KR102680307B1 - Method, apparatus, and system for transmitting and receiving/decoding control channel - Google Patents

Abstract

The present invention is a method in which a base station (eNB) transmits a control channel in a downlink subframe in a mobile communication system. It relates to a method for informing the NR-CCE (Control Channel Element) aggregation level and NR-CCE allocation information that constitutes the NR-CCE (Control Channel Element) and the resulting devices and systems. According to an embodiment of the present invention, the base station masks and sends a sequence to the NR-CCE according to the NR-CCE aggregation level and NR-CCE allocation information, and the user device detects the sequence of the NR-CCE to determine the priority of the search space. can be determined, and blind decoding can be performed according to the determined priority.

Description

Control channel transmission and reception method, device and system {METHOD, APPARATUS, AND SYSTEM FOR TRANSMITTING AND RECEIVING/DECODING CONTROL CHANNEL}

The present invention relates to a wireless communication system, and more specifically, the present invention relates to a method for transmitting and receiving a control channel in a wireless communication system.

3GPP LTE(-A) defines uplink/downlink physical channels for physical layer signal transmission. For example, the Physical Uplink Shared Channel (PUSCH), which is a physical channel for transmitting data in the uplink, the Physical Uplink Control Channel (PUCCH), which is a physical channel for transmitting control signals, and the Physical Random Access Channel (PRACH) are defined, In addition to the physical downlink shared channel (PDSCH) that transmits data in the downlink, the physical control format indicator channel (PCFICH) that transmits L1/L2 control signals, the physical downlink control channel (PDCCH), and the physical hybrid ARQ indicator channel (PHICH) ), etc.

Among the channels, the downlink control channel (PDCCH/EPDCCH) is a channel for the base station to transmit uplink/downlink scheduling allocation control information, uplink transmission power control information, and other control information to one or multiple terminals. Since there is a limit to the resources available for the PDCCH that the base station can transmit at once, different resources cannot be allocated to each terminal, and the resources must be shared to transmit control information to an arbitrary terminal. For example, in 3GPP LTE(-A), four REs (Resource Elements) are combined to create a REG (Resource Element Group), nine CCEs (Control Channel Elements) are created, and one or multiple CCEs can be combined to send. The resources available are notified to the terminal, and multiple terminals can share and use the CCE. Here, the number of CCEs combined is called the CCE combination level, and the resources to which CCEs are allocated according to the possible CCE combination levels are called search space. The search space may include a common search space defined for each base station and a specific terminal search space (terminal-specific or UE-specific search space) defined for each terminal. The UE performs decoding for all possible CCE combination cases in the search space and can determine whether it corresponds to its PDCCH through the user equipment (UE) identifier included in the PDCCH. Therefore, the operation of such a terminal inevitably requires a long time to decode the PDCCH and consumes a lot of energy.

The present invention is intended to solve the problems of the prior art as described above. In order for a terminal to find a control channel (e.g. PDCCH/EPDCCH or NR-PDCCH) assigned to it, it uses a search space among CCEs in the search space shared with other terminals. The purpose is to provide a method, device, and system that can quickly decode and receive a control channel by searching from the part that is most likely to be assigned to the user. For the above purpose, the base station is an aggregation of the allocation information for the minimum control channel allocation unit (e.g., CCE or NR-CCE) to which the user's control channel is mapped and the minimum control channel allocation unit (e.g. For example, a method for reporting the number of cases (CCE combination or NR-CCE combination) is included.

The objects that can be achieved by the present invention are not limited to those specifically described herein.

In order to solve the above technical problem, the first technical aspect of the present invention is a method for a base station to transmit control information in a wireless communication system, consisting of control channel (e.g. PDCCH/EPDCCH or NR-PDCCH) candidates on a subframe. determining a search space; and determining allocation information for an allocation unit (eg, CCE or NR-CCE) of a minimum control channel to be allocated to the terminal in the determined search space; Determining a masking sequence to be mapped to a reference signal for demodulating the control channel (e.g., a reference signal (RS) for NR-PDCCH) according to the allocation information in the allocation unit of the minimum control channel. ; mapping a masking sequence to the reference signal; To provide a control information transmission method including the step of transmitting the control channel according to the masking sequence.

In order to solve the above technical problem, the second technical aspect of the present invention is a method for a terminal to receive control information in a wireless communication system, consisting of control channel (e.g. PDCCH/EPDCCH or NR-PDCCH) candidates on a subframe. Calculating a distance index according to a masking sequence for each allocation unit (eg, CCE or NR-CCE) of the minimum control channel likely to be assigned to the terminal in the search space; Prioritizing the search space based on the distance indicator; It provides a method of receiving control information that includes performing blind decoding according to a set priority.

In order to solve the above technical problem, the third technical aspect of the present invention includes the steps of the base station determining the masking sequence differently according to the CCE combining level and CCE allocation information; It includes the step of estimating a masking sequence before the terminal performs blind decoding. In a preferred embodiment of the present invention, the base station can use two masking sequences for each CCE, and the terminal includes a process of determining which of the two masking sequences is used. In a preferred embodiment of the present invention, the masking sequence that the base station can use includes a sequence in which a specific phase rotates.

The fourth technical aspect of the present invention to solve the above technical problem is that the terminal can determine the CCE combining level at which to perform blind decoding and the priority of CCE allocation information. Preferably, the terminal can perform blind decoding according to the CCE aggregation level and the priority of CCE allocation information.

The technical solutions described above are only a part of the preferred embodiments of the present invention, and various modifications to which the technical features of the present invention are applied can be understood by those skilled in the art to which the present invention pertains, referring to the following detailed description of the present invention. do.

According to an embodiment of the present invention, reception and processing of control information transmitted through a control channel can be performed more efficiently.　Specifically, the base station designs and transmits the NR-PDCCH so that the allocated CCE and CCE combination level in the user's search space can be known before decoding, and the terminal does not perform blind decoding for all possible CCE combinations in the search space, You can determine in advance which CCEs in your search space have been assigned, and perform blind decoding first on the CCE combination that is most likely to be assigned to you. Through the above method, the processing time and energy consumption required for the terminal to perform blind decoding can be reduced.

Figure 1 shows an example of a radio frame structure used in a wireless communication system.
Figure 2 shows an example of a downlink (DL)/uplink (UL) slot structure in a wireless communication system.
Figure 3 is a diagram to explain physical channels used in the 3GPP system and a general signal transmission method using them.
Figure 4 illustrates a radio frame structure for transmission of a synchronization signal (SS).
Figure 5 is a diagram illustrating the structure of a downlink radio frame used in the LTE system.
Figure 6 illustrates the configuration of a Cell Specific Common Reference Signal.
Figure 7 shows an example of an uplink subframe structure used in a wireless communication system.
Figure 8 is a conceptual diagram explaining the carrier aggregation (CA) technique.
Figure 9 is a diagram for explaining single carrier communication and multiple carrier communication.
FIG. 10 is a diagram illustrating an example in which a cross-carrier scheduling technique is applied.
Figure 11 is a diagram showing a deployment scenario of a terminal and a base station in an LTE and LAA service environment.
Figure 12 is a block diagram showing the configuration of a terminal and a base station, respectively, according to an embodiment of the present invention.
Figure 13 is a diagram of the control region of PDCCH for control channel transmission in LTE(-A).
Figure 14 is a diagram of the transmission procedure of control information in LTE(-A) and CCE aggregation of PDCCH and multiplexing of PDCCH in LTE(-A).
Figure 15 is a diagram showing search space allocation by CCE aggregation for common search space and UE specific (or terminal specific) search space in LTE(-A).
Figure 16 is a diagram showing the NR-CCE combination level and NR-CCE allocation in the search space according to an embodiment of the present invention.
Figure 17 is a diagram showing RE allocation of PRB according to an embodiment of the present invention.
Figure 18 is a block diagram showing a procedure for transmitting NR-PDCCH in an eNB according to an embodiment of the present invention.
Figure 19 is a block diagram showing a procedure for receiving NR-PDCCH in a UE according to an embodiment of the present invention.
Figure 20 is a diagram showing sequence masking and phase rotation in an eNB to transmit NR-PDCCH according to an embodiment of the present invention.
Figure 21 is a diagram of detecting sequence de-masking or phase rotation in order to receive NR-PDCCH in a UE according to an embodiment of the present invention.

The terms used in this specification are general terms that are currently widely used as much as possible while considering the function in the present invention, but this may vary depending on the intention of a person skilled in the art, custom, or the emergence of new technology. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in the description of the relevant invention. Therefore, we would like to clarify that the terms used in this specification should be interpreted based on the actual meaning of the term and the overall content of this specification, not just the name of the term.

Throughout the specification, when a component is said to be “connected” to another component, this includes not only “directly connected” but also “electrically connected” with other components in between. do. Additionally, when a composition is said to “include” a specific component, this does not mean excluding other components, but may include other components, unless specifically stated to the contrary. In addition, the limitations of “more than” or “less than” a specific threshold may be appropriately replaced with “more than” or “less than” depending on the embodiment.

Figure 1 shows an example of a wireless frame structure used in a wireless communication system.

In particular, Figure 1(a) shows the frame structure for Frequency Division Duplex (FDD) used in the 3GPP LTE/LTE-A system, and Figure 1(b) shows the frame structure used in the 3GPP LTE/LTE-A system. This shows the frame structure for Time Division Duplex (TDD).

Referring to Figure 1, the radio frame used in the 3GPP LTE/LTE-A system has a length of 10ms (307200Ts) and consists of 10 equally sized subframes (SF). Each of the 10 subframes within one radio frame may be assigned a number. Here, Ts represents the sampling time, and is expressed as Ts=1/(2048*15kHz). Each subframe is 1ms long and consists of two slots. The 20 slots within one radio frame may be numbered sequentially from 0 to 19. Each slot has a length of 0.5ms. The time for transmitting one subframe is defined as a transmission time interval (TTI). Time resources can be classified by a radio frame number (also called a radio frame index), a subframe number (also called a subframe number), a slot number (or slot index), etc.

A wireless frame may be configured differently depending on the duplex mode. For example, in FDD mode, downlink transmission and uplink transmission are distinguished by frequency, so a radio frame includes only one of a downlink subframe or an uplink subframe for a specific frequency band. In TDD mode, downlink transmission and uplink transmission are separated by time, so for a specific frequency band, a radio frame includes both a downlink subframe and an uplink subframe.

Table 1 illustrates the DL-UL configuration of subframes within a radio frame in TDD mode.

[Table 1]

In Table 1, D represents a downlink subframe, U represents an uplink subframe, and S represents a special subframe. The special subframe includes three fields: Downlink Pilot TimeSlot (DwPTS), Guard Period (GP), and Uplink Pilot TimeSlot (UpPTS). DwPTS is a time section reserved for downlink transmission, and UpPTS is a time section reserved for uplink transmission. Table 2 illustrates the configuration of a special frame.

