KR102294661B1 - Method and apparatus for data transmission in wireless communication system - Google Patents

Abstract

The present invention relates to a communication technique that converges a 5G communication system for supporting a higher data rate after a 4G system with IoT technology and a system thereof. The present invention provides intelligent services (eg, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety related services, etc.) based on 5G communication technology and IoT-related technology. ) can be applied to

Description

Method and apparatus for data transmission in a mobile communication system {METHOD AND APPARATUS FOR DATA TRANSMISSION IN WIRELESS COMMUNICATION SYSTEM}

In New Radio (NR), the base station and the terminal can support subband precoding in uplink resources in order to efficiently use system resources and optimize performance. However, the performance of such sub-band precoding may be effective only under specific conditions. Therefore, the present invention proposes a condition and an indication method for operating the corresponding subband precoding.

Efforts are being made to develop an improved 5G communication system or pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of the 4G communication system. For this reason, the 5G communication system or the pre-5G communication system is called a system after the 4G network (Beyond 4G Network) communication system or the LTE system after (Post LTE). In order to achieve a high data rate, the 5G communication system is being considered for implementation in a very high frequency (mmWave) band (eg, such as a 60 gigabyte (60 GHz) band). In order to mitigate the path loss of radio waves and increase the propagation distance of radio waves in the ultra-high frequency band, in the 5G communication system, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) are used. ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, for network improvement of the system, in the 5G communication system, an evolved small cell, an advanced small cell, a cloud radio access network (cloud RAN), and an ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation Technology development is underway. In addition, in the 5G system, FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), which are advanced coding modulation (ACM) methods, and FBMC (Filter Bank Multi Carrier), which are advanced access technologies, NOMA (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

On the other hand, the Internet is evolving from a human-centered connection network where humans create and consume information to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers, etc. with IoT technology, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired and wireless communication and network infrastructure, service interface technology, and security technology are required. , M2M), and MTC (Machine Type Communication) are being studied. In the IoT environment, an intelligent IT (Internet Technology) service that collects and analyzes data generated from connected objects and creates new values in human life can be provided. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliance, advanced medical service, etc. can be applied to

Accordingly, various attempts are being made to apply the 5G communication system to the IoT network. For example, in technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC), 5G communication technology is implemented by techniques such as beam forming, MIMO, and array antenna. there will be The application of a cloud radio access network (cloud RAN) as the big data processing technology described above is an example of the convergence of 5G technology and IoT technology.

In the mobile communication system, as the number of antennas supported by the base station increases and UE-specific beamformed CSI-RS transmission is supported, CSI-RS resource configuration for each UE is required, thereby increasing CSI-RS overhead. CSI-RS transmission was introduced. Meanwhile, in the 5G communication system, various technologies requiring multiple CSI-RS resources, such as multi-TRP transmission and multi-panel transmission, will be additionally supported, and the CSI-RS overhead will further increase. Meanwhile, the existing aperiodic CSI-RS transmission is not suitable to support aperiodic transmission for multiple CSI-RS resources because it is designed in consideration of single-TRP and single-panel transmission. Therefore, there is a need for a method for aperiodic CSI-RS transmission through a plurality of CSI-RS resources and for reporting channel state information accordingly for efficient system and CSI-RS operation.

During uplink transmission in a wireless communication system such as LTE/LTE-A, the base station estimates the uplink channel through a reference signal such as a sounding reference signal (SRS), and then sets precoding information and modulation & coding scheme (MCS) to be used by the terminal. It decides and notifies the terminal. The UE receives the precoding information and the MCS information through uplink (UL) downlink control information (DCI) and performs uplink transmission accordingly. In this case, the capacity of the UL DCI is limited for reasons such as securing sufficient coverage and cannot transmit too much information. Therefore, current wireless communication systems support only wideband precoding through single precoding information notification.

Meanwhile, in the wideband precoding, the precoding accuracy is lower than that of the subband precoding, and the difference in uplink transmission efficiency between the wideband precoding and the subband precoding increases in proportion to the number of transmission antennas of the terminal. do. Unlike the current wireless communication system that assumes a maximum of 4 terminal transmission antennas, in the future new radio (NR, 5G) wireless communication system, the antenna form factor is improved due to the high-frequency carrier and the RF technology is advanced, so that more than 4 There is a high probability that the transmit antenna will become available. Accordingly, in the NR wireless communication system, there is a high demand for subband precoding support in the uplink. However, the performance of such subband precoding is optimized when supporting a large number of transmit antennas of a terminal or supporting a large number of transmit precodings as described above. Accordingly, the present invention proposes a condition and an indication method for operating the corresponding subband precoding.

In addition, the present invention relates to a wireless communication system, and more specifically, when the base station and the terminal support analog, digital or hybrid beamforming, the beam quality is measured according to the beam switching capability of the corresponding base station and the terminal and the channel state information generation is successful. We propose a method to report whether or not this has been done.

The reference signal is a data symbol received by measuring the channel status between the base station and users, such as channel strength or distortion, interference strength, and Gaussian noise in a wireless mobile communication system. A signal used to aid in demodulation and decoding. Another use of a reference signal is the measurement of radio channel conditions. The receiver may determine the state of the radio channel between itself and the transmitter by measuring the reception strength at which the reference signal transmitted by the transmitter with the promised transmission power is received through the radio channel. The determined state of the radio channel is used to determine what data rate the receiver will request from the transmitter.

However, in the case of a general mobile communication system, since radio resources such as time, frequency, and transmission power for transmitting a signal are limited, when many radio resources are allocated to a reference signal, radio resources that can be allocated to a data signal This is relatively reduced. For this reason, the radio resource allocated to the reference signal should be appropriately determined in consideration of system throughput. In particular, when MIMO (Multiple Input Multiple Output) that transmits and receives using a plurality of antennas is applied, it is a very important technical matter to allocate a reference signal and measure it.

NR (New Radio) MIMO for 5G supports a large number of antennas such as 1024 and high frequency bands such as 30GHz. Wireless communication using these millimeter waves exhibits high straightness and high path loss due to the characteristics of the corresponding band. need. In this case, the CSI-RS transmitted for the channel state report may be measurable or impossible depending on the beam switching capability of the UE when the UE switches the beam. In addition, NR supports a wider system band compared to LTE. In this case, a band supported by one terminal may be a different band from such a system band, and RS transmission is performed in full or partial band even within the band supported by the terminal. may vary with When the UE lacks RF switching capability in such a band switching situation, the CSI-RS transmitted for channel state reporting may also be unmeasurable. Therefore, the present invention proposes a method for the UE to efficiently transmit the measurement impossibility situation to the base station in the measurement impossibility situation.

In addition, the present invention proposes a method in which the base station determines a new CSI-RS transmission method and the terminal receives it for efficient system and CSI-RS operation in a mobile communication system.

The present invention for solving the above problems is a control signal processing method in a wireless communication system, the method comprising: receiving a first control signal transmitted from a base station; processing the received first control signal; and transmitting a second control signal generated based on the processing to the base station.

The present invention proposes a condition and an indication method for operating the corresponding subband precoding.

In addition, the present invention proposes a method for efficiently transmitting the measurement impossibility situation to the base station in the measurement impossibility situation by the UE when the base station and the UE support analog, digital or hybrid beamforming.

In addition, the present invention provides aperiodic CSI-RS transmission based on an existing single CSI-RS resource in a mobile communication system and generation/reporting of channel state information accordingly, as well as aperiodic CSI-RS transmission based on multiple CSI-RS resources and It enables support for generating/reporting channel state information accordingly.

1A is a diagram illustrating a downlink time-frequency domain transmission structure of an LTE or LTE-A system according to the prior art.
1B is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-A system according to the prior art.
1C is a diagram illustrating an example in which various verticals (or slices) such as eMBB, URLLC, and mMTC are transmitted in the time-frequency domain.
1D is a diagram illustrating another example in which various verticals (or slices) such as eMBB, URLLC, and mMTC are transmitted in the time-frequency domain.
1E is a diagram illustrating an example of codeblock segmentation of an LTE or LTE-A system according to the prior art.
1F is a diagram illustrating an example of an outer code in NR.
1G is a diagram illustrating an example of uplink transmission according to dynamic beamforming or semi-dynamic beamforming in NR.
1H is a diagram illustrating an example of uplink resource allocation and uplink subband precoding in NR.
1I is a diagram illustrating an example of resource allocation and subband precoding for uplink transmission.
1J is a diagram illustrating time and frequency resources used by a plurality of terminals to transmit uplink data.
1K is a diagram illustrating an SRS candidate resource activation through MAC CE and an actual activation operation through DCI.
11 is a diagram illustrating the configuration of a terminal according to the present invention.
1M is a diagram showing the configuration of a base station according to the present invention.
2A is a diagram illustrating a radio resource configuration of an LTE system.
2B is a diagram illustrating 2, 4, 8 antenna port CSI-RS transmission of an LTE system.
2C is a diagram illustrating a communication system to which the present invention is applied.
2D is a diagram illustrating a hybrid beamforming system.
2E is a diagram illustrating beam sweeping operations of a terminal and a base station in time resources.
2F is a diagram illustrating the structure of an OFDM symbol.
2G is a diagram illustrating operations of a terminal and a base station according to the first embodiment of the present invention.
2H is a diagram illustrating operations of a terminal and a base station according to a second embodiment of the present invention.
2J is a flowchart illustrating an operation sequence according to an embodiment of the present invention.
2K is a flowchart illustrating an operation sequence of a terminal according to an embodiment of the present invention.
2L is a flowchart illustrating an operation sequence of a base station according to an embodiment of the present invention.
2M is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention.
2N is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention.
3A is a diagram illustrating the structure of an existing LTE system.
3B is a diagram illustrating a radio protocol structure of an existing LTE system.
3C is a diagram illustrating 2, 4, 8 antenna port CSI-RS transmission using radio resources of 1 subframe and 1 RB, which are the minimum units that can be scheduled in downlink in the existing LTE system.
3D is a diagram for explaining periodic CSI-RS configuration and operation in an existing LTE system.
FIG. 3E is a diagram for explaining multi-transmission CSI-RS and aperiodic CSI-RS configuration and activation/deactivation operations considered in the present invention.
3F is a diagram illustrating a first method of a MAC control signal instructing activation and deactivation of a CSI-RS resource, proposed by the present invention.
3G is a diagram illustrating a second method of a MAC control signal indicating activation and deactivation of a CSI-RS resource, proposed by the present invention.
3H is a diagram for explaining the entire operation in the multi-shot CSI-RS mode to which the present invention is applied.
3I is a diagram for explaining the entire operation in the aperiodic CSI-RS mode to which the present invention is applied.
FIG. 3j is a diagram illustrating the entire UE operation of CSI-RS activation and deactivation using MAC CE proposed in the present invention.
3K is a diagram illustrating a method of using a counter in the operation of CSI-RS activation and deactivation using MAC CE proposed in the present invention.
3ka is a diagram illustrating an aperiodic CSI-RS and multi-shot CSI-RS transmission procedure.
3kaa is a diagram illustrating the configuration of CSI-RS and reporting in NR proposed in the present invention.
3kb, 3kc, 3kd, and 3ke are diagrams illustrating an embodiment for extending aperiodic transmission/measurement for a single CSI-RS resource to aperiodic transmission/measurement for multiple CSI-RS resources.
FIG. 3kba is a diagram illustrating one detailed example of signaling for activation and deactivation of a CSI-RS resource subgroup through MACE CE.
3kca is a diagram for explaining CSI-RS subgroup configuration through RRC.
3L is a block diagram showing the configuration of a terminal according to an embodiment of the present invention.
3M is a block diagram illustrating the configuration of a base station, an MME, and an S-GW according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

