other words, in the present embodiment, EPDCCH aggregation may be configured with (i)2N ECCEs (e.g., ECCE #0 to ECCE # (2N-1)) or (ii)4N ECCEs (e.g., ECCE #0 to ECCE # (4N-1)) according to a PRB size associated with one EPDCCH set (e.g., an N value corresponding to the number of PRBs), a downlink subframe type configured with the corresponding EPDCCH set, a Cyclic Prefix (CP) length, and the like. Hereinafter, the total number of ECCEs may be referred to as N_ECCE. The expression ECCE # indicates an index of the corresponding ECCE.

Fig. 8 is a flow chart describing a method of configuring a downlink control channel located in a data region in an EPDCCH UE-specific search space of a transmission/reception point in accordance with at least one embodiment.

Referring to fig. 8, the transmission/reception point may perform a method of configuring the downlink control channel located in a data region in an EPDCCH UE-specific search space (800) according to at least one embodiment. More specifically, the method (800) may include (i) configuring (or defining) ECCEs of a basic transmission unit corresponding to an EPDCCH in an EPDCCH UE-specific search space at step S810, and (ii) transmitting the ECCEs configured (or defined) in the EPDCCH UE-specific search space to a user equipment through the EPDCCH at step S820.

More specifically, the transmission/reception point may define (or form) ECCEs corresponding to basic transmission units of the EPDCCH in the EPDCCH UE-specific search space at step S810. Here, the EPDCCH may be located in a data region of N resource block pairs (e.g., PRB pairs) forming each of the K EPDCCH sets in a subframe. Each EPDCCH set may include N resource block pairs (e.g., PRB pairs). The K and N may be natural numbers greater than or equal to 1. As described above, each PRB pair may include 16 EREGs, and each ECCE may include 4 or 8 EREGs.

Referring back to step S810, the transmission/reception point may determine a search space start offset (referred to herein as an ECCE start offset) using one of (i) an implicit configuration scheme, (ii) an explicit configuration scheme, and (iii) a hybrid configuration scheme. Hereinafter, each of the configuration schemes will be described in more detail. For example, in case of an implicit configuration scheme, the transmission/reception point may define (or form) ECCEs in an EPDCCH UE-specific search space using a function of (i) a Radio Network Temporary Identity (RNTI) of the user equipment, (ii) a subframe index, (iii) an aggregation level, and (iv) a total number of ECCEs included in one EPDCCH set.

In the operation of forming (or defining) ECCEs (S810), ECCEs may be formed (or defined) to be consecutive in the number of monitoring operations to be performed based on a corresponding aggregation level in an aggregation level unit, i.e., in an ECCE number unit corresponding to an aggregation level. Alternatively, the ECCEs may be formed to be discontinuous in the aggregation level unit. In particular, in case of a distributed EPDCCH set and/or a localized EPDCCH set, ECCEs may be contiguous. Meanwhile, in case of a distributed EPDCCH set and/or a localized EPDCCH set, the ECCEs may be non-continuous. Herein, the terms "continuous" and "non-continuous" may not necessarily mean "physically continuous" and "physically non-continuous". That is, these terms may be concepts including logically continuous/non-continuous and physically continuous/non-continuous.

As described later, the ECCE hopping value associated with a non-consecutive ECCE may be defined by a function of (i) a total number of ECCEs of the respective EPDCCH set, (ii) an aggregation level, and (iii) a number of candidate EPDCCH (i.e. EPDCCH interface candidates) to be monitored by the user equipment based on the respective aggregation level.

Meanwhile, in case that the user equipment is configured to have a carrier indicator field, a value of the carrier indicator field may be applied to a function defining the ECCE.

In addition, the transmission type of the EPDCCH set may correspond to one of localized EPDCCH transmissions and distributed EPDCCH transmissions. The aggregation level may be selected to be one of 1,2, 4, 8, 16, and 32. For when the number of REs for a possible EPDCCH transmission is less than a threshold value (X)_thresh) Normal subframe and normal CP when and for when the number of REs for possible EPDCCH transmission is less than a threshold value (X)_thresh) (hereinafter referred to as example 1) with special subframe configuration 3, 4 or 8 and normal CP, the localized EPDCCH set may be defined to support aggregation levels 2, 4, 8, and 16, and the distributed EPDCCH may be defined to support aggregation levels 2, 4, 8, 16, and 32. Otherwise (hereinafter referred to as example 2), the localized EPDCCH set may be defined to support aggregation levels 1,2, 4, and 8, and the distributed EPDCCH may be defined to support aggregation levels 1,2, 4, 8, and 16.

The transmission/reception point may transmit ECCEs formed (or defined) in the EPDCCH UE-specific search space to the user equipment through the EPDCCH at step S820.

To this end, a method of configuring a downlink control channel located in a data region in an EPDCCH UE-specific search space in a transmission/reception point according to at least one embodiment is described in connection with fig. 8. Hereinafter, embodiments associated with a method of determining a search space start offset (ECCE start offset) and a method of determining an ECCE index for a subsequent blind decoding attempt in an operation (S810) of configuring an ECCE are described in more detail.

<1. search space initiation offset (ECCE initiation offset) >

Example 1: explicit configuration

In case an EPDCCH set is formed for a given user equipment, a search space starting offset value for blind decoding by the user equipment in the respective EPDCCH set may be signaled by higher layers. In other words, in case of forming EPDCCH sets for EPDCCH user equipments, the ECCE start offset values may be signaled by dynamic or higher layer signaling (e.g. higher layer RRC signaling) used to form the respective EPDCCH sets. I.e., the ECCE start offset value may be included in a Radio Resource Control (RRC) message. In addition, in this case, the ECCE start offset value may be signaled together with (i) PRB group (i.e., N PRB) configuration information forming the EPDCCH set and (ii) transmission type information (such as localized type or distributed type) of the EPDCCH set. Here, the ECCE start offset value may indicate a start ECCE to be monitored by the user equipment at each aggregation level among the 2N ECCSs or the 4N ECCSs forming the corresponding EPDCCH set.

