KR20180122892A - Method, apparatus, and system for control channel in wireless communication system - Google Patents

Abstract

The present invention relates to a common control resource set (CORESET) for transmitting a PDCCH in a mobile communication system. Specifically, a method of indicating the time and the frequency resource of a common CORESET includes a step of determining the position of a frequency bandwidth according to a PSS/SSS/PBCH; and a step of limiting the common search space of the common CORESET to the first OFDM symbol of a slot. In addition, the present invention features a method of determining a search space for receiving a random access response in a random access process.

Description

TECHNICAL FIELD [0001] The present invention relates to a control channel transmission and reception method, apparatus, and system for a control channel of a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a method and a device for receiving a control channel and a design method regarding a structure of a control channel in a wireless communication system.

The 3GPPP NR (New Radio), a candidate for the 5G mobile communication system, can support a single bandwidth of 400MHz or more by using up to 6GHz carrier as well as the carrier of 6GHz or less. Such ultra-wideband can be used to improve the spectral efficiency of the network to provide more data and voice services.

In 3GPP LTE (-A), the maximum bandwidth of 20MHz was supported, and both the terminal and the base station had to be able to transmit and receive the maximum bandwidth of 20MHz. However, since the bandwidth supported by 3GPP NR is as large as 400 MHz, it is inefficient for all terminals to always support 400 MHz because of the complexity of the terminal's transceiver and the power consumption of the terminal. Therefore, in 3GPP NR, the minimum bandwidth to be supported by the UE is defined, and the maximum bandwidth can be set differently according to the UE.

As the bandwidth supported by the BS and the MS varies, the design of the downlink physical control channel (PDCCH) transmitted by the BS must be changed. In the 3GPP LTE (-A), if the base station uses a bandwidth of 20 MHz, the terminal can always receive the 20 MHz bandwidth, so the PDCCH can be transmitted with a full bandwidth of 20 MHz. However, in the 3GPP NR, since the bandwidth that the UE can receive can vary from UE to UE, the NR-PDCCH can not be transmitted in the entire bandwidth of the Node B. Therefore, a PDCCH design suitable for the bandwidth of the UE is required.

In 3GPP NR, the concept of CORESET (Control resource set) is introduced to allocate a control channel according to the bandwidth of the UE. CORESET is a collection of frequency resources to which a UE must perform blind decoding in order to receive a PDCCH, and a CORESET can be allocated to each UE. The UE blind-decodes possible NR-PDCCH candidates according to the search space defined in the assigned CORESET and receives the NR-PDCCH allocated to the UE.

The present invention aims at solving the problems that occur when a terminal and a base station support different bandwidths in 3GPP NR. More specifically, when the network needs to transmit the NR-PDCCH to be commonly received to the UEs, it is a CORESET allocation and a search space allocation for transmitting the corresponding NR-PDCCH.

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

The first technical aspect of the present invention is to design a frequency and a bandwidth of a common CORESET in accordance with a frequency location and a bandwidth of a PSS / SSS / PBCH, Frequency resource of a common CORESET to a UE, including defining a common search space for certain OFDMs independently of the number of OFDM symbols included in a common CORESET.

According to a second technical aspect of the present invention, there is provided a method for detecting a common search space of a common CORESET when a terminal performs random access using an index of a preamble selected as a method for solving the problem It provides a way to change the search space within a CORESET to receive a RAR or to receive it in a different CORESET.

It will be understood by those skilled in the art that various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the following detailed description of the invention, do.

According to the embodiment of the present invention, the UE can know the CORESET and the search space in which the NR-PDCCH for transmitting common information is transmitted. According to the CORESET and the structure of the search space proposed by the present invention, the UE can operate by monitoring only a small number of OFDM symbols, so that low power consumption can be expected. Further, according to the CORESET and the structure of the search space proposed by the present invention, it is expected that the network can reduce the signaling, thereby reducing the overhead of the entire network.

1 shows an example of a radio frame structure used in a wireless communication system.
2 shows an example of a downlink (DL) / uplink (UL) slot structure in a wireless communication system.
3 is a view for explaining a physical channel used in a 3GPP system and a general signal transmission method using the same.
FIG. 4 illustrates a radio frame structure for transmission of a synchronization signal (SS).
5 is a diagram illustrating a structure of a downlink radio frame used in an LTE system.
6 illustrates a configuration of a cell specific common reference signal.
FIG. 7 shows an example of a UL subframe structure used in a wireless communication system.
8 is a conceptual diagram illustrating a carrier aggregation (CA) technique.
FIG. 9 is a diagram for explaining Single Carrier Communication and Multiple Carrier Communication. FIG.
10 is a diagram showing an example in which a cross carrier scheduling technique is applied.
11 is a diagram illustrating a deployment scenario of a UE and a BS in an LTE and LAA service environment.
12 is a block diagram showing the configuration of a terminal and a base station according to an embodiment of the present invention.
13 is a diagram of a control region of a PDCCH for control channel transmission in LTE (-A).
14 is a diagram of a CORESET of a PDCCH for control channel transmission in NR.
FIG. 15 is a diagram showing a search space allocation by CCE aggregation for a common search space in the LTE (-A) and a UE specific (or terminal specific) search space.
16- (a) is a diagram of a procedure for transmitting control information in LTE (-A).
FIG. 16- (b) is a diagram for CCE aggregation of PDCCH and multiplexing of PDCCH in LTE (-A).
FIG. 17 is a view showing a frequency band position of a common CORESET. FIG.
18 is a view showing a position of the time domain of the common search space of the common CORESET.
19 is a diagram illustrating a search space for receiving a random access response.
20 is a diagram illustrating a resource set for receiving a random access response.

As used herein, terms used in the present invention are selected from general terms that are widely used in the present invention while taking into account the functions of the present invention. However, these terms may vary depending on the intention of a person skilled in the art, custom or the emergence of new technology. Also, in certain cases, there may be a term arbitrarily selected by the applicant, and in this case, the meaning thereof will be described in the description of the corresponding invention. Therefore, it is intended that the terminology used herein should be interpreted relative to the actual meaning of the term, rather than the nomenclature, and its content throughout the specification.

Throughout the specification, when a configuration is referred to as being "connected" to another configuration, it is not limited to the case where it is "directly connected," but also includes "electrically connected" do. Also, when an element is referred to as " including " a specific element, it is meant to include other elements, rather than excluding other elements, unless the context clearly dictates otherwise. In addition, the limitations of " above " or " below ", respectively, based on a specific threshold value may be appropriately replaced with "

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

Particularly, FIG. 1 (a) shows a frame structure for a frequency division duplex (FDD) used in a 3GPP LTE / LTE-A system and FIG. 1 Time division duplex (TDD) frame structure.

Referring to FIG. 1, a radio frame used in the 3GPP LTE / LTE-A system has a length of 10 ms (307200 Ts) and is composed of 10 equal sized subframes (SF). 10 subframes within one radio frame may be assigned respective numbers. Here, Ts represents the sampling time, and is represented by Ts = 1 / (2048 * 15 kHz). Each subframe is 1 ms long and consists of two slots. 20 slots in one radio frame can be sequentially numbered from 0 to 19. [ Each slot has a length of 0.5 ms. The time for transmitting one subframe is defined as a Transmission Time Interval (TTI). The time resource may be classified by a radio frame number (or a radio frame index), a subframe number (also referred to as a subframe number), a slot number (or a slot index), and the like.

