KR20180053174A - Method and apparatus for transmitting and receiving control information in a wireless communication system supporting mu-mimo supporting - Google Patents

Abstract

The present invention relates to a communication method for fusing a 5G communication system and an IoT technique to support a data transmission rate higher than a 4G communication system, and a system thereof. The present invention can be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail business, security and safety related services, etc.) based on 5G communication technology and IoT-related technology. The present invention relates to a method for transmitting and receiving control information by a base station in a wireless communication system, and a device therefor. The method in accordance with an embodiment of the present invention, comprises: a process of determining terminals scheduled with an MU-MIMO transmission scheme to transmit the control information; a process of allocating resources to transmit the control information to a specific region to which the control information is to be transmitted from exploration spaces of a down link control channel; and a process of transmitting the control information in the specific region by using the MU-MIMO transmission scheme.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for transmitting / receiving control information in a wireless communication system supporting MU-MIMO, and a method and apparatus for transmitting / receiving control information in a wireless communication system supporting MU-

The present invention relates to a wireless communication system, and more particularly, to a transmission / reception method in a wireless communication system supporting MU-MIMO (Multi-User Multiple Input Multiple Output).

Efforts have been made to develop an improved 5G (5 ^th -Generation) communication system or a pre-5G communication system to meet the increasing demand for wireless data traffic after commercialization of 4G (4 ^th -Generation) communication system . For this reason, a 5G communication system or a pre-5G communication system is called a system after a 4G network (Beyond 4G network) or a system after a long term evolution (LTE) communication system (Post LTE).

To achieve a high data rate, 5G communication systems are being considered for implementation in very high frequency (mmWave) bands (e.g., 60 gigahertz (60GHz) bands). In order to alleviate the path loss of the radio wave in the very high frequency band and to increase the propagation distance of the radio wave, the 5G communication system uses beamforming, massive multi-input multi-output (massive MIMO) (FD-MIMO), array antennas, analog beam-forming, and large scale antenna technologies are being discussed.

In order to improve the network of the system, the 5G communication system has developed an advanced small cell, an advanced small cell, a cloud radio access network (cloud RAN), an ultra-dense network, (D2D), a wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMP), and interference cancellation (CoMP) Have been developed.

In addition, in the 5G system, advanced coding modulation (ACM) schemes such as hybrid FSK and QAM modulation and sliding window superposition coding (SWSC), advanced connection technology such as FBMC (filter bank multi carrier), NOMA (non-orthogonal multiple access), and SCMA (sparse code multiple access).

Meanwhile, the Internet has evolved into an internet of things (IoT) network in which information is exchanged between distributed components such as objects in a human-centered connection network where humans generate and consume information. IoE (internet of everything) technology can be an example of IoT technology combined with big data processing technology through connection with cloud server.

In order to implement IoT, technology elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology and security technology are required. In recent years, sensor network for connecting objects, machine to machine , M2M), and machine type communication (MTC).

In the IoT environment, an intelligent internet technology (IT) service can be provided that collects and analyzes data generated from connected objects to create new value in human life. IoT can be applied to fields such as smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliances and advanced medical service through fusion and combination of existing IT technology and various industries have.

Accordingly, various attempts have been made to apply the 5G communication system to the IoT network. For example, sensor network, object communication, and MTC technologies are implemented by techniques such as beamforming, MIMO, and array antennas. The application of the cloud wireless access network as the big data processing technology described above is an example of the convergence of 5G technology and IoT technology.

In order to support transmission of downlink and uplink transport channels in a wireless communication system, related downlink control information (DCI) is required. In the conventional LTE system, the DCI is transmitted through a physical downlink control channel (PDCCH), which is a separate physical channel through which downlink control information is transmitted. The PDCCH is transmitted every subframe over the entire system band. One PDCCH carries one DCI message, and a plurality of UEs can be scheduled simultaneously on the downlink and uplink, so that a plurality of PDCCHs are simultaneously transmitted in each cell. A cell-specific reference signal (CRS) is used as a reference signal (RS) for decoding the PDCCH. CRS is an always-on signal transmitted every subframe over the entire band, and scrambling and resource mapping are changed according to a cell ID (Identity). All terminals monitoring the PDCCH estimate the channel using the CRS and perform decoding on the PDCCH. UE-specific beamforming can not be used because the CRS is a reference signal transmitted in a broadcast manner to all UEs. Therefore, the multi-antenna transmission scheme for the PDCCH in the LTE system is limited to open-loop transmission diversity.

Various technologies such as Carrier Aggregation (CA) and Coordinated MultiPoint (CoMP) are supported in the conventional LTE system, and it becomes difficult to secure a sufficient transmission capacity for transmitting the downlink control information using only the PDCCH that has been used in the past. Therefore, in Release 11 of LTE specification, EPDCCH (Enhanced PDCCH) is added as a physical channel for transmitting DCI. The EPDCCH is designed to meet the requirements of increasing the control channel transmission capacity, frequency-axis adjacent cell interference control, frequency-selective scheduling, and coexistence with existing LTE terminals. Since the demodulation reference signal (DMRS) is used as the reference signal for decoding the EPDCCH, the terminal-specific beamforming can be used for the EPDCCH. Therefore, in the case of EPDCCH, a multi-antenna transmission scheme using precoding is supported, a transmit diversity scheme using precoder cycling and a multiuser MIMO (MU-MIMO) transmission scheme according to a resource allocation scheme .

On the other hand, the 5G wireless communication system aims to support not only services requiring high transmission speed but also services having very short transmission delay and services requiring high connection density. Such scenarios should be able to provide various services with different transmission / reception techniques and transmission / reception parameters in one system in order to satisfy various requirements and services of users, It is important to design so that the service is not constrained by the current system. For example, scalable numerology can be used for the interval between subcarriers, and simultaneously, various services having different TTI (Transmission Time Interval) can be simultaneously serviced in one system. Inevitably, 5G should be able to use time and frequency resources more flexibly than LTE. Especially, it is very important to have flexibility in control channel design.

Due to such a technical problem, it is discussed that NR-PDCCH decoding based on DMRS, which is a UE-specific reference signal, is supported in a 5G downlink control channel (NR-PDCCH). Therefore, in the NR-PDCCH, it is possible to support UE-specific beamforming and thus support MU-MIMO transmission. The MU-MIMO transmission for the control channel can play a very important role in increasing the capacity of the control channel by enabling simultaneous transmission of NR-PDCCH of multiple terminals with the same time-frequency resource. Accordingly, the present invention provides various embodiments for supporting MU-MIMO transmission based on the 5G downlink control channel structure currently being discussed. The MU-MIMO transmission scheme for the NR-PDCCH proposed in the present invention introduces a new search space and is set to each mobile station according to a transmission mode, thereby supporting MU-MIMO transmission more efficiently do.