In this case, the blind decoding process of the respective user equipment may be performed from ECCE indexes corresponding to ECCE start offset values determined in all EPDCCH monitoring subframes.

In an example (first example) of determining an ECCE start offset value, one ECCE start offset value (ECCE) to be applied to all aggregation levels supported by a corresponding EPDCCH set when the EPDCCH set is configured is to be used_offset) May be determined and transmitted by higher layer signaling to the respective user equipment. In this case, the user equipment may apply the same ECCE start offset value to all aggregation levels defined for blind decoding in the corresponding EPDCCH set. That is, in the case where a certain EPDCCH set is configured with 2N ECCEs or 4N ECCEs, the ECCEs_offsetMay be determined to be N and signaled (at N) as described in fig. 9_ECCEIn the case of 4N). Here, the 2N ECCEs may include ECCE #0 to ECCE # (2N-1), and the 4N ECCEs may include ECCE #0 to ECCE #_offsetECCE # (4N-1). In this case, the corresponding user equipment may transmit the same ECCE_offset(e.g., ECCE # N) is applied to all Aggregation Levels (AL) defined for blind decoding in the corresponding EPDCCH set. Thus, in this case, the blind decoding may start from ECCE # N at all Aggregation Levels (AL).

In another example (second example) of determining the ECCE start offset value, the ECCE start offset value may be determined separately at each Aggregation Level (AL) supported by the respective EPDCCH set and transmitted by higher layer signaling to the respective user equipment. In other words, ECCE start bias in case a certain EPDCCH set is formed to support X aggregation levelsThe shift value may be differentially determined at each Aggregation Level (AL) and transmitted to the corresponding user equipment by higher layer signaling. Here, the different ECCE start offset values determined at each aggregation level may be expressed as ECCE_offset,1、ECCE_offset,2… and ECCE_offset,x. In this case, the respective user equipment may apply a different ECCE start offset value (i.e., an ECCE start offset value separately determined at each aggregation level) to each Aggregation Level (AL) defined for blind decoding in the respective EPDCCH set. Thus, in this case, the blind decoding may start from an ECCE index corresponding to an ECCE start offset value separately determined at each Aggregation Level (AL).

For example, in the case of forming localized EPDCCH sets, if Aggregation Levels (AL) associated with blind decoding of a user equipment are defined as 1,2, and 4, then three ECCE starting offset values (e.g., ECCE) for the user equipment_offset,1、_,ECCE_offset,2And ECCE_offset,3) May be determined. Accordingly, in case of Aggregation Level (AL)1, blind decoding performed by a corresponding user equipment may be selected from those corresponding to ECCE_offset,1The ECCE index of (a) starts. Similarly, in case of Aggregation Level (AL)2, the respective blind decoding performed by the respective user equipment may be selected from the group consisting of_offset,2The ECCE index of (a) starts. In case of Aggregation Level (AL)4, the respective blind decoding performed by the respective user equipment may be selected from the group consisting of_offset,3The ECCE index of (a) starts.

Example 2: implicit configuration

Typically, a UE-specific search space (USS) may be defined in the legacy (or typical) PDCCH at each aggregation level of the user equipment. An ECCE index start offset for performing blind decoding by a corresponding user equipment in an EPDCCH set formed by each user equipment may be defined in a manner similar to the exemplary scheme. More specifically, the ECCE index start offset may be defined as (i) RNTI of a corresponding user equipment, (ii) subframe index (e.g., as

Wherein n is_sFor the slot index (i.e. the slot number in a radio frame)), (iii) the Aggregation Level (AL), and (iv) the size of the corresponding EPDCCH set (i.e. the number of ECCEs (N))_ECCE) Such as 2N or 4N).

In more detail, the search space start offset (i.e., ECCE start offset) may indicate a position from which blind decoding of a corresponding user equipment starts in a certain EPDCCH set formed for the user equipment. The search space start offset (i.e., ECCE start offset) may be defined as a function of the above parameters. For example, the search space start offset may be defined by the following equation 2.

[ formula 2]

ECCE_offsetF (RNTI, subframe index, AL, N)_ECCE)

In formula 2, N_ECCEThe total ECCE is indicated. In addition, N may be determined based on the PRB size (i.e., N value, such as the number of PRBs forming one EPDCCH set) associated with the corresponding EPDCCH set and the number of EREGs (M) forming one ECCE_ECCE。

In at least one embodiment, the function of determining UE-specific PDCCH monitoring candidates in the legacy PDCCH, i.e., the function defined by equation 1 above, may be reused. However, in this case, the total number of ECCEs (N) corresponding to the corresponding EPDCCH set according to the PDCCH size in the corresponding subframe_ECCE) Can be applied instead of the total number of CCEs (N)_CCE，k)。

Example 3: hybrid configuration

The method of determining an ECCE start offset according to embodiment 3 may correspond to a hybrid type combining an implicit configuration and an explicit configuration. First, an ECCE start offset value of each EPDCCH set may be determined by a method of determining an ECCE start offset according to embodiment 1 and transmitted to a corresponding user equipment by higher layer signaling. However, the user equipment may use a different ECCE start offset (i.e., an ECCE start offset different from the ECCE start offset value signaled by a higher layer) based on the index of the downlink subframe transmitting the corresponding EPDCCH. That is, an ECCE start offset value to be used by a respective user equipment in a respective EPDCCH set may be determined based on a function of: (i) the ECCE start offset value (referred to herein as an ECCE start offset value with explicit signaling) determined by higher layer signaling for the corresponding user equipment and (ii) the downlink subframe index. Therefore, the same ECCE start offset value is not applied to all downlink subframes transmitting EPDCCH. That is, by performing ECCE start offset value hopping every downlink subframe, the user equipment can always provide a corresponding diversity effect for the same search space.