<First embodiment>

A wireless communication system, for example, 3GPP's HSPA (High Speed Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), 3GPP2 HRPD (High Rate Packet Data), UMB (Ultra Mobile Broadband), and IEEE 802.16e, such as communication standards such as communication standards, such as high-speed, high-quality packet data service is developed as a broadband wireless communication system are doing In addition, a communication standard of 5G or NR (new radio) is being made as a 5G wireless communication system.

As a representative example of the broadband wireless communication system, in the LTE system, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is employed in a Downlink (DL), and Single Carrier Frequency Division Multiple (SC-FDMA) is used in an Uplink (UL). Access) method is adopted. Uplink refers to a radio link in which a UE (User Equipment) or MS (Mobile Station) transmits data or control signals to a base station (eNode B, or base station (BS)). It means a wireless link that transmits data or control signals. The multiple access method as described above divides the data or control information of each user by allocating and operating the time-frequency resources to which data or control information is to be transmitted for each user so that they do not overlap each other, that is, orthogonality is established. do.

The LTE system employs a Hybrid Automatic Repeat reQuest (HARQ) method for retransmitting the corresponding data in the physical layer when a decoding failure occurs in the initial transmission. In the HARQ scheme, when the receiver fails to correctly decode (decode) data, the receiver transmits information (Negative Acknowledgment; NACK) notifying the transmitter of decoding failure so that the transmitter can retransmit the data in the physical layer. The receiver combines the data retransmitted by the transmitter with the previously unsuccessful data to improve data reception performance. In addition, when the receiver correctly decodes the data, the transmitter may transmit new data by transmitting an acknowledgment (ACK) informing the transmitter of decoding success.

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

In FIG. 1A , 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 are gathered to form one slot 106, and two slots are gathered to form one subframe 105. The length of the slot is 0.5 ms, and the length of the subframe is 1.0 ms. And the radio frame 114 is a time domain section consisting of 10 subframes. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth consists of a total of N _BW 104 subcarriers.

A basic unit of a resource in the time-frequency domain is a resource element 112 (Resource Element; RE) and may be represented by an OFDM symbol index and a subcarrier index. A resource block 108 (Resource Block; RB or Physical Resource Block; PRB) is defined as N _symb (102) consecutive OFDM symbols in the time domain and N _RB (110) consecutive subcarriers in the frequency domain. Accordingly, one RB 108 is composed of N _symb x N _RB REs 112 . In general, the minimum transmission unit of data is the RB unit. In the LTE system, in general, N _symb = 7, N _RB = 12, and N _BW and N _RB are proportional to the bandwidth of the system transmission band. The data rate increases in proportion to the number of RBs scheduled for the UE. The LTE system defines and operates six transmission bandwidths. In the case of an FDD system operating by dividing downlink and uplink by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth may be different from each other. The channel bandwidth represents an RF bandwidth corresponding to a system transmission bandwidth. Table 1 shows the correspondence between the system transmission bandwidth and the channel bandwidth defined in the LTE system. For example, an LTE system having a 10 MHz channel bandwidth has a transmission bandwidth of 50 RBs.

Channel bandwidth
BW _Channel [MHz] 1.4 3 5 10 15 20 Transmission bandwidth configuration N _RB 6 15 25 50 75 100

Downlink control information is transmitted within the first N OFDM symbols in the subframe. In general, N = {1, 2, 3}. Accordingly, the value of N varies for each subframe according to the amount of control information to be transmitted in the current subframe. The control information includes a control channel transmission interval indicator indicating how many OFDM symbols the control information is transmitted over, scheduling information for downlink data or uplink data, HARQ ACK/NACK signals, and the like.

In the LTE system, scheduling information for downlink data or uplink data is transmitted from the base station to the terminal through downlink control information (DCI). DCI defines various formats, whether it is scheduling information for uplink data (UL grant) or scheduling information for downlink data (DL grant), whether it is a compact DCI with a small size of control information, using multiple antennas It operates by applying a DCI format determined according to whether spatial multiplexing is applied or whether it is DCI for power control. For example, DCI format 1, which is scheduling control information (DL grant) for downlink data, is configured to include at least the following control information.

- Resource allocation type 0/1 flag (Resource allocation type 0/1 flag): Notifies whether the resource allocation method is type 0 or type 1. Type 0 allocates resources in a RBG (resource block group) unit by applying a bitmap method. The basic unit of scheduling in the LTE system is an RB expressed 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 allocating a specific RB within an RBG.

- Resource block assignment: Notifies the RB allocated for data transmission. The resource to be expressed is determined according to the system bandwidth and 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 (HARQ process number): Notifies the process number of HARQ.

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

- Redundancy version: Notifies the redundancy version of HARQ.

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

The DCI is a downlink physical control channel (PDCCH) (Physical downlink control channel) (or control information, hereinafter to be used in combination) or EPDCCH (Enhanced PDCCH) (or enhanced control information, hereinafter) through a channel coding and modulation process It is transmitted through the mixed use).

In general, the DCI is independently scrambled with a specific RNTI (Radio Network Temporary Identifier) (or terminal identifier) for each terminal, a cyclic redundancy check (CRC) is added and channel-coded, and is configured as an independent PDCCH for transmission. do. In the time domain, the PDCCH is mapped and transmitted during the control channel transmission period. The frequency domain mapping position of the PDCCH is determined by the identifier (ID) of each terminal, and is spread over the entire system transmission band.

Downlink data is transmitted through a Physical Downlink Shared Channel (PDSCH), which is a physical channel for downlink data transmission. The PDSCH is transmitted after the control channel transmission period, and the DCI transmitted through the PDCCH informs scheduling information such as a specific mapping position and a modulation method in the frequency domain.

Among the control information constituting the DCI, the base station notifies the terminal of the modulation scheme applied to the PDSCH to be transmitted and the size of the data to be transmitted (transport block size; TBS) through the MCS composed of 5 bits. The TBS corresponds to a size before channel coding for error correction is applied to data (transport block, TB) to be transmitted by the base station.

Modulation schemes supported by the LTE system are Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (16QAM), and 64QAM, and each modulation order (Qm) corresponds to 2, 4, and 6. That is, in case of QPSK modulation, 2 bits per symbol, in case of 16QAM modulation, 4 bits per symbol, in case of 64QAM modulation, 6 bits per symbol may be transmitted.

1B is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource domain in which data or a control channel is transmitted in an uplink in an LTE-A system according to the prior art.

Referring to FIG. 1B , the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is the SC-FDMA symbol 202 , and N _symb ^UL SC-FDMA symbols are gathered to form one slot 206 . And two slots are gathered to configure one subframe 205 . The minimum transmission unit in the frequency domain is a subcarrier, and the entire system transmission bandwidth 204 is composed _{of a total of N BW subcarriers.} N _BW has a value proportional to the system transmission band.

A basic unit of a resource in the time-frequency domain is a resource element (RE) 212 and may be defined as an SC-FDMA symbol index and a subcarrier index. A resource block pair (Resource Block pair; RB pair) is defined as N _symb ^UL consecutive SC-FDMA symbols in the time domain and N _sc ^RB consecutive subcarriers in the frequency domain. Accordingly, one RB consists of N _symb ^UL x N _sc ^RB REs. In general, the minimum transmission unit of data or control information is an RB unit. In the case of PUCCH, it is mapped to a frequency domain corresponding to 1 RB and transmitted for 1 subframe.

In the LTE system, PUCCH or PUSCH which is an uplink physical channel through which HARQ ACK/NACK corresponding to PDSCH, which is a physical channel for downlink data transmission, or PDCCH/EPDDCH including semi-persistent scheduling release (SPS release) is transmitted. The timing relationship of . For example, in an LTE system operating in frequency division duplex (FDD), HARQ ACK/NACK corresponding to PDCCH/EPDCCH including PDSCH or SPS release transmitted in the n-4th subframe is transmitted to PUCCH or PUSCH in the nth subframe. is sent

In the LTE system, downlink HARQ adopts an asynchronous HARQ scheme in which a data retransmission time point is not fixed. That is, when the HARQ NACK is fed back from the terminal for the initial transmission data transmitted by the base station, the base station freely determines the transmission time of the retransmission data by the scheduling operation. For HARQ operation, the UE performs buffering on data determined to be an error as a result of decoding received data, and then combines with the next retransmission data.

Upon receiving the PDSCH including downlink data transmitted from the base station in subframe n, the terminal transmits uplink control information including HARQ ACK or NACK of the downlink data to the base station through PUCCH or PUSCH in subframe n+k send to In this case, k is defined differently according to the FDD or time division duplex (TDD) of the LTE system and its subframe settings. For example, in the case of an FDD LTE system, k is fixed to 4. Meanwhile, in the case of the TDD LTE system, k may be changed according to the subframe configuration and the subframe number.