The present invention also provides a method and apparatus for efficiently transmitting and receiving control information in a wireless communication system supporting MU-MIMO.

The present invention also provides a method and apparatus for allocating resources for transmitting control information in a wireless communication system supporting MU-MIMO.

A method for transmitting control information by a base station in a wireless communication system according to an exemplary embodiment of the present invention includes the steps of determining MU-MIMO transmission scheme scheduled UEs for transmission of the control information, Allocating a resource for transmission of the control information to a specific region to which the control information is to be transmitted from the MIMO transmission system and transmitting the control information in the specific region using the MU-MIMO transmission scheme. In an embodiment of the present invention, the control information may be transmitted using UE-specific beamforming.

In addition, in the embodiment of the present invention, the step of allocating resources may include the steps of: determining whether an overlapping area exists between search spaces set for the determined terminals; if the overlapping area exists, And allocating the resource to the area.

In addition, the method of the present invention further includes setting an MU-MIMO transmission mode using RRC signaling to the determined terminals.

In the embodiment of the present invention, the method uses at least one search space commonly set for the determined terminals as the specific region.

Also, in the embodiment of the present invention, the method uses search spaces differently set for the determined terminals as the specific area.

In addition, in the method of the present invention, the determined UEs are divided into at least one group, and the step of setting different search spaces corresponding to the specific region is performed for each of the at least one group.

In addition, the method of the present invention may further include transmitting setting information of a search space corresponding to the specific area using RRC signaling or physical layer signaling to the determined terminals.

Also, in the embodiment of the present invention, the setting information of the search space corresponding to the specific area includes a setting indicator for the search space.

Also, in the embodiment of the present invention, the setting indicator includes offset information indicating a difference between a first search space set in each terminal and a second search space corresponding to the specific region.

In addition, according to an exemplary embodiment of the present invention, a base station in a wireless communication system includes a transceiver for transmitting and receiving data, a UE for scheduling MU-MIMO transmission schemes for transmission of the control information, Allocates resources for transmission of the control information to a specific area to which the control information is to be transmitted, and controls transmission of the control information in the specific area using the MU-MIMO transmission scheme.

In addition, according to an embodiment of the present invention, a method of receiving control information by a UE in a wireless communication system includes: when the MU-MIMO transmission scheme is set for the UE, the control information is transmitted using the MU- Performing blind decoding on a specific one of search spaces of a downlink control channel to be transmitted; and receiving the control information in the specific area when the blind decoding is successful.

In addition, according to an embodiment of the present invention, a terminal in a wireless communication system includes a transceiver for transmitting and receiving data, and a control unit for transmitting the control information using the MU-MIMO transmission scheme when the MU- And a controller for performing blind decoding on a specific one of the search spaces of the downlink control channel to be transmitted and receiving the control information in the specific area when the blind decoding is successful.

As described above, according to the present invention, it is possible to simultaneously support various services having different requirements by providing an efficient MU-MIMO transmission method for a downlink control channel in a wireless communication system supporting MU-MIMO.

1 shows a basic structure of a time-frequency domain in an LTE system,
2 shows PDCCH and EPDCCH as downlink control channels in the LTE system,
3 is a diagram illustrating a search space of a downlink control channel in an LTE system,
4 is a diagram illustrating an example of a downlink control channel in an embodiment of the present invention.
5 is a diagram illustrating an MU-MIMO transmission method according to a first embodiment of the present invention.
6A and 6B illustrate operations of a base station and a terminal according to a first embodiment of the present invention;
7 is a diagram illustrating an MU-MIMO transmission method according to a second embodiment of the present invention.
8A and 8B are diagrams illustrating base station and terminal operations according to a second embodiment of the present invention;
9 is a diagram illustrating an MU-MIMO transmission method according to a third embodiment of the present invention.
10A and 10B are diagrams illustrating operations of a base station and a terminal according to a third embodiment of the present invention;
11 is a block diagram showing a configuration of a terminal according to an embodiment of the present invention;
12 is a block diagram showing a configuration of a base station according to an embodiment of the present invention;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of well-known functions and constructions that may obscure the gist of the present invention will be omitted.

A typical example of a wireless communication system to which the present invention can be applied is an Orthogonal Frequency Division Multiplexing (OFDM) scheme in a downlink (DL) and an SC-FDMA Carrier Frequency Division Multiple Access (CDMA) scheme. The uplink refers to a radio link through which a UE (User Equipment) or an MS (Mobile Station) transmits data or control information to a base station (eNode B or base station (BS) Lt; RTI ID = 0.0 > data / control < / RTI > In the multiple access scheme, data or control information of each user is distinguished by assigning and operating so that time-frequency resources for transmitting data or control information for each user do not overlap each other, that is, orthogonality is established.

For example, in a communication system after an LTE system, which is referred to as a 5G communication system, a user must be able to freely reflect various requirements such as a user and a service provider. The services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), ultra reliable low latency communication (URLLC), etc. This can be.

eMBB aims to provide a higher data transfer rate than the data rates supported by traditional LTE, LTE-A or LTE-Pro. An LTE, LTE-A or LTE-Pro system may be briefly referred to as an LTE system, unless otherwise specified herein. For example, in the 5G communication system, the eMBB can provide a peak transmission rate of 20 Gbps in the downlink and a maximum transmission rate of 10 Gbps in the uplink from the viewpoint of one base station. In addition, the 5G communication system should provide a maximum transmission rate and at the same time provide an increased user perceived data rate of the terminal. In order to meet such requirements, various improvements in transmission and reception techniques are required, including a more advanced multi-antenna transmission technology (e.g., Multi Input Multi Output (MIMO)). In addition, while 5G communication systems transmit signals using a transmission bandwidth of up to 20MHz in the 2GHz band used in the current LTE system, the 5G communication system uses a frequency bandwidth wider than 20MHz in a frequency band of, for example, 3-6GHz or 6GHz or higher, It is possible to satisfy the data transmission rate required by the system.

At the same time, mMTC is considered to support application services such as Internet of Thing (IoT) in 5G communication systems. The mMTC is required to support connection of a large scale terminal in a cell, enhancement of coverage of the terminal, improved battery time, and cost reduction of the terminal in order to efficiently provide the object Internet. Object The Internet must be able to support a large number of terminals (for example, 1,000,000 terminals / km2) in a cell because it is attached to various sensors and various devices and provides communication functions. In addition, terminals supporting mMTC are more likely to be located in shaded areas that can not be covered by a cell, such as a building underground, due to the nature of the service, thus requiring a wider coverage than other services provided by the 5G communication system. Terminals supporting mMTC should be configured as inexpensive terminals and battery life time is required to be very long like 10 ~ 15 years because it is difficult to change the terminal battery frequently.