The wireless frame may be configured differently according to the duplex mode. For example, in the FDD mode, since the downlink transmission and the uplink transmission are divided by frequency, the radio frame includes only one of the downlink subframe and the uplink subframe for a specific frequency band. In the TDD mode, since the downlink transmission and the uplink transmission are divided by time, the radio frame includes both the downlink subframe and the uplink subframe for a specific frequency band.

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

[Table 1]

In Table 1, D denotes a downlink subframe, U denotes an uplink subframe, and S denotes a special subframe. The specific subframe includes three fields of Downlink Pilot Time Slot (DwPTS), Guard Period (GP), and UpPTS (Uplink Pilot Time Slot). DwPTS is a time interval reserved for downlink transmission, and UpPTS is a time interval reserved for uplink transmission. Table 2 illustrates the configuration of the singular frames.

[Table 2]

2 illustrates 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 a time domain and a plurality of resource blocks (RB) in a frequency domain. The OFDM symbol also means one symbol period. Referring to FIG. 2, a signal transmitted in each slot may be expressed as a resource grid consisting of N ^{DL / UL} _RB * N ^RB _sc subcarriers and N ^{DL / UL} _symb OFDM symbols. have. 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 the UL transmission bandwidth, respectively. N ^DL _symb denotes the number of OFDM symbols in the downlink slot, and N ^UL _symb denotes 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 referred to as an OFDM symbol, an SC-FDM (Single Carrier Frequency Division Multiplexing) symbol, or the like according to a multiple access scheme. The number of OFDM symbols included in one slot can be variously changed according to the channel bandwidth and the length of the cyclic prefix (CP). For example, in the case of a normal CP, one slot includes 7 OFDM symbols

In the case of an extended CP, one slot includes six OFDM symbols. Although FIG. 2 illustrates a subframe in which one slot is composed of seven OFDM symbols for convenience of description, embodiments of the present invention may be applied to subframes having a different number of OFDM symbols in a similar manner. Referring to FIG. 2, each OFDM symbol includes N ^{DL / UL} _RB * N ^RB _sc subcarriers in the frequency domain. The type of subcarrier may be a data subcarrier for data transmission, a reference signal subcarrier for transmission of a reference signal, a null subcarrier for a guard band or a direct current (DC) ≪ / RTI > The DC component is mapped to a carrier frequency (f ₀ ) in an OFDM signal generation process or a frequency up-conversion process. The carrier frequency is also referred to as the center frequency (f _c ).

One RB is defined as N ^{DL / UL} _symb consecutive OFDM symbols in the time domain (for example, seven), and N ^RB _scrambled (e.g., twelve) consecutive subcarriers in the frequency domain . For reference, a resource composed of one OFDM symbol and one subcarrier is referred to as 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) in one slot. k is an index assigned from 0 to N ^{DL / UL} _RB * N ^RBsc -1 in the frequency domain, and 1 is an index assigned from 0 to N ^{DL / UL} _symb -1 in the time domain.

One RB is mapped to one physical resource block (PRB) and one virtual resource block (VRB). The PRB is defined as N ^{DL / UL} _symb (e.g., 7) consecutive OFDM symbols or SC-FDM symbols in the time domain, and N ^RB _scrambled (e.g., twelve) Is defined by the subcarrier. Therefore, one PRB consists of N ^{DL / UL} _symb * N ^RB _sc resource elements. Two RBs, one in each of two slots of the subframe occupying N ^RB _sc consecutive identical subcarriers in one subframe, are called a PRB pair. The two RBs constituting the PRB pair have the same PRB number (or PRB index).

In order for the UE to receive a signal from the eNB or to transmit a signal to the eNB, the time / frequency synchronization of the UE should be synchronized with the time / frequency synchronization of the eNB. since it can determine the time and frequency parameters necessary for the UE to perform the demodulation of the DL signal and the transmission of the UL signal at the correct time, as long as it is synchronized with the eNB.

3 is a view for explaining a physical channel used in a 3GPP system and a general signal transmission method using the same.

The terminal performs an initial cell search operation such as synchronizing with a base station when power is increased or newly enters a cell (S301). To this end, the terminal receives a primary synchronization channel (P-SCH) and a secondary synchronization channel (S-SCH) from a base station and synchronizes with the base station and acquires information such as a cell ID have. Then, the terminal can receive the physical broadcast channel from the base station and acquire the in-cell broadcast information. Meanwhile, the UE can receive the downlink reference signal (DL RS) in the initial cell search step to check the downlink channel state.

Upon completion of the initial cell search, the UE receives more detailed system information by receiving a Physical Downlink Control Channel (PDCCH) and a Physical Downlink Control Channel (PDSCH) according to the information on the PDCCH (S302).

On the other hand, if the base station is initially connected or there is no radio resource for signal transmission, the terminal can perform a random access procedure (RACH) on the base station (steps S303 to S306). To this end, the UE transmits a specific sequence through a Physical Random Access Channel (PRACH) (S303 and S305), and receives a response message for the preamble on the PDCCH and the corresponding PDSCH S304 and S306). In case of the contention-based RACH, a contention resolution procedure can be additionally performed.

The UE having performed the procedure described above transmits PDCCH / PDSCH reception (S307) and physical uplink shared channel (PUSCH) / physical uplink control channel Control Channel, PUCCH) (S308). In particular, the UE receives downlink control information (DCI) through the PDCCH. Here, the DCI includes control information such as resource allocation information for the UE, and formats are different according to the purpose of use.

Meanwhile, the control information that the UE transmits to the base station through the uplink or receives from the base station includes a downlink / uplink ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI) ) And the like. In the case of the 3GPP LTE system, the UE can transmit control information such as CQI / PMI / RI as described above through PUSCH and / or PUCCH.

FIG. 4 illustrates a radio frame structure for transmission of a synchronization signal (SS). In particular, FIG. 4 illustrates a radio frame structure for transmission of a synchronous signal and a PBCH in a frequency division duplex (FDD). FIG. 4A illustrates a radio frame in a normal CP (normal cyclic prefix) SS and PBCH. FIG. 4 (b) shows transmission positions of SS and PBCH in a radio frame configured with an extended CP.

The UE obtains time and frequency synchronization with the cell when it is powered on or newly connected to the cell, and performs cell search such as detecting the physical cell identity N ^cell _ID of the cell cell search procedure. 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, , ID) can be obtained.