Unlike the downlink HARQ in the LTE system, the uplink HARQ adopts a synchronous HARQ scheme with a fixed data transmission time. That is, a Physical Uplink Shared Channel (PUSCH) which is a physical channel for uplink data transmission, a PDCCH which is a downlink control channel preceding it, and a Physical Hybrid (PHICH) which is a physical channel through which a downlink HARQ ACK/NACK corresponding to the PUSCH is transmitted. Indicator Channel), the uplink/downlink timing relationship is fixed according to the following rule.

When the terminal receives a PDCCH including uplink scheduling control information transmitted from the base station in subframe n or a PHICH in which downlink HARQ ACK/NACK is transmitted, uplink data corresponding to the control information in subframe n+k It is transmitted through PUSCH. In this case, k is defined differently according to the FDD or TDD (time division duplex) of the LTE system and its settings. For example, in the case of an FDD LTE system, k is fixed to 4. Meanwhile, in the case of the TDD LTE system, k may be changed according to the subframe configuration and the subframe number.

And when the UE receives a PHICH carrying downlink HARQ ACK/NACK from the base station in subframe i, the PHICH corresponds to the PUSCH transmitted by the UE in subframe i-k. In this case, k is defined differently depending on the FDD or TDD of the LTE system and its configuration. For example, in the case of an FDD LTE system, k is fixed to 4. Meanwhile, in the case of the TDD LTE system, k may be changed according to the subframe configuration and the subframe number.

The description of the wireless communication system has been described based on the LTE system, and the content of the present invention is not limited to the LTE system, but can be applied to various wireless communication systems such as NR and 5G.

3 and 4 show how data for eMBB, URLLC, and mMTC, which are services considered in a 5G or NR system, are allocated from frequency-time resources. In FIG. 3 , data for eMBB, URLLC, and mMTC are allocated in the entire system frequency band 300 . When the eMBB 301 and the mMTC 309 are allocated in a specific frequency band and the URLLC data 303, 305, 307 is generated and transmission is required, the eMBB 301 and the mMTC 309 are already allocated. It is a diagram showing a state in which URLLC data (303, 305, 307) is transmitted after emptying . Among the above services, since a short delay time is particularly important for URLLC, URLLC data may be allocated (303, 305, 307) and transmitted to a part of the resource 301 to which eMBB is allocated. Of course, when URLLC is additionally allocated and transmitted in the resource to which the eMBB is allocated, the eMBB data may not be transmitted in the overlapping frequency-time resource, and thus the transmission performance of the eMBB data may be lowered. That is, in the above case, eMBB data transmission failure may occur due to URLLC allocation. In FIG. 4 , the entire system frequency band 400 may be divided and used for service and data transmission in each subband 402 , 404 , and 406 . The subbands may be divided in advance and signaled higher to the UE, or the base station may arbitrarily divide and provide services to the UE without subband information. 4 shows an example in which subband 402 is used for eMBB data transmission, subband 404 is used for URLLC data transmission, and subband 406 is used for mMTC data transmission. 3 and 4, the length of a transmission time interval (TTI) used for URLLC transmission may be shorter than the TTI length used for eMBB or mMTC transmission.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the description of the present invention, if it is determined that a detailed description of a related function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification. Hereinafter, the base station is a subject that performs resource allocation of the terminal, and may be at least one of an eNode B, a Node B, a base station (BS), a radio access unit, a base station controller, or a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. In the present invention, a downlink (DL) is a wireless transmission path of a signal transmitted from a base station to a terminal, and an uplink (UL) is a wireless transmission path of a signal transmitted from a terminal to a flag station. In addition, although the embodiment of the present invention is described below using LTE or LTE-A system as an example, the embodiment of the present invention may be applied to other communication systems having a similar technical background or channel type. For example, 5G mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in this. In addition, the embodiments of the present invention can be applied to other communication systems through some modifications within the scope of the present invention as judged by a person having skilled technical knowledge.

The eMBB service described below is referred to as a first type service, and data for eMBB is referred to as first type data. The first type service or first type data is not limited to eMBB and may correspond to a case where high-speed data transmission is required or broadband transmission is performed. Also, URLLC service is referred to as a second type service, and data for URLLC is referred to as second type data. The second type service or the second type data is not limited to URLLC and may correspond to a case in which a low delay time is required or high reliability transmission is required. In addition, the mMTC service is referred to as a third type service, and the data for mMTC is referred to as the third type data. The third type service or third type data is not limited to mMTC and may correspond to a case in which a low speed or wide coverage or low power is required.

The structure of a physical layer channel used for each type to transmit the three services or data may be different. For example, the length of a transmission time interval (TTI), an allocation unit of a frequency resource, a structure of a control channel, a data mapping method, etc. may be different.

Although three types of services and three types of data have been described above, more types of services and corresponding data may exist, and even in this case, the contents of the present invention may be applied.

In the present invention, the terms physical channel and signal in the conventional LTE or LTE-A system may be used to describe the proposed method and apparatus. However, the content of the present invention can be applied to a wireless communication system other than LTE and LTE-A systems.

As described above, the present invention defines transmission/reception operations between a terminal and a base station for first-type, second-type, and third-type service or data transmission, and allows terminals receiving different types of services or data scheduling within the same system. Suggests specific methods for working together in In the present invention, type 1, type 2, and type 3 terminals refer to terminals that have received type 1, type 2, or type 3 service or data scheduling, respectively.

The contents of the present invention are applicable to FDD and TDD systems.

Hereinafter, in the present invention, physical layer signaling is a signal transmission method in which a base station uses a downlink control channel of a physical layer to a terminal or from a terminal to a base station using an uplink control channel of a physical layer, L1 signaling, or PHY It may also be referred to as signaling.

Hereinafter, in the present invention, higher signaling or higher layer signaling is a signal transmission method from the base station to the terminal using the downlink data channel of the physical layer, or from the terminal to the base station using the uplink data channel of the physical layer, RRC signaling , or L2 signaling, or PDCP signaling, or MAC control element (MAC control element; MAC CE) may be referred to.

Hereinafter, in the present invention, TPMI means transmit precoding matrix indicator or information, and similarly, it is possible to be expressed by beamforming vector information, beam direction information, and the like.

Hereinafter, in the present invention, uplink (UL) DCI or UL-related DCI refers to uplink resource configuration information and resource configuration type information, uplink power control information, cyclic shift or orthogonal cover code ( Physical layer control signaling including information necessary for uplink transmission such as orthogonal cover code (OCC), channel state information (CSI) request, SRS request, MCS information for each codeword, and uplink precoding information field (L1 control) ) means

Hereinafter, in the present invention, it is assumed that dynamic beamforming or semi-dynamic beamforming is supported in order to perform uplink transmission in various scenarios.

1G is a diagram illustrating an example of uplink transmission through dynamic beamforming and semi-dynamic beamforming.

Dynamic beamforming is suitable when accurate uplink channel information is available, such as when the mobile speed of the UE is low, cell-to-cell separation is good, or inter-cell interference management is excellent. In this case, the terminal may perform uplink transmission using a beam having a narrow beam width based on accurate uplink channel direction information ( 702 ). The base station 701 notifies the UE of the TPMI through UL DCI such as a UL grant. After receiving the TPMI signaling, the terminal transmits uplink data to the base station using a precoder or beamforming vector/matrix indicated by the TPMI. The codebook-based MIMO transmission for supporting the dynamic beamforming may be operated by UL DCI including a precoding information (PMI) field (determined according to the RI when a rank indicator (RI) exists). In this case, the precoding information field indicates a precoding matrix used for uplink transmission allocated to the corresponding terminal. In the case of wideband precoding information, the precoding matrix points in one direction in all allocated bands, but in the case of subband precoding information, it may be promised to point in one direction for each subband. In this case, the precoding vector designated by the subband precoding information may be limited to be included in the precoding vector group designated by the wideband precoding information. Through this, it is possible to reduce the signaling burden for subband precoding information.

The dynamic beamforming is suitable when the uplink channel information is inaccurate, such as when the mobile speed of the UE is high, the cell separation is not well done, or the inter-cell interference management is insufficient. In this case, the terminal 703 may perform uplink transmission using a beam group consisting of beams in various directions based on rough uplink channel direction information. The base station 701 notifies the UE of the TPMI through UL DCI such as a UL grant. After receiving the TPMI signaling, the terminal transmits uplink data to the base station using a subset of a precoder or a subset of a beamforming vector/matrix indicated by the TPMI. The codebook-based MIMO transmission for supporting the dynamic beamforming may be operated by UL DCI including a precoding information (PMI) field (determined according to the RI when a rank indicator (RI) exists). In this case, the precoding information field indicates a group of precoding vectors used for uplink transmission allocated to a corresponding terminal. The precoding vector group information is equally used in the entire uplink band allocated as wideband information. The UE can apply precoder cycling according to a predetermined pattern to beams included in the notified precoding vector group.

1h is a diagram illustrating that a terminal and a base station transmit a reference signal to obtain channel state information necessary for uplink transmission in NR.

Non-precoded CSI-RS (NP CSI-RS, 1h-10) or Beamformed CSI-RS (BF CSI-RS, 1h-20) in which CSI-RS overhead is reduced by applying beamforming to the antenna may be used. In the case of the corresponding NP CSI-RS, a plurality of unit resource settings can be used to support a large number of antenna ports, and in the case of BF CSI-RS, a plurality of CSI-RS resources are set instead of a unit resource The UE may select one or a plurality of resources and report the channel state information.

Similarly, even when the UE transmits SRS, an NP SRS (1h-20) supporting many antennas in one SRS resource and a plurality of SRS resources are set to the UE and the BF SRS using information on one or a plurality of SRS resources. (1h-30) is possible. Using the SRS resource set by the base station, the terminal transmits the SRS, and the base station receives the SRS, instructs the terminal to an optimal transmission beam required between the terminal and the base station, and finds a reception beam optimized for the base station. In addition, when channel reciprocity or beam determination coincides between uplink and downlink, using the above-mentioned NP CSI-RS (1h-10) and BF CSI-RS (1h-20) An uplink beam can be selected.