Finally, in the case of URLLC, it is a cellular-based wireless communication service used for mission-critical purposes. For example, remote control for a robot or a machine, industrial automation, unmanaged aerial vehicle, remote health care, emergency situation, Services used for emergency alert and the like can be considered. Therefore, the communication provided by URLLC should provide very low latency and very high reliability. For example, a service that supports URLLC must meet Air interface latency of less than 0.5 milliseconds and at the same time have a packet error rate of less than 10-5. Therefore, for a service supporting URLLC, the 5G system should provide a smaller transmission time interval (TTI) than other services, and at the same time, it is necessary to allocate a wide resource in the frequency band in order to secure the reliability of the communication link Are required.

The above-mentioned services provided in the 5G communication system, eMBB, URLLC, mMTC, for example, can be multiplexed and transmitted in one system. In this case, different transmission / reception techniques and transmission / reception parameters may be used between services in order to satisfy different requirements of the respective services.

Hereinafter, the frame structure of the LTE and LTE-A systems will be described in more detail with reference to the drawings.

FIG. 1 is a diagram illustrating a basic structure of a time-frequency domain in a LTE system, which is a radio resource region in which data or a control channel is transmitted in a downlink of an LTE system.

In Fig. 1, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol. N _{symb (} 102) OFDM symbols constitute one slot 106, and two slots form one subframe 105. The length of the slot is 0.5 ms and the length of the subframe is 1.0 ms. The radio frame 114 is a time domain unit consisting of 10 subframes. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is composed of a total of N _sc ^BW (104) subcarriers. In a time-frequency domain, a basic unit of a resource can be represented by an OFDM symbol index and a subcarrier index as a Resource Element (RE) A resource block (RB or physical resource block, PRB) 108 is defined as N _{symb (} 102) consecutive OFDM symbols in the time domain and N _sc ^RB (110) consecutive subcarriers in the frequency domain do. Thus, one RB 108 is comprised of N R _symb x N _sc ^RB _112s . In general, the minimum transmission unit of data is the RB unit. In the LTE system, N _symb = 7, N _RB = 12, and N _BW and N _RB are generally proportional to the bandwidth of the system transmission band.

Next, downlink control information (DCI) in the LTE and LTE-A systems will be described in detail.

In the LTE system, the scheduling information for the downlink data or the uplink data is transmitted from the base station to the mobile station through the DCI. The DCI defines various formats and determines whether it is scheduling information for uplink data or scheduling information for downlink data, whether it is a compact DCI having a small size of control information, and spatial multiplexing using multiple antennas Whether DCI is used for power control, and the like. For example, DCI format 1, which is scheduling control information for downlink data, is configured to include at least the following control information.

- Resource allocation type 0/1 flag: Notifies whether the resource allocation scheme is Type 0 or Type 1. Type 0 allocates resources in RBG (resource block group) by applying bitmap method. In the LTE system, the basic unit of scheduling is an RB (resource block) represented by time and frequency domain resources, and the RBG is composed of a plurality of RBs and becomes a basic unit of scheduling in the type 0 scheme. Type 1 allows a specific RB to be allocated within the RBG.

- Resource block assignment: Notifies the RB allocated to data transmission. The resources to be represented are determined according to the system bandwidth and the resource allocation method.

Modulation and coding scheme (MCS): Notifies the modulation scheme used for data transmission and the size of the transport block, which is the data to be transmitted.

- HARQ process number: Notifies the HARQ process number.

- New data indicator: Notifies HARQ initial transmission or retransmission.

- Redundancy version: Notifies redundancy version of HARQ.

- Transmit power control command for PUCCH (Physical Uplink Control CHannel): Notifies a transmission power control command for PUCCH, which is an uplink control channel.

The DCI is transmitted through a PDCCH or EPDCCH (Enhanced PDCCH), which is a downlink physical control channel, through channel coding and modulation processes.

A CRC (Cyclic Redundancy Check) is attached to the DCI message payload, and the CRC is scrambled into a Radio Network Temporary Identifier (RNTI) corresponding to the identity of the UE. Different RNTIs are used depending on the purpose of the DCI message, e.g., UE-specific data transmission, power control command or random access response. Soon, the RNTI is not explicitly transmitted but is included in the CRC computation and transmitted. Upon receiving the DCI message transmitted on the PDCCH, the UE checks the CRC using the allocated RNTI, and if the CRC check result is correct, the UE can know that the corresponding message is transmitted to the UE.

Next, the downlink control channel through which the DCI is transmitted in LTE and LTE-A will be described in more detail with reference to the drawings.

2 is a diagram illustrating a PDCCH and an EPDCCH as downlink control channels in an LTE system, and shows a PDCCH 201 and an Enhanced PDCCH 202 as downlink physical channels through which an LDCI is transmitted.

2, the PDCCH 201 is time multiplexed with the PDSCH 203, which is a data transmission channel, and is transmitted over the entire system bandwidth. The area of the PDCCH 201 is expressed by the number of OFDM symbols, which is indicated to the UE by a CFI (Control Format Indicator) transmitted through a Physical Control Format Indicator Channel (PCFICH). PDCCH 201 is allocated to an OFDM symbol located in a front part of a subframe so that the UE can decode the downlink scheduling assignment as soon as possible so that a decoding delay for a DL-SCH (Downlink Shared Channel) There is an advantage that the link transmission delay can be reduced. One PDCCH carries one DCI message, and a plurality of UEs can be scheduled simultaneously on the downlink and uplink, so that a plurality of PDCCHs are simultaneously transmitted in each cell.

The CRS 204 is used as a reference signal for decoding the PDCCH 201. The CRS 204 is transmitted every subframe over the entire band, and the scrambling and resource mapping are changed according to the cell ID (Identity). UE-specific beamforming can not be used because the CRS 204 is a reference signal commonly used by all terminals. Therefore, the multi-antenna transmission scheme for the PDCCH of the LTE system is limited to open loop transmit diversity. The number of ports of the CRS is implicitly known to the UE from the decoding of the PBCH (Physical Broadcast Channel).

The resource allocation of the PDCCH 201 is based on a CCE (Control-Channel Element), and one CCE is composed of 9 resource elements (REGs), that is, a total of 36 resource elements (REs). The number of CCEs required for a particular PDCCH 201 may be 1, 2, 4, or 8, depending on the channel coding rate of the payload of the DCI message. Thus, different CCE numbers are used to implement the link adaptation of the PDCCH 201. [

The terminal must detect a signal without knowing information about the PDCCH 201. In the LTE system, a search space representing a set of CCEs for blind decoding is defined. The search space is composed of a plurality of aggregates at the aggregation level (AL) of each CCE, which is not explicitly signaled but is implicitly defined (set) through the function and subframe number by the terminal identification information . In each subframe, the UE decodes the PDCCH 201 for all possible candidate candidates that can be generated from the CCEs in the set search space, and transmits the information declared as valid to the UE through the CRC check .