[Table 2]

Figure 2 shows an example of a downlink (DL)/uplink (UL) slot structure in a wireless communication system. In particular, Figure 2 shows the structure of the resource grid of the 3GPP LTE/LTE-A system. There is one resource grid per antenna port. Referring to FIG. 2, a slot includes a plurality of OFDM symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. The OFDM symbol also means one symbol section. Referring to FIG. 2, the signal transmitted in each slot can be expressed as a resource grid consisting of N ^{DL / UL} _RB * N ^RB _sc subcarriers and N ^{DL / UL} _symb OFDM symbols. there is. Here, N ^DL _RB represents the number of resource blocks (RBs) in the downlink slot, and N ^UL _RB represents the number of RBs in the UL slot. N ^DL _RB and N ^UL _RB depend on the DL transmission bandwidth and UL transmission bandwidth, respectively. N ^DL _symb represents the number of OFDM symbols in the downlink slot, and N ^UL _symb represents the number of OFDM symbols in the UL slot. N ^RB _sc represents the number of subcarriers constituting one RB. The OFDM symbol may be called an OFDM symbol, a Single Carrier Frequency Division Multiplexing (SC-FDM) symbol, etc., depending on the multiple access method. The number of OFDM symbols included in one slot can vary depending on the channel bandwidth and the length of the CP (cyclic prefix). For example, in the case of normal CP, one slot contains 7 OFDM symbols.

First, in the case of extended CP, one slot includes 6 OFDM symbols. In FIG. 2, for convenience of explanation, a subframe in which one slot consists of 7 OFDM symbols is illustrated, but embodiments of the present invention can be applied in the same way to subframes having a different number of OFDM symbols. Referring to FIG. 2, each OFDM symbol includes N ^{DL / UL} _RB *N ^RB _sc subcarriers in the frequency domain. The types of subcarriers are data subcarrier for data transmission, reference signal subcarrier for transmission of reference signal, and null subcarrier for guard band or Direct Current (DC) component. It can be divided into: The DC component is mapped to the carrier frequency (f ₀ ) during the OFDM signal generation process or frequency up-conversion process. Carrier frequency is also called center frequency (f _c ).

One RB is defined as N ^{DL / UL} _symbs (e.g., 7) consecutive OFDM symbols in the time domain, and N ^RB _sc (e.g., 12) consecutive OFDM symbols in the frequency domain. is defined by For reference, a resource consisting of one OFDM symbol and one subcarrier is called a resource element (RE) or tone. Therefore, one RB consists of N ^DL/UL _symb *N ^RB _sc resource elements. Each resource element in the resource grid can be uniquely defined by an index pair (k, 1) within one slot. k is an index given from 0 to N ^DL/UL _RB *N ^RBsc -1 in the frequency domain, and l is an index given from 0 to N ^{DL / UL} _symb -1 in the time domain.

Meanwhile, one RB is mapped to one physical resource block (PRB) and one virtual resource block (VRB), respectively. A PRB is defined as N ^{DL / UL} _symbol (e.g., 7) consecutive OFDM symbols or SC-FDM symbols in the time domain, and N ^RB _sc (e.g., 12) consecutive symbols in the frequency domain. It is defined by the subcarrier. Therefore, one PRB consists of N ^{DL / UL} _symb *N ^RB _sc resource elements. Two RBs that occupy the same N ^RB _sc consecutive subcarriers in one subframe and are located one in each of the two slots of the subframe are called a PRB pair. The two RBs that make up a PRB pair have the same PRB number (or also called PRB index).

In order for the UE to receive a signal from an eNB or transmit a signal to the eNB, the time/frequency synchronization of the UE must be aligned with the time/frequency synchronization of the eNB. This is because the UE must be synchronized with the eNB to determine the time and frequency parameters required to perform demodulation of the DL signal and transmission of the UL signal at the correct time.

Figure 3 is a diagram to explain physical channels used in the 3GPP system and a general signal transmission method using them.

When the terminal increases power or enters a new cell, it performs an initial cell search task such as synchronizing with the base station (S301). To this end, the terminal receives the Primary Synchronization Channel (P-SCH) and Secondary Synchronization Channel (S-SCH) from the base station to synchronize with the base station and obtain information such as cell ID. there is. Afterwards, the terminal can receive broadcast information within the cell by receiving a physical broadcast channel from the base station. Meanwhile, the terminal can check the downlink channel status by receiving a downlink reference signal (DL RS) in the initial cell search stage.

After completing the initial cell search, the terminal acquires more specific system information by receiving a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) according to the information carried in the PDCCH. You can do it (S302).

Meanwhile, when accessing the base station for the first time or when there are no radio resources for signal transmission, the terminal may perform a random access procedure (RACH) on the base station (steps S303 to S306). To this end, the terminal may transmit a specific sequence as a preamble through a physical random access channel (PRACH) (S303 and S305) and receive a response message for the preamble through the PDCCH and the corresponding PDSCH ( S304 and S306). In the case of contention-based RACH, an additional conflict resolution procedure (Contention Resolution Procedure) can be performed.

The terminal that has performed the above-described procedure can then perform PDCCH/PDSCH reception (S307) and Physical Uplink Shared Channel (PUSCH)/Physical Uplink Control Channel (Physical Uplink) as a general uplink/downlink signal transmission procedure. Control Channel, PUCCH) transmission (S308) can be performed. In particular, the terminal receives downlink control information (DCI) through PDCCH. Here, DCI includes control information such as resource allocation information for the terminal, and has different formats depending on the purpose of use.

Meanwhile, the control information that the terminal transmits to the base station through the uplink or that the terminal receives from the base station includes downlink/uplink ACK/NACK signals, CQI (Channel Quality Indicator), PMI (Precoding Matrix Index), and RI (Rank Indicator). ), etc. In the case of the 3GPP LTE system, the terminal can transmit control information such as the above-described CQI/PMI/RI through PUSCH and/or PUCCH.

Figure 4 illustrates a radio frame structure for transmission of a synchronization signal (Synchronization Signal, SS). In particular, Figure 4 illustrates a radio frame structure for transmission of a synchronization signal and PBCH in Frequency Division Duplex (FDD), and Figure 4(a) is a radio frame configured as a normal cyclic prefix (CP). It shows the transmission positions of SS and PBCH, and FIG. 4(b) shows the transmission positions of SS and PBCH in a radio frame configured as an extended CP (extended CP).

When the UE is turned on or wants to newly access a cell, it acquires time and frequency synchronization with the cell and performs cell search (initial), such as detecting the physical cell identity (N ^cell _ID ) of the cell. Cell search) process is performed. To this end, the UE receives a synchronization signal, for example, a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) from the eNB, synchronizes with the eNB, and identifies a cell identifier (identity). , ID), etc. can be obtained.

Referring to FIG. 4, SS will be described in more detail as follows. SS is divided into PSS and SSS. PSS is used to obtain time domain synchronization and/or frequency domain synchronization, such as OFDM symbol synchronization, slot synchronization, etc., and SSS is used to obtain frame synchronization, cell group ID, and/or CP configuration of the cell (i.e., use of regular CP or extended CP). It is used to obtain information). Referring to Figure 4, PSS and SSS are each transmitted in two OFDM symbols of every radio frame. Specifically, SS is performed in the first slot of subframe 0 and the first slot of subframe 5, considering the GSM (Global System for Mobile communication) frame length of 4.6 ms to facilitate inter-RAT (inter Radio Access Technology) measurement. are transmitted respectively. In particular, PSS is transmitted in the last OFDM symbol of the first slot of subframe 0 and the last OFDM symbol of the first slot of subframe 5, respectively, and SSS is transmitted in the second-to-last OFDM symbol of the first slot of subframe 0 and the subframe Each is transmitted in the second-to-last OFDM symbol of the first slot of 5. The boundary of the corresponding radio frame can be detected through SSS. PSS is transmitted in the last OFDM symbol of the slot, and SSS is transmitted in the OFDM symbol immediately before the PSS. SS's transmission diversity method uses only a single antenna port and is not separately defined in the standard. That is, a single antenna port transmission or a transmission method transparent to the UE (e.g., Precoding Vector Switching (PVS), Time Switched Diversity (TSTD), Cyclic Delay Diversity (CDD)) can be used for transmission diversity of the SS. .

SS can represent a total of 504 unique physical layer cell identifiers (physical layer cell ID) through a combination of 3 PSS and 168 SS. In other words, the physical layer cell IDs are 168 physical-layer cell-identifier groups with each group containing three unique identifiers such that each physical layer cell ID is part of only one physical-layer cell-identifier group. are grouped into . Therefore, the physical layer cell identifier N ^cell _ID = 3N ⁽¹⁾ _ID + N ⁽²⁾ _ID is a number in the range from 0 to 167 representing a physical-layer cell-identifier group N ⁽¹⁾ _ID and the physical-layer cell -Uniquely defined by N ⁽²⁾ _ID , a number from 0 to 2 that represents the physical-layer identifier within the identifier group. The UE can detect the PSS to know one of the three unique physical-layer identifiers, and detect the SSS to identify one of the 168 physical layer cell IDs associated with the physical-layer identifier. A ZC (Zadoff-Chu) sequence of length 63 is defined in the frequency domain and used as the PSS.

Referring to FIG. 4, since the PSS is transmitted every 5ms, the UE can detect the PSS and know that the subframe is one of subframe 0 and subframe 5. However, the UE can know that the subframe is one of subframe 0 and subframe 5. I don't know what it is. Therefore, the UE cannot recognize the boundary of the radio frame using PSS alone. In other words, frame synchronization cannot be obtained with PSS alone. The UE detects the boundary of the radio frame by detecting the SSS, which is transmitted twice within one radio frame but in different sequences.

Figure 5 is a diagram illustrating a control channel included in the control area of one subframe in a downlink radio frame.

Referring to FIG. 5, a subframe consists of 14 OFDM symbols. Depending on the subframe setting, the first 1 to 3 OFDM symbols are used as a control area and the remaining 13 to 11 OFDM symbols are used as a data area. In the drawing, R1 to R4 represent reference signals (Reference Signal (RS) or Pilot Signal) for antennas 0 to 3. RS is fixed to a certain pattern within the subframe regardless of the control area and data area. The control channel is allocated to a resource to which an RS is not allocated in the control area, and the traffic channel is also allocated to a resource to which an RS is not allocated to the data area. Control channels allocated to the control area include PCFICH (Physical Control Format Indicator CHannel), PHICH (Physical Hybrid-ARQ Indicator CHannel), and PDCCH (Physical Downlink Control CHannel).