Referring to FIG. 4, the 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, and the like. SSS is used for frame synchronization, cell group ID, and / or cell CP configuration Information). Referring to FIG. 4, the PSS and the SSS are transmitted in two OFDM symbols of each radio frame, respectively. In order to facilitate inter Radio Access Technology ("RAT") measurement, the SS considers 4.6 ms, which is the Global System for Mobile communication (GSM) frame length, in the first slot of subframe 0 and the first slot of subframe 5 Respectively. Specifically, the PSS is transmitted in the last OFDM symbol of the first slot of the subframe 0 and the last OFDM symbol of the first slot of the subframe 5, respectively, and the SSS is transmitted from the second OFDM symbol at the end of the first slot of the subframe 0, Lt; RTI ID = 0.0 > OFDM < / RTI > The boundary of the corresponding radio frame can be detected through the SSS. The PSS is transmitted in the last OFDM symbol of the slot and the SSS is transmitted in the OFDM symbol immediately before the PSS. SS's transmit diversity scheme uses only a single antenna port and is not defined in the standard. That is, a single antenna port transmission or a UE transparent transmission scheme (e.g., Precoding Vector Switching (PVS), Time Switched Diversity (TSTD), Cyclic Delay Diversity (CDD)) can be used for SS transmission diversity .

The SS can represent a total of 504 unique physical layer cell IDs through a combination of three PSSs and 168 SSs. In other words, the physical layer cell IDs are allocated to 168 physical-layer cell-identifier groups, each group including three unique identifiers, such that each physical-layer cell ID is part of only one physical-layer cell- . Thus, the physical layer cell ID _{^{N cell ID = 3N (1)}} ID + N (2) ID is a physical-layer cell - the range of 0 [identifier group to the 167 number N ⁽¹⁾ _ID and the physical-layer cell - a unique number N ⁽²⁾ _ID of 0 to 2 indicating the physical-layer identifier in the identifier group. The UE may detect the PSS to know one of the three unique physical-layer identifiers and may 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 5 ms, the UE can detect that the corresponding subframe is one of the subframe 0 and the subframe 5 by detecting the PSS. However, I do not know what it is. Therefore, the UE can not recognize the boundary of the radio frame only by the PSS. That is, frame synchronization can not be obtained with only PSS. The UE detects an SSS transmitted twice in one radio frame but transmitted as a different sequence and detects the boundary of the radio frame.

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

Referring to FIG. 5, a subframe is composed of 14 OFDM symbols. According to the subframe setting, the first to third OFDM symbols are used as a control region and the remaining 13 to 11 OFDM symbols are used as a data region. In the figure, R1 to R4 represent a reference signal (RS) or pilot signal for antennas 0 to 3. The RS is fixed in a constant pattern in the subframe regardless of the control region and the data region. The control channel is allocated to a resource to which the RS is not allocated in the control region, and the traffic channel is also allocated to the resource to which the RS is not allocated in the data region. Control channels allocated to the control region include a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid-ARQ Indicator CHannel (PHICH), and a Physical Downlink Control Channel (PDCCH).

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

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

The PDCCH is allocated to the first n OFDM symbols of the subframe as the physical downlink control channel. Here, n is an integer of 1 or more and is indicated by the PCFICH. The PDCCH consists of one or more CCEs. The PDCCH notifies each terminal or group of terminals of information related to resource allocation of a paging channel (PCH) and a downlink-shared channel (DL-SCH), an uplink scheduling grant, and HARQ information. A paging channel (PCH) and a downlink-shared channel (DLSCH) are transmitted on the PDSCH. Therefore, the BS and the MS generally transmit and receive data via the PDSCH, except for specific control information or specific service data.

PDSCH data is transmitted to a terminal (one or a plurality of terminals), and information on how the terminals receive and decode PDSCH data is included in the PDCCH and transmitted. For example, if a particular PDCCH is CRC masked with an RNTI (Radio Network Temporary Identity) of "A ", and a DCI format called " C" Assume that information on data to be transmitted using information (e.g., transport block size, modulation scheme, coding information, etc.) is transmitted through a specific subframe. In this case, the UE in the cell monitors the PDCCH using its RNTI information, and if there is more than one UE having the "A" RNTI, the UEs receive the PDCCH, B "and" C ".

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

[Equation 1]

Where k is a subcarrier index, 1 is an OFDM symbol index, p is an antenna port number, and ^{Nmax and DL} _RB represent the largest downlink bandwidth configuration, expressed as an integer multiple of N ^RB _sc .

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

&Quot; (2) "

Where n _s is the slot number in the radio frame and the cell specific frequency transition is given by:

&Quot; (3) "

Referring to FIG. 6 and Equations 1 and 2, the current 3GPP LTE / LTE-A standard defines a cell-specific CRS used for demodulation and channel measurement among the various RSs defined in the corresponding system, To be transmitted over the entire downlink band. Also, in the 3GPP LTE / LTE-A system, the cell-specific CRS is used for demodulation of the downlink data signal, and thus is transmitted every antenna port for downlink transmission.

Meanwhile, the cell-specific CRS can be used not only for channel state measurement and data demodulation, but also for tracking after the UE acquires time synchronization and frequency synchronization of a carrier used for communication with the UE, It is also used for tracking.

FIG. 7 shows an example of a UL subframe structure used in a wireless communication system.

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

In the UL subframe, subcarriers far away from each other based on a DC (Direct Current) subcarrier are used as a control region. In other words, the subcarriers located at both ends of the UL transmission bandwidth are allocated for transmission of the UL control information. The DC subcarrier is a component that is left unused for signal transmission and is mapped to the carrier frequency f ₀ in the frequency up conversion process. In one subframe, the PUCCH for one UE is allocated to an RB pair belonging to resources operating at one carrier frequency, and RBs belonging to the RB pair occupy different subcarriers in two slots. The PUCCH allocated as described above is expressed as the RB pair allocated to the PUCCH is frequency hopped at the slot boundary. However, when frequency hopping is not applied, the RB pairs occupy the same subcarrier.

The PUCCH may be used to transmit the following control information.

- SR (Scheduling Request): Information used for requesting uplink UL-SCH resources. OOK (On-Off Keying) method.

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

Indicates whether PDCCH or PDSCH has been successfully received. In response to a single downlink codeword, one bit of HARQACK is transmitted and two bits of HARQ-ACK are transmitted in response to two downlink codewords. The HARQ-ACK response includes positive ACK (simply ACK), negative ACK (NACK), DTX (Discontinuous Transmission) or NACK / DTX. Here, the term HARQ-ACK is mixed 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 RI (Rank Indicator) and PMI (Precoding Matrix Indicator).

Hereinafter, a carrier aggregation technique will be described. 8 is a conceptual diagram illustrating carrier aggregation.

Carrier aggregation is a technique in which a radio communication system uses a frequency block or a (logical sense) cell composed of uplink resources (or component carriers) and / or downlink resources (or component carriers) Which is used as a single large logical frequency band. Hereinafter, the term "component carrier" is used for the convenience of description.

Referring to FIG. 8, the total system bandwidth (System BW) has a bandwidth of 100 MHz as a logical bandwidth. The total system bandwidth includes five component carriers, each of which has a bandwidth of up to 20 MHz. A component carrier comprises one or more contiguous subcarriers physically contiguous. In FIG. 8, each of the component carriers is shown to have the same bandwidth, but this is merely an example, and each component carrier may have a different bandwidth. In addition, although each component carrier is shown as being adjacent to each other in the frequency domain, this figure is shown in a logical concept, wherein each component carrier may physically be adjacent to or spaced from one another.