The search space is classified into a UE-specific search space and a common search space. The UEs in a certain group or all the UEs can check the common search space of the PDCCH 201 to receive control information common to cells such as dynamic scheduling and paging messages for system information. For example, the scheduling assignment information of the DL-SCH for transmission of the SIB (System Information Block) -1 including the cell operator information can be received by checking the common search space of the PDCCH 201. [

In FIG. 2, the EPDCCH 202 is frequency-multiplexed with the PDSCH 203 and transmitted. The base station can appropriately allocate resources of the EPDCCH 202 and the PDSCH 203 through scheduling, thereby effectively supporting coexistence with data transmission for existing LTE terminals. However, since the EPDCCH 202 is allocated and transmitted in one subframe on the time axis, there is a problem of transmission delay. A plurality of EPDCCHs 202 constitute one EPDCCH 202 set and an EPDCCH 202 ) Allocation of set is made by physical resource block (PRB) pairs. The location information for the EPDCCH set is set UE-specific and is signaled via RRC (Remote Radio Control). A maximum of two sets of EPDCCHs 202 may be set for each UE, and one set of EPDCCHs 202 may be multiplexed and set to different UEs at the same time.

The resource allocation of the EPDCCH 202 is based on ECCE (Enhanced CCE), and one ECCE can be composed of four or eight EREGs (Enhanced REGs), and the number of EREGs per ECCE is determined by cyclic prefix ) Length and subframe setting information. One EREG is composed of 9 REs, so there can be 16 EREGs per PRB pair. The EPDCCH transmission scheme is classified into localized / distributed transmission according to the RE mapping scheme of EREG. The aggregation level of the ECCE can be 1, 2, 4, 8, 16, 32, which is determined by the CP length, subframe setting, EPDCCH format, and transmission mode.

In the LTE system, the EPDCCH 202 supports only the UE-specific search space. Therefore, a UE desiring to receive a system message must examine the common search space on the existing PDCCH 201.

Unlike the PDCCH 201, a demodulation reference signal (DMRS) 205 is used as a reference signal for decoding in the EPDCCH 202. Thus, precoding for the EPDCCH 202 can be established by the base station and use terminal-specific beamforming. Through the DMRS 205, the UEs can perform decoding on the EPDCCH 202 without knowing what precoding is used. In the EPDCCH 202, the same pattern as the DMRS of the PDSCH 203 is used. However, unlike the PDSCH 203, the DMRS 205 in the EPDCCH 202 can support transmission using up to four antenna ports. The DMRS 205 is transmitted only in the corresponding PRB to which the EPDCCH is transmitted.

The port setting information of the DMRS 205 depends on the EPDCCH transmission scheme. In the case of the localized transmission scheme, the antenna port corresponding to the ECCE to which the EPDCCH 202 is mapped is randomly selected based on the identification information (ID) of the UE. If different UEs share the same ECCE, i.e., multi-user MIMO (MU-MIMO) transmission is used, a DMRS antenna port can be assigned to each UE. Or a DMRS 205 may be shared and transmitted. In this case, the DMRS 205 may be divided into a scrambling sequence that is set as an upper layer signaling. In the case of the distributed transmission scheme, up to two antenna ports of the DMRS 205 are supported, and a precoder cycling diversity scheme is supported. The DMRS 205 may be shared for all REs transmitted in one PRB pair.

Next, a search space for downlink control channel transmission in LTE and LTE-A will be described in more detail with reference to the drawings.

3 is a diagram illustrating a search space to which a downlink control channel can be allocated in an LTE system. 3, the entire PDCCH area 301 is composed of a set of CCEs 304 in a logical area, and a search space consisting of a set of CCEs 304 exists. The search space is divided into a common search space 302 and a UE-specific search space 303. In FIG. 3, for example, two UE-specific search spaces for the UE # 1 311 and the UE # 303) is shown as an example. FIG. 3 is a conceptual diagram for simplifying the understanding of the present invention, and it should be noted that the actual search space may be different.

 The search space for the PDCCH in the LTE standard is defined as shown in Table 1 below.

According to the definition of the search space for the PDCCH described in Table 1, the UE-specific search space 303 is not explicitly signaled, and the RNTI (Radio Network Temporary Identifier) and the UE identification information Lt; RTI ID = 0.0 > subframe < / RTI > In other words, since the terminal-specific search space can be changed according to the subframe number, this means that the search space can be changed over time, and the problem that a specific terminal can not use the search space by other terminals among the terminals It solves. Since all of the CCEs 304 that are searched by the UE are used by other UEs that are already scheduled in the same subframe, if any UE can not be scheduled in the corresponding subframe, the search space changes with time, The problem that the specific terminal can not use the search space in the next subframe may not occur. 3, a part of the terminal-specific search space 303 of the terminal # 1 311 and the terminal # 2 312 is overlapped, but the terminal-specific search space 303 is divided into sub- The overlap in the next subframe can be expected to be different from this.

According to the definition of the search space for the PDCCH described above, in the common search space 302, a certain group of terminals or all terminals are defined as a set of promised CCEs 304 because they must receive a PDCCH. In other words, the common search space 302 does not vary depending on the identification information of the terminal, the subframe number, or the like. Although the common search space 302 exists for transmission of various system messages, it can also be used to transmit control information of individual terminals. Accordingly, the common search space 302 can be used as a solution to the problem that the UE does not receive scheduling due to a shortage of available resources in the UE-specific search space 303.

The search space is a set of candidate control channels made up of CCEs 304 to which the UE should attempt to decode at a given aggregation level and is a set of one, two, four, or eight CCEs 304 Because there are several aggregation levels to create, the terminal has multiple search spaces. The number of PDCCH candidates to be monitored by the UE in the search space defined by the aggregation level in the PDCCH of the LTE system is defined in Table 2 below.

According to Table 2, the UE-specific search space 301 supports aggregation levels {1, 2, 4, 8}, and {6, 6, 2, 2} . For the common search space 302, aggregation level {4, 8} is supported, with {4, 2} PDCCH candidates each. The reason why the common search space 302 supports only the aggregation level {4, 8} is to improve the coverage characteristics because system messages generally reach the cell edge.

The DCI transmitted to the common search space 302 is defined only for a specific DCI format such as 0 / 1A / 3 / 3A / 1C corresponding to the use of system messages or power control for terminal groups. In the common search space 302, DCI format having spatial multiplexing is not supported. The downlink DCI format to be decoded in the UE-specific search 301 space depends on a transmission mode set for the corresponding UE. Since the transmission mode is set through RRC signaling, an accurate sub-frame number is not specified as to whether the setting is effective for the terminal. Therefore, the terminal can be operated so as not to lose communication by always performing decoding on the DCI format 1A regardless of the transmission mode.