PCFICH is a physical control format indicator channel that informs the UE of the number of OFDM symbols used in PDCCH in each subframe. PCFICH is located in the first OFDM symbol and is set prior to PHICH and PDCCH. PCFICH consists of four REGs (Resource Element Groups), and each REG is distributed within the control area based on cell ID (Cell IDentity). One REG consists of 4 RE (Resource Elements). RE represents the minimum physical resource defined as one subcarrier × one OFDM symbol. The PCFICH value indicates a value of 1 to 3 or 2 to 4 depending on the bandwidth and is modulated with QPSK (Quadrature Phase Shift Keying).

PHICH is a physical HARQ (Hybrid - Automatic Repeat and request) indicator channel and is used to carry HARQ ACK/NACK for uplink transmission. That is, PHICH indicates a channel through which DL ACK/NACK information for UL HARQ is transmitted. PHICH consists of one REG and is scrambled in a cell-specific manner. ACK/NACK is indicated by 1 bit and is modulated with BPSK (Binary Phase Shift Keying). The modulated ACK/NACK is spread with a spreading factor (SF) = 2 or 4. Multiple PHICHs mapped to the same resource constitute a PHICH group. The number of PHICHs multiplexed in a PHICH group is determined according to the number of spreading codes. PHICH (group) is repeated three times to obtain diversity gain in the frequency domain and/or time domain.

PDCCH is a physical downlink control channel and is allocated to the first n OFDM symbols of a subframe. Here, n is an integer greater than or equal to 1 and is indicated by PCFICH. PDCCH consists of one or more CCE. PDCCH informs each terminal or terminal group of information related to resource allocation of the transmission channel PCH (Paging channel) and DL-SCH (Downlink-shared channel), uplink scheduling grant, HARQ information, etc. Paging channel (PCH) and downlink-shared channel (DLSCH) are transmitted through PDSCH. Therefore, the base station and the terminal generally transmit and receive data through the PDSCH, respectively, except for specific control information or specific service data.

Information on which terminal (one or multiple terminals) the PDSCH data is transmitted to and how the terminals should receive and decode the PDSCH data are transmitted in the PDCCH. For example, a specific PDCCH is CRC masked with an RNTI (Radio Network Temporary Identity) called "A", a radio resource (e.g. frequency location) called "B", and a DCI format called "C", that is, a transmission format. It is assumed that information about data transmitted using information (e.g., transport block size, modulation method, coding information, etc.) is transmitted through a specific subframe. In this case, the terminal in the cell monitors the PDCCH using its own RNTI information, and if there is one or more terminals with “A” RNTI, the terminals receive the PDCCH and use the information on the received PDCCH to Receive the PDSCH indicated by “B” and “C”.

Figure 6 illustrates the configuration of a cell specific common reference signal. In particular, Figure 6 shows a CRS structure for a 3GPP LTE system supporting up to 4 antennas.

[Equation 1]

Here, k is the subcarrier index, l is the OFDM symbol index, p is the antenna port number, and N ^max,DL _RB represents the largest downlink bandwidth configuration, expressed as an integer multiple of N ^RB _sc .

The variables v and v _shift define the positions in the frequency domain for different RSs, and v is given by:

[Equation 2]

Here, n _s is the slot number within the radio frame, and the cell-specific frequency shift is given as follows.

[Equation 3]

Referring to FIG. 6 and Equations 1 and 2, the current 3GPP LTE/LTE-A standard requires that, among various RSs defined in the system, the cell-specific CRS used for demodulation and channel measurement is the carrier's signal in all DL subframes. It is requested to be transmitted across the entire downlink band. Additionally, in the 3GPP LTE/LTE-A system, cell-specific CRS is also used to demodulate downlink data signals, so it is transmitted through all antenna ports for downlink transmission.

Meanwhile, cell-specific CRS not only measures channel state and demodulates data, but also performs tracking such as maintaining time synchronization and correcting frequency offset after the UE obtains time synchronization and frequency synchronization of the carrier used by the eNB for communication with the UE. It is also used for tracking.

Figure 7 shows an example of an uplink subframe structure used in a wireless communication system.

Referring to FIG. 7, the UL subframe can be divided into a control area and a data area in the frequency domain. One or several physical uplink control channels (PUCCH) may be assigned to the control area to carry uplink control information (UCI). One or several physical uplink shared channels (PUSCH) may be allocated to the data area of the UL subframe to carry user data.

In the UL subframe, subcarriers that are distant from the DC (Direct Current) subcarrier are used as a control area. In other words, subcarriers located at both ends of the UL transmission bandwidth are allocated to the transmission of uplink control information. The DC subcarrier is a component that is not used in signal transmission and is mapped to the carrier frequency f ₀ during the frequency upconversion process. PUCCH for one UE is allocated to an RB pair belonging to resources operating at one carrier frequency in one subframe, and RBs belonging to the RB pair each occupy different subcarriers in two slots. The PUCCH allocated in this way is expressed as the RB pair allocated to the PUCCH performing frequency hopping at the slot boundary. However, when frequency hopping is not applied, the RB pair occupies the same subcarrier.

PUCCH can be used to transmit the following control information.

- SR (Scheduling Request): Information used to request uplink UL-SCH resources. It is transmitted using OOK (On-Off Keying) method.

- HARQ-ACK: A response to the PDCCH and/or a downlink data packet (e.g., codeword) on the PDSCH.

Indicates whether PDCCH or PDSCH has been successfully received. 1 bit of HARQACK is transmitted in response to a single downlink codeword, and 2 bits of HARQ-ACK are transmitted in response to two downlink codewords. The HARQ-ACK response includes positive ACK (simply ACK), negative ACK (hereinafter NACK), Discontinuous Transmission (DTX), or NACK/DTX. Here, the term HARQ-ACK is used interchangeably with HARQ ACK/NACK and ACK/NACK.

- CSI (Channel State Information): Feedback information for the downlink channel. Multiple Input Multiple Output (MIMO)-related feedback information includes a Rank Indicator (RI) and a Precoding Matrix Indicator (PMI).

Below, the carrier aggregation technique will be described. Figure 8 is a conceptual diagram explaining carrier aggregation.

Carrier aggregation is a process in which a terminal multiple frequency blocks or cells (in a logical sense) composed of uplink resources (or component carriers) and/or downlink resources (or component carriers) in order for a wireless communication system to use a wider frequency band. This refers to a method of using multiple frequencies as one large logical frequency band. Hereinafter, for convenience of explanation, the term will be unified as component carrier.

Referring to FIG. 8, the entire system bandwidth (System BW) is a logical band and has a bandwidth of up to 100 MHz. The entire system band includes five component carriers, and each component carrier has a bandwidth of up to 20 MHz. A component carrier includes one or more physically contiguous subcarriers. In FIG. 8, each component carrier is shown as having the same bandwidth, but this is only an example and each component carrier may have a different bandwidth. In addition, each component carrier is shown as being adjacent to each other in the frequency domain, but the drawing is illustrated in a logical concept, and each component carrier may be physically adjacent to each other or may be separated from each other.

The center carrier (center frequency) may be used differently for each component carrier, or a common center carrier may be used for physically adjacent component carriers. As an example, assuming that all component carriers in FIG. 8 are physically adjacent, the central carrier A can be used. Additionally, assuming a case where each component carrier is not physically adjacent, center carrier A, center carrier B, etc. can be used separately for each component carrier.

In this specification, the component carrier may correspond to the system band of the legacy system. By defining the component carrier based on the legacy system, backward compatibility and system design can be facilitated in a wireless communication environment where advanced terminals and legacy terminals coexist. For example, when the LTE-A system supports carrier aggregation, each component carrier may correspond to a system band of the LTE system. In this case, the component carrier can have any of the following bandwidths: 1.25, 2.5, 5, 10, or 20 Mhz.

When the overall system band is expanded through carrier aggregation, the frequency band used for communication with each terminal is defined on a component carrier basis. Terminal A can use the entire system band of 100 MHz and performs communication using all five component carriers. Terminals B1 to B5 can only use 20 MHz bandwidth and perform communication using one component carrier. Terminals C ₁ and C ₂ can use a 40 MHz bandwidth and each perform communication using two component carriers. The two component carriers may or may not be logically/physically adjacent. Terminal C ₁ represents a case where two non-adjacent component carriers are used, and terminal C ₂ represents a case where two adjacent component carriers are used.

While the LTE system uses one downlink component carrier and one uplink component carrier, the LTE-A system may use multiple component carriers as shown in FIG. 8. A downlink component carrier or a combination of a corresponding downlink component carrier and a corresponding uplink component carrier may be referred to as a cell, and the correspondence relationship between the downlink component carrier and the uplink component carrier can be indicated through system information. You can.

At this time, the method by which the control channel schedules the data channel can be divided into the existing link carrier scheduling method and the cross carrier scheduling method.

More specifically, link carrier scheduling, like the existing LTE system using a single component carrier, schedules only the data channel for the control channel transmitted through a specific component carrier. That is, the downlink grant/uplink grant transmitted in the PDCCH area of the downlink component carrier of a specific component carrier (or a specific cell) can be scheduled only for the PDSCH/PUSCH of the cell to which the downlink component carrier belongs. That is, the search space, which is an area where downlink grant/uplink grant is attempted to be detected, exists in the PDCCH area of the cell where the scheduled PDSCH/PUSCH is located.

On the other hand, cross-carrier scheduling uses a carrier indicator field (CIF) to control the control channel transmitted through the primary component carrier (Primary CC) and data transmitted through the primary component carrier or other component carriers. Schedule channels. In other words, a monitored cell (Monitored Cell or Monitored CC) of cross-carrier scheduling is set, and the downlink grant/uplink grant transmitted in the PDCCH area of the monitored cell is the PDSCH/PUSCH of the cell set to be scheduled in that cell. Schedule. That is, a search area for multiple component carriers exists in the PDCCH area of the monitored cell. Among the plurality of cells, the PCell is set by transmitting system information, an initial access attempt, or transmitting uplink control information, and the PCell is composed of a downlink main component carrier and a corresponding uplink main component carrier. It is composed.

Figure 9 is a diagram for explaining single carrier communication and multi-carrier communication. In particular, Figure 9(a) shows the subframe structure of a single carrier and Figure 9(b) shows the subframe structure of multiple carriers.