A precoding vector group or beam group in the uplink can be defined through the following two methods.

The first method is a beam group definition method based on hierarchical PMI. For example, a PMI indicating one code point may be composed of two or more sub-PMIs. If it is assumed that the PMI consists of two sub-PMIs, the first PMI means one of the beam group indexes including a specific number of precoding vectors, and the second PMI indicates one of the precoding vector indexes included in the beam group. can be promised to mean For example, an uplink codebook composed of beam groups G _i including M transmission antennas and B DFT precoding vectors v _k based on an oversampling factor of O may be defined as in Equation 1 below.

[Equation 1]

의 payload를 가지는 두 번째 PMI에 의하여 단일 precoding vector가 지정되는 것이 가능하다.Here, A is a beam skipping factor and means the interval between beam groups (beam units). In this example, the first PMI i means the index of the beam group.

It is possible to specify a single precoding vector by the second PMI with a payload of .

The second method is a beam/beam group definition method based on PMI of a single structure. For example, one PMI may be understood as an indicator indicating a single beam or a beam group according to higher layer or physical layer signaling. _{For example, an uplink codebook consisting of beam groups G i} including M transmit antennas, an i-th DFT precoding vector v _i based on an oversampling factor of O, and B DFT precoding vectors is expressed in Equation 2 below. can be defined.

[Equation 2]

In this example, the i-th PMI may be understood _{to indicate v i} when the higher layer or physical layer signaling indicates dynamic beamforming or wideband precoding. On the other hand, when the higher layer or physical layer signaling indicates semi-dynamic beamforming or subband precoding, it may be understood as indicating _{G i.} Table 2 shows an example of a TPMI interpretation method when dynamic or semi-dynamic beamforming transmission or wideband or subband precoding is designated by higher layer signaling in this example. Table 3 shows an example of a TPMI interpretation method when dynamic or semi-dynamic beamforming transmission or wideband or subband precoding is designated by physical layer signaling in this example.

PMI
value i
Precoder or precoder group BeamformingScheme = 'Dynamic' BeamformingScheme = 'Semi-dynamic' 0 v _o G ₀ One v ₁ G ₁ 2 v ₂ G ₂ ... ... ... 0M-1 v _{0M -1} G _{0M -1}

Table 2 Exemplary PMI table for embodiment 1

PMI
value i Interpretation Beamforming scheme Precoder or precoder group 0 Dynamic Precoder v _o One Dynamic Precoder v ₁ 2 Dynamic Precoder v ₂ ... ... ... 0M-1 Dynamic Precoder v _{0M -1} 0M semi-dynamic Precoder group G ₀ 0M+1 semi-dynamic Precoder group G ₁ 0M+2 semi-dynamic Precoder group G ₂ ... ... ... 20M-1 semi-dynamic Precoder group G _{0M -1}

Table 3 Exemplary PMI table for embodiment 2 (2 ^nd example)

그리고 빔 그룹

을 정의할 수 있다. In Equations 1 and 2, a codebook composed of a one-dimensional DFT vector is assumed on the assumption that the transmit antennas of the terminal are formed of a one-dimensional antenna array. However, when the transmit antennas of the terminal are formed of a two-dimensional antenna array, another form An uplink codebook of may be used. For example, if the transmit antenna array of the terminal includes M ₁ antenna ports in the first dimension and M ₂ antenna ports in the second dimension, the equation is expressed through a pair of indices (m ₁ , m _{2 ).} precoding vector like 3

and the beam group

can be defined.

[Equation 3]

In Equation 1, Equation 2, and Equation 3, it is assumed that the transmit antennas of the terminal all have the same polarization, but when the transmit antennas of the terminal are configured in a dual-polarized arrangement, the uplink codebook examples are modified in consideration of this. it is possible to be For example, if the transmit antenna of the terminal is a one-dimensional array consisting of M antenna ports for each polarization and a total of 2M antenna ports, it is possible to define the _{rank 1 precoding vector v i,k} and the beam group G _{m as in Equation 4 below.} do.

[Equation 4]

In Equation 4, K means a co-phasing quantization level.

를 정의하는 것이 가능하다. 여기서 M₁ 및 M₂는 각각 첫 번째 차원 그리고 두 번째 차원에 포함되는 polarization 별 단말 송신 안테나 포트 수 이다. 빔 그룹의 경우 수학식 5의

를 바탕으로 상기 수학식 3과 유사하게 구성되는 것이 가능하다.In the transmission antenna of the user terminal in another example, each polarization by M ₁ M ₂ M 2 ₁ in total when the two-dimensional array consisting of M ₂ of antenna ports, as in the following Equation 5 rank 1 precoding vector

It is possible to define Here, M ₁ and M ₂ are the number of terminal transmit antenna ports for each polarization included in the first dimension and the second dimension, respectively. In the case of a beam group, Equation 5

It is possible to be configured similarly to Equation 3 based on .

[Equation 5]

It is apparent that the dynamic/semi-dynamic beamforming or wideband/subband precoding signaling examples, that is, Tables 2 and 3, can be easily applied to all of the codebook examples.

Although the above examples have been described based on the rank 1 codebook pointing to a single direction, the actual implementation is not limited thereto, and the same can be applied to codebooks of rank 2 or higher pointing to two or more directions.

In the above examples, it is assumed that one TPMI is included in the UL DCI. It is recommended that the terminal receiving this applies uplink precoding for one beam direction or one beam group to the entire uplink band allocated to it. possible.

1I is a diagram illustrating an example of resource allocation and subband precoding for uplink transmission. For example, the base station may transmit _{N PMI} TPMIs including precoding information for a _{plurality of, for example, N PMI subbands to UL DCI for subband precoding.} The N _PMI value is determined by the number of uplink resources (RBs) RA _RB allocated to the terminal, the number of RBs constituting the subband P _SUBBAND , and the uplink resource allocation method. As in i1-10 of FIG. 1I, when contiguous RBs are allocated, and 802 shows uplink resources when RBs are allocated discontinuously (clustered). In FIG. 1I, it is assumed _{that P SUBBAND =4.} According to FIG. 1i, when resources are allocated as shown in 1i-10, that is, when resources composed of one cluster are allocated, the required number of _subbands can be calculated as in Equation 6 based on _{RA RB} and P SUBBAND. Here, the cluster means a set of consecutively allocated uplink RBs.

[Equation 6]

.

.

However, when resources composed of one or more clusters are allocated, such as 1i-20, the calculation of Equation 6 may not be accurate. In this case, N _PMI may be calculated based on the method of Equation 7 or Equation 8. Equation 7 is a method of calculating _{N PMI} based on the lowest index RB _low and the highest index RB _{high among the allocated RBs.} Equation 8 is a method of calculating _{N PMI} based on the number of consecutive RBs allocated to each cluster. In Equation 8, RA _RB,n is the number of consecutive RBs allocated to the n-th cluster, and N is the number of clusters allocated to the UE.

[Equation 7]

[Equation 8]

If one uplink PMI consists of T bits, TPMI payload transmission of _{N PMI} T bits may be required for uplink subband precoding in this example. This means that tens of bits or more may be required for TPMI signaling when several subbands and a codebook of several bits are used. This may be too heavy a burden to be transmitted to the UL DCI, and it is necessary to define a new UL subband precoding method to reduce the UL DCI burden. In addition, at this time, if an environment in which subband precoding is supported in uplink transmission is defined, UL DCI coverage can be improved for a terminal with a small number of transmit and receive antennas, and subband free for a terminal with a large number of transmit and receive antennas. By supporting coding, the uplink transmission performance of the terminal and the overall system performance can be improved.

<Example 1-1>

In order for the terminal to check the precoding applied to the uplink subband precoding, one or a plurality of SRS resources previously set as RRC may be instructed from the base station to the terminal. In addition, the number of SRS resources indicated by the base station to the terminal may vary depending on whether the terminal supports subband precoding or not. 1J illustrates time and frequency resources used by a plurality of terminals to transmit uplink data.

As shown in FIG. 1J, the uplink transmission allocation is changed according to the channel condition of the terminal. In particular, the transmit power of the uplink is limited due to the battery characteristics of the terminal and the limitation of hardware. Therefore, it is necessary to consider the downlink and other resource allocation characteristics. In 1j-10 of FIG. 1J, a UE having a good channel state may transmit uplink data using a wide frequency band and a short time. This is because the channel condition between the terminal and the base station is good, so that data can be transmitted well enough only with the power transmitted by the terminal. The terminal in 1j-20 transmits data using a somewhat limited frequency band and extended time. This is because the channel condition is relatively worse than that of the terminal in 1j-10. In the uplink, as shown in FIG. 1j , the power spectral density of the frequency can be increased by reducing the transmission band and increasing the transmission time. In addition, although the transmission power of the terminal is limited within a specific time, when the same power is repeatedly used several times, it has the effect of actually improving the coverage of the terminal transmission data. In addition, when the channel between the terminal and the base station is very poor, as shown in 1j-30, resources can be allocated to transmit in a very narrow band for a long time. As shown in FIG. 1J, since the characteristics of uplink transmission are different for each UE, precoding related information required for transmission by the UE may also vary for each band. Therefore, as mentioned above, when the UE applies full-band precoding, one SRS is indicated, and when supporting subband precoding, the number of SRSs equal to the number of subbands or the number of bandwidth parts that is a set of subbands By indicating the resource, the terminal can support uplink transmission, and the terminal determines how many antenna port-based codebooks should be used for the codebook used by the terminal when the terminal transmits through the indicated SRS resource as described above. You can check how the codebook subset restriction is set.

In addition, in order to efficiently use the SRS resource at the time of the indication, some of the SRS resources previously set through a higher layer such as RRC may be activated, and only some of the activated resources may be indicated through DCI. In particular, in the case of a higher frequency band, the data beam of the terminal becomes narrow due to the reduction of the antenna form factor, and accordingly, it may be necessary to support a large number of beams and thus the number of SRS resources. In this case, by enabling and deactivating these SRS resources, it is possible to optimize the resources suitable for the location of the terminal and the optimal beam group. The actual transmission of the SRS may be as follows.