The structure and transmission method of the downlink control channel in the conventional LTE and LTE-A have been described above.

Unlike the downlink control channel in the LTE system, the downlink control channel in the 5G system discussed in 3GPP should satisfy the following requirements.

- Satisfies the requirements of eMBB, URLLC, mMTC

- Supports multiple TTIs simultaneously

- Supports simultaneous service of different numerology

- Ensure future compatibility

It is difficult to satisfy the above requirements with the control channel structure of the existing LTE system. For example, PDCCH is not suitable for mMTC which mainly supports narrow band because it is transmitted in full band. Since EPDCCH is transmitted during one subframe, it is not suitable for URLLC requiring very low latency. In order to support various numerology and TTI, and to ensure future compatibility, it is necessary to flexibly allocate control channels in time and frequency domains. However, it is difficult to flexibly allocate existing PDCCHs and EPDCCHs. Therefore, it is essential to design a new structure of control channel for 5G system.

Hereinafter, a downlink control channel (NR-PDCCH) considered in the 5G system will be described in more detail with reference to the drawings.

FIG. 4 is a diagram illustrating an example of a downlink control channel (NR-PDCCH) applicable to an embodiment of the present invention. Referring to FIG. 4, there is shown an example of time and frequency resources constituting NR- Fig.

Referring to FIG. 4, the basic unit of the time and frequency resources constituting the control channel is composed of one OFDM symbol 401 on the time axis and one FU (Frequency Unit) 402 on the frequency axis have. At this time, one FU is defined as a basic unit of a frequency resource for performing scheduling from a base station to a mobile station. For example, if 12 subcarriers or one PRB (Physical Resource Block) unit is scheduled in the frequency domain as a basic unit, one FU may be defined as a size corresponding to 12 subcarriers (i.e., 12 REs) have. The data channel and the control channel can be time multiplexed in one subframe by assuming that the basic unit of time axis is one OFDM symbol 401 in constituting the basic unit of the control channel. By placing the control channel ahead of the data channel, the processing time of the user can be reduced and it is easy to satisfy the delay time requirement. It is possible to more efficiently perform frequency multiplexing between the control channel and the data channel by setting the frequency axis basic unit of the control channel to one FU 402. However, if the frequency axis base unit is composed of arbitrary subcarriers smaller than one FU (401), the frequency axis start point for the scheduled data should be indicated in subcarrier units.

By connecting the basic units of the NR-PDCCH shown in FIG. 4, control channel regions of various sizes can be set. For example, in a 5G system, when a basic unit to which a downlink control channel is allocated is an NR-CCE 405, one NR-CCE 405 is a basic unit of a downlink control channel PRB units). For example, if one NR-CCE 405 is configured with four PRBs, it means that one NR-CCE can be composed of, for example, 48 REs. When a downlink control region is set, the corresponding control region may be composed of a plurality of NR-CCEs 405. The specific downlink control channel may include one or a plurality of NR-CCEs 405, and transmitted. The NR-CCEs 405 in the control area are numbered, and the numbers can be assigned according to a logical mapping scheme. The physical resource allocation to the NR-CCE 405 may be mapped in PRB units. In order to make the control channel robust, a block interleaver and a cell-specific cyclic shift Can be used additionally.

The basic unit of the NR-PDCCH shown in FIG. 4 may include both a data area 404 to which a DCI is mapped and an area to which a reference signal for decoding the DMRS 403 is mapped. At this time, the DMRS 403 can be efficiently transmitted considering an overhead due to the RS assignment. For example, the transmission of the DMRS 403 may be turned on / off depending on the antenna port setting used by the base station or the manner in which the downlink control channel is allocated. In other words, it is noted that within the PRB, the DMRS 403 may or may not be transmitted. The DMRS 403 is off and can be used to transmit the DCI for an unreceived RE.

As described above, the downlink control channel in the 5G system should be flexibly allocated to satisfy various service requirements, and it is desirable to maximize the control channel capacity by increasing transmission efficiency by supporting various transmission modes . For this reason, it is important to support the MU-MIMO transmission mode for the NR-PDCCH. In NR-PDCCH, it is expected that it is possible to support UE-specific beamforming by using DMRS. In this case, in order to minimize the complexity of the blind decoding, the configuration information for the DMRS may be indicated to the UE by RRC (Remote Radio Control) signaling or may be implicitly known as a function of other system parameters. Thus, it is possible to minimize the additional overhead of using UE-specific beamforming and more efficiently support MU-MIMO transmission for the NR-PDCCH.

Embodiments of the present invention provide various embodiments for more efficiently supporting MU-MIMO transmission based on the transmission structure of NR-PDCCH currently being discussed. The MU-MIMO transmission scheme for the NR-PDCCH proposed in the embodiments of the present invention introduces a new search space and sets the new search space to each UE according to the transmission mode, so that more MU-MIMO transmission for the NR- The LTE system and the 5G system will be the main object, but the embodiments of the present invention can be applied to other systems having a similar technical background and channel form The present invention can be applied to other communication systems without departing from the scope of the present invention, and this can be done by a person skilled in the art.

≪ Embodiment 1 >

5 is a diagram illustrating an MU-MIMO transmission method according to the first embodiment of the present invention.

According to the example shown in FIG. 5, the search space in the 5G system includes a first search space 501 and a second search space 502, and the search space includes one or a plurality of NR-CCEs 504 And may be made up of a set of assemblies. The first search space 501 is an area to which an NR-PDCCH for transmitting a common DCI broadcasted simultaneously to all or a plurality of terminals such as a system message, power adjustment, paging, and the like can be allocated. Therefore, the first search space 501 may be referred to as a common search space in which all the terminals (terminals # 1 and # 2 511 in FIG. 5) monitor. In the first search space 501, supporting a relatively high aggregation level (for example, 4 or 8) improves the coverage characteristics, and thus the control information can be effectively transmitted to the terminals located at the edge of the cell. The second search space 502 is an area in which an NR-PDCCH for transmitting a UE-specific DCI can be allocated, and may be referred to as a UE-specific search space. The second search space 502 may be set differently for each terminal (terminal # 1 512 and terminal # 2 513 in FIG. 5). For example, the second search space 502 may be expressed as a function of system parameters such as the identification information of each terminal and the subframe number, and may be changed with time. The NR-PDCCH can be briefly referred to as a downlink control channel, PDCCH, x-PDCCH, or the like.