Referring to FIG. 9(a), a typical wireless communication system transmits or receives data through one DL band and one UL band corresponding thereto (in the case of frequency division duplex (FDD) mode). , a predetermined radio frame is divided into an uplink time unit and a downlink time unit in the time domain, and data is transmitted or received through the uplink/downlink time unit (time division duplex). , for TDD mode). However, in recent wireless communication systems, the introduction of carrier aggregation technology that uses a larger UL/DL bandwidth by gathering a plurality of UL and/or DL frequency blocks to use a wider frequency band is being discussed. In that carrier aggregation performs DL or UL communication using multiple carrier frequencies, OFDM (orthogonal frequency band) performs DL or UL communication by carrying the basic frequency band divided into multiple orthogonal subcarriers on one carrier frequency. It is distinguished from the division multiplexing system. Hereinafter, each carrier aggregated through carrier aggregation is referred to as a component carrier (CC). Referring to FIG. 9(b), a bandwidth of 60MHz can be supported by gathering three 20MHz CCs in each of the UL and DL. Each CC may be adjacent or non-adjacent to each other in the frequency domain. For convenience, Figure 9(b) illustrates the case where the bandwidth of the UL CC and the bandwidth of the DL CC are both equal and symmetrical, but the bandwidth of each CC can be determined independently. Additionally, asymmetric carrier aggregation with different numbers of UL CCs and DL CCs is also possible. A DL/UL CC limited to a specific UE may be referred to as a configured serving UL/DL CC in the specific UE.

The eNB can be used for communication with the UE by activating some or all of the serving CCs configured in the UE or deactivating some CCs. The eNB can change activated/deactivated CCs and change the number of activated/deactivated CCs. When the eNB allocates available CCs to the UE cell-specifically or UE-specifically, unless the CC allocation for the UE is completely reconfigured or the UE hands over, at least one of the allocated CCs One is not disabled. Unless there is a complete reconfiguration of CC allocation to the UE, a CC that cannot be deactivated is called a Primary CC (PCC), and a CC that the eNB can freely activate/deactivate is called a Secondary CC (Secondary CC, SCC). It is called. PCC and SCC may be classified based on control information. For example, specific control information may be set to be transmitted and received only through a specific CC. This specific CC may be referred to as a PCC, and the remaining CC(s) may be referred to as SCC(s).

Meanwhile, 3GPP LTE(-A) uses the concept of a cell to manage radio resources. A cell is defined as a combination of downlink resources (DL resources) and uplink resources (UL resources), that is, a combination of DL CC and UL CC. A cell may consist of DL resources alone or a combination of DL resources and UL resources. When carrier aggregation is supported, the linkage between the carrier frequency of DL resources (or, DL CC) and the carrier frequency of UL resources (or, UL CC) is indicated by system information. It can be. For example, the combination of DL resources and UL resources may be indicated by System Information Block Type2 (SIB2) linkage. Here, the carrier frequency means the center frequency of each cell or CC. Hereinafter, the primary frequency (Primary

A cell operating on a frequency is called a primary cell (PCell) or PCC, and a cell operating on a secondary frequency (or SCC) is called a secondary cell (SCell) or SCC. It is called. The carrier corresponding to the PCell in the downlink is called the downlink primary CC (DL PCC), and the carrier corresponding to the PCell in the uplink is called the UL primary CC (DL PCC). SCell refers to a cell that can be configured after RRC (Radio Resource Control) connection establishment and can be used to provide additional radio resources. Depending on the capabilities of the UE, the SCell, together with the PCell, may form a set of serving cells for the UE. The carrier corresponding to the SCell in the downlink is called the DL secondary CC (DL SCC), and the carrier corresponding to the SCell in the uplink is called the UL secondary CC (UL SCC).

do. For a UE that is in the RRC_CONNECTED state but has not configured carrier aggregation or does not support carrier aggregation, there is only one serving cell consisting of only PCell.

As previously mentioned, the term cell used in carrier aggregation is distinguished from the term cell, which refers to a certain geographical area where communication services are provided by one eNB or one antenna group. In order to distinguish between a cell indicating a certain geographical area and a cell of carrier aggregation, in the present invention, a cell of carrier aggregation is called CC, and a cell of a geographical area is called a cell. It is called.

In the existing LTE/LTE-A system, when multiple CCs are aggregated and used, it is assumed that the UL/DL frame time synchronization of the SCC matches the time synchronization of the PCC under the assumption that CCs that are not too far apart in the frequency domain are aggregated. However, in the future, there is a possibility that a plurality of CCs with UEs belonging to different frequency bands or separated by a large distance in frequency, that is, with different propagation characteristics, will be aggregated. In this case, the assumption that the time synchronization of the PCC and the time synchronization of the SCC are the same as in the prior art may have a serious adverse effect on the synchronization of the DL/UL signal of the SCC.

Meanwhile, in the case of LCT CC, among the radio resources operating in the LCT CC, radio resources available for transmission/reception of physical uplink/downlink channels and radio resources available for transmission/reception of physical uplink/downlink signals Resources, as previously explained, are predetermined. In other words, the LCT CC is not configured to carry physical channels/signals through a certain time frequency in a certain time resource, but rather carries the corresponding physical channel/signal through a certain time frequency in a specific time resource depending on the type of physical channel or physical signal. It must be configured to carry signals. For example, physical downlink control channels may be configured only in the leading OFDM symbol(s) among the OFDM symbols of a DL subframe, and the PDSCH may be configured in the leading OFDM symbol(s) to which physical downlink control channels are likely to be mapped. cannot be configured. As another example, CRS(s) corresponding to the eNB's antenna port(s) are transmitted every subframe in the REs shown in FIG. 6 across the entire band regardless of the eNB's DL BW. Accordingly, when the number of antenna ports of the eNB is 1, REs indicated as '0' in FIG. 6, and when the number of antenna ports of the eNB is 4, REs indicated as '0', '1', '2', and ' in FIG. 6 REs marked as 3' cannot be used for other downlink signal transmission. In addition, there are various constraints regarding the configuration of the LCT CC, and these constraints have increased significantly with the development of communication systems. Some of these constraints were created due to the level of communication technology at the time the constraints were created, and some became unnecessary as communication technology developed. There are constraints on existing technologies and constraints on new technologies for the same purpose. In some cases, they exist simultaneously. As the number of constraints increases, the constraints introduced for the development of the communication system actually act as a factor that makes it impossible to use the wireless resources of the corresponding CC efficiently. Therefore, the introduction of NCT CC, which is free from constraints that have become unnecessary due to the development of communication technology and can be configured according to simplified constraints rather than existing constraints, is being discussed. Because the NCT CC is not configured according to the constraints of the existing system, it cannot be recognized by a UE implemented according to the existing system. Hereinafter, a UE that is implemented according to the existing system and cannot support NCT CC is referred to as a legacy UE, and a UE implemented to support NCT CC is referred to as an NCT UE.

It is being considered that NCT CC will be used as an SCC in the future LTE-A system. Because the NCT CC does not consider use by the legacy UE, the legacy UE does not need to perform cell search, cell selection, cell reselection, etc. in the NCT CC. When the NCT CC is not used as a PCC and the NCT CC is used only as an SCC, unnecessary constraints on the SCC can be reduced compared to the existing LCT CC, which can also be used as a PCC, enabling more efficient use of the CC. However, the time/frequency synchronization of the NCT CC may not match that of the PCC, and even once the time/frequency synchronization of the NCT CC is obtained, the time/frequency synchronization may also change according to changes in the communication environment. A RS is needed where time synchronization and/or frequency synchronization can be used for tracking. In addition, RS is also needed to enable the UE to detect the NCT CC during a neighbor cell search process. CRS can be used for purposes such as time/frequency synchronization of NCT CC and neighboring cell search using NCT CC. CRS may be configured in the NCT CC in the same form as in the existing LTE/LTE-A system shown in Figure 6, and has less density in the time axis or frequency axis compared to the existing LTE/LTE-A system. If possible, it may be configured in NCT CC.

In the present invention, it is proposed that the CRS on the NCT CC be configured to have less density in the time axis than the CRS on the LCT CC of the existing LTE/LTE-A system. Accordingly, in the present invention, the NCT CC has a constraint that a CRS must be configured in the corresponding CC for each DL subframe, a constraint that a CRS must be configured in the corresponding CC for each antenna port of the eNB, and a predetermined number of lead OFDM conditions in the DL subframe. At least one of the constraints that a symbol must be reserved for transmission of a control channel such as PDCCH across the entire frequency band of the corresponding CC may not be satisfied. For example, on NCT CC, CRS may be configured for a certain number (>1) of subframes rather than for every subframe. Alternatively, on the NCT CC, only CRS can be configured for one antenna port (e.g., antenna port 0) regardless of the number of antenna ports of the eNB. Unlike the existing CRS shown in FIG. 6, the CRS of the present invention may not be used for demodulation of data. Therefore, instead of the existing CRS used for channel state measurement and demodulation, a tracking RS is newly defined for tracking time synchronization and/or frequency synchronization, and the tracking RS is connected to some subframes and/or some frequency resources on the NCT CC. It can be configured. Alternatively, a PDSCH may be configured in the leading OFDM symbols on the NCT CC, a PDCCH may be configured in an existing PDSCH area other than the leading OFDM symbols, or the PDCCH may be configured using some frequency resources. Hereinafter, regardless of the name, it can be used by any UE for time synchronization and/or frequency synchronization of NCT CC, or neighboring cell search, etc. Unlike the existing LTE/LTE-A system, RS transmitted in some subframes is common. It is collectively referred to as RS (common RS, CRS).

FIG. 10 is a diagram illustrating an example in which a cross-carrier scheduling technique is applied. In particular, in Figure 10, the number of allocated cells (or component carriers or component carriers) is 3, and a cross-carrier scheduling technique is performed using CIF as described above. Here, downlink cell #0 is assumed to be the downlink primary component carrier (i.e., Primary Cell, PCell), and the remaining component carriers #1 and component carrier #2 are assumed to be secondary component carriers (i.e., Secondary Cell, SCell).

The present invention provides an effective method for managing uplink resources for a primary component carrier (primary component carrier or primary cell or PCell) or secondary component carrier (secondary cell or SCell) while the terminal is performing a carrier aggregation operation. suggest. Below, a case where the terminal operates by merging two component carriers will be described, but it is obvious that this can also be applied when merging three or more component carriers.

Figure 11 is a diagram showing a deployment scenario of a terminal and a base station in an LTE and LAA service environment.

In the case of the frequency band targeted by the LAA service environment, the wireless communication range is not long due to the high frequency characteristics. Considering this, the deployment scenario between the terminal and the base station in an environment where existing LTE-licensed services and LAA services coexist is the overlay model shown on the left side of FIG. 11 and the co-located model shown on the right side of FIG. 11 (co-located model).