● SRS resource setting and triggering method 1: A method of setting a plurality of aperiodic CSI-RS resources in advance, activating some of the set resources, and triggering some of the activated resources

● SRS resource setting and triggering method 2: A method of setting a plurality of aperiodic CSI-RS resources in advance and periodically transmitting the CSI-RS resources according to activation until deactivated.

SRS resource setting and triggering method 1 is a method of setting a plurality of aperiodic SRS resources in advance, activating some of the set resources, and triggering some of the activated resources. In order to activate such a resource, the base station may transmit it using a MAC CE (Control Element) signal. The terminal receiving the activation signal may transmit the corresponding SRS when the DCI trigger of the base station for transmitting the corresponding SRS resource is transmitted.

SRS resource setting and triggering method 2 is a method of setting a plurality of semi-persistent SRS resources in advance and periodically transmitting the corresponding SRS resources according to activation until deactivated. In order to activate such a resource, the base station may transmit it using a MAC CE signal. In addition, the base station activates/deactivates candidate resources through the MAC CE signal, and for actual activation, it is also possible to activate or deactivate some of the candidate resources activated through the MAC CE signal through DCI. 1K is a diagram illustrating an SRS candidate resource activation through the above-mentioned MAC CE and an actual activation operation through DCI.

In this case, detailed information of the SRS required for the SRS transmission may be set. The SRS transmission band, transmission period, and slot/subframe/mini-slot offset may be configured. In addition, the number of antenna ports or a cyclic shift and a transmission comb for Zadoff-Chu sequence transmission may also be transmitted for each SRS group.

In this case, the set number of the plurality of SRS antenna ports may be all the same or only the number of one antenna port may be configured. Unlike a base station that supports a relatively large number of antennas (eg, 16 ports or 32 ports), the terminal has no choice but to have a relatively small number of antennas due to the form factor of the corresponding terminal. Accordingly, there may be little need to set the number of corresponding antennas differently, and by matching the number of antenna ports of all SRS resources to the same, the complexity of varying the number of antenna ports supported by subband precoding for each resource is reduced and UL using the same wideband TPMI DCI overhead can be reduced.

<Example 1-2>

In addition, as mentioned above, when the UE matches the channel reversibility or beam determination during uplink transmission, uplink data transmission may be supported by referring to the CSI-RS used for downlink data transmission. At this time, the CSI-RS may be delivered to the UE using the following method.

● CSI-RS indication method for uplink transmission 1: Instruction through DCI

● CSI-RS indication method for uplink transmission 2: indication through RRC or MAC CE

● CSI-RS instruction method for uplink transmission 3: Indirectly indicated through the indicated SRS resource

CSI-RS indication method 1 for uplink transmission is a method of indicating through DCI. By placing a field indicating the CSI-RS resource in the UL DCI to which the base station allocates data transmission to the terminal, the terminal can determine accurate channel information through the CSI-RS. These CSI-RS resources may deliver one CSI-RS resource to support full-band precoding, and even support subband precoding, one CSI-RS for channel identification may deliver one. Also, it is possible to transmit a plurality of CSI-RSs during subband precoding.

CSI-RS indication method 2 for uplink transmission is a method of indicating through RRC or MAC CE. When the CSI-RS is dynamically transmitted as in the indication method 1, the corresponding CSI-RS can be adapted quickly and flexibly, but DCI overhead becomes large. Therefore, in order to minimize this, it is possible to help uplink transmission by indicating one CSI-RS resource per UE or one CSI-RS per cell through RRC or MAC CE.

CSI-RS indication method 3 for uplink transmission is a method of indirectly indicating through the indicated SRS resource. In this case, the CSI-RS resource may be set to RRC or MAC CE for each SRS resource, or the configured resource may be activated/deactivated. The basic activation and deactivation operations may be similar to or the same as the SRS activation/deactivation operations described in Embodiment 1-1. Accordingly, when an SRS resource is indicated to the UE for uplink data transmission, the UE may identify channel state information through a CSI-RS resource preset or activated in the corresponding SRS resource and support data transmission.

<Example 1-3>

The base station may instruct the terminal using the following method to determine whether the terminal uses subband precoding.

● Subband precoding usage instruction method 1: Instruct through DCI

● Subband precoding usage instruction method 2: Instruct through RRC or MAC CE

● Subband precoding usage indication method 3: Indicated through the number of antenna ports of the indicated SRS resource

● Subband precoding usage indication method 4: Indicate through the number of SRS resources configured to the UE

Subband precoding usage indication method 1 is a method of indicating through DCI. When the base station schedules uplink data transmission to the terminal, as mentioned above, information such as TRI, wideband TPMI, and resource allocation may be transmitted to the UL DCI. In addition, it is possible to indicate whether to use subband precoding by using 1 bit. For example, 0 indicates use of full-band precoding, and 1 indicates use of subband precoding. When the UE receives an instruction for subband precoding using the 1 bit, preset information, for example, subband TPMI information within the same DCI, subband TPMI information of the second DCI, or subband TPMI preset through MAC CE Information or pre-set subband TPMI information can be checked through RRC. In this case, when the UE receives subband TPMI through MAC CE or RRC, the corresponding subband TPMI information may be set for each SRS resource that can be indicated to the UE or configured, and the UE uses the corresponding 1-bit information and the indicated SRS resource to subband through the SRS resource. You can check the TPMI.

Subband precoding usage indication method 2 is a method of indicating through RRC or MAC CE. By setting whether the base station uses subband precoding to the terminal in advance through RRC or MAC CE, the terminal can check whether the corresponding subband precoding is used. In this case, the amount of UL DCI information transmitted by the base station to the terminal is reduced, so that the coverage of the UL DCI can be secured.

Subband precoding usage indication method 3 is a method of indicating through the number of antenna ports of the indicated SRS resource. As mentioned above, the performance improvement of subband precoding of the uplink is large when the number of transmit antennas of the terminal is sufficiently secured. Accordingly, subband precoding may not be supported when the number of antenna ports of the SRS resource indicated to the UE is small, and subband precoding may be supported when the number of antenna ports is greater than the specific number of antenna ports. For example, when the number of SRS ports indicated to the UE is greater than 2 or greater than 4, subband precoding may be used. In addition, when the number of ports of all SRS resources is set to be the same or has one value, the UE checks whether uplink subband precoding is performed through the number of SRS antenna ports previously configured through RRC or MAC CE rather than UL DCI of the base station. can

Subband precoding usage indication method 4 is a method of instructing the UE through the number of SRS resources configured. As described in FIG. 1H, in the method of supporting a terminal having a large number of transmit antennas, it is possible to support many antenna ports in one or a few SRS resources, but it is possible to use many SRS resources by using a small number of antenna ports. is also possible. Accordingly, when the number of resources is set to be greater than a specific number, the UE may use subband precoding. For example, when two or more SRS resources are configured for the UE, subband precoding may be used, which may be three or four.

In addition, the subband precoding usage indication method may be used in a plurality of combinations. For example, when the indication methods 3 and 4 are simultaneously satisfied (indicated, when the number of antenna ports of the configured SRS resource is greater than a predetermined number and the number of configured SRS resources is greater than a predetermined number), it can be used. In addition, it is also possible to use when the indication methods 1 and 3 are simultaneously satisfied (when the number of antenna ports of the SRS resource indicated and configured to use subband precoding is set in advance as RRC is greater than a certain number). As another example, it is also possible to use when all of the instruction methods 1, 3, and 4 are satisfied.

In addition, the use of the indication method can be used only when the UE uses CP-OFDM when transmitting uplink data. In the case of DFT-S OFDM, subband precoding cannot be applied due to the characteristics of the corresponding waveform. Therefore, it is also possible to assume full-band precoding in DFT-S OFDM and to apply subband precoding only to CP-OFDM. This method may vary depending on the rank at which the UE transmits data. Currently, since DFT-S OFDM in NR is used only for rank1 transmission, full-band precoding is assumed in case of rank1, and subband precoding can be applied only in case of CP-OFDM.

<Example 1-4>

When the base station supports the subband TPMI to the terminal, it can be transmitted using the following method.

● Subband TPMI delivery method 1: Delivery using subband TPMI payload that matches the number of indicated SRS resources

● Subband TPMI delivery method 2: Delivered using subband TPMI payload corresponding to the indicated number of SRS resources

Subband TPMI delivery method 1 is a method of delivery using a subband TPMI payload corresponding to the indicated number of SRS resources. The size of this subband TPMI may be linked to an SRS resource having the largest number of antenna ports among SRS resources configured for the UE. In general, as the number of antenna ports increases, a beam width supported by a corresponding antenna decreases, so that a higher SINR can be secured, but a relatively large number of TPMIs are required. Accordingly, the number of bits of the subband TPMI may vary according to the indicated SRS resource, and this method makes it possible to minimize DCI coverage waste by using an optimal DCI overhead. This method may be more suitable for transmission of subband TPMI through the second DCI, which is decoded after the UE confirms the existence of the subband TPMI through the first UL DCI, because the number of blind decodings may increase according to the DCI size.

Subband TPMI delivery method 2 is a method of delivery using a subband TPMI payload corresponding to the indicated number of SRS resources. In order for the UE to receive the DCI, it must know the payload size of the corresponding DCI in advance. In general, as the number of antenna ports increases, a beam width supported by a corresponding antenna decreases, so that a higher SINR can be secured, but a relatively large number of TPMIs are required. Accordingly, when the TPMI bit is matched based on the SRS resource having the highest number of antennas, the DCI size does not change and an additional blind decoding burden can be reduced for the UE. As mentioned in Embodiment 1-1, when all SRS resources have one or the same number of antenna ports, the corresponding TPMI may be transmitted according to the number of subband TPMIs required by the corresponding antenna port.

The subband TPMI mentioned in this embodiment 1-4 may be delivered through DCI, second DCI, MAC CE, RRC, PDSCH, and the like.

In order to carry out the above embodiments of the present invention, the transmitting unit, the receiving unit, and the processing unit of the terminal and the base station are shown in FIGS. 1L and 1M, respectively. A method of transmitting and receiving a base station and a terminal for determining whether there is a collision with a second type service and processing a second signal based thereon is shown from the 1-1 to the 1-4 embodiments, To perform this, the receiving unit, processing unit, and transmitting unit of the base station and the terminal must operate according to the embodiment.