5, the MU-MIMO transmission of the NR-PDCCHs of the UE # 1 512 and the UE # 2 513 is performed in an MU-MIMO enabled area 503 indicated by a dotted line . MU-MIMO transmission is a multi-antenna transmission scheme in which two different data are spatially separated and transmitted using beamforming in the same time-frequency resource. In the example of FIG. 5, the MU-MIMO transmission of the NR-PDCCH of the UE # 1 512 and the UE # 2 513 is possible in the overlapped area 503 among the search spaces of the UEs.

The BS allocates the NR-PDCCH of the UE # 1 512 and the UE # 2 513 to the MU-MIMO-capable area 503 and transmits the NR-PDCCH to the MU-MIMO It is possible to transmit to each terminal in the transmission mode. At this time, the base station can use the UE-specific beamforming to support the MU-MIMO transmission mode. The terminal # 1 512 and the terminal # 2 513 perform blind decoding within a predetermined search space (the first search space 501 and the second search space 502) in order to find their own NR-PDCCH . At this time, the blind decoding operation may be different according to the transmission mode of the NR-PDCCH set in each terminal. For example, if the transmission mode for the NR-PDCCH of the terminal # 1 512 is set to transmit diversity, the terminal # 1 512 transmits the transmit diversity mode and the terminal-specific Blind decoding can be performed assuming both transmission modes of the beam forming mode. In another example, if the transmission mode for the NR-PDCCH of the UE # 1 512 is set to UE-specific beamforming, the UE # 1 512 performs a UE-specific beamforming Blind decoding can be performed assuming a mode.

6A is a diagram illustrating an operation of a base station according to the first embodiment of the present invention.

First, the operation of the base station of the present invention will be described. In step 601, the BS selects, determines, or confirms the MSs to which the MU-MIMO transmission for the NR-PDCCH is to be used through the scheduling. In step 602, the base station determines whether there is an overlapping area of the second search spaces of the selected (or determined) terminals. If there is an overlapping region, the base station determines that MU-MIMO transmission is possible for the selected (or determined or confirmed) terminals. Accordingly, in step 603, the base station can allocate the corresponding NR-PDCCH to the specific resource (s) in the overlapped area using the MU-MIMO transmission mode. If the overlapping region does not exist, the BS determines that the MU-MIMO transmission for the selected UEs is impossible, and allocates each NR-PDCCH based on the transmission of SU (Single User) to the search space of each UE . When the resource allocation for the NR-PDCCH is completed, the base station transmits the NR-PDCCH in step 605.

6B is a diagram illustrating an operation of a terminal according to the first embodiment of the present invention.

Next, the terminal procedure of the present invention will be described. The UE receives the NR-PDCCH in step 611. In step 612, the UE performs blind decoding on the NR-PDCCH in the set search space. The search space may be composed of a plurality of aggregates at an aggregation level (AL) of each CCE, and may be set through a function such as terminal identification information or a subframe number without being explicitly signaled. In step 613, the UE determines whether the decoding of the NR-PDCCH is successful by checking a cyclic redundancy check (CRC). If the decoding fails, the UE returns to step 612 to perform blind decoding for the other resource candidate Lt; / RTI > If decoding is successful, the terminal may proceed to step 614 to receive the DCI.

≪ Embodiment 2 >

7 is a diagram illustrating an MU-MIMO transmission method according to a second embodiment of the present invention.

7, the search space for the NR-PDCCH includes a first search space 701, a second search space 702, and a third search space 703, And a plurality of NR-CCEs 711. As described in the first embodiment, the first search space 701 can be used for common DCI transmission, and thus all terminals (terminals # 1, # 2, # 3, and # 4 705 in the example of FIG. 7) This is a common search space. The second search space 702 can be used for terminal-specific DCI transmission and thus each terminal (terminal # 1 706, terminal # 2 707, terminal # 3 708, terminal # 4 709), and a part of the second search space 702 of each terminal may overlap with each other. The third search space 703 is a search space for allocating a corresponding NR-PDCCH when a DCI having a special transmission purpose is to be transmitted to a new search space proposed in an embodiment of the present invention. Here, the special transmission purpose for the DCI may be, for example, an ultra-low latency transmission, an ultra-high reliability transmission, or a UE group-specific transmission. In the second embodiment of the present invention, the third search space 703 includes all terminals (UEs # 1, # 2, # 3, # 7 in the example of FIG. 7) 704 when transmitting MU- 4 (710)), which can be set in common (704). Since the third search space 703 needs to be able to search all the UEs as in the first search space 701, the third search space 703 may include identification information previously set in a fixed area of a whole CCE aggregate, The area can be defined by a function such as a subframe number.

Unlike the first embodiment described above, in the second embodiment, MU-MIMO can be more positively utilized by separately setting the resource (s) used in the MU-MIMO transmission mode for the NR-PDCCH. For example, in FIG. 7, the terminal # 1 706 and the terminal # 2 707 can not support the MU-MIMO transmission if they follow the first embodiment since there is no second search space 702 overlapping each other. On the other hand, in the second embodiment, MU-MIMO transmission for the corresponding NR-PDCCH is possible using the third search space 703 without overlapping the second search space 702, And MU-MIMO can be supported.

In the second embodiment, since additional blind decoding is required for each terminal in the third search space 703, an additional technique for increasing the decoding complexity and minimizing power consumption can be applied.

For example, unnecessary blind decoding can be minimized by searching for the third search space 703 only when the MU-MIMO transmission mode is set by using signaling on whether the MU-MIMO transmission is possible for the NR-PDCCH. For example, if the UE # 1 706 is set to the MU-MIMO transmission mode for the NR-PDCCH, the UE # 1 706 can perform blind decoding on the third search space 703. [ On the contrary, when the UE is not set to the MU-MIMO transmission mode for the NR-PDCCH, only the blind decoding for the first search space 701 and the second search space 703 can be performed according to the conventional method. NR The MU-MIMO transmission mode setting for the PDCCH can be indicated to each terminal, for example, by RRC signaling.

In another embodiment, there may be a method of sequentially searching each search space with priority for the search space. More specifically, when the MU-MIMO transmission mode is set for the NR-PDCCH, the UE can give priority to blind decoding for the third search space 703. [ In this case, since the corresponding NR-PDCCH can exist in the third search space 703 with high probability, if the UE successfully decodes NR-PDCCH in the third search space 703, It is possible to omit the blind decoding for the space 701 and the second search space 702 (in this case, for the first search space 701, It may be searched without the need).

In another embodiment, it may be considered to use a very limited resource candidate group for the third search space 703. More specifically, the number of blind decodings of the NR-PDCCH is determined by the number of NR-PDCCH candidates that should be monitored according to the aggregation level. In order to reduce the number of NR-PDCCH candidates, for example, the number of aggregation levels may be limited. Since the MU-MIMO transmission mode for the NR-PDCCH can be applied mainly to terminals having good channel characteristics (e.g., terminals inside a cell), it may be inefficient to support up to a high aggregation level. Therefore, by supporting only a relatively low aggregation level (e.g., 1, 2, etc.) for the NR-PDCCH in the third search space 703, unnecessary blind decoding can be minimized while ensuring performance.