The center frequency may use different common carriers for each component carrier or common for physically contiguous component carriers. For example, assuming that all of the component carriers are physically adjacent in FIG. 8, the center carrier A can be used. Further, assuming that the respective component carriers are not physically adjacent to each other, the center carrier A, the center carrier B, and the like 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 a component carrier based on a legacy system, it is possible to provide backward compatibility and system design in a wireless communication environment in which an evolved terminal and a legacy terminal coexist. In one example, if the LTE-A system supports carrier aggregation, each component carrier may correspond to the system band of the LTE system. In this case, the component carrier may have any of the following bandwidths: 1.25, 2.5, 5, 10, or 20 Mhz.

The frequency band used for communication with each terminal when the entire system band is expanded by carrier aggregation is defined in units of component carriers. Terminal A can use 100 MHz, which is the entire system band, and performs communication using all five component carriers. The terminals B1 to B5 can use only a 20 MHz bandwidth and perform communication using one component carrier. Terminals C ₁ and C ₂ can use a 40 MHz bandwidth and each communicate using two component carriers. The two component carriers may be logically / physically adjacent or non-contiguous. The terminal C ₁ shows a case in which two non-adjacent component carriers are used and the terminal C ₂ shows a case in which two adjacent component carriers are used.

In the LTE system, one downlink component carrier and one uplink component carrier are used, while in the LTE-A system, a plurality of component carriers can be used as shown in FIG. A combination of a downlink component carrier or a corresponding downlink component carrier and a corresponding uplink component carrier may be referred to as a cell and a corresponding relationship between a downlink component carrier and an uplink component carrier may be indicated through system information .

At this time, the scheme of scheduling the data channel by the control channel may be classified into a link carrier scheduling method and a cross carrier scheduling method.

More specifically, link carrier scheduling schedules data channels only through the particular component carrier, such as existing LTE systems that use a single component carrier, over a particular component carrier. That is, the downlink grant / uplink grant transmitted to the PDCCH region of the downlink component carrier of a specific component carrier (or specific cell) can be scheduled only for the PDSCH / PUSCH of the cell to which the corresponding downlink component carrier belongs. That is, the search space, which is an area for attempting to detect the downlink grant / uplink grant, exists in the PDCCH region of the cell where the PDSCH / PUSCH to be scheduled is located.

On the other hand, in the cross carrier scheduling, when a control channel transmitted through a primary component carrier (Primary CC) using a Carrier Indicator Field (CIF) is transmitted through the main component carrier or through another component carrier Schedules the channel. In other words, a monitored cell (Monitored Cell or Monitored CC) of the cross-carrier scheduling is set, and the downlink grant / uplink grant transmitted in the PDCCH region of the monitored cell is set to PDSCH / PUSCH of a cell set to be scheduled in the corresponding cell Scheduling. That is, a search area for a plurality of component carriers is present in a PDCCH area of a cell to be monitored. Among the plurality of cells, system information is transmitted, an initial access attempt is made, and the PCell is set by transmission of uplink control information. The PCell is a downlink main component carrier and an uplink main component carrier corresponding to the downlink main component carrier .

9 is a diagram for explaining single carrier communication and multiple carrier communication. Particularly, FIG. 9A shows a subframe structure of a single carrier and FIG. 9B shows a subframe structure of multiple carriers.

Referring to FIG. 9A, a general wireless communication system performs data transmission or reception (in a frequency division duplex (FDD) mode) through one DL band and one UL band corresponding thereto , A radio frame is divided into an uplink time unit and a downlink time unit in a time domain and data transmission or reception is performed through an uplink / downlink time unit (time division duplex , TDD) mode). However, in recent wireless communication systems, introduction of a carrier aggregation technique using a larger UL / DL bandwidth by collecting a plurality of UL and / or DL frequency blocks in order to use a wider frequency band is being discussed. Carrier aggregation is an orthogonal frequency division multiplexing (OFDM) scheme that performs DL or UL communication by putting a fundamental frequency band divided into a plurality of orthogonal subcarriers on one carrier frequency in that DL or UL communication is performed using a plurality of carrier frequencies division multiplexing system. Hereinafter, each of the carriers collected by carrier aggregation is referred to as a component carrier (CC). Referring to FIG. 9 (b), three 20 MHz CCs can be grouped into UL and DL, respectively, so that a bandwidth of 60 MHz can be supported. Each CC may be adjacent or non-adjacent to one another in the frequency domain. FIG. 9B shows a case where the bandwidth of the UL CC and the bandwidth of the DL CC are the same and symmetric, but the bandwidth of each CC can be determined independently. Asymmetric carrier aggregation in which the number of UL CCs is different from the number of DL CCs is also possible. A DL / UL CC specific to a particular UE may be referred to as a configured serving UL / DL CC in a particular UE.

The eNB may be used to communicate with the UE by activating some or all of the serving CCs configured in the UE, or by deactivating some CCs. The eNB can change the CC to be activated / deactivated, and can change the number of CCs to be activated / deactivated. When the eNB allocates a CC available for the UE in a cell-specific or UE-specific manner, at least one of the assigned CCs is used, as long as the CC allocation for the UE is not completely reconfigured or the UE does not perform a handover. One is not disabled. A CC that is not deactivated is referred to as a primary CC (PCC), and a CC that can be freely activated / deactivated by the eNB is called a secondary CC (SCC), unless it is a full reconfiguration of the CC assignment to the UE It is called. PCC and SCC may be distinguished based on control information. For example, specific control information may be set to be transmitted and received only via a specific CC, which may be referred to as PCC and the remaining CC (s) 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 DL resources and 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. If carrier aggregation is supported, the linkage between the carrier frequency of the DL resource (or DL CC) and the carrier frequency of the UL resource (or UL CC) . For example, a combination of a DL resource and a UL resource can be indicated by linkage of System Information Block Type 2 (SIB2). Here, the carrier frequency means a center frequency of each cell or CC. In the following,

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

do. For UEs that are in the RRC_CONNECTED state but no carrier aggregation is set or that do 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 geographical area in which a communication service is provided by a single eNB or a group of antennas. In order to distinguish between a cell designating a certain geographical area and a cell of carrier aggregation, a carrier aggregation cell is referred to as a CC and a cell in a geographical area is referred to as a cell. Quot;

In the existing LTE / LTE-A system, when multiple CCs are used together, it is assumed that the UL / DL frame time synchronization of the SCC coincides with the time synchronization of the PCC, assuming that the CCs that are not so far away in the frequency domain are clustered. However, there is a possibility that a plurality of CCs belonging to different frequency bands or spaced apart from each other in frequency, that is, a plurality of CCs having different propagation characteristics, may be gathered in the future. In this case, assuming that the time synchronization of the PCC and the time synchronization of the SCC are the same as in the conventional case, the synchronization of the DL / UL signal of the SCC may be seriously adversely affected.