Specifically, FIG. 11 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. 11, the terminal of the present invention may include a terminal receiving unit 11-10, a terminal transmitting unit 11-20, and a terminal processing unit 11-30. In the embodiment of the present invention, the terminal receiving unit 11-10 and the terminal collectively refer to the transmitting unit 11-20, and may be referred to as a transceiver. The transceiver may transmit/receive a signal to/from the base station. The signal may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for low-noise amplifying and down-converting a received signal. In addition, the transceiver may receive a signal through a wireless channel, output it to the terminal processing unit 11-30, and transmit a signal output from the terminal processing unit 11-30 through a wireless channel. The terminal processing unit 11-30 may control a series of processes so that the terminal can operate according to the above-described embodiment of the present invention. For example, the terminal receiving unit 11-10 may receive a signal including the second signal transmission timing information from the base station, and the terminal processing unit 11-30 may control to interpret the second signal transmission timing. Thereafter, the terminal transmitter 11-20 transmits the second signal at the above timing.

1M is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 1m, the base station of the present invention may include a base station receiving unit 1m-10, a base station transmitting unit 1m-20, and a base station processing unit 1m-30. In an embodiment of the present invention, the base station receiving unit 1m-10 and the base station transmitting unit 1m-20 may be collectively referred to as a transceiver. The transceiver may transmit/receive a signal to/from the terminal. The signal may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and an RF receiver for low-noise amplifying and down-converting a received signal. In addition, the transceiver may receive a signal through a wireless channel and output it to the base station processing unit 1m-30, and transmit the signal output from the terminal processing unit 11-30 through the wireless channel. The base station processing unit 1m-30 may control a series of processes so that the base station can operate according to the above-described embodiment of the present invention. For example, the base station processing unit 1m-30 may determine a second signal processing method and control to generate the second signal information to be transmitted to the terminal. Thereafter, the base station transmitter 1m-20 transmits the second signal information to the terminal, and the base station receiver 1m-10 combines initial transmission and retransmission according to the second signal.

In addition, according to an embodiment of the present invention, the base station processing unit 1m-30 controls to generate downlink control information (DCI) including reference signal processing information for the uplink precoding. can

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to easily explain the technical contents of the present invention and help 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 of ordinary skill in the art to which the present invention pertains that other modifications are possible based on the technical spirit of the present invention. In addition, each of the above embodiments may be operated in combination with each other as needed. For example, the base station and the terminal may be operated by combining parts of embodiments 1-1 and 1-2 of the present invention. In addition, although the above embodiments have been presented based on the FDD LTE system, other modifications based on the technical idea of the embodiment may be implemented in other systems such as the TDD LTE system, 5G or NR system.

<Second embodiment>

The present invention relates to a general wireless mobile communication system, and in particular, a reference signal in a wireless mobile communication system to which a multiple access scheme using a multi-carrier such as OFDMA: Orthogonal Frequency Division Multiple Access is applied. It is about how to map Signal).

The current mobile communication system is developing into a high-speed, high-quality wireless packet data communication system to provide data service and multimedia service, away from the initial voice-oriented service provision. To this end, various standardization organizations such as 3GPP, 3GPP2, and IEEE are proceeding with the 3rd generation evolutionary mobile communication system standard applying multiple access method using multi-carrier. Recently, various mobile communication standards such as Long Term Evolution (LTE) of 3GPP, Ultra Mobile Broadband (UMB) of 3GPP2, and 802.16m of IEEE are providing high-speed, high-quality wireless packet data transmission service based on multiple access method using multi-carrier. was developed to support

Existing 3G evolutionary mobile communication systems such as LTE, UMB, and 802.16m are based on the multi-carrier multiple access method, and to improve transmission efficiency, Multiple Input Multiple Output (MIMO, multiple antennas) is applied and beam- It has the characteristics of using various techniques such as forming (beamforming), Adaptive Modulation and Coding (AMC, adaptive modulation and coding) method, and channel sensitive (channel sensitive) scheduling method. The above various technologies improve transmission efficiency through methods such as concentrating transmission power transmitted from multiple antennas or controlling the amount of transmitted data according to channel quality, etc., and selectively transmitting data to users with good channel quality. Improve system capacity performance. Since most of these techniques operate based on channel state information between a base station (eNB: evolved Node B, BS: base station) and a user equipment (UE: User Equipment, MS: Mobile Station), an eNB or UE is a base station and a terminal. It is necessary to measure the channel state between the two, and in this case, a Channel Status Indication reference signal (CSI-RS) is used. The aforementioned eNB means a downlink transmission and uplink reception device located at a predetermined place, and one eNB performs transmission/reception for a plurality of cells. In one mobile communication system, a plurality of eNBs are geographically distributed, and each eNB performs transmission/reception for a plurality of cells.

Existing 3G and 4G mobile communication systems such as LTE/LTE-A utilize MIMO technology that transmits using a plurality of transmit/receive antennas to increase data rates and system capacity. The MIMO technology uses a plurality of transmit/receive antennas to spatially separate and transmit a plurality of information streams. In this way, spatially separating and transmitting a plurality of information streams is called spatial multiplexing. In general, the number of information streams to which spatial multiplexing can be applied depends on the number of antennas of the transmitter and receiver. In general, the number of information streams to which spatial multiplexing can be applied is called the rank of the transmission. In the case of MIMO technology supported by standards up to LTE/LTE-A Release 11, spatial multiplexing is supported when there are 16 transmit antennas and 8 receive antennas, and a rank of up to 8 is supported.

In the case of NR (New Radio access technology), a 5th generation mobile communication system currently being discussed, the design goal of the system is to support various services such as eMBB, mMTC, and URLLC mentioned above, and for this purpose, always transmit The time and frequency resources can be flexibly transmitted by minimizing the reference signal that is used and allowing the transmission of the reference signal to be transmitted aperiodically.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention without obscuring the gist of the present invention by omitting unnecessary description.

For the same reason, some components are exaggerated, omitted, or schematically illustrated in the accompanying drawings. In addition, the size of each component does not fully reflect the actual size. In each figure, the same or corresponding elements are assigned the same reference numerals.

Advantages and features of the present invention, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

At this time, it will be understood that each block of the flowchart diagrams and combinations of the flowchart diagrams may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment are not described in the flowchart block(s). It creates a means to perform functions. These computer program instructions may also be stored in a computer-usable or computer-readable memory that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable memory. It is also possible that the instructions stored in the flow chart block(s) produce an article of manufacture containing instruction means for performing the function described in the flowchart block(s). The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in the flowchart block(s).

Additionally, each block may represent a module, segment, or portion of code that includes one or more executable instructions for executing specified logical function(s). It should also be noted that in some alternative implementations it is also possible for the functions recited in blocks to occur out of order. For example, two blocks shown one after another may in fact be performed substantially simultaneously, or it is possible that the blocks are sometimes performed in the reverse order according to the corresponding function.

At this time, the term '~ unit' used in this embodiment means software or hardware components such as FPGA or ASIC, and '~ unit' performs certain roles. However, '-part' is not limited to software or hardware. The '~ unit' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Thus, as an example, '~' denotes components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, and procedures. , subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functions provided in the components and '~ units' may be combined into a smaller number of components and '~ units' or further separated into additional components and '~ units'. In addition, components and '~ units' may be implemented to play one or more CPUs in a device or secure multimedia card.

And, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms described below are terms defined in consideration of functions in the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

Hereinafter, in this specification, the NR system and the LTE (Long Term Evolution) system and the LTE-A (LTE-Advanced) system have been described as examples, but the present invention is not specifically added or subtracted to other communication systems using licensed and unlicensed bands. can be applied without

FIG. 2A shows radio resources of 1 subframe and 1 RB, which are the minimum units that can be scheduled in downlink in the LTE/LTE-A system.

The radio resource shown in FIG. 2A consists of one subframe on the time axis and one RB on the frequency axis. Such a radio resource consists of 12 subcarriers in the frequency domain and 14 OFDM symbols in the time domain to have a total of 168 unique frequencies and time positions. In LTE/LTE-A, each natural frequency and time position of FIG. 2A is referred to as a resource element (RE).

A plurality of different types of signals as follows may be transmitted to the radio resource shown in FIG. 2A.

1. CRS (Cell Specific RS): A reference signal periodically transmitted for all terminals belonging to one cell and can be commonly used by a plurality of terminals.

2. DMRS (Demodulation Reference Signal): A reference signal transmitted for a specific terminal and transmitted only when data is transmitted to the corresponding terminal. DMRS may consist of a total of 8 DMRS ports. In LTE/LTE-A, port 7 to port 14 correspond to DMRS ports, and ports maintain orthogonality so that they do not interfere with each other using CDM or FDM.

3. PDSCH (Physical Downlink Shared Channel): This is a data channel transmitted through downlink, which is used by the base station to transmit traffic to the UE and is transmitted using REs in which a reference signal is not transmitted in the data region of FIG. 2B .

4. CSI-RS (Channel Status Information Reference Signal): A reference signal transmitted for terminals belonging to one cell is used to measure the channel state. A plurality of CSI-RSs may be transmitted to one cell.

5. Other control channels (PHICH, PCFICH, PDCCH): ACK/NACK transmission for providing control information necessary for the UE to receive the PDSCH or operating HARQ for uplink data transmission

In addition to the above signals, in the LTE-A system, muting may be set so that CSI-RSs transmitted by other base stations can be received without interference by terminals of the corresponding cell. The muting may be applied at a position where CSI-RS can be transmitted, and in general, the UE receives a traffic signal by skipping the corresponding radio resource. In the LTE-A system, muting is another term called zero-power CSI-RS. This is because, due to the nature of muting, it is applied to the location of the CSI-RS and transmission power is not transmitted.