8A is a diagram illustrating an operation of a base station according to a second embodiment of the present invention.

First, the base station procedure of the present invention will be described. In step 801, the BS selects, determines, or confirms the UEs to which the MU-MIMO transmission for the NR-PDCCH is to be transmitted through scheduling. In step 802, the base station sets the MU-MIMO transmission mode for the NR-PDCCH using the RRC signaling to the selected (or determined or confirmed) UEs. In step 803, the BS allocates the resource (s) in the third search space to the NR-PDCCH corresponding to the MU-MIMO transmission mode. When the resource allocation for the NR-PDCCH is completed, the base station transmits the NR-PDCCH in step 804.

8B is a diagram illustrating an operation of a terminal according to a second embodiment of the present invention.

Next, the terminal procedure of the present invention will be described. The UE receives the NR-PDCCH in step 811. In step 812, the UE determines whether the NR-PDCCH is set to the MU-MIMO transmission mode. If the MU-MIMO transmission mode is set in step 812, the terminal performs blind decoding on the third search space in step 814. If the MU-MIMO transmission mode is not set in the above step, the terminal performs blind decoding in the existing first search space and the second search space in step 813. In step 815, the UE determines whether decoding of the NR-PDCCH is successful by checking the CRC. If the decoding fails, the UE proceeds to step 813 (or step 812) to continue blind decoding for other resource candidates in the search space do. If decoding is successful, the UE may proceed to step 816 to receive the DCI.

≪ Third Embodiment >

FIG. 9 is a diagram illustrating an MU-MIMO transmission method according to a third embodiment of the present invention.

According to the example shown in FIG. 9, the search space for the NR-PDCCH is divided into a first search space 901, a second search space 902, a third search space (e.g., a third search space # 1 903, 3 search space # 2 904), and each search space may be composed of one or a plurality of sets of NR-CCEs 711. As in the second embodiment of the present invention, the third search space (e.g., the third search space # 1 903 and the third search space # 2 904) is used in the MU-MIMO transmission mode for the NR-PDCCH . In the third embodiment, the third search space can be set differently for each terminal operating in the MU-MIMO transmission mode. For example, if the base station desires to support MU-MIMO transmission for the NR-PDCCH of the UE # 1 908 and the UE # 2 909, the third search space # 1 903 can be used (905). Likewise, if the base station wishes to support MU-MIMO transmission for the NR-PDCCH of the UE # 3 911 and the UE # 4 912, the third search space # 2 904 may be used (906).

In the second embodiment of the present invention described above, the third search space 703 is defined as a search space commonly set for all terminals, while in the third embodiment of the present invention, the third search spaces 903 and 904 ) May be defined as a third search space different for each terminal group that performs MU-MIMO transmission for the actual NR-PDCCH. Since the MU-MIMO transmission to the NR-PDCCH can be performed dynamically, the third search spaces 903 and 904 of the third embodiment can be set dynamically. For example, in the third embodiment, the terminal groups performing the MU-MIMO transmission for the NR-PDCCH are instructed through the RRC signaling or the physical layer (L1) signaling for the configuration information for the third search spaces 903 and 904 have. In another embodiment, the setting information for the third search spaces 903 and 904 may be transmitted using the first search space 901 in the form of a newly defined DCI format. The UEs set in the MU-MIMO transmission mode for the NR-PDCCH perform additional blind decoding on the DCI including the setting information for the third search spaces 903 and 904 when blind decoding the first search space 901 can do. At this time, each terminal may define a new RNTI, e.g., M-RNTI (MU-MIMO RNTI), to scramble the DCI to know that the corresponding DCI is an indicator of the configuration information for the third search spaces 903 and 904 . More specifically, each terminal can acquire configuration information for the third search space 903 and 904 through additional blind decoding on the DCI set in the M-RNTI in the first search space 901. [ As another example, the setting information for the third search spaces 903 and 904 may be transmitted to the UE-specific using the resources of the second search space 902. [ The terminal receives setting information for the third search spaces 903 and 904 transmitted using the promised specific resources in the second search space 902 and performs blind decoding on the third search spaces 903 and 904 can do.

When setting indicators (or setting information) for the third search spaces 903 and 904 are transmitted through additional L1 signaling, the setting indicator (or setting information) is transmitted in a small size in consideration of signaling overhead . For example, the setting indicator for the third search spaces 903 and 904 may be offset information between the second search space 902 and the third search spaces 903 and 904. Here, the offset may be defined using a difference between a specific CCE index in the second search space 902 and a specific CCE index in the third search spaces 903 and 904. In general, since the search space is composed of a set of contiguous CCEs at each aggregation level, the CCE index at the start point of the second search space 902 and the CCE index at the start point of the third search space 903 and 904 The difference between the indices can be used as the offset information. For example, the second search space 902 of the terminal # 1 908 is set as CCE # 5 to CCE # 12, and the second search space 902 of the terminal # 2 909 is set as CCE # If the third search space 903 of the terminal # 1 908 and the terminal # 2 909 is set as CCE # 25 to CCE # 30, assuming that the CCE # The offset values between the second search space 902 and the third search space 903 of the terminal # 1 908 and the terminal # 2 909 may be 20 and 9, respectively. Therefore, the third search space 903 and 904 of each terminal can be efficiently indicated with a small signaling overhead. In yet another embodiment, the configuration indicator for the third search space 903, 904 may use temporary terminal-group identification information. The third search space 903 or 904, which is a terminal-group specific region, is used as a function for the terminal-group identification information, as the second search space 902, which is a terminal-specific region, Lt; / RTI >

10A is a diagram illustrating an operation of a base station according to the third embodiment of the present invention.

First, the base station procedure of the present invention will be described. In step 1001, the BS selects, determines, or confirms the UEs to which the MU-MIMO transmission for the NR-PDCCH is to be transmitted through scheduling. In step 1002, the base station sets the MU-MIMO transmission mode for the NR-PDCCH using the RRC signaling to the selected (or determined or confirmed) terminals. In step 1003, the BS allocates the resource (s) in the third search space to the NR-PDCCH corresponding to the MU-MIMO transmission mode. In step 1004, the base station transmits configuration information for the third search space to the corresponding terminals using RRC signaling or L1 signaling. The base station transmits the NR-PDCCH in step 1005.

10B is a diagram illustrating an operation of a terminal according to the third embodiment of the present invention.