Meanwhile, in the case of the 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 / The resources, as described above, are predetermined. In other words, the LCT CC is not configured to carry physical channels / signals through arbitrary time frequency in arbitrary time resources, but may be configured to transmit the physical channel / Signal should be configured to carry. For example, the physical downlink control channels may be configured only in the first OFDM symbol (s) of the OFDM symbols in the DL subframe, and the PDSCH may include the first OFDM symbol (s) that are likely to be mapped physical downlink control channels. Lt; / RTI > As another example, the CRS (s) corresponding to the antenna port (s) of the eNB are transmitted every subframe in the REs shown in Fig. 6 over the entire band regardless of the DL BW of the eNB. Accordingly, when the number of antenna ports of the eNB is 1, REs indicated by '0' in FIG. 6 are '0', '1', '2' and ' 3 'can not be used for other downlink signal transmission. In addition, there are various constraints on the composition of the LCT CC, and these constraints are greatly increased as the communication system develops. Some of these constraints arise because of the level of communication technology at the time the constraint is created, and there are some constraints that are unnecessary as communication technology develops, and constraints of existing and new technologies for the same purpose It may be present at the same time. As the constraints become so large, the constraints introduced for the development of the communication system are making the wireless resources of the CC ineffective. Therefore, the introduction of NCT CC, which can be constructed according to the simplified constraints rather than the existing constraints, is free from the constraints that are unnecessary according to the development of the communication technology. Since the NCT CC is not constructed according to the constraints of the existing system, it can not be recognized by the UE implemented according to the existing system. Hereinafter, UEs which are implemented according to the existing system and can not support NCT CC are called legacy UEs, and UEs implemented to support NCT CCs are called NCT UEs.

It is considered that NCT CC will be used as SCC in LTE-A system in the future. Since 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. If 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 an existing LCT CC that can be used as a PCC, enabling more efficient use of the CC. However, the time / frequency synchronization of the NCT CC may not coincide with the synchronization of the PCC. Even if the time / frequency synchronization of the NCT CC is obtained once, the time / frequency synchronization may be changed according to the change of the communication environment. An RS in which time synchronization and / or frequency synchronization can be used for tracking is required. An RS is also needed to allow the UE to detect the NCT CC in the neighbor cell search process. CRS can be used for purposes such as time / frequency synchronization of NCT CC and neighbor cell search using NCT CC. The CRS may be configured in the NCT CC in the same manner as in the existing LTE / LTE-A system shown in FIG. 6 and may have a smaller density in the time axis or frequency axis than the existing LTE / LTE- It may be configured in the NCT CC.

In the present invention, it is proposed that the CRS on the NCT CC is configured to have a lower density on 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 includes a constraint condition that the CRS is configured in the corresponding CC for every DL subframe, a constraint condition that the CRS is configured in the CC for each antenna port of the eNB, a predetermined number of OFDM It may not satisfy at least one of the constraint conditions that the symbol should be reserved for transmission of the control channel such as the PDCCH over the frequency band of the corresponding CC. For example, on the NCT CC, a CRS may be configured for every predetermined number (> 1) of subframes, not every subframe. Or, on the NCT CC, only the CRS for one antenna port (e.g., antenna port 0) can be configured regardless of the number of antenna ports of the eNB. The CRS of the present invention may not be used for data demodulation unlike the existing CRS shown in FIG. Therefore, instead of the existing CRS used for channel state measurement and demodulation, a tracking RS is newly defined for tracking of time synchronization and / or frequency synchronization, and the tracking RS is added to some subframes and / or some frequency resources on the NCT CC Lt; / RTI > Alternatively, the PDSCH may be configured in the leading OFDM symbols on the NCT CC, the PDCCH may be configured in the existing PDSCH region other than the initial OFDM symbols, or the PDCCH may be configured using some frequency resources. Hereinafter, unlike the existing LTE / LTE-A system, unlike the existing LTE / LTE-A system, the RSs transmitted in some subframes can be used in common by any UE regardless of the name, such as time synchronization and / or frequency synchronization of the NCT CC, RS (common RS, CRS).

10 is a diagram showing an example in which a cross carrier scheduling technique is applied. In particular, in FIG. 10, the number of allocated cells (or component carriers or component carriers) is three and the cross carrier scheduling technique is performed using CIF as described above. Here, it is assumed that the downlink cell # 0 is a downlink main component carrier (i.e., a primary cell, PCell) and the remaining component carriers # 1 and # 2 are subsidiary components (i.e., a secondary cell, SCell).

In the present invention, an effective management method of uplink resources for a main component carrier (primary component carrier, primary cell or PCell) or a subsidiary component carrier (secondary component carrier or secondary cell or SCell) during a carrier aggregation operation I suggest. Hereinafter, the case where the terminal operates by merging two component carriers is explained, but it is obvious that the present invention can also be applied to the case of merging three or more component carriers.

11 is a diagram illustrating a deployment scenario of a UE and a BS in an LTE and LAA service environment.

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

In the case of the overlay model shown in the left side of FIG. 11, the macro eNB performs wireless communication with the X terminal and the X 'terminal in the macro area 32 using a licensed carrier, and a plurality of RRHs and an X2 interface Lt; / RTI > Each RRH may perform wireless communication with an X terminal or an X 'terminal in a certain area 31 using an unlicensed carrier. In this case, there is no mutual interference between the macro eNB and the RRH. However, in order to use the LAA service as an auxiliary downlink channel of the LTE-licensed service through carrier aggregation, an X2 interface between the macro eNB and the RRH A fast data exchange should be made.

In the case of the co-located model shown on the right-hand side of FIG. 11, the pico / femto eNB can perform wireless communication with the Y terminal simultaneously using an authorized carrier and an unauthorized carrier. However, the use of the LTE service and the LAA service together is considered in the downlink data transmission. In this case, coverage for LTE service and coverage for LAA service may differ depending on frequency band, transmission power, and the like.

A terminal according to an embodiment of the present invention can be implemented by various types of wireless communication devices or computing devices that are guaranteed to be portable and mobility.

The base station according to the embodiment of the present invention controls and manages a cell (for example, a macro cell, a femtocell, a picocell, etc.) corresponding to a service area and transmits a signal, channel designation, channel monitoring, Can be performed.

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

As shown, a 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 have.

First, the processor 110 may execute various commands or programs, and may process data inside the terminal 100. [ In addition, the processor 100 can control the entire operation including each unit of the terminal 100, and can control data transmission / 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 connection using a wireless LAN. To this end, the communication module 120 may include a plurality of network interface cards such as the cellular communication interface cards 121 and 122 and the wireless LAN interface card 123, either internally or externally. 12, the communication module 120 is shown as an integrated integrated module, but each network interface card may be independently arranged according to the circuit configuration or use, unlike in FIG.