In the case of the overlay model shown on the left side of FIG. 11, the macro eNB performs wireless communication with the It can be connected through . Each RRH can perform wireless communication with the X terminal or X' terminal within a certain area 31 using an unlicensed carrier. In this case, the frequency bands between the macro eNB and the RRH are different, so there is no mutual interference, but in order to use the LAA service as an auxiliary downlink channel for the LTE-licensed service through carrier aggregation, an Fast data exchange must occur through

In the case of the co-located model shown on the right side of FIG. 11, the pico/femto eNB can perform wireless communication with the Y terminal using a licensed carrier and an unlicensed carrier simultaneously. However, using LTE service and LAA service together is considered when transmitting downlink data. In this case, coverage for LTE service and coverage for LAA service may be different depending on frequency band, transmission power, etc.

A terminal according to an embodiment of the present invention may be implemented as various types of wireless communication devices or computing devices that ensure portability and mobility.

The base station according to an embodiment of the present invention controls and manages cells corresponding to the service area (e.g., macro cell, femto cell, pico cell, etc.), and performs signal transmission, channel designation, channel monitoring, self-diagnosis, relay, etc. can perform the function.

Figure 12 is a block diagram showing the configuration of a terminal and a base station, respectively, according to an embodiment of the present invention.

As shown, the terminal 100 according to an embodiment of the present invention may include a processor 110, a communication module 120, a memory 130, a user interface unit 140, and a display unit 150. there is.

First, the processor 110 can execute various commands or programs and process data inside the terminal 100. Additionally, the processor 100 can control the entire operation including each unit of the terminal 100 and control data transmission and reception between the units.

Next, the communication module 120 may be an integrated module that performs wireless communication using a wireless communication network and wireless LAN access using a wireless LAN. To this end, the communication module 120 may be equipped with a plurality of network interface cards, such as cellular communication interface cards 121 and 122 and wireless LAN interface cards 123, in built-in or external form. In FIG. 12, the communication module 120 is shown as an integrated integrated module, but unlike FIG. 12, each network interface card may be independently arranged depending on circuit configuration or purpose.

The cellular communication interface card 121 using the first frequency band transmits and receives a wireless signal with at least one of the base station 200, an external device, and a server using a mobile communication network, and transmits and receives a wireless signal at the first frequency based on a command from the processor 110. Provides cellular communication service by band. Here, the wireless signal may include various types of data or information, such as a voice call signal, a video call signal, or a text/multimedia message.

According to an embodiment of the present invention, the cellular communication interface card 121 using the first frequency band may include at least one NIC module using the LTE-Licensed frequency band. According to an embodiment of the present invention, at least one NIC module independently performs cellular communication with at least one of the base station 200, an external device, and a server according to the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module. You can. The cellular communication interface card 121 can operate only one NIC module at a time or operate multiple NIC modules simultaneously, depending on the performance and requirements of the terminal 100.

The cellular communication interface card 122 using the second frequency band transmits and receives wireless signals with at least one of the base station 200, an external device, and a server using a mobile communication network, and transmits and receives wireless signals at the second frequency based on a command from the processor 110. Provides cellular communication service by band. According to an embodiment of the present invention, the cellular communication interface card 122 using the second frequency band may include at least one NIC module using the LTE-Unlicensed frequency band. For example, the LTE-Unlicensed frequency band may be a 2.4GHz or 5GHz band. According to an embodiment of the present invention, at least one NIC module independently performs cellular communication with at least one of the base station 200, an external device, and a server according to the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module. You can. The cellular communication interface card 122 can operate only one NIC module at a time or operate multiple NIC modules simultaneously, depending on the performance and requirements of the terminal 100.

The wireless LAN interface card 123 using the second frequency band transmits and receives a wireless signal with at least one of the base station 200, an external device, and a server through a wireless LAN connection, and transmits and receives a wireless signal to the second frequency based on a command from the processor 110. Provides wireless LAN service by band. According to an embodiment of the present invention, the wireless LAN interface card 123 using the second frequency band may include at least one NIC module using the wireless LAN frequency band. For example, the wireless LAN frequency band may be an unlicensed radio band such as a 2.4GHz or 5GHz band. According to an embodiment of the present invention, at least one NIC module independently performs wireless communication with at least one of the base station 200, an external device, and a server according to the wireless LAN standard or protocol of the frequency band supported by the NIC module. You can. The wireless LAN interface card 123 can operate only one NIC module at a time or operate multiple NIC modules simultaneously, depending on the performance and requirements of the terminal 100.

According to an embodiment of the present invention, the above-described processor 110 provides information about whether the wireless LAN communication service of the second frequency band is available through the base station 200 and the cellular communication channel of the first frequency band, and predetermined information. exchange information about the period of Here, the information about the predetermined period is information set to receive downlink data from the base station 200 through the cellular communication channel of the second frequency band.

In addition, according to an embodiment of the present invention, since the base station 200, which will be described later, supports a wireless LAN communication service, the processor 110 receives a predetermined signal from the base station 200 through a wireless LAN communication channel of the second frequency band. A base station coexistence message containing information about the period is received.

In addition, according to an embodiment of the present invention, in response to the received base station coexistence message, the processor 110 provides a peripheral device capable of communicating with the terminal 100 through the base station 200 and the wireless LAN communication service of the second frequency band. To the terminal, a terminal coexistence message containing information for a predetermined period is transmitted according to a standard or protocol specified in the wireless LAN communication service of the second frequency band.

Additionally, according to one embodiment of the present invention, the processor 110 receives downlink data from the base station 200 for a predetermined period of time through a cellular communication channel of the second frequency band.

Next, the memory 130 stores the control program used in the terminal 100 and various data accordingly. This control program may include a predetermined program necessary for the terminal 100 to perform wireless communication with at least one of the base station 200, an external device, and a server.

Next, the user interface 140 includes various types of input/output means provided in the terminal 100. That is, the user interface 140 can receive user input using various input means, and the processor 110 can control the terminal 100 based on the received user input. Additionally, the user interface 140 may perform output based on commands from the processor 110 using various output means.

Next, the display unit 150 outputs various images on the display screen. The display unit 150 may output various display objects, such as content executed by the processor 110 or a user interface based on control commands of the processor 110.

In addition, as shown in FIG. 12, the base station 200 according to an embodiment of the present invention may include a processor 210, a communication module 220, and a memory 230.

First, the processor 210 can execute various commands or programs and process data inside the base station 200. Additionally, the processor 210 can control the entire operation including each unit of the base station 200 and control data transmission and reception between the units.

Next, the communication module 220 may be an integrated module that performs mobile communication using a mobile communication network and wireless LAN connection using a wireless LAN, like the communication module 120 of the terminal 100 described above. To this end, the communication module 120 may be equipped with a plurality of network interface cards, such as cellular communication interface cards 221 and 222 and wireless LAN interface cards 223, in built-in or external form. In FIG. 12, the communication module 220 is shown as an integrated integrated module, but unlike FIG. 12, each network interface card may be independently arranged depending on circuit configuration or purpose.

The cellular communication interface card 221 using the first frequency band transmits and receives wireless signals with at least one of the above-described terminal 100, an external device, and a server using a mobile communication network, and transmits and receives wireless signals based on instructions from the processor 210. 1 Provides cellular communication services by frequency band. Here, the wireless signal may include various types of data or information, such as a voice call signal, a video call signal, or a text/multimedia message.

According to an embodiment of the present invention, the cellular communication interface card 221 using the first frequency band may include at least one NIC module using the LTE-Licensed frequency band. According to an embodiment of the present invention, at least one NIC module independently performs cellular communication with at least one of the above-described terminal 100, an external device, and a server according to the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module. It can be done. The cellular communication interface card 221 can operate only one NIC module at a time or operate multiple NIC modules simultaneously, depending on the performance and requirements of the base station 200.

The cellular communication interface card 222 using the second frequency band transmits and receives wireless signals with at least one of the above-described terminal 100, an external device, and a server using a mobile communication network, and transmits and receives wireless signals based on instructions from the processor 210. It provides cellular communication services using 2 frequency bands. According to an embodiment of the present invention, the cellular communication interface card 222 using the second frequency band may include at least one NIC module using the LTE-Unlicensed frequency band. For example, the LTE-Unlicensed frequency band may be a 2.4GHz or 5GHz band. According to an embodiment of the present invention, at least one NIC module independently performs cellular communication with at least one of the above-described terminal 100, an external device, and a server according to the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module. It can be done. The cellular communication interface card 222 can operate only one NIC module at a time or operate multiple NIC modules simultaneously, depending on the performance and requirements of the base station 200.

The wireless LAN interface card 223 using the second frequency band transmits and receives wireless signals with at least one of the above-described terminal 100, an external device, and a server through a wireless LAN connection, and transmits and receives wireless signals based on instructions from the processor 210. 2 Provides wireless LAN service by frequency band. According to an embodiment of the present invention, the wireless LAN interface card 223 using the second frequency band may include at least one NIC module using the wireless LAN frequency band. For example, the wireless LAN frequency band may be an unlicensed radio band such as a 2.4GHz or 5GHz band. According to an embodiment of the present invention, at least one NIC module independently communicates wirelessly with at least one of the above-described terminal 100, an external device, and a server according to the wireless LAN standard or protocol of the frequency band supported by the corresponding NIC module. It can be done. The wireless LAN interface card 223 can operate only one NIC module at a time or operate multiple NIC modules simultaneously, depending on the performance and requirements of the base station 200.

According to an embodiment of the present invention, the above-described processor 210 provides information about whether the wireless LAN communication service of the second frequency band is available through the terminal 100 and the cellular communication channel of the first frequency band, and predetermined information. exchange information about the period of Here, the information about the predetermined period is information set to transmit downlink data to the terminal 100 through a cellular communication channel of the second frequency band.

In addition, according to an embodiment of the present invention, the above-described processor 210 is a peripheral terminal capable of communicating with the terminal 100 and the base station 200 through a wireless LAN communication service in the second frequency band. In a wireless LAN communication service, a base station coexistence message containing information for a predetermined period is transmitted according to a specified standard or protocol, and downlink data is transmitted to the terminal 100 for a predetermined period through a cellular communication channel in the second frequency band. transmit.

In addition, according to an embodiment of the present invention, since the terminal 100 supports a wireless LAN communication service, the processor 210 receives the base station coexistence message from the terminal 100 through a wireless LAN communication channel of the second frequency band. In response, a terminal coexistence message is received. Here, the terminal coexistence message includes information about a predetermined period.

The terminal 100 and the base station 200 shown in FIG. 12 are block diagrams according to an embodiment of the present invention, and the separately displayed blocks are shown to logically distinguish device elements. Accordingly, the elements of the above-described device may be mounted as one chip or as multiple chips depending on the design of the device. Additionally, in an embodiment of the present invention, some components of the terminal 100, such as the user interface 140 and the display unit 150, may be optionally provided in the terminal 100. Additionally, in an embodiment of the present invention, a user interface 140 and a display unit 150 may be additionally provided in the base station 200 as needed.