Next, the terminal procedure of the present invention will be described. The UE receives the NR-PDCCH in step 1011. In step 1012, the UE determines whether the NR-PDCCH is set to the MU-MIMO transmission mode. If the MU-MIMO transmission mode is set, the UE receives the setting information for the third search space in step 1014, and performs blind decoding on the NR-PDCCH in the set third search space in step 1015. If the MU-MIMO transmission mode is not set, the terminal performs blind decoding in the existing first search space and the second search space in step 1013. In step 1016, the UE determines whether decoding of the NR-PDCCH is successful by checking the CRC. If the decoding fails, the UE proceeds to step 1013 (or step 1015) to perform blind decoding on other candidate groups in the search space Continue. If the decoding is successful, the process proceeds to step 1017 to receive the DCI.

In order to perform the above-described embodiments of the present invention, the terminal and the base station may be implemented as shown in FIGS. 11 and 12, respectively, including a transmitter, a receiver, and a controller. 11 is a block diagram illustrating a configuration of a UE according to an exemplary embodiment of the present invention. Referring to FIG. As shown in FIG. 11, the terminal of the present invention may include a controller 1101, a receiver 1102, and a transmitter 1103.

The controller 1101 can control a series of processes in which the terminal can operate according to at least one of the first to third embodiments of the present invention. For example, the PDCCH decoding operation of the UE can be controlled according to the PDCCH setting information, the MU-MIMO transmission mode, the search space setting information, and the like according to the embodiment of the present invention. The receiver 1102 and the terminal collectively referred to as the transmitter 1103 may be referred to as a transceiver in the embodiment of the present invention. The transceiver can send and receive signals to and from the base station. The signal may include at least one of control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the frequency of a transmitted signal, and an RF receiver for low-noise amplifying the received signal and down-converting the frequency of the received signal. Also, the transceiver may receive a signal through a wireless channel, output it to the controller 1101, and transmit the signal output from the controller 1101 through a wireless channel.

12 is a block diagram showing a configuration of a base station according to an embodiment of the present invention. As shown in FIG. 12, the base station of the present invention may include a controller 1201, a receiver 1202, and a transmitter 1203.

The controller 1201 can control a series of processes so that the base station can operate according to at least one of the first to third embodiments of the present invention. For example, the BS operation can be controlled differently according to the PDCCH setup information, the MU-MIMO transmission mode, the search space setup information, and the like according to the embodiment of the present invention. In addition, according to the PDCCH MU-MIMO transmission mode, it is possible to perform scheduling for the uplink / downlink control channel and the data channel, and to instruct the terminal to the setup information. The receiver 1202 and the transmitter 1203 may be collectively referred to as a transceiver in the embodiment of the present invention. The transceiver can send and receive signals to and from the terminal. The signal may include at least one of control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the frequency of a transmitted signal, and an RF receiver for low-noise amplifying the received signal and down-converting the frequency of the received signal. Also, the transceiver may receive a signal through a wireless channel, output it to the controller 1201, and transmit the signal output from the controller 1201 through a wireless channel.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of the present invention in order to facilitate the understanding of the present invention and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible. Further, each of the above embodiments can be combined with each other as needed.

Claims (22)

A method for a base station to transmit control information in a wireless communication system,
Determining a scheduled UE based on a MU-MIMO (Multi-User Multiple Input Multiple Output) transmission scheme for transmission of the control information;
Allocating a resource for transmission of the control information from a search space of a downlink control channel to a specific region to which the control information is to be transmitted; And
And transmitting the control information in the specific area using the MU-MIMO transmission scheme.
The method according to claim 1,
Wherein the control information is transmitted using UE-specific beamforming.
The method according to claim 1,
Wherein the allocating the resource comprises:
Determining whether an overlapping area exists between search spaces set for the determined terminals; And
And allocating the resource to the overlapping region as the specific region when the overlapping region exists.
The method according to claim 1,
And setting an MU-MIMO transmission mode using the Radio Resource Control (RRC) signaling to the determined UEs.
The method according to claim 1,
And using at least one search space commonly set for the determined terminals as the specific region.
The method according to claim 1,
And a search space differently set for the determined terminals is used as the specific region.
The method according to claim 1,
Wherein the determined UEs are divided into at least one group and setting different search spaces corresponding to the specific region for each of the at least one group.
The method according to claim 1,
And transmitting configuration information of a search space corresponding to the specific region using RRC signaling or physical layer signaling to the determined terminals.
The method according to claim 1,
Wherein the setting information of the search space corresponding to the specific area includes a setting indicator for the search space.
10. The method of claim 9,
Wherein the setting indicator includes offset information indicating a difference between a first search space set in each terminal and a second search space corresponding to the specific region.
A base station in a wireless communication system,
A transceiver for transmitting and receiving data; And
The MU-MIMO (Multi-User Multiple Input Multiple Output) transmission scheme determines scheduled UEs for transmission of the control information and transmits the control information to a specific area to which the control information is to be transmitted from search spaces of a downlink control channel. And a controller for controlling transmission of the control information in the specific region using the MU-MIMO transmission scheme.
12. The method of claim 11,
Wherein the control information is transmitted using UE-specific beamforming.
12. The method of claim 11,
Wherein the controller further determines whether there is an overlapping region between search spaces set for the determined terminals and allocates the resource to the overlapping region as the specific region when the overlapping region exists.
12. The method of claim 11,
And setting an MU-MIMO transmission mode using the Radio Resource Control (RRC) signaling to the determined MSs.
12. The method of claim 11,
And using at least one search space commonly set for the determined terminals as the specific region.
12. The method of claim 11,
And a search space differently set for each of the determined terminals is used as the specific region.
12. The method of claim 11,
Wherein the controller is further configured to divide the determined terminals into at least one group, and the controller further controls setting a different search space corresponding to the specific area for each of the at least one group.
12. The method of claim 11,
Wherein the controller further controls transmission of setting information of a search space corresponding to the specific area using RRC signaling or physical layer signaling to the determined terminals.
12. The method of claim 11,
Wherein the setting information of the search space corresponding to the specific area includes a setting indicator for the search space.
20. The method of claim 19,
Wherein the setting indicator includes offset information indicating a difference between a first search space set in each terminal and a second search space corresponding to the specific region.
A method for a terminal to receive control information in a wireless communication system,
When a MU-MIMO (Multi-User Multiple Input Multiple Output) transmission scheme is set for the UE, a specific area of a search space of a downlink control channel to which the control information is to be transmitted using the MU- Performing blind decoding; And
And receiving the control information in the specific area when the blind decoding is successful.
A terminal in a wireless communication system,
A transceiver for transmitting and receiving data; And
When a MU-MIMO (Multi-User Multiple Input Multiple Output) transmission scheme is set for the UE, a specific area of a search space of a downlink control channel to which the control information is to be transmitted using the MU- Performing blind decoding and receiving the control information in the specific area when the blind decoding is successful.

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