The cellular communication interface card 121 according to the first frequency band transmits and receives a radio signal with at least one of the base station 200, the external device, and the server using the mobile communication network, Band cellular communication service. 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 by 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 performs cellular communication with at least one of the base station 200, the external device, and the server independently in accordance with the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module . The cellular communication interface card 121 may operate only one NIC module at a time or may operate a plurality of NIC modules at the same time according to the performance and requirements of the terminal 100. [

The cellular communication interface card 122 in the second frequency band transmits and receives a radio signal to and from a base station 200, an external device, and a server using a mobile communication network, Band cellular communication service. According to an embodiment of the present invention, the cellular communication interface card 122 by 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 band of 2.4 GHz or 5 GHz. According to an embodiment of the present invention, at least one NIC module performs cellular communication with at least one of the base station 200, the external device, and the server independently in accordance with the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module . The cellular communication interface card 122 may operate only one NIC module at a time or may operate a plurality of NIC modules at the same time according to the performance and requirements of the terminal 100. [

The wireless LAN interface card 123 according to the second frequency band transmits and receives a radio signal to at least one of the base station 200, the external device, and the server through the wireless LAN connection, Band wireless LAN service. According to an embodiment of the present invention, the wireless LAN interface card 123 according to the second frequency band may include at least one NIC module using the wireless LAN frequency band. For example, the WLAN frequency band may be an unlicensed radio band such as a band of 2.4 GHz or 5 GHz. According to an embodiment of the present invention, at least one NIC module performs wireless communication with at least one of the base station 200, the external device, and the server independently in accordance with a wireless LAN standard or protocol of a frequency band supported by the corresponding NIC module . The wireless LAN interface card 123 may operate only one NIC module at a time or may operate a plurality of NIC modules at the same time according to the performance and requirements of the terminal 100. [

According to an embodiment of the present invention, the processor 110 transmits information on whether or not the wireless LAN communication service of the second frequency band is available through the cellular communication channel of the first frequency band with the base station 200, Information on the period of time. Here, the information on the predetermined period is information set for receiving the 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 supports a wireless LAN communication service, the processor 110 can receive a predetermined signal from the base station 200 through a wireless LAN communication channel of a second frequency band And receives the base station coexistence message including information on the period.

In addition, according to an embodiment of the present invention, the processor 110 may be configured to transmit, in response to the received base station coexistence message, The terminal transmits a terminal coexistence message including information on a predetermined period according to a standard or protocol specified in the wireless LAN communication service of the second frequency band.

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

Next, the memory 130 stores a control program used in the terminal 100 and various data corresponding thereto. The control program may include a predetermined program required for the terminal 100 to perform wireless communication with at least one of the base station 200, the external device, and the 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. In addition, the user interface 140 may perform output based on instructions of 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 a content executed by the processor 110 or a user interface based on a control command of the processor 110. [

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

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

Next, the communication module 220 may be an integrated module for performing mobile communication using a mobile communication network and wireless LAN connection using a wireless LAN, such as the communication module 120 of the terminal 100 described above. To this end, the communication module 120 may include a plurality of network interface cards, such as the cellular communication interface cards 221 and 222 and the wireless LAN interface card 223, either internally or externally. 12, the communication module 220 is shown as an integrated integration module, but each network interface card may be independently arranged according to the circuit configuration or use, unlike in FIG.

The cellular communication interface card 221 according to the first frequency band transmits and receives a radio signal to at least one of the terminal 100, the external device, and the server using the mobile communication network, And provides cellular communication service by one 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 by 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, the at least one NIC module can perform cellular communication with at least one of the terminal 100, the external device, and the server independently according to the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module. Can be performed. The cellular communication interface card 221 may operate only one NIC module at a time or may operate a plurality of NIC modules at the same time according to the performance and requirements of the base station 200.

The cellular communication interface card 222 according to the second frequency band transmits and receives a radio signal to at least one of the terminal 100, the external device, and the server using the mobile communication network, And provides a cellular communication service by two frequency bands. According to an embodiment of the present invention, the cellular communication interface card 222 by 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 band of 2.4 GHz or 5 GHz. According to an embodiment of the present invention, the at least one NIC module can perform cellular communication with at least one of the terminal 100, the external device, and the server independently according to the cellular communication standard or protocol of the frequency band supported by the corresponding NIC module. Can be performed. The cellular communication interface card 222 may operate only one NIC module at a time or may operate a plurality of NIC modules at the same time according to the performance and requirements of the base station 200. [

The wireless LAN interface card 223 according to the second frequency band transmits and receives a wireless signal to at least one of the terminal 100, the external device, and the server through the wireless LAN connection, 2 frequency band. According to an embodiment of the present invention, the wireless LAN interface card 223 according to the second frequency band may include at least one NIC module using the wireless LAN frequency band. For example, the WLAN frequency band may be an unlicensed radio band such as a band of 2.4 GHz or 5 GHz. According to an embodiment of the present invention, at least one NIC module independently communicates with at least one of the terminal 100, the external device, and the server in accordance with a wireless LAN standard or protocol of a frequency band supported by the corresponding NIC module Can be performed. The wireless LAN interface card 223 can operate only one NIC module at a time or operate a plurality of NIC modules at the same time according to the performance and requirements of the base station 200. [

According to an embodiment of the present invention, the processor 210 transmits information on whether or not the wireless LAN communication service of the second frequency band is available through the cellular communication channel of the first frequency band with the terminal 100, Information on the period of time. Here, the information on the predetermined period is information set for transmitting the downlink data to the terminal 100 through the cellular communication channel of the second frequency band.

In addition, according to an embodiment of the present invention, the processor 210 may be a peripheral terminal capable of communicating with the base station 200 through the terminal 100 and the wireless LAN communication service of the second frequency band, And transmits the base station coexistence message including information on a predetermined period according to a standard or protocol defined in the wireless LAN communication service to the terminal 100 for a predetermined period on the cellular communication channel of the second frequency band, .

In addition, according to an embodiment of the present invention, since the terminal 100 supports the wireless LAN communication service, the processor 210 transmits the base station coexistence message Lt; RTI ID = 0.0 > coexistence < / RTI > Here, the terminal coexistence message includes information on 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. Blocks that are separately displayed are logically distinguished from elements of a device. Thus, the elements of the device described above can be mounted as one chip or as a plurality of chips depending on the design of the device. In addition, in the 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. In addition, in the embodiment of the present invention, the user interface 140, the display unit 150, and the like may be additionally provided to the base station 200 as needed.

FIG. 13 shows a control region in which a PDCCH is transmitted in an LTE (-A) system. The control resign may be composed of 1 to 3 OFDM symbols (s) and may extend to 4 OFDM symbols when the system BW is 1.4 MHz. The PDCCH of the control region can be transmitted over 1 to 3 OFDM symbols (s) according to the size of the control region. And the PDCCH may be transmitted over the frequency axis or time axis within the control region.

FIG. 14 shows a control region in which a PDCCH is transmitted in the NR system. In the NR system, the control region can contain only some bandwidth. More specifically, CORESET is a time-frequency resource with which the PDCCH is likely to be transmitted, and each terminal should monitor more than one CORESET. In 3GPP NR, at least one CORESET can be configured for one carrier. First, at least one CORESET may inform the UE from the PBCH for initial access to the cell. In the MIB transmitted from the PBCH of the LTE (-A), there is no CORESET configuration information, but the NR system can transmit the configuration information of the CORESET to the UE through the PBCH. Therefore, the UE can know how the time-frequency resources of at least one CORESET are configured according to the information informed from the PBCH after the cell initial connection. Since the PBCH is transmitted equally to all UEs in the cell, the CORESET can be monitored by all UEs in the cell. Therefore, in the present invention, this CORESET is called Common CORESET.

Common CORESET can transmit scheduling information of system information that can not be transmitted by the PBCH and can transmit scheduling information of a random access response (RAR) corresponding to message 2 at the time of random access, . Also, the common CORESET can be transmitted with scheduling information of the PDSCH or PUSCH for data transmission of the UE.