In FIG. 2A, the CSI-RS is to be transmitted using a portion of the positions indicated by A, B, C, D, E, E, F, G, H, I, J according to the number of antennas for transmitting the CSI-RS. can Also, muting can be applied to some of the positions indicated by A, B, C, D, E, E, F, G, H, I, J. In particular, the CSI-RS may be transmitted with 2, 4, or 8 REs according to the number of transmitting antenna ports. When the number of antenna ports is 2, the CSI-RS is transmitted in half of the specific pattern in FIG. 2a. When the number of antenna ports is 4, the CSI-RS is transmitted over the entire specific pattern, and when the number of antenna ports is 8, two patterns are used. CSI-RS is transmitted. On the other hand, muting is always done in one pattern unit. That is, muting can be applied to a plurality of patterns, but cannot be applied to only a part of one pattern when the CSI-RS and the position do not overlap. However, only when the position of the CSI-RS and the position of the muting overlap, it can be applied only to a part of one pattern. When the CSI-RS for two antenna ports is transmitted, the CSI-RS transmits a signal of each antenna port in two REs connected in the time axis, and the signal of each antenna port is divided by an orthogonal code. In addition, when CSI-RSs for four antenna ports are transmitted, two additional REs are used in addition to CSI-RSs for two antenna ports, and signals for two additional antenna ports are transmitted in the same manner. The same is true when CSI-RSs for 8 antenna ports are transmitted. In the case of CSI-RS supporting 12 and 16 antenna ports, three CSI-RS transmission positions for the existing 4 antenna ports are combined or two CSI-RS transmission positions for 8 antenna ports are combined.

In addition, the UE may be allocated CSI-IM (or IMR, interference measurement resources) together with the CSI-RS, and the resource of the CSI-IM has the same resource structure and location as the CSI-RS supporting 4port. CSI-IM is a resource for a terminal receiving data from one or more base stations to accurately measure interference from an adjacent base station. For example, if it is desired to measure the amount of interference when the neighboring base station transmits data and the amount of interference when it does not transmit data, the base station configures a CSI-RS and two CSI-IM resources, and one CSI-IM is The signal is always transmitted and the other CSI-IM prevents the neighboring base station from always transmitting the signal, so that the amount of interference of the neighboring base station can be effectively measured.

Table 4 below shows the RRC field constituting the CSI-RS configuration.

Table 4 RRC settings to support periodic CSI-RS in the CSI process

The configuration for reporting the channel state based on the periodic CSI-RS in the CSI process can be classified into four types as shown in Table 2. The CSI-RS config is for setting the frequency and time location of the CSI-RS RE. Here, the number of ports of the corresponding CSI-RS is set by setting the number of antennas. Resource config sets the RE location in the RB, and Subframe config sets the period and offset of the subframe. Tables 5 and 6 are tables for resource config and subframe config settings currently supported by LTE.

CSI Reference
signal
configuration Number of CSI reference signals configured 1 or 2 4 8 (k', l') n _s mod 2 (k', l') n _s mod 2 (k', l') n _s mod 2


fra
me

str
uct
ure

ty
pe

One
and
2 0 (9,5) 0 (9,5) 0 (9,5) 0 One (11,2) One (11,2) One (11,2) One 2 (9,2) One (9,2) One (9,2) One 3 (7,2) One (7,2) One (7,2) One 4 (9,5) One (9,5) One (9,5) One 5 (8,5) 0 (8,5) 0 6 (10,2) One (10,2) One 7 (8,2) One (8,2) One 8 (6,2) One (6,2) One 9 (8,5) One (8,5) One 10 (3,5) 0 11 (2,5) 0 12 (5,2) One 13 (4,2) One 14 (3,2) One 15 (2,2) One 16 (1,2) One 17 (0,2) One 18 (3,5) One 19 (2,5) One fra
me

str
uct
ure

ty
pe2
on
ly 20 (11,1) One (11,1) One (11,1) One 21 (9,1) One (9,1) One (9,1) One 22 (7,1) One (7,1) One (7,1) One 23 (10,1) One (10,1) One 24 (8,1) One (8,1) One 25 (6,1) One (6,1) One 26 (5,1) One 27 (4,1) One 28 (3,1) One 29 (2,1) One 30 (1,1) One 31 (0,1) One

Table 5 Resource config settings

CSI-RS
Subframe config I _{CSI - RS} CSI-RS periodicity
T _{CSI - RS} (subframes)

(subframes)CSI-RS subframe offset

(subframes) 0 - 4 5 I _{CSI - RS} 5 - 14 10 I _{CSI - RS} -5 15 - 34 20 I _{CSI - RS} -15 35 - 74 40 I _{CSI - RS} -35 75 - 154 80 I _{CSI - RS} -75

Table 6 Subframe config settings

It is possible for the UE to check the frequency and time position, and the period and offset through Tables 5 and 6 above. Qcl-CRS-info sets quasi co-location information for CoMP. The CSI-IM config is for setting the frequency and time location of the CSI-IM for measuring interference. Since CSI-IM is always set based on 4 ports, there is no need to set the number of antenna ports, and Resource config and Subframe config are set in the same way as CSI-RS. The CQI report config exists to set how to report the channel status using the CSI process. The configuration includes periodic channel status report configuration, aperiodic channel status report configuration, PMI/RI report configuration, RI reference CSI process configuration, and subframe pattern configuration. In addition to this, there are a PC, which means a power ratio between the PDSCH and CSI-RS RE required for the UE to generate a channel state report, and a Codebook subset restriction that sets which codebook to use.

As described above, in the case of an FD-MIMO base station, a reference signal resource for measuring channels of eight or more antennas must be configured and transmitted to the terminal. In this case, the number of reference signals depends on the base station antenna configuration and measurement type. may be different. For example, in LTE/LTE-A release 13, it is possible to configure {1, 2, 4, 8, 12, 16}-port CSI-RS assuming full port mapping. Here, full port mapping means that all TXRUs have a dedicated CSI-RS port for channel estimation.

Meanwhile, as described above, there is a high possibility that 16 or more TXRUs will be introduced in LTE/LTE-A release 14 and later. In addition, the supported antenna array shape will be greatly increased compared to release 13. This means that various numbers of TXRUs should be supported in LTE/LTE-A release 14. Table 7 is a list of available two-dimensional antenna array structures according to the number of CSI-RS ports in the full port mapping situation.

Number of
aggregated
CSI-RS ports Number of aggregated
CSI-RS ports per polarization Available 2D antenna array geometry, (N ₁ , N ₂ )
(1D configurations were omitted) Impact on 2D RS and feedback design 18 9 (3,3) - - - Low 20 10 (2,5) (5,2) - - Med 22 11 - - - - - 24 12 (2,6) (3,4) (4,3) (6,2) High 26 13 - - - - - 28 14 (2,7) (7,2) - - Med 30 15 (3,5) (5,3) - - Med 32 16 (2,8) (4,4) (8,2) - High

Table 7 Available 2D antenna array geometry according to the number of aggregated CSI-RS ports based on full port mapping

In Table 7, {18, 20, 22, 24, 26, 28, 30, 32}-port CSI-RS is considered, and considering that two different polarized antennas may exist in the same position in the polarized antenna structure, { 9, 10, 11, 12, 13, 14, 15, 16} different AP positions may be considered. On the other hand, the shape of the two-dimensional rectangular or square antenna array is determined by the number of branches N1 of different AP positions in the first dimension (vertical or horizontal direction) and the number of branches N2 of different AP positions in the second dimension (horizontal or vertical direction). can be represented and the possible combinations for each port number are as (N1, N2) in Table 7. Table 7 means that various cases of antenna array shapes may exist according to the number of CSI-RS ports.

In the cellular system, the base station must transmit a reference signal to the terminal in order to measure the downlink channel state. In the case of 3GPP's LTE-A (Long Term Evolution Advanced) system, the terminal measures the channel state between the base station and itself using CRS or Channel Status Information Reference Signal (CSI-RS) transmitted by the base station. do. In the channel state, several factors should be basically considered, and this includes the amount of interference in the downlink. The amount of interference in the downlink includes an interference signal and thermal noise generated by an antenna belonging to an adjacent base station, and is important for the UE to determine the downlink channel condition. For example, when a signal is transmitted from a base station having one transmit antenna to a terminal having one receive antenna, the terminal uses a reference signal received from the base station to receive energy per symbol in downlink and in a section for receiving the corresponding symbol. At the same time, it is necessary to determine the amount of interference to be received and determine Es/Io. The determined Es/Io is converted into a data rate or a value corresponding thereto, and is notified to the base station in the form of a channel quality indicator (CQI), so that the base station transmits the data to the terminal at a certain data rate in the downlink. to be able to decide whether

In the case of the LTE-A system, the terminal feeds back information on the downlink channel state to the base station so that it can be utilized for downlink scheduling of the base station. That is, the terminal measures the reference signal transmitted by the base station in the downlink and feeds back the information extracted thereto to the base station in the form defined by the LTE/LTE-A standard. In LTE/LTE-A, there are three main types of information fed back by the UE.

- Rank indicator (RI): the number of spatial layers that the UE can receive in the current channel state

- Precoder Matrix Indicator (PMI): An indicator for the precoding matrix preferred by the UE in the current channel state

- Channel Quality Indicator (CQI): the maximum data rate that the terminal can receive in the current channel state (data rate). CQI may be replaced with SINR, a maximum error-correcting code rate and modulation scheme, and data efficiency per frequency, which can be utilized similarly to the maximum data rate.

The RI, PMI, and CQI are related to each other and have meaning. For example, the precoding matrix supported by LTE/LTE-A is defined differently for each rank. Therefore, when RI has a value of 1, the PMI value and when RI has a value of 2, the PMI value is interpreted differently even if the value is the same. Also, it is assumed that the rank value and PMI value notified to the base station are applied by the base station even when the terminal determines the CQI. That is, when the terminal notifies the base station of RI_X, PMI_Y, and CQI_Z, when the rank is RI_X and the precoding is PMI_Y, it means that the terminal can receive the data rate corresponding to CQI_Z. In this way, when the UE calculates the CQI, it assumes which transmission method to perform to the base station, so that optimized performance can be obtained when actual transmission is performed using the corresponding transmission method.