Control information for uplink/downlink transmission transmitted in downlink, DCI ( Downlink control information)

The base station provides downlink control such as control information for downlink scheduling, control information for uplink scheduling, control information for performing terminal transmission power control, random access response, and paging information to the terminal or terminals. Information (Downlink Control Information, DCI) can be transmitted through PDCCH (Physical Downlink Control Channel) or EPDCCH (Enhanced Physical Downlink Control Channel). The base station can send DCI of multiple terminals through PDCCH/EPDCCH. In this case, the terminal needs to determine whether it is its own DCI. For this purpose, DCI's CRC (Cyclic Redundancy Check) is scrambled with the terminal's unique RNTI (Radio Network Temporary Identifier). Additionally, as described above, DCI formats of various lengths may exist to transmit various control information. According to 3GPP LTE(-A), DCI formats 0, 0A, 0B, 1, 1A, 1C, 1D, 2, 2A, 2B, 2C, 3, 3A, 4, 4A, 4B are defined. In order to determine which DCI format was transmitted according to the transmission mode and transmission scheme set by the base station, the terminal performs decoding on all possible DCI formats that can be set according to the transmission mode and transmission scheme and uses the terminal's own RNTI and CRC bits. It is necessary to compare . This process is called blind decoding and will be described later.

In LTE(-A) system Downlink control channel, PDCCH (Physical Downlink (Control Channel)

Figure 13 shows the control region where PDCCH is transmitted in the LTE(-A) system. Control resign can consist of 1 to 3 OFDM symbol(s), and can be expanded to 4 OFDM symbols if the system BW is 1.4 MHz. Among the control regions, PDCCH can be transmitted over 1 to 3 OFDM symbol(s) depending on the size of the control region. And the PDCCH can be transmitted over the frequency axis or time axis within the control region.

Figure 14-(a) relates to procedures for transmitting control information and control channels in LTE(-A). Each control information is assigned a CRC according to the RNTI value according to the purpose, and after performing tailed biting convolution coding, rate matching is performed according to the amount of resource(s) used for PDCCH transmission. PDCCH(s) to be transmitted in a given subframe are mapped to the resource to be transmitted by multiplexing the PDCCHs using a CCE-based PDCCH structure. The number of CCEs used for one PDCCH is defined as the aggregation level, and 1, 2, 4, and 8 can be used in LTE(-A). Figure 14-(b) is a diagram of CCE aggregation and PDCCH multiplexing and shows the type of CCE aggregation level used for one PDCCH and the CCE(s) transmitted in the control region accordingly.

Figure 15 is a diagram for setting the PDCCH search space in the LTE(-A) system. In order to transmit a PDCCH to a UE, there may be at least one search space per UE in the control region. In the present invention, the search space refers to all time-space resource combinations through which the PDCCH of the terminal can be transmitted, including a common search space that all terminals in 3GPP LTE(-A) must commonly search for; It may include a terminal-specific or UE-specific search space that a specific UE must search. The common search space is set to monitor the PDCCH that all UEs in a cell belonging to the same base station are commonly set to search for, and the specific UE search space monitors the PDCCH assigned to each UE at a different search space location depending on the UE. It can be set for each terminal to enable monitoring, but the specific-terminal search space may be allocated with a partial overlap between search spaces between terminals due to the limited control region where PDCCH can be allocated.

DL control channel for NR (e.g. NR-PDCCH)

In the present invention, the amount of resources is different from the CCE defined in LTE(-A), but it is the basic unit of PDCCH in LTE(-A) and is the minimum unit for one control channel in NR (New Radio) in a similar concept to CCE. NR-CCE is defined as . One control channel can be mapped to one or more NR-CCE(s), and one NR-CCE can be configured to be transmitted contiguously or non-contiguously with one or more PRBs (Physical Resource Blocks). there is. One PRB may consist of multiple subcarriers. The number of NR-CCEs required for a specific NR-PDCCH may vary depending on the DCI payload, which is the size of control information, cell bandwidth, terminal channel quality, channel coding rate, etc.

Figure 16 is a diagram to explain a specific search space in the control region where NR-PDCCH is transmitted as an embodiment of the present invention. NR-CCE combining level and NR-CCE allocation of the search space according to an embodiment of the present invention. This is a drawing showing . In a slot under the frame structure in NR (e.g. the number of OFDMs that can be assigned to a slot can be 7 or 14), the area where the NR-PDCCH can be located is defined as the Control region, and the NR-PDCCH among the control regions is It can be located in the first OFDM symbol, the second OFDM symbol, or two or more OFDM symbol(s) from the start of the control region. NR-PDCCH can be transmitted over the frequency axis or time axis within the control region. Here, for convenience of explanation, the description is focused on an embodiment in which the NR-PDCCH is transmitted across the frequency axis of the control region, but other embodiments such as the case where the NR-PDCCH can be allocated to the frequency axis and time axis within the control region This does not exclude examples.

Below is an example where the number of NR-CCEs that can configure NR-PDCCH, that is, the NR-CCE aggregation level is 1, 2, 4, 8 as in LTE(-A), is used for NR. The explanation is given considering the case, and the case where NR-CCE consists of four PRBs is considered. That is, referring to Table 3, the NR-CCE required to transmit a specific NR-PDCCH may be composed of 1, 2, 4, or 8 groups. Table 3 shows the case where one NR-CCE consists of 4 PRBs and one PRB consists of 12 subcarriers as an embodiment, but the aggregation level of the NR-CCE constituting the NR-PDCCH is Unlike in LTE(-A), the case where it is set to 4 or more or less than 4 is not excluded, and also when one NR-CCE is composed of more than or less than 4 PRBs and the PRB is not 12 subcarriers. The present invention may include all various combinations such as, but for convenience of explanation, considering the configuration of four NR-CCE aggregation levels, one NR-CCE into four PRBs, and 12 subcarriers per NR-PRB Although explained, the present invention does not exclude other cases.

[Table 3]

Blind Decoding

When the search space allocated to the UE is given as shown in FIG. 16, as described above, the UE determines at what NR-CCE aggregation level the NR-PDCCH transmitted to the UE within the allocated search space was performed and at what level. CCE(s) must be used to determine whether the control information (e.g., DCI) that the terminal wants to receive has been transmitted. To this end, the UE requires a decoding process for all possible NR-CCE combinations in the search space designated for the UE (e.g., common search space or UE search space). In order to decode its own control information, the terminal receives data transmitted to the PRB corresponding to the NR-CCE combination for each NR-CCE aggregation, performs channel decoding, and then checks whether the CRC of the DCI is masked with the terminal's unique RNTI. Confirm. Referring to Table 4 in an example of performing blind decoding at the terminal according to an embodiment in Table 3, the terminal may have four aggregation levels in the search space, and a plurality of NRs for each aggregation level. -Can have CCE combinations. In addition, referring to FIG. 16, when configured to have a hierarchical PDCCH search space type or a nested PDCCH search space, the combination of NR-CCEs that the UE can decode through full search in the hierarchical PDCCH search space is at the NR-CCE aggregation level. It can include 8 types when the NR-CCE aggregation level is 1, 4 types when the NR-CCE aggregation level is 2, 2 types when the NR-CCE aggregation level is 4, and 1 type when the NR-CCE aggregation level is 8. In addition, given that there are two DCI formats that can be transmitted considering uplink and downlink as the number of control information that the terminal must receive, the terminal can perform blind decoding up to 30 times to find its DCI. There may be a need. On average, 15.5 blind decodings must be performed. If the search space for UEs to perform NR-PDCCH monitoring is multiple (e.g. common search space and UE-specific search space), the number of blind decoding may be further increased.

[Table 4]

DM-RS allocation for NR-PDCCH

In order for the terminal to blind decode the NR-PDCCH, downlink channel information must be obtained. To this end, the base station can allocate some REs in the PRB constituting the NR-CCE as DM-RS (Demodulation Reference Signal) for demodulation of the NR-PDCCH, where the DM-RS for the NR-PDCCH is common. /shared DM-RS or UE specific DM-RS or PDCCH specific DM-RS. Figure 17 shows, as an example, whether the DM-RS for NR-PDCCH demodulation is allocated in single PRB units (Figure 17-(a)) or in multiple PRB units (Figure 17- This is an example according to (b)). Referring to Figure 17-(a), the RE corresponding to the DM-RS in one NR-CCE can be defined within the PRB, and an embodiment in which the DM-RS uses two REs within one PRB is shown. However, the RE where the DM-RS is located may be considered in cases where the DM-RS is assigned to positions in different subcarriers, and may include cases where two or more REs are assigned to RSs in the PRB. For example, the case of using 4 REs as DM-RS can be considered. As an example of using 4 REs as DM-RS, if there are 12 REs (Resource Elements) in the PRB from 0 to 11, the DM-RS is in the {0,3,6,9}th RE. can be assigned. The RE where the DM-RS is located may be considered as a case in which the DM-RS is assigned to a location in a different subcarrier, and various methods of designing the RE location of the DM-RS to have equal spacing may be possible. . Referring to FIG. 17(b), a method of defining the RE corresponding to the DM-RS in NR-CCE within a continuous PRB unit can also be considered. As an embodiment, two consecutive PRBs exist in one NR-CCE, and DM-RS allocation can be performed by defining the location of REs, etc., according to the number of RE allocations of DM-RSs within two consecutive PRBs. For example, referring to FIG. 17(b), when the indices of REs of two PRBs are 0 to 23, a DM-RS may be assigned to the {4, 12, 20}th RE. The RE where the DM-RS is located may be considered as a case in which the DM-RS is assigned to a location in a different subcarrier, and various methods of designing the RE location of the DM-RS to have equal spacing may be possible. . For convenience, the present invention focuses on the method of determining the DM-RS location within the PRB as shown in Figure 17-(a), but a method of determining the DM-RS location within the continuous PRB as shown in Figure 17-(b) is also possible. .

NR-PDCCH transmission

Figure 18 relates to the NR-PDCCH transmission procedure in the present invention. Referring to FIG. 18, the process of transmitting the NR-PDCCH from the base station includes a CRC attachment step using RNTI that informs the purpose of the NR-PDCCH and which UE it is assigned to, a channel coding step to be robust to channel characteristics, and the used NR-PDCCH. Rate matching step to adjust to the CCE coupling level, QPSK modulation step to convert the rate matched bits into complex symbols, NR-CCE aggregation and NR-CCE aggregation to map DM-RS for NRPDCCH and the modulated symbols to NR-CCE. CCE mapping step, sequence masking step using a sequence generated according to the results of the NR-CCE aggregation and NR-CCE mapping, or setting to perform phase rotation according to the results of each NR-CCE aggregation and NR-CCE mapping. It may consist of a step of performing phase rotation on the RS in the PRB to which the NR-CCE is assigned according to the results of each NR-CCE aggregation and NR-CCE mapping. In the above process, the RNTI may be a value notified to the UE in advance by the system or a value derived therefrom. In the above process, the DM-RS may be a value notified to the UE in advance by the system or a value derived therefrom. In the above process, the NR-CCE binding level may be a set value. As an example, in the present invention, referring to FIG. 16, the coupling level may be 1, 2, 4, or 8.