Additional CORESET (s) may be assigned to the terminal in addition to the Common CORESET. Since this CORESET (s) can be assigned differently for each UE, it is called UE-specific CORESET. In the UE-specific CORESET, PDSCH or PUSCH scheduling information for data transmission of a UE can be transmitted. In addition, information on the fallback transmission of the UE, information on the transmission power control of the UEs, and the like may be transmitted.

Fig. 15 is a diagram for the search space.

In order to transmit the PDCCH to the UE, at least one search space per UE may exist in CORESET. In the present invention, the search space refers to all the time-space resource combinations to which the PDCCH of the UE can be transmitted, and includes a common search space common to all terminals of 3GPP LTE (-A) Specific or UE-specific search space to which a specific UE must search. The common search space is set to monitor a PDCCH that is set so that all terminals in a cell belonging to the same base station are commonly found. A specific terminal search space is defined as a PDCCH allocated to each terminal in search space positions However, the search space between the UEs may be partially overlapped due to the limited CORESET to which the PDCCH can be allocated.

In the Common CORESET, there may be only a common search space and either a specific-terminal search space or a common search space. In the common search space of the common CORESET, scheduling information of system information that can not be transmitted by the PBCH, scheduling information of a random access response (RAR) corresponding to the message 2 at the time of random access, and scheduling information of paging information are broadcast and can be broadcasted. If there is a specific UE search space in the common CORESET, scheduling information of PDSCH or PUSCH for data transmission of a specific UE may be unicasted in this specific UE search space.

The UE-specific CORESET may have both a common search space and a specific-terminal search space or a specific-terminal search space. The specific UE search space of the UE-specific CORESET may be unicasting the PDSCH or PUSCH scheduling information for data transmission of a specific UE. If there is a common terminal search space in the UE-specific CORESET, information for performing the fallback operation of the UE and information on the transmission power control of the UEs can be transmitted in the common terminal search space. However, in the common search space of the UE-specific CORESET, the system information related to the cell connection and the scheduling information of the RAR can not be transmitted.

16 is a diagram of a configuration of a search space and a PDCCH transmitted to a search space.

One PRB (physical resource block) of CORESET and 12 REs corresponding to one OFDM symbol constitute one NR-REG. The NR-REGs can be grouped into K and constitute one NR-CCE. K may be six. The NR-CCE is the minimum unit through which the PDCCH can be transmitted. However, it is difficult to transmit the PDCCH to one NR-CCE according to the amount of information transmitted from the base station and the channel environment of the UE. In order to overcome this problem, a plurality of NR-CCEs can be combined to generate one PDCCH candidate. Here, the number of bundled NR-CCEs is called an aggregation level. The aggregation level may be 1, 2, 4, or 8. The NR-CCEs do not overlap with each other, but the PDCCH candidates may overlap each other. That is, one NR-CCE can be mapped to different PDCCHs. The set of these PDCCH candidates is the search space described above.

16- (a) relates to a procedure for generating a PDCCH. Each control information is assigned a CRC according to the RNTI value according to the purpose, performs channel coding, and performs rate matching according to the amount of resource (s) used for PDCCH transmission. The PDCCHs (s) to be transmitted in a given subframe are multiplexed with PDCCHs using the NR-CCE-based PDCCH structure to map resources to be transmitted. FIG. 16- (b) is a diagram of CCE aggregation and multiplexing of a PDCCH, and shows the types of NR-CCE aggregation levels used for one PDCCH and the NR-CCE (s) transmitted in the corresponding control region.

Referring to Fig. 14, the frequency position at which the CORESET can be located may vary. The number of PRBs that CORESET occupies may also vary. Therefore, the UE shall receive the frequency position of the CORESET to be monitored and the number of occupied PRBs from the base station. In particular, after performing initial access, the frequency position of the common CORESET, the number of PRBs occupied, and the number of OFDM symbols occupied by the common CORSET are set so as to receive the time / frequency position from the base station, , And the number of OFDM symbols that can be occupied by the common CORESET is set to be received through the PBCH that transmits limited system information, the overhead of the PBCH may be increased, and the overhead of the PBCH may be increased. It may not be able to include all of the information about it. Also, in general, common CORESET and US specific CORESET may be composed of one or more OFDM symbols. When the CORESET is composed of one or more OFDM symbols, the NR-CCE may be configured by grouping K NR-REGs in the time domain, and NR-CCEs may be formed by grouping K NR-REGs in the frequency domain It is possible. One CORESET is configured to perform the NR-REG to NR-CCE mapping with the time domain being prioritized and the frequency domain being next, or NR-REG to NR-CCE mapping with the frequency domain being prioritized and the time domain being next However, one CORESET is configured to use one NR-REG to NR-CCE mapping. Also, in the mapping of the NR-CCE to the PDCCH, the NR-CCE to NR-PDCCH mapping may be performed with one CORESET in the time domain and the frequency domain in the next, or the frequency domain may be prioritized and the time domain may be next CCE to NR-PDCCH mapping, but one CORESET is configured to use one NR-CCE to NR-PDCCH mapping. In order for the UE to receive the PDCCH from one CORESET, the UE can receive the PDCCH if the NR-REG to NR-CCE mapping and the NR-CCE to PDCCH mapping of the corresponding CORESET are set to one. Therefore, the base station needs to inform one NR-REG to NR-CCE mapping and NR-CCE to PDCCH mapping scheme per CORESET. If the number of OFDM symbols constituting the CORESET is different, the NR-REG configuration and the NR-CCE configuration and further the configuration of the PDCCH candidate may be changed in CORESET. Therefore, the UE must know the number of OFDM symbols constituting the CORESET in order to know how the PDCCH candidates are configured in the CORESET. The present invention is based on the assumption that the number of OFDM symbols that can be constituted by the common CORESET and the UE specific CORESET is flexibly allocated from the base station and the length of time resources for the common CORESET due to limited information that can be transmitted in the PBCH, In other words, we propose a method of informing the number of OFDM symbols of common CORESET or the configuration of information of frequency resources occupied by common CORESET. This is a method to reduce the overhead of PBCH that informs the time-frequency configuration of common CORESET.

Referring to FIG. 17, a method for informing the position of a frequency domain and the number of BWs or PRBs in a frequency domain where a common CORESET can be constructed, according to an embodiment of the present invention, It can be expected that the maximum bandwidth is equal to or not exceeding the maximum bandwidth among the bandwidths that are always occupied by the primary synchronization signal (PSS), the secondary synchronization signal (SSS), and the PBCH. For example, if the BW of the PBCH is composed of 288 subcarriers (24 RBs if 1RB = 12 subcarriers) of the sum of the subcarriers that can be occupied by the corresponding PBCH with a bandwidth greater than the PSS, SSS, the UE will have a bandwidth of the common CORESET, Can be expected to occupy. The bandwidth occupied by the PSS, the SSS, and the PBCH may vary depending on the carrier frequency or the subcarrier spacing used. In this case, the bandwidth of the common CORESET expected by the UE may be set differently according to the carrier frequency or the subcarrier spacing to be used. Referring to FIG. 17, let X be the number of PRBs included in the common CORESET, and let Y be the maximum number of PRBs among PRBs occupied by PSS, SSS, and PBCH, X = Y in the frequency domain of common CORESET A method of setting the number of BWs or PRBs to detect the frequency configuration information of the implicitly common CORESET through detection of the PSS / SSS / PBCH can be considered. At this time, the position of the frequency in the system BW that can be occupied by the common CORESET can be explicitly transmitted through the PBCH, or it can be informed about the position of the frequency domain according to the following method.