In the case of a base station having a large-scale antenna in order to generate and report the channel information, a reference signal resource for measuring channels of eight or more antennas must be configured and transmitted to the terminal. As shown in FIG. 2b , the available CSI-RS resources can use up to 48 REs, but it is currently possible to configure up to 8 CSI-RSs per one CSI process. Therefore, a new CSI-RS configuration method is needed to support an FD-MIMO system that can operate based on 8 or more CSI-RS ports. For example, in LTE/LTE-A release 13, 1, 2, 4, 8, 12 or 16 CSI-RS ports may be configured in one CSI process. Specifically, in the case of {1, 2, 4, 8}-port CSI-RS, the same mapping rule is followed, and in the case of 12-port CSI-RS, it is a combination of three 4-port CSI-RS patterns (aggregation) configured, and in the case of a 16-port CSI-RS, it is composed of a combination of two 8-port CSI-RS patterns. In addition, in LTE/LTE-A release 13, code division multiplexing (CDM)-2 or CDM-4 using an orthogonal cover code (OCC, orthogonal cover code) of length 2 or 4 for 12-/16-port CSI-RS support The description of FIG. 2C relates to CSI-RS power boosting based on CDM-2. According to the description, for full power utilization of the CDM-2 based 12-/16-port CSI-RS, a maximum of 9 dB compared to PDSCH power boosting is required. This means that high-performance hardware is required for full power utilization when operating CDM-2 based 12-/16-port CSI-RS. In release 13, in consideration of this, a 12-/16-port CSI-RS based on CDM-4 was introduced. In this case, full power utilization is possible through the same 6dB power boosting as before. In addition, in release 14, CDM-8-based CSI-RS was introduced for CSI-RS up to 32-port.

As mentioned above, in NR (New Radio) MIMO for 5G, a large number of antennas such as 1024 are supported and a high frequency band such as 30 GHz is supported. Wireless communication using these millimeter waves exhibits high straightness and high path loss due to the characteristics of the corresponding band. need. 2D is a diagram illustrating such a hybrid beamforming system.

In FIG. 2D , the base station and the terminal include an RF chain and a phase shifter for digital beamforming and analog beamforming. The analog beamforming method at the transmitting side is a method of focusing a signal transmitted from each antenna using a plurality of antennas in a specific direction by changing the phase of a signal transmitted from each antenna through a phase shifter. For this purpose, an array antenna in a form in which a plurality of antenna elements are aggregated is used. If such transmission beamforming is used, it is possible to increase the propagation distance of the signal, and since the signal is hardly transmitted in any direction other than the corresponding direction, there is an advantage in that interference to other users is greatly reduced. Similarly, the receiving side can also perform receive beamforming by using the receiving array antenna, which also concentrates the reception of radio waves in a specific direction to increase the sensitivity of the received signal coming in that direction, and receives the signal coming in the direction other than the corresponding direction. Interfering signals can be blocked by excluding them from the signal.

On the other hand, since the wavelength of the radio wave becomes shorter as the transmission frequency increases, for example, when the antenna is configured at half-wavelength intervals, the array antenna may be configured with more element antennas in the same area. Accordingly, since a communication system operating in a high frequency band can obtain a relatively higher antenna gain compared to using the beamforming technique in a low frequency band, it is advantageous to apply the beamforming technique.

In such a beamforming technology, in order to obtain a higher antenna gain, in addition to applying an analog beamforming technology, hybrid beamforming is applied to digital precoding used to obtain a high data rate effect in an existing multi-antenna system. beamforming) is used. In this case, when a beam is formed through analog beamforming and one or more analog beams are formed, digital precoding similar to that applied in the existing multi-antenna is applied and transmitted in the baseband to receive a more reliable signal or to achieve a higher system capacity. can be expected In the present invention, when a base station and a terminal support analog, digital, or hybrid beamforming, a method for measuring beam quality according to the beam switching capability of the corresponding base station and the terminal, and reporting and using the corresponding information is proposed.

The most important thing in applying the beamforming is to select a beam direction optimized for the corresponding base station and the terminal. In order to select an optimized beam direction, the base station and the terminal may support beam sweeping using a plurality of time and frequency resources. 2E is a diagram illustrating beam sweeping operations of a terminal and a base station in time resources.

In FIG. 2E , a terminal or a base station transmits a reference signal using a different beam for a time resource for beam selection of the corresponding terminal or base station. At this time, the base station or the terminal that has received the reference signal measures the quality of the reference signal based on CSI, RSRP (Reference Signals Received Power), RSRQ (Reference Signals Received Quality), etc. One or a plurality of transmit or receive beams may be selected according to the. Although FIG. 2E shows that a reference signal based on a different beam is transmitted through a different time resource, the same may be applied to frequency and code resources. In such resource allocation for beam sweeping, the time required for beam sweeping should also be considered. In FIG. 2E, in the case of (a), beams are allocated to 6 consecutive symbols in order to sweep 6 beams, and accordingly, it takes 6 TS (assuming that one symbol length is TS). However, in the case of FIG. (b), it takes 11 TS to sweep the same beam, and accordingly, the time required for beam selection increases, which may decrease efficiency.

When performing beam sweeping for such analog, digital, and hybrid beamforming, characteristics of the corresponding beamforming and beam switching capabilities of the terminal and the base station must all be considered. In the case of an analog beam, the characteristics of a hardware-based phase shifter should be considered. In the case of an analog beam, since a hardware-based phase shifter is used, another analog beam cannot be transmitted in a frequency band. Therefore, other time resources must be considered for beam sweeping. In addition, in order to support different beam measurement in different time resources, the structure of the OFDM symbol should also be considered. 2F is a diagram illustrating the structure of an OFDM symbol.

In FIG. 2F, the OFDM symbol is divided into a CP (Cyclic Prefix) part for preventing interference between OFDM symbols and a part in which data and reference signals are transmitted. The actual reference signal must be transmitted in the data and reference signal sections, and accordingly, the phase shift operation of the phase shifter of the base station or the terminal must be performed within the CP length of the corresponding OFDM symbol. However, the phase shift operation support of the terminal phase shifter may differ for each terminal depending on the structure of the phase shifter implemented in the terminal, and accordingly, the possibility of supporting the beam sweeping operation in consecutive symbols for each symbol may also be different for each terminal. have. In addition, in addition to the phase shift switching capability of the terminal, the OFDM symbol structure according to the numerology supported by the base station and the terminal should also be considered. Table 4 shows the CP length according to subcarrier spacing.

Subcarrier spacing
(kHz) CP length
(us) Subcarrier spacing
(kHz) CP length
(us) 15 4.7 120 585 30 2.35 240 293 60 1.17 480 146

Table 8 CP length of OFDM symbol according to subcarrier spacing

As shown in the table above, when the subcarrier spacing is increased, the CP length is reduced in inverse proportion to this. Accordingly, the time during which the terminal and the base station can switch beams through the phase shift of the RF circuit is reduced. For example, if beam switching of the terminal is possible within 400 ns, 15, 30, 60, and 120 kHz marked in black in Table 3 are capable of beam switching through consecutive symbols, but 240 and 480 kHz are consecutive symbols. It is impossible to switch beams using The present invention selects and allocates or measures another beam according to the beam switching capabilities of the terminal and the base station, so that the terminal and the base station can perform beam sweeping according to the beam switching capabilities of the corresponding terminal and the base station. Also, in the present invention, the corresponding resource is described based on a time resource (OFDM symbol), but the corresponding resource may include a frequency, a code division resource, and the like. In addition, in the above, only the beam switching capability according to the time required by the phase shifter of the terminal was included, but various beam switching capabilities such as a beam switching capability for digital precoding, hybrid beamforming, and a beam switching capability considering a plurality of panels are included. can be considered. In addition to this, the following is exemplified as a beam switching capability in a continuous resource, but the corresponding resource does not necessarily have to be continuous, and the difference between the corresponding time period, frequency, or code division resource is all that the terminal cannot handle with switching capability. cases may be included.

A method applicable when the transmitter transmitting the reference signal for beam sweeping does not have information on the beam switching capability of the receiver or when a terminal supporting beam switching in an allocated resource and a terminal not supporting it are mixed, etc. The receiver measures a reference signal within a measurable range, and in the case of a beam that has not been measured, it can be measured at a later transmission time or resource. 2G is a diagram illustrating operations of the terminal and the base station according to the first embodiment.

It is assumed that the receiver is allocated a reference signal for beam sweeping as shown in (a) of FIG. 2E. In this case, the beam switching capability of the terminal may not support beam switching in the allocated resource. When all terminals share the corresponding condition, the base station can allocate a reference signal for beam sweeping to the terminal as shown in (b) of FIG. 2e, but a specific terminal performs beam sweeping even under the reference signal as shown in (a) of FIG. If this is possible, the reference signal allocation based on continuous resources as shown in (a) of FIG. 2E is advantageous because it enables efficient use of resources such as time required for beam sweeping. However, in the case of a specific terminal, since measurement is impossible in the allocated resource, a method for measuring all beams based on the corresponding reference signal allocation is required. In FIG. 2G, it is assumed that one OFDM symbol is possible as a guard period for the corresponding terminal for beam switching. In FIG. 2G, since the UE cannot measure all of the given OFDM symbols 1/2/3/4/5/6, it has to select and measure the assigned reference signal. Therefore, in the first measurement period, the beam quality is measured and determined by measuring the reference signal of symbols 1/3/5 of FIG. 2G among the allocated reference signals. When the corresponding reference signal is periodically transmitted in the time resource, the terminal measures the reference signal of the 2/4/6 symbols that have not been measured except for the 1/3/5 symbols of FIG. 2g already measured at the second measurement time. Beam quality can be measured and determined. Therefore, by dividing the beam sweeping into several times and performing the beam sweeping, it is possible to perform beam sweeping according to the beam switching capabilities of the corresponding terminal and the base station. Although one OFDM symbol is required for beam switching in the above, the amount of resources required for such switching may vary, and frequency and code resources may also be considered.

However, the above operation is possible only when the corresponding base station allocates the corresponding reference signal to the terminal periodically or semi-persistently, which can be measured at the next reception, even if it is not received, and periodically or semi-persistently. Even if it is assigned, if a measurement restriction is set or assumed in which the reference signal transmission at a specific time point and the reference signal transmission at the previous time point are not assumed to be the same, such subsequent reception operation cannot be performed. 2H shows a case in which a reference signal having the same characteristics is not transmitted.