NR-PDCCH reception

Figure 19 relates to the NR-PDCCH reception procedure in the present invention. Referring to FIG. 19, the process of receiving the NR-PDCCH at the UE is a sequence de-masking step using all possible sequences and signals received in the search space allocated to the UE, or a detection step or DM according to all possible combinations of phase rotation. -A detection step according to all possible combinations of phase rotation in RS, a search space ordering step to determine which NR-CCE in the search space the NR-PDCCH was transmitted to, using the results of the sequence demasking or phase rotation detection step, It can be comprised of a demodulation step to decode the received signal of the NR-CCE at the corresponding location according to the determined search space ordering, a channel decoding step to decode the channel code to be robust to channel characteristics, and a CRC check step to check the validity of the RNTI. there is. The above step can be terminated when a valid RNTI is found in the CRC check step. In the above step, if a valid RNTI is not found in the CRC check step, the demodulation step, channel decoding step, and CRC check step can be performed using the signal received in the next search space according to the above search space ordering. When a valid RNTI is not found in the CRC check step and there are no more NR-CCE candidates remaining in the search space ordering step, it can be determined that the NR-PDCCH has not been received. In Figure 19 is the number of NR-CCE combinations determined to have the possibility of transmitting NR-PDCCH in the above search space ordering. In the above process, RNTI and DM-RS may be values notified to the UE in advance by the system or values derived therefrom.

Sequence masking step or phase rotation performance step

Referring to FIG. 20 (a), in a preferred embodiment of the present invention, when a DM-RS is assigned to a RE at a specific DM-RS location in one PRB, for example, to the {1,7}th RE, The remaining REs may be assigned NR-PDCCH for specific UEs. At this time, the NR-PDCCH may be composed of one or more NR-CCE(s), and one NR-CCE may be composed of one or more PRBs. When allocating the NR-PDCCH for a specific UE to a PRB composed of NR-CCE, the sequence used when using sequence masking is the sequence corresponding to the RE location to which the NR-PDCCH is allocated b = [b ₁ ,b _2, b ₃ ,b ₄ ,b ₅ ,b ₆ ,b ₇ ,b ₈ ,b ₉ ,b ₁₀ ] and the sequence a = [a ₁ , a ₂ ] corresponding to the RE position to which the DM-RS is assigned. there is. The type and number of the above sequences a and b may be predetermined or may be known to the eNB and the UE through signaling. The above sequence may be different for each PRB allocated to the NR-CCE. For convenience of explanation, the present invention describes that each PRB has the same sequences a and b , but this does not limit the invention. The above two sequences can be combined into one sequence c . Here, the sequence c may vary depending on the RE location where the DM-RS and NR-PDCCH are allocated in the PRB. Referring to Figure 20 (a), the sequence c is c = [a ₁ ,b ₁ ,b _2, b ₃ ,b ₄ ,b ₅ ,a ₂ ,b ₆ ,b ₇ ,b ₈ ,b ₉ ,b ₁₀ ] It can be expressed as . Alternatively, a method of applying a masking sequence without distinguishing between DM-RS and NR-PDCCH may be considered. The sequence c can be expressed as c = [c ₁ ,c _2, c ₃ ,c ₄ ,c ₅ ,c ₆ ,c ₇ ,c ₈ ,c ₉ ,c ₁₀ ,c ₁₁ ,c ₁₂ ]. The above sequence c can be transmitted by multiplying the NR-PDCCH and DM-RS signal assigned to the corresponding PRB.

In contrast, different phase rotation values (e.g. pi/2 or pi/4 phase rotation) are assigned to the PRB or NR to which the NR-CCE constituting the NR-PDCCH is assigned depending on the NR-CCE aggregation level of one NR-PDCCH. -A method of applying to the PRB to which the NR-CCE constituting the PDCCH is allocated may be considered.

Referring to FIG. 20 (b), as another preferred embodiment of the present invention, a method of performing sequence masking or applying phase rotation only to REs to which a DM-RS is assigned can be considered. That is, the value of sequence b assigned to NR-PDCCH may be b = [1,1,1,1,1,1,1,1,1,1], and the value of sequence a assigned to DM-RS may be 1 or another complex number.

In contrast, as a method of applying phase rotation, different phase rotation values (e.g., pi/2 or pi/4 phase rotation) are applied to the NRs constituting the NR-PDCCH according to the NR-CCE aggregation level of one NR-PDCCH. -A method of applying only the DM-RS in the PRB where the CCE is allocated may be considered.

Referring to FIG. 20 (c), as another preferred embodiment of the present invention, a method of performing sequence masking or applying phase rotation only to REs to which NR-PDCCH is allocated can be considered. That is, the value of sequence a assigned to DM-RS is a = [1,1], and the value of sequence b assigned to NR-PDCCH may be 1 or another complex number.

In contrast, as a method of applying phase rotation, different phase rotation values (e.g., pi/2 or pi/4 phase rotation) are applied to the NRs constituting the NR-PDCCH according to the NR-CCE aggregation level of one NR-PDCCH. -A method of applying only to resources to which NR-PDCCH is allocated, excluding DM-RS in PRB to which CCE is allocated, can be considered.

Sequence masking or phase rotation is used to indicate the CCE configuration information required in the NR-CCE aggregation level or PDCCH decoding process, and the sequence element applied to each RE defined in sequence masking is a complex value with size and phase and phase rotation. It can be defined including the phase change of . In other words, even if it is composed of a specific masking sequence, the complex value applied to each RE can represent a specific phase change value, and this phase change can be used in the PDCCH decoding process to reduce the complexity of blind decoding. There will be. Therefore, the change value of the phase or size of the RE constituting the PDCCH can be used for PDCCH blind decoding, such as the CCE aggregation level. In addition, sequence masking or phase rotation can be applied by separating the RE area where DCI is transmitted from the RE area where DM-RS is transmitted, and can also be applied selectively or integratedly.

How to assign sequence type and phase rotation values

In a preferred embodiment of the present invention, there may be two types of sequences used for the above sequence masking. The sequence a corresponding to the RE at the location where the DM-RS is assigned may be determined as a ⁽¹⁾ or a ⁽²⁾ depending on the NR-CCE coupling level and NR-CCE mapping. The sequence b corresponding to the RE at the location where the NR-PDCCH is assigned may be determined as b ⁽¹⁾ or b ⁽²⁾ depending on the NR-CCE combining level of the NR-PDCCH and the NR-CCE mapping. The sequence type determined according to the above NR-CCE coupling level and NR-CCE mapping is predetermined or can be known to the eNB and UE through signaling. Also, when using phase rotation, similar to sequence masking, one phase rotation value (e.g., pi/2 or pi/4 phase rotation) is set and NR is used to determine whether phase rotation occurs or not according to the phase rotation value. -A method of making a decision based on the NR-CCE combining level and NR-CCE mapping of the PDCCH and allowing the terminal and base station to know each other may be considered.

Referring to Table 5, in an embodiment of the present invention, it shows what types of sequences a and b can be assigned to the NR-CCE according to the NR-CCE coupling level and NR-CCE mapping. Here, all PRBs of each NR-CCE may have the same sequence. Here, the number 1 assigns the first type of sequence, that is, sequences a ⁽¹⁾ and b ⁽¹⁾ , to the PRB constituting the corresponding NR-CCE, and the number 2 assigns the second type of sequence to the PRB constituting the corresponding NR-CCE. , that is, assign the sequences a ⁽²⁾ and b ⁽²⁾ . Here, among the NR-CCEs to which the NR-PDCCH is allocated, the first type of sequences, a ⁽¹⁾ and b ⁽¹⁾ , are assigned to the starting NR-CCE and the ending NR-CCE, and the starting NR-CCE among the allocated NR-CCEs NR-CCEs other than NR-CCEs that end with CCE can be assigned the second kind of sequences, a ⁽²⁾ and b ⁽²⁾ . For example, when the 13th combination is selected based on the NR-CCE combination level and NR-CCE mapping, a ⁽¹⁾ and b ⁽¹⁾ are assigned to PRBs corresponding to NR-CCE0 and NR-CCE3, and NR -a ⁽²⁾ and b ⁽²⁾ can be assigned to PRBs corresponding to CCE1 and NR-CCE2.

[Table 5]

Referring to Table 6, in another embodiment of the present invention, it shows what types of sequences a and b can be assigned to PRBs of NR-CCE according to the NR-CCE coupling level and NR-CCE mapping. there is. According to this embodiment, PRBs constituting each NR-CCE may have different sequence types. In Table 6, the PRB corresponding to the front half and the PRB corresponding to the back half of each NR-CCE may have different sequence types. Here, the first type of sequences a ⁽¹⁾ and b ⁽¹⁾ can be assigned to the PRB corresponding to the front half of the combined NR-CCEs assigned to the UE, and the second type of sequence a ^{( 2)} and b ⁽²⁾ can be assigned. For example, when the 13th combination is selected based on the NR-CCE combination level and NR-CCE mapping, a ⁽¹⁾ and b ⁽¹⁾ are assigned to PRBs corresponding to NR-CCE0 and NR-CCE1, and NR- a ⁽²⁾ and b ⁽²⁾ can be assigned to PRBs corresponding to CCE2 and NR-CCE3.

[Table 6]

Sequence Generation

In a preferred embodiment of the present invention, the sequence a used for the RE at the location where the DM-RS is assigned can be transmitted by rotating the phase of the transmitting DM-RS. The two types of a ⁽¹⁾ and a ⁽²⁾ used can be expressed as follows.

[Equation 4]

Here, CCE_Index_start represents the index of the lowest numbered NR-CCE among the NR-CCEs to which the NR-PDCCH is assigned, and CCE_Index_End represents the index of the highest numbered NR-CCE among the NR-CCEs to which the NR-PDCCH is assigned. For example, when the 13th combination is selected referring to Table 5, CCE_Index_Start = 0 and CCE_Index_End = 3. In equation 4: is predetermined or can be known to the eNB and UE through signaling. In one embodiment of the present invention, a ⁽¹⁾ and a ⁽²⁾ can be designed to be orthogonal or to differ in phase by π. That is, for an integer n

[Equation 5]

can be designed satisfactorily. for example satisfies Equation 5, from which a ⁽¹⁾ = [1,1], a ⁽²⁾ = [1,-1] can be obtained.