Referring to FIG. 17, the positions of the common CORESET frequency bands expected by the UE can be determined according to the positions of the bands transmitted by the PSS, SSS, and PBCH with respect to the positions of the frequency regions where the common CORESET can be configured. In a preferred embodiment of the present invention, the base station sets the position of the frequency band of the common CORESET to be allocated to the same position as the band where the PSS, SSS and PBCH are transmitted, and the UE sets the position of the frequency band of the common CORESET to PSS, Can be set to be always the same as the band to be transmitted. At this time, as to the number of BW or PRB in the frequency domain that can be occupied by the common CORESET, a method that can explicitly indicate in the PBCH independently of the detection of the PSS / SSS / PBCH may be used. Alternatively, A method of setting the frequency configuration information of the implicitly common CORESET to be known through the detection of the PSS / SSS / PBCH can be used. Therefore, according to the bandwidth and frequency location of the common CORESET according to the proposed scheme, the base station can know the frequency band position and frequency bandwidth of the common CORESET to the UE without additional signaling at the PBCH, thereby reducing the PBCH overhead.

Referring to FIG. 18, in an embodiment of the present invention, the UE determines whether the common CORESET is a common search space (common search space) and a UE specific search space, the common search space is set to indicate the time resource length of the common CORESET through the common search space. The common search space is the length of the time resource for the common CORESET, And the UE searches the common search space for the length of the time resource of the common CORESET in the fixed OFDM symbol length to recognize the length of the OFDM symbol that the common CORESET can occupy . In this case, the UE expects that the mapping between the NR-REG and the NR-CCE and the mapping between the NR-CCE and the PDCCH candidates always takes priority in the frequency domain in one or several OFDM symbols located at the beginning, It is possible to search for the common search space. In order to receive the PDCCH corresponding to the system information scheduling, the RAR scheduling, and the paging scheduling, the UE blindly decodes only the common search space in the corresponding OFDM symbol to obtain a desired PDCCH . The number of OFDM symbols constituting the common CORESET can be known through the system information or the RRC signal scheduled in the common search space of the common CORESET, and the specific terminal search space of the common CORESET can be determined through this information.

The base station can set the group common PDCCH to allow the UE to receive the group common PDCCH for the purpose of reducing blind decoding by the UE and inform the slot common information at least to the group common PDCCH so that the slot having the slot format in which the PDCCH is not transmitted to the DL It is possible to skip blind decoding of the PDCCH to reduce battery consumption of the UE. In addition, by informing the duration of the CORESET time resource, it is avoided that the BD is performed in a specific OFDM symbol in which the PDCCH is not transmitted unnecessarily. The common common PDCCH may be included in the common search space in the common CORESET. In this case, for the common CORESET in which the group common PDCCH is transmitted, the BS transmits the NR-REG to the NR-CCE and the NR- The mapping method of freq. first mapping, and the terminal shall always transmit freq to the common CORESET set to transmit the group common PDCCH. it is possible to set the group common PDCCH to be detected based on the first mapping. In order to detect the length of the OFDM symbol of the common CORESET by performing detection of the group common PDCCH as soon as possible and to inform the length of the time resource of the CORESET on the group common PDCCH, a specific OFDM symbol in which the PDCCH is not unnecessarily transmitted BD is prevented from being performed.

Referring to FIG. 18, if the UE is configured to configure the common CORESET to include only the common search space (common search space), if the UE sets the time resource length of the common CORESET to indicate on the common CORESET through the group common PDCCH, For the common CORESET, the base station allocates freq. NR-REG to NR-CCE and NR-CCE to PDCCH. first mapping, and the terminal shall always transmit freq to the common CORESET set to transmit the group common PDCCH. it is possible to set the group common PDCCH to be detected based on the first mapping. In order to detect the length of the OFDM symbol of the common CORESET by performing detection of the group common PDCCH as soon as possible and to inform the length of the time resource of the CORESET on the group common PDCCH, a specific OFDM symbol in which the PDCCH is not unnecessarily transmitted BD is prevented from being performed.

Another problem to be solved by the present invention is to solve a situation in which a plurality of PDCCHs can not be simultaneously transmitted to the common search space due to insufficient amount of resources occupied by the common search space of Common CORESET. In particular, if a plurality of UEs simultaneously request random access in a cell access process, the RAR must be transmitted to the common search space of the common CORESET in response to the random access request, but a plurality of RARs may not be simultaneously transmitted. Therefore, although sufficient resources should be secured in the common search space of the common CORESET, the method proposed in the present invention may not have an effect because the frequency-time domain of the common search space is fixed even if the resources of the common CORESET are increased.

As an embodiment of the present invention, as a method of solving a situation in which a plurality of PDCCHs can not be simultaneously transmitted in a common search space due to insufficient amount of resources occupied by the common search space of Common CORESET, And to inform the length of the common CORESET through the group common PDCCH.

Referring to FIG. 19, as a method for solving a situation in which a plurality of PDCCHs can not be transmitted simultaneously in the common search space due to a shortage of resources occupied by the common search space of the common CORESET according to another embodiment of the present invention, The UE attempting random access can change the search space that expects the RAR to be received in the Common CORESET by using the index of the preamble used. In FIG. 19, indexes of preamble are grouped into N sets, and search spaces 0, 1, 2, ... , N-1. Here, the case where N = 4 is shown. Here, one of the search spaces corresponding to each set may be a common search space. The terminal may select one of the search spaces defined according to the preamble index selected by the terminal and receive the RAR. In an embodiment of the present invention, when N search spaces are constructed in advance, when the index of the search space to be selected is b and the index of the selected preamble is a,

b = a mod N

. ≪ / RTI > For reference, the UE can know the number of OFDM symbols constituting the common CORESET, the number of search spaces expected for the RAR, and the configuration thereof through the scheduled system information in the common search space of the common CORESET.

 In another embodiment of the present invention for solving the above-mentioned problem, referring to FIG. 20, a UE attempting to randomly access a RAR using a index of a used preamble as a common search space of CORESET You can expect. In FIG. 20, indexes of preambles are grouped into N sets, and CORESET 0, 1, 2, ... , N-1. Here, the case where N = 4 is shown. Where one of the CORESETs corresponding to each set may be a Common CORESET. The UE may select one CORESET according to the preamble index selected by the UE and receive the RAR through the common search space of the CORESET. In an embodiment of the present invention, when N CORESETs are configured in advance, the index of the CORESET to be selected is c and the index of the selected preamble is a,

c = a mod N

. ≪ / RTI > For reference, the UE can already know the time-frequency configuration information of other CORESET through the scheduled system information in the common search space of Common CORESET.

While the methods and systems of the present invention have been described in connection with specific embodiments, some or all of those elements or operations may be implemented using a computer system having a general purpose hardware architecture.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (1)

Method and apparatus for transmitting and receiving data between a terminal and a base station

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