Alternatively, the search space start offset value (i.e., ECCE start offset value) to be actually applied may be obtained based on parameters such as (i) an ECCE start offset value with explicit signaling, (ii) a downlink subframe index, and (iii) an RNTI of a corresponding user equipment. That is, the EPDCCH search space to be monitored by the user equipment may be determined based on a function of: (i) a search space start offset value determined by higher layer signaling (i.e., an ECCE start offset value determined by explicit signaling), (ii) a downlink subframe index, and (iii) an RNTI of the corresponding user equipment. Here, the EPDCCH search space may represent a search space to be monitored by a respective user equipment in a certain EPDCCH set formed for the respective user equipment in an EPDCCH-monitored downlink subframe. Alternatively, the search space start offset (i.e., ECCE start offset) to be monitored may be determined based on a function of: (i) a signaling parameter (search space starting offset value as determined by higher layer signaling), (ii) downlink subframe index, and (iii) a size of EPDCCH set.

So far, a method of determining a search space start offset (i.e., ECCE start offset) is described according to embodiments 1 to 3. Hereinafter, embodiments associated with a method of determining an ECCE index for a subsequent blind decoding attempt will be described in more detail.

ECCE skip >

A given EPDCCH user equipment may perform blind decoding from ECCE indices corresponding to ECCE start offset values. Here, the ECCE start offset value may be determined at each Aggregation Level (AL) according to embodiments 1 to 3 described above. The Aggregation Level (AL) may be defined for blind decoding in the EPDCCH set formed for the respective user equipment. Meanwhile, the number of blind decodings to be performed at a certain Aggregation Level (AL) may be a complex number. That is, the number of candidate EPDCCH (i.e. EPDCCH monitoring candidate) to be monitored by the respective user equipment at the certain Aggregation Level (AL) may be a complex number. In this case, ECCE indices for which subsequent blind decoding is performed after the first blind decoding attempt may need to be defined. Here, the first blind decoding attempt is associated with the ECCE start offset described above.

The present embodiments may provide a method of determining an ECCE index (or ECCE indices) for subsequent blind decoding attempts. More specifically, the present embodiment may provide a method of sequentially performing blind decoding of consecutive ECCEs and a method of performing ECCE hopping according to blind decoding attempts.

Example 4: continuous ECCE

According to embodiment 4, blind decoding of consecutive ECCEs may be performed sequentially. As described above, the ECCE start offset value for each aggregation level in a corresponding EPDCCH set monitoring downlink subframes formed for a given user equipment may be determined according to embodiments 1 to 3. When the ECCE start offset value is determined according to embodiments 1 to 3, the above-described method of sequentially performing blind decoding of consecutive ECCEs according to embodiment 4 may be applied. More specifically, when the ECCE start offset value is determined according to embodiments 1 to 3, the user equipment may perform EPDCCH monitoring (i.e., blind decoding) for L × T consecutive ECCEs in the EPDCCH set. Here, L represents the size of a corresponding Aggregation Level (AL), and T represents the determined number of blind decodings. The L x T consecutive ECCEs may start from a respective ECCE start offset value. In particular, this EPDCCH monitoring for L × T consecutive ECCEs may be performed in units of L CCEs (i.e. in units of L CCEs). That is, the number of blind decodings performed based on the corresponding aggregation level (having a size of L) supported by the corresponding EPDCCH set is set to T, and the ECCE start offset value determined according to embodiments 1 to 3 is offset_LIn case that corresponding user equipment can perform offset corresponding to ECCE # offset_LUp to ECCE # (offset)_L+ L × T-1) of ECCEs. In particular, in this case, the blind decoding may be performed in L ECCE units.

For example, a certain localized EPDCCH set of a given user equipment may be configured with 8 consecutive PRBs. In case the number of EREGs forming one ECCE according to the above standard is 4, the localized EPDCCH set may be configured with a total of 32 (8 × 4) ECCEs. In addition, in case that the number of blind decodings to be performed by the corresponding user equipment at Aggregation Level (AL)2 in the corresponding EPDCCH set is defined as 6 and the ECCE start offset value is 16, the user equipment may continue to blind decode (i) ECCE #18 and ECCE #19, (ii) ECCE #20 and ECCE #21, (iii) ECCE #22 and ECCE #23, (iv) ECCE #24 and ECCE #25, and (v) ECCE #26 and ECCE # 27.

However, in this case, if there is a correspondence (offset)_LThe value of + L x T) exceeds the total number of ECCEs (N) forming the respective EPDCCH set_ECCE2N or 4N), the respective blind decoding may be performed from the ECCE #0 loop corresponding to the search space to be performed by the respective user equipment. That is, is configured with (offset)_L+L*T-N_ECCE) The search space for an ECCE may be defined as ECCE #0 through ECCE # (offset)_L+L*T-N_ECCE-1)。

Example 5: ECCE hopping

According to another method of forming a search space for blind decoding by a user equipment, an EPDCCH monitoring candidate (referred to herein as a candidate EPDCCH) to which subsequent blind decoding is applied may be determined (or defined) at each Aggregation Level (AL) in an EPDCCH set. Here, the subsequent blind decoding may represent a next blind decoding to be continuously performed after an ECCE associated with the ECCE start offset is blind decoded. The ECCE start offset may be determined according to embodiments 1 to 3 described above. In particular, the EPDCCH monitoring candidate associated with the subsequent blind decoding may be determined by a constant number of hops ECCEs. In other words, the number of blind decodings (i.e., the number of EPDCCH monitoring candidates) to be performed based on the corresponding aggregation level (having a size L) supported by the corresponding EPDCCH set is set to T, and the ECCE start offset value is determined as offset_LIn this case, ECCE indexes forming T EPDCCH search spaces based on corresponding Aggregation Levels (AL) may be defined using an ECCH hopping parameter (H) as follows.

[ formula 3]

At the (p +1) th search space of the aggregation level (L): ECCE # (offset)_L+ p × H) to ECCE # (offset)_L+ p H + L-1), for p 0,1,2 … T-1

That is, after blind decoding the first search space, the inclusion of ECCE # (offset) may be blind decoded_L+ H to ECCE # (offset)_L+ H + L-1). Here, the second search space may be determined according to the ECCE jump value (H). In addition, blind decoding may be performed including ECCE # (offset)_L+2H) to ECCE # (offset)_L+2H+L-1)}…{ECCE#(offset_L+ (T-1) H) to ECCE # (offset_LEach of the T search spaces of + (T-1) H + L-1). In this case, if the ECCE index value forming a certain (N +1) th search space (i.e., when p ═ N) exceeds the total number of ECCEs forming the corresponding EPDCCH set (i.e., N)_ECCE) Then the corresponding decoding process may loop back to ECCE #0 corresponding to the first ECCE of the corresponding EPDCCH set as in the case of consecutive ECCEs described in embodiment 4. Therefore, in this case, the corresponding search space (i.e., the (n +1) th search space) may be allocated from ECCE # 0.

However, in case that cyclic shift is applied to determine EPDCCH monitoring candidates, an overlap may occur between (i) ECCEs forming an (n +1) th EPDCCH monitoring candidate and a corresponding subsequent EPDCCH monitoring candidate and (ii) ECCEs forming a previous EPDCCH monitoring candidate of the (n +1) th EPDCCH monitoring candidate (i.e., when p ═ n). Thus, the EPDCCH monitoring candidate set may be determined by performing as many ECCE shifts as the size of the respective aggregation level (L), thus avoiding this overlap. In other words, if the offset is in equation 3 above_L+n*H>N_ECCE(for p ═ n), the search space for p ═ n can be defined by the following equation 4.

[ formula 4]

At the (p +1) th search space of the aggregation level (L): ECCE # (offset)_L+p*H-N_ECCE+ L) to ECCE # (offset)_L+p*H-N_ECCE+2L-1), for p ═ n

In equation 4, p is 0,1,2 … T-1, and offset_L+n*H≥N_ECCE

Summarizing the above description in the case of p ═ n, m ECCE cyclic shifts may be performed for the respective search spaces. Thus, the corresponding search space may be shifted by mL by the ECCE cyclic shift. I.e. if offset in equation 3 above_L+n*H≥mN_ECCEThen the search space for p ═ n can be defined by equation 5 below.

[ formula 5]

At the (p +1) th search space of the aggregation level (L): ECCE # (offset)_L+p*H-m N_ECCE+ mL) to ECCE # (offset)_L+p*H-m N_ECCE+ mL + L-1), for p ═ n

In equation 5, n is 0,1,2, …, T-1, and offset_L+n*H≥mN_ECCE(m＝0,1,2,3,…)。

Alternatively, in case of applying the cyclic shift, it is not necessary to unconditionally perform the ECCE shift as much as the size of the aggregation level (L). That is, it is possible to perform ECCE shift as much as the size of the aggregation level (L) only if an overlap with an ECCE corresponding to the previous EPDCCH monitoring candidate occurs.

The method of determining the ECCE jump value (H) may be performed in the same manner as in the explicit configuration (or determination) method of the search space start offset according to embodiment 2. More specifically, in case of forming EPDCCH sets, corresponding ECCE hopping values (H) may be transmitted to the user equipment by higher layer signaling. As such, a separate H value may be determined at each EPDCCH set in case the corresponding ECCE hopping value (H) is included in the higher layer signaling for EPDCCH set configuration. Therefore, in this case, the same H value may be applied to all aggregation levels defined in the corresponding EPDCCH set. Alternatively, the H value may be determined separately at each Aggregation Level (AL) defined in the corresponding EPDCCH set and signaled by higher layers.

In other embodiments, the respective H value (i.e., the respective hop value) may be implicitly determined based on (i) a size of a respective EPDCCH set, (ii) a number of EREGs forming one of the ECCEs, and/or (iii) an Aggregation Level (AL) size, and is not limited thereto. For example, the H value may be determined as (i) N_ECCEI.e., the number of ECCEs contained in one PRB and (ii) the maximum value among the Aggregation Level (AL) size (L). Here, in the case where the number of EREGs forming one ECCE is referred to as E, the number of ECCEs (i.e., N) contained in one PRB_ECCE) May correspond to 16/E. That is, the value of H may be determined by

And (4) determining. Here, in the case of (i) a normal subframe having a normal CP and (ii) a special subframe having a special subframe configuration of 3, 4, or 8 and a normal CP, the E value may be 4(E ═ 4). In the case of (i) a special subframe having a special subframe configuration of 1,2, 6, 7, or 9 and a normal CP, (ii) a normal subframe having an extended CP, and (iii) a special subframe having a special subframe configuration of 1,2, 3, 5, or 6 and an extended CP, the E value may be 8 (E-8).

In other embodiments, the respective H value (i.e., the respective hop value) may be implicitly determined based on a function including at least one of (i) a size of a respective EPDCCH set (e.g., an N value when an EPDCCH set is configured with a set of N PRBs), (ii) a T value, i.e., a number of blind decodes (i.e., a number of EPDCCH monitoring candidates) to be performed in the respective EPDCCH set based on a respective aggregation level (having a size L), (iii) an Aggregation Level (AL) size L, and (iv) an E value, i.e., a value of an EREG forming an ECCE. For example, and without limitation, ECCE hopping values for non-consecutive ECCEs may be determined using a function of a total number of ECCEs based on a respective aggregation level, and/or number of candidate EPDCCH sets monitored by the user equipment. More specifically, the ECCE hopping value of non-consecutive ECCEs may be determined by a function of the operation value when the total number of ECCEs of the corresponding EPDCCH set is divided by a product of the aggregation level and the number of candidate EPDCCH monitored by the user equipment based on the corresponding aggregation level.

In this case, the corresponding ECCE jump value (H) may be determined by the following equation 6 or equation 7. Here, [ X ] represents the largest integer not exceeding X.

[ formula 6]

H ═ max (a · b, L), where a ═ max (1, [ N/T ]) and b ═ 16/E

[ formula 7]

H ═ max (a · b, L), where a ═ N/T ] and b ═ 16/E

When the EPDCCH set is configured, H max (or hopping parameter) may be signaled by higher layers. Here, H ═ max may be simply referred to as H. Meanwhile, the ECCE hopping value (H) to be actually applied may be signaled by the hopping parameter (H) and/or other implicit parameters (e.g., aggregation level size (L), EPDCCH set size (N or N)_ECCE(2n or 4N)), etc.). For example, a hybrid configuration method of determining a hopping value (e.g., H ═ max (H, L)) for each aggregation level (AG) according to the H value signaled for the corresponding user equipment may be included in the scope of the present embodiment.

In other embodiments, in case of activating a user equipment for cross-carrier scheduling in a Carrier Aggregation (CA) user equipment, the above search space starting offset value (i.e., ECCE starting offset value) may be allocated (or determined) separately at each corresponding Component Carrier (CC). That is, different search space starting offset values may be signaled at each Component Carrier (CC). In another embodiment, the carrier index value of each Component Carrier (CC) may be applied to the above function that generates (or determines) the search space start offset value. Here, the carrier index value may correspond to a value of a Carrier Indicator Field (CIF) applied to a scheduling grant. Alternatively, in case of monitoring EPDCCH (i.e. in case of performing blind decoding based on a certain Aggregation Level (AL) in the EPDCCH set), the search space may be configured continuously or by ECCE hopping according to embodiment 4 or embodiment 5 described above. In particular, in these cases, a primary cell (P) may be employed_cell) Search space and secondary cell (S)_cell) To increase CIF. That is, the primary cell (P) is adopted_cell) After the search space, the secondary cell (S) may be employed_cell) The search space of (2).

In the present embodiment, EPDCCH monitoring candidates (i.e., search spaces) may be determined in an EPDCCH set for user equipment performing an EPDCCH monitoring operation (i.e., blind decoding) as described above. Specifically, in the present embodiment, all EPDCCH monitoring candidate determination methods (i.e., all search space determination methods) that can be embodied by combining (i) at least one of embodiment 1 to embodiment 3 and (ii) at least one of embodiment 4 and embodiment 5 may be applied.

In other embodiments, (i) the search space starting offset value (i.e., ECCE starting offset value) may be signaled directly and explicitly by higher layers, or (ii) a parameter for determining the search space starting offset value according to a hybrid configuration scheme may be signaled by higher layers. In this case, the ECCE hop value (H) and/or related parameters may be further signaled. That is, the ECCE start offset parameter and the ECCE hopping related parameter, which correspond to the search space configuration parameter for a given user equipment in the EPDCCH set, may both be signaled. In this case, after defining the configuration table for parameter determination, a configuration index to be applied per EPDCCH set may be signaled. A search space configuration table may be defined at each EPDCCH type. Thus, the search space configuration table may include (i) a configuration table for localized EPDCCH sets and (ii) a configuration table for distributed EPDCCH sets. Alternatively, the search space configuration table may be defined based on (i) the size of the EPDCCH set or (ii) the number of EREGs forming one ECCE. Specifically, in the case where a search space configuration table is defined based on the number of EREGs (E), two search space configuration tables (e.g., configuration tables for E-4 and E-8) may be defined. All embodiments associated with configuration table based search space mapping are included within the scope of the present embodiments.

In case that the user equipment is configured to receive Downlink Control Information (DCI) through EPDCCH, the present embodiment may provide a method of receiving the DCI.

Fig. 10 is a flowchart describing a method of receiving a downlink control channel located in a data region in a user equipment according to other embodiments.

Referring to fig. 10, the user equipment may perform a method (1000) of receiving a downlink control channel located in a data region. More specifically, in step S1010, the user equipment may receive EPDCCH from a transmission/reception point through the data region of N resource block pairs (e.g., PRB pairs) forming each of the K EPDCCH sets in the subframe. Here, K and N are natural numbers greater than or equal to 1. In step S1020, the user equipment may perform decoding of the EPDCCH in each EPDCCH set according to a Downlink Control Information (DCI) format in an EPDCCH UE-specific search space.

As described above, each PRB pair may include 16 Enhanced Resource Element Groups (EREGs). Each Enhanced Control Channel Element (ECCE) corresponding to an EPDCCH transmission base unit may include 4 or 8 EREGs.

More specifically, in step S1020, the user equipment may decode the EPDCCH in each EPDCCH set according to the Downlink Control Information (DCI) format in the EPDCCH UE-specific search space. In this case, the ECCEs associated with the EPDCCH decoding may be formed (or defined) by using one of (i) an explicit configuration scheme, (ii) an implicit configuration scheme, and (iii) a hybrid configuration scheme according to embodiments 1 to 3 as described above. For example, in case of an implicit configuration scheme, the ECCEs may be formed (or defined) by a function of (i) a Radio Network Temporary Identity (RNTI) of the user equipment, (ii) a subframe index, (iii) an aggregation level, and/or (iv) a total number of ECCEs included in one EPDCCH set. As described above, the start offset of the ECCE index for blind decoding performed by the corresponding user equipment in the EPDCCH set may be defined as (i) the RNTI of the corresponding user equipment, (ii) a subframe index (e.g., such as

Wherein n is_sIs a slot index), (iii) an Aggregation Level (AL), and (iv) a size of a corresponding EPDCCH set (i.e., a number of ECCEs (N)_ECCE) Such as 2N or 4N). Here, the EPDCCH set may be formed at each user equipment.

In more detail, the search space start offset (i.e., ECCE start offset) may indicate a position from which blind decoding of a corresponding user equipment starts in a certain EPDCCH set formed for the user equipment. The search space start offset (i.e., ECCE start offset) may be defined as a function of the above parameters. For example, the search space start offset may be determined by ECCE_offsetF (RNTI, subframe index, AL, N)_ECCE) And (4) defining.

The function defined by equation 1 above, i.e., the function for determining UE-specific PDCCH monitoring candidates in the legacy PDCCH, may be reused. However, in this case, as described above, the corresponding ECCE total number (N) according to the PDCCH size in the corresponding subframe_{ECCE CCK,K})2N or 4N.

Meanwhile, in the operation of decoding EPDCCH (S1020), the user equipment may monitor as many consecutive ECCEs as the number of monitoring operations to be performed based on the corresponding aggregation level in an aggregation level unit. As described above, the ECCE start offset value for each aggregation level in a corresponding EPDCCH set monitoring downlink subframes formed for a given user equipment may be determined according to embodiments 1 to 3. When the ECCE start offset value is determined according to embodiments 1 to 3, the method of sequentially performing blind decoding of consecutive ECCEs according to embodiment 4 described above may be applied. More specifically, when the ECCE start offset value is determined according to embodiments 1 to 3, the user equipment may perform an EPDCCH monitoring operation (i.e., blind decoding) for L × T consecutive ECCEs in the EPDCCH set. Here, L represents the size of a corresponding Aggregation Level (AL), and T represents the determined number of blind decodings. The L x T consecutive ECCEs may start from a respective ECCE start offset value. In particular, the EPDCCH monitoring for L × T consecutive ECCEs may be performed in units of L CCEs.

Meanwhile, in the operation of decoding EPDCCH (S1020), the user equipment may monitor the non-consecutive ECCEs in an aggregation level cell (in a cell corresponding to the number of ECCEs of the aggregation level) as described in embodiment 5. In this case, the ECCE jump value of a non-contiguous ECCE may be determined by the following function: (i) a total number of ECCEs included in the respective EPDCCH set, (ii) an aggregation level, and (iii) a number of EPDCCH candidates monitored by the user equipment based on the respective aggregation level. As described above, according to another method of forming a search space to be blind-decoded by the user equipment, an EPDCCH monitoring candidate to apply subsequent blind-decoding may be determined (or defined) at each Aggregation Level (AL) in an EPDCCH set. Here, the subsequent blind decoding may represent a next blind decoding to be continuously performed after an ECCE corresponding to the ECCE start offset is blind decoded. The ECCE start offset may be determined according to embodiments 1 to 3 described above. In particular, the EPDCCH monitoring candidate associated with the subsequent blind decoding may be determined by a constant number of hops ECCEs. As described above, according to another method of implicitly determining a search space, the search space may be determined by the following function: (i) an N value, i.e. the size of the corresponding EPDCCH set (in case an EPDCCH set is configured with a set of N PRBs), (ii) a T value, i.e. the number of blind decoding at an Aggregation Level (AL) (i.e. the number of EPDCCH monitoring candidates) that is to perform blind decoding in a certain EPDCCH set, (iii) an L value, i.e. the size of the aggregation level, and/or (iv) an E value, i.e. the number of EREGs forming one ECCE.

Meanwhile, in case that the user equipment is configured to have a Carrier Indicator Field (CIF), a value of the Carrier Indicator Field (CIF) is applied to a function defining the ECCE to be blind-decoded. A Carrier Index (CI) of each Component Carrier (CC) may be applied to a function that generates an offset value. Here, the Carrier Index (CI) value may be a value of a Carrier Indicator Field (CIF) applied to a scheduling grant.

Meanwhile, an EPDCCH set may be formed for one of localized EPDCCH transmission and distributed EPDCCH transmission. The aggregation level may correspond to one of 1,2, 4, 8, 16, and 32. In addition, for when the number of REs for a possible EPDCCH transmission is less than a threshold value X_thresh(X_thresh) Normal subframe and normal CP when and for when the number of REs for possible EPDCCH transmission is less than a threshold value (X)_thresh) (hereinafter referred to as example 1) with special subframe configuration 3, 4 or 8 and normal CP, the localized EPDCCH set may be defined to support aggregation levels 2, 4, 8, and 16, and the distributed EPDCCH may be defined to support aggregation levels 2, 4, 8, 16, and 32. Otherwise (hereinafter referred to as example 2), the localized EPDCCH set may be defined to support aggregation levels 1,2, 4, and 8, and the distributed EPDCCH may be defined to support aggregation levels 1,2, 4, 8, and 16.

Fig. 11 is a schematic diagram depicting a base station according to several embodiments.

Referring to fig. 11, a base station 1100 in accordance with at least one embodiment may include a control processor 1110, a transmitter 1120, and a receiver 1130. Here, the base station 1100 may be a transmission/reception point for configuring a downlink control channel located in a data region in an EPDCCH UE-specific search space.

Control processor 1110 may control the operations (i.e., the operation of base station 1100) needed to perform the present embodiment described above. More specifically, control processor 1110 may control operations associated with blind decoding for each aggregation level in an EPDCCH set formed for a user equipment (i.e., operations of base station 1100) -here, the user equipment is configured to receive Downlink Control Information (DCI) over an EPDCCH corresponding to a downlink control channel.

More specifically, control processor 1110 may form (or define) ECCEs corresponding to basic transmission units of EPDCCH in the EPDCCH UE-specific search space. Here, the EPDCCH may be located in a data region of N resource block pairs (e.g., PRB pairs) forming each of the K EPDCCH sets in a subframe. The K and N are natural numbers greater than or equal to 1. As described above, each PRB pair may include 16 EREGs, and each ECCE may include 4 or 8 EREGs.

In addition, control processor 1110 may determine the search space start offset (i.e., ECCE start offset) using one of (i) an implicit configuration scheme, (ii) an explicit configuration scheme, and (iii) a hybrid configuration scheme, as described above. For example, in case of an implicit configuration scheme, the control processor 1110 may form (or define) ECCEs in the EPDCCH UE-specific search space by using a function of a Radio Network Temporary Identity (RNTI) of the user equipment, an index of the subframe, an aggregation level, and a total number of ECCEs per EPDCCH set.

The transmitter 1120 and the receiver 1130 may transmit and receive signals, messages and/or data, respectively, associated with the user equipment as needed to perform the present embodiment above. For example, the transmitter 1120 may transmit the ECCEs formed (or defined) in the EPDCCH UE-specific search space to the user equipment via the EPDCCH.

Fig. 12 is a schematic diagram depicting a user device according to several embodiments.

Referring to fig. 12, a user equipment 1200 according to the present embodiment may include a receiver 1210, a control processor 1220, and a transmitter 1230.

Receiver 1210 can receive downlink control information, data, and/or messages from a base station (e.g., base station 1100) over corresponding channels. Here, the base station may correspond to a transmission/reception point. More specifically, receiver 1210 may receive an EPDCCH from the base station over the data region of the N PRB-pairs forming each of the K EPDCCH sets in the subframe. Here, K and N may be natural numbers greater than or equal to 1.

The control processor 1220 may control operations (i.e., operations of the user device 1200) required for performing the present embodiment described above. More specifically, control processor 1210 may control operations associated with blind decoding for each aggregation level in an EPDCCH set formed for user equipment 1200 (i.e., operations of user equipment 1200). here, user equipment 1200 is configured to receive Downlink Control Information (DCI) over an EPDCCH corresponding to a downlink control channel. In addition, control processor 1210 may decode EPDCCH in each EPDCCH set according to a respective DCI format in an EPDCCH UE-specific search space. In this case, the ECCEs associated with the EPDCCH decoding in the EPDCCH UE-specific search space may be identified by (i) a Radio Network Temporary Identity (RNTI) of the user equipment, (ii) a subframe index, (iii) an aggregation level, and (iv) N_ECCEI.e. the total number of ECCEs contained in an EPDCCH set.

The transmitter 1230 may transmit control information, data, and/or messages to the base station over the corresponding channels.

ECCE may be continuous or discontinuous in relation to the operation of the base station 1100 or the user equipment 1200. More specifically, ECCEs may be formed to be continuous in the number of monitoring operations to be performed based on the respective aggregation levels in an aggregation level unit (i.e., in an ECCE number unit corresponding to an aggregation level). Alternatively, the ECCEs may be formed to be discontinuous in the aggregation level unit. In particular, in case of a distributed EPDCCH set and/or a localized EPDCCH set, ECCEs may be contiguous. Meanwhile, in case of a distributed EPDCCH set and/or a localized EPDCCH set, the ECCEs may be non-continuous. As described above, the ECCE hopping value associated with a non-consecutive ECCE may be defined by a function of (i) a total number of ECCEs of the respective EPDCCH set, (ii) an aggregation level, and (iii) a number of candidate EPDCCH to be monitored by the user equipment 1200 based on the respective aggregation level. Meanwhile, in the case where the user equipment 1200 is configured to have a carrier indicator field, the value of the carrier indicator field may be applied to a function defining the ECCE (i.e., an ECCE defining function). In addition, the transmission type of the EPDCCH set may correspond to one of localized EPDCCH transmissions and distributed EPDCCH transmissions.

Although the contents of the technical standards mentioned in the above-described embodiments are omitted for the purpose of general description of the present specification, the contents related to the technical standards may constitute a part of the present specification. Accordingly, the addition of a portion of the standard-related content in the specification and/or the claims is to be understood as being included within the scope of the present invention.

More specifically, the included documents may form part of the specification as part of a published document. Accordingly, the addition of standard-related content and/or portions of standard documents in the specification and/or the claims is to be understood as being included within the scope of the present invention.

As described above, since the technical concept of the present invention is described by way of exemplary embodiments, those skilled in the art can make various substitutions, modifications and changes in the form described above without departing from the essential characteristics of the present invention. Therefore, the embodiment disclosed in the present invention is intended to illustrate the technical idea of the present invention, and the scope of the present invention is not limited by the embodiment. The scope of the present invention should be construed based on the appended claims so that all technical concepts included in the scope equivalent to the claims belong to the present invention.

Cross Reference to Related Applications

The present application claims priority from korean patent application No. 10-2012 § 0101747 (filed 9/13/2012) and korean patent application No. 10-2013 § 0027866 (filed 03/15/2013) according to 35u.s.c. § 119, which are incorporated herein by reference in their entirety.

Claims (12)

1. A method of receiving a downlink control channel located in a data region in a user equipment, UE, the method comprising:

receiving an enhanced physical downlink control channel, EPDCCH, from a transmission/reception point, wherein:

the EPDCCH comprises a data region for forming one or more Physical Resource Block (PRB) pairs for each of a plurality of EPDCCH sets in a subframe; and is

(i) Each PRB pair includes 16 enhanced resource element groups EREGs;

(ii) the enhanced control channel element ECCE corresponding to the EPDCCH transmission basic unit includes 4 or 8 EREGs;

each EPDCCH set is formed for one of localized EPDCCH transmissions and distributed EPDCCH transmissions; and

decoding an EPDCCH in a corresponding EPDCCH set according to a downlink control information, DCI, format in an EPDCCH UE-specific search space, wherein:

the ECCE monitored by the user equipment for decoding the EPDCCH is determined by (i) a radio network temporary identity, RNTI, of the user equipment; (ii) an index of the subframe; (iii) a polymerization grade; and (iv) a function of the total number of ECCEs for the respective set of EPCDDH; and

the aggregation level is determined based on at least one of: a type of EPDCCH transmission, a subframe type, a cyclic prefix, CP, type, and a number of REs for possible EPDCCH transmissions are less than a threshold.

2. The method of claim 1, in which decoding the EPDCCH comprises:

monitoring non-consecutive ECCEs in units of a number of ECCEs corresponding to the aggregation level.

3. The method of claim 2, wherein decoding the EPDCCH comprises:

determining an ECCE hop value for the non-contiguous ECCEs based on the aggregation level using a function of the total number of ECCEs of the corresponding EPDCCH set, the aggregation level, and the number of EPDCCH candidates monitored by the user equipment.

4. The method of claim 1, wherein a value of a carrier indicator field is applied to a function defining the ECCE if the user equipment is configured with the carrier indicator field.

5. The method of claim 1, wherein:

the type of the EPDCCH transmission comprises the localized EPDCCH transmission and the distributed EPDCCH transmission;

the subframe types comprise normal subframes and special subframes; and

the cyclic prefix CP types include a normal CP and an extended CP.

6. A method of configuring a downlink control channel located in a data region in a user equipment, UE, dedicated search space in a transmission/reception point, the method comprising:

forming an enhanced physical downlink control channel, EPDCCH, wherein:

forming the EPDCCH includes: defining an Enhanced Control Channel Element (ECCE) corresponding to a basic unit for EPDCCH transmission in an EPDCCH UE-specific search space by using a function of a Radio Network Temporary Identifier (RNTI) of the user equipment, an index of a subframe, an aggregation level and a total number of ECCEs of a corresponding EPDCCH set; and

(i) the EPDCCH comprises a data region for forming one or more physical resource block, PRB, pairs for each of a plurality of EPDCCH sets in the subframe;

(ii) each PRB pair includes 16 enhanced resource element groups EREGs; and

(iii) each of the ECCEs comprises 4 or 8 EREGs;

each EPDCCH set is formed for one of localized EPDCCH transmissions and distributed EPDCCH transmissions; and

transmitting the ECCEs defined in the EPDCCH UE-specific search space to the user equipment over the EPDCCH, wherein:

the aggregation level is determined based on at least one of: a type of EPDCCH transmission, a subframe type, a cyclic prefix, CP, type, and a number of REs for possible EPDCCH transmissions are less than a threshold.

7. The method of claim 6, wherein defining the ECCE comprises:

defining the ECCEs such that the ECCEs are non-consecutive in units of the number of ECCEs corresponding to the aggregation level.

8. The method of claim 7, wherein an ECCE hopping value defined as the ECCEs that are non-consecutive is determined based on the aggregation level as a function of a total number of ECCEs of a corresponding EPDCCH set, the aggregation level, and a number of EPDCCH candidates monitored by the user equipment.

9. The method of claim 6, wherein:

in case the user equipment is configured with a carrier indicator field, the value of the carrier indicator field is applied to a function defining the ECCE.

10. The method of claim 6, wherein:

the type of the EPDCCH transmission comprises the localized EPDCCH transmission and the distributed EPDCCH transmission;

the subframe types comprise normal subframes and special subframes; and

the cyclic prefix CP types include a normal CP and an extended CP.

11. A user equipment, UE, for receiving a downlink control channel located in a data region, the user equipment comprising:

a receiver configured to receive an enhanced physical downlink control channel, EPDCCH, from a transmission/reception point, wherein:

the EPDCCH comprises a data region for forming one or more Physical Resource Block (PRB) pairs for each of a plurality of EPDCCH sets in a subframe; and is

(i) Each PRB pair includes 16 enhanced resource element groups EREGs;

(ii) the enhanced control channel element ECCE corresponding to a basic unit of EPDCCH transmission includes 4 or 8 EREGs;

each EPDCCH set is formed for one of localized EPDCCH transmissions and distributed EPDCCH transmissions; and

a control processor configured to: decoding an EPDCCH in a corresponding EPDCCH set according to a downlink control information, DCI, format in an EPDCCH UE-specific search space, wherein:

the ECCE monitored by the user equipment for the EPDCCH is defined by a function of a Radio Network Temporary Identity (RNTI) of the user equipment, an index of the subframe, an aggregation level, a total number of ECCEs of the corresponding EPCDDH set; and

the aggregation level is determined based on at least one of: a type of EPDCCH transmission, a subframe type, a cyclic prefix, CP, type, and a number of REs for possible EPDCCH transmissions are less than a threshold.

12. A transmission/reception point for configuring a downlink control channel located in a data region in an EPDCCH user equipment, UE, dedicated search space, the transmission/reception point comprising:

a control processor configured to: forming an enhanced physical downlink control channel, EPDCCH, wherein:

forming the EPDCCH includes: defining an Enhanced Control Channel Element (ECCE) corresponding to a basic element of an EPDCCH transmission in an EPDCCH UE-specific search space by using a function of a Radio Network Temporary Identity (RNTI) of the user equipment, an index of a subframe, an aggregation level, and a total number of ECCEs of a corresponding EPDCCH set, and

(i) the EPDCCH comprises a data region for forming one or more physical resource block, PRB, pairs for each of a plurality of EPDCCH sets in the subframe;

(ii) each PRB pair includes 16 enhanced resource element groups EREGs;

(iii) each of the ECCEs comprises 4 or 8 EREGs;

each EPDCCH set is formed for one of localized EPDCCH transmissions and distributed EPDCCH transmissions; and

a transmitter configured to transmit the ECCEs defined in the EPDCCH UE-specific search space to the user equipment over the EPDCCH, wherein:

the aggregation level is determined based on at least one of: a type of EPDCCH transmission, a subframe type, a cyclic prefix, CP, type, and a number of REs for possible EPDCCH transmissions are less than a threshold.

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