In a preferred embodiment of the present invention, the sequence b used for the RE at the location where the NR-PDCCH is allocated can be transmitted by rotating the phase of the NR-PDCCH to be transmitted. The two types of sequences b ⁽¹⁾ and b ⁽²⁾ used are as follows.

[Equation 6]

In Equation 6, ψ _i,j , i=1,2, j=1,2,… ,10 is predetermined or can be known to the eNB and UE through signaling. In one embodiment of the present invention, each element of b ⁽¹⁾ and b ⁽²⁾ may have a phase difference of 0, π/4, 3π/4, 5π/4, or 7π/4. Among the b ⁽¹⁾ and b ⁽²⁾ elements above, the number of those with a phase difference of 0 and those without may be the same or differ by one. That is, j=1,...,10, for integer n

[Equation 7]

can be designed satisfactorily.

Sequence Demasking Phase or Phase Rotation

Referring to FIG. 21, the UE uses a distance indicator ( distance measure) can be obtained. In the present invention, the distance index can be defined for each NR-CCE, and the above distance index can be used to determine which sequence was used for each NR-CCE or whether phase rotation was performed. Additionally, a distance index can be defined for each NR-PDCCH search space, and the distance index can be used to determine which sequence is used in the NR-PDCCH search space or whether phase rotation has been performed.

In a preferred embodiment of the present invention, referring to FIG. 20(b), the distance index can be determined by the phase difference of the DM-RS signal received for each NR-CCE. Since DM-RSs placed in adjacent REs experience similar channel environments, the phase or magnitude components of the arriving signals may be similar. Therefore, it can be determined which sequence was used or whether phase rotation was performed depending on the degree of similarity of the channel environment experienced by DM-RSs deployed in adjacent REs.

For the 4 PRBs constituting the p-th NR-CCE, the signal received at the RE location corresponding to the DM-RS is x(p,q)=[x ₁ (p,q),x ₂ (p,q)] , let’s say p=1,2,3,4. In one embodiment, the decision can be made based only on the phase component of the channel experienced by the DM-RS placed in the adjacent RE. Assuming that the sequence type is masked or phase rotated with m=1 or 2, the distance index D ^(m) (p) of the pth NR-CCE may be as follows.

[Equation 8]

인 phase rotation으로 나타낼 수도 있다. 또한, 수학식 8에서 기호 은 phase의 합을 나타내고, 는 의 복소수 conjugate를 나타낸다. 또 다른 일 실시 예로, 인접한 RE에 배치된 DM-RS가 겪은 채널의 phase 성분과 magnitude 성분을 가지고 판단 할 수 있다. 시퀀스 종류 m=1 또는 2로 마스킹 또는 phase rotation되었다고 가정했을 때, p번째 NR-CCE의 거리 지표 D^(m)(p)는 다음과 같을 수 있다.here are two complex numbers and Indicates the phase difference. In equation 8: is the received signal is the DM-RS signal corresponding to the RE of is the received signal The sequence corresponding to the RE of is a sequence of type m. Referring to Equation 4, the sequence is

It can also be expressed as phase rotation. Additionally, in Equation 8, the symbol represents the sum of phases, Is Represents the complex number conjugate of . As another example, it can be determined based on the phase and magnitude components of the channel experienced by the DM-RS placed in the adjacent RE. Assuming that the sequence type is masked or phase rotated with m=1 or 2, the distance index D ^(m) (p) of the pth NR-CCE may be as follows.

[Equation 9]

.

As another preferred embodiment of the present invention, referring to FIG. 20(c), the distance index can be determined by the phase difference of the NR-PDCCH signal received for each NR-CCE. Since the NR-PDCCH is modulated and transmitted with QPSK, it is possible to determine which sequence was used or whether phase rotation was performed using the phase difference information of the received constellation of the NR-PDCCH. For the 4 PRBs constituting the pth NR-CCE, the received signal is received at the RE location corresponding to the NR-PDCC. , Let's say Assuming that the sequence type is masked or phase rotated with m=1 or 2, the distance index D ^(m) (p) of the pth NR-CCE is as follows.

[Equation 10]

인 phase rotation으로 나타날 수 있다. Here, S is a set of QPSK symbols, receives a signal using DM-RS. This is the RE estimated channel value corresponding to is the received signal The sequence corresponding to the RE of is a sequence of type m. Referring to Equation 6, the sequence is

It can appear as phase rotation.

In another preferred embodiment of the present invention, referring to FIG. 20(a), the distance indicator can be determined using the signals of the DM-RS and NR-PDCCH received for each NR-CCE. Referring to Equations 8, 9, and 10, the distance index can be obtained as the sum of those obtained using only DM-RS and those obtained using only NR-PDCCH. here is the channel value estimated by the UE using DM-RS.

Search Space Ordering

Referring to FIG. 21, the UE uses the calculated distance index D ⁽¹⁾ (p), From D ⁽²⁾ (p), p=1,2,...,8, the NR-PDCCH search space distance index can be obtained according to each NR-CCE combination level and NR-CCE allocation combination. Using the obtained NR-PDCCH search space distance index, high priority is given to the NR-CCE combining level and NR-CCE allocation combination with a low NR-PDCCH search space distance index, and when the UE performs blind decoding, You can search starting from the NR-CCE combination level and NR-CCE allocation combination that has been given high priority.

Search Space Ordering

Referring to FIG. 21, the UE uses the calculated distance index D ⁽¹⁾ (p), From D ⁽²⁾ (p), p=1,2,...,8, the NR-PDCCH search space distance index can be obtained according to each NR-CCE combination level and NR-CCE allocation combination. Using the obtained NR-PDCCH search space distance index, high priority is given to the NR-CCE combining level and NR-CCE allocation combination with a low NR-PDCCH search space distance index, and when the UE performs blind decoding, You can search starting from the NR-CCE combination level and NR-CCE allocation combination that has been given high priority.

In a preferred embodiment of the present invention, referring to Tables 5 and 7, in order to determine which NR-CCE combining level and NR-CCE allocation is used among the NR-PDCCH search space set for the UE, masked for each NR-CCE By estimating the sequence, the NR-PDCCH search space distance index can be calculated for each combination that can be assigned to the eNB. Among the distance indicators D ⁽¹⁾ (p) and D ⁽²⁾ (p) calculated for each NR-CCE, if the distance indicator is lower than a certain threshold, it can be determined that the corresponding sequence has been transmitted. For example, when the limit is π/2 and D ⁽¹⁾ (p) is less than D ⁽²⁾ (p), when the value of D ⁽¹⁾ (p) is less than the limit π/2, the first It can be determined that a type of sequence has been transmitted. However, when the value of D ⁽¹⁾ (p) is greater than the threshold π/2, the UE may determine that it has failed to find the sequence. Referring to Table 7, if it fails to find a sequence, it is expressed as Referring to Table 7, the search space distance index for each combination can be calculated using the sequence types obtained above. For example, the search space distance index can be obtained as the number of differences between the sequence type obtained above and the sequence type used for each combination. Given that the type of sequence obtained above is (X,X,1,X,1,2,2,1), the sequence of combination 13 is (1,2,2,1,X, Therefore, the search space distance index of combination 13 can be obtained as 8. Referring to Table 7, combination 12 has the lowest NR-PDCCH search spatial distance index, so it can receive the highest priority.

In another preferred embodiment of the present invention, in order to determine which NR-CCE combining level and NR-CCE allocation is used among the NR-PDCCH search space set for the UE, the eNB does not estimate the masked sequence for each NR-CCE. The NR-PDCCH search space distance index can be calculated for each assignable combination. For example, the UE can obtain the distance index of NR-CCE according to the sequence or phase rotation type given for each combination. The distance indices obtained from eight NR-CCEs are D ⁽¹⁾ (p), D ⁽²⁾ (p), p=1,2,… ,8, the NR-PDCCH search space distance index of combination 13 is Δ ₁₃ =(D ⁽¹⁾ (1)+D ⁽²⁾ (2)+D ⁽²⁾ (3)+D ⁽¹⁾ ( It can be obtained with 4))/4. After obtaining the search space distance index for each combination, the combination with the smallest search space distance index can have the highest priority.

[Table 7]

Although the methods and systems of the present invention have been described with respect to specific embodiments, some or all of their components or operations may be implemented using a computer system having a general-purpose hardware architecture.

The description of the present invention described above is for illustrative purposes, and those skilled in the art will understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. will be. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. do.

Claims (8)

In a method for a base station to transmit a downlink control channel to a terminal in a wireless communication system,
Setting a CCE (Control Channel Element) aggregation level and CCE mapping information for transmission of the downlink control channel to be transmitted by the base station to the terminal;
Determining, by the base station, a sequence and phase rotation value to mask REs included in the CCE for transmission of the downlink control channel based on the set CCE aggregation level and the set CCE mapping information; and
Comprising the step of the base station transmitting the downlink control channel based on the determined sequence and the phase rotation value in a resource element (RE) included in the CCE for transmitting the downlink control channel,
The sequence and phase rotation values used for REs to which DMRS is mapped among REs included in the CCE and the sequence and phase rotation values used for REs excluding REs to which DMRS is mapped among REs included in the CCE are set independently of each other.
How it works. delete In paragraph 1:
The base station performs transmission of the downlink control channel in the RE included in the CCE by masking the determined sequence and the phase rotation value only to the RE to which the DMRS included in the CCE is mapped.
How it works. In paragraph 1:
The base station masks the determined sequence and the phase rotation value in REs excluding REs to which DMRS is mapped among REs included in the CCE, and performs transmission of the downlink control channel in REs included in the CCE.
How it works. In a method for a terminal to receive a downlink control channel from a base station in a wireless communication system,
The terminal receiving a CCE aggregation level and CCE (Control Channel Element) mapping information as search space information for receiving the downlink control channel set for the terminal from the base station;
The terminal determines a sequence and phase rotation value to demask REs (resource elements) included in the CCE for transmission of the downlink control channel based on the CCE aggregation level and the CCE mapping information. step;
Demasking, by the terminal, a signal received from a RE included in the CCE based on the determined sequence and the phase rotation value;
Calculating, by the terminal, a value of a distance index according to each CCE set level and CCE mapping information in the search space;
determining the priority of the search space according to the calculated distance index value; and
Decoding the downlink control channel according to the determined priority,
The sequence and phase rotation values used for REs to which DMRS is mapped among REs included in the CCE and the sequence and phase rotation values used for REs excluding REs to which DMRS is mapped among REs included in the CCE are set independently of each other.
How it works. delete In paragraph 5,
Only REs to which the DMRS included in the CCE is mapped are demasked with the determined sequence and the phase rotation value.
How it works. In paragraph 5,
Among REs included in the CCE, only signals transmitted from REs excluding REs to which DMRS is mapped are demasked with the determined sequence and the phase rotation value.
How it works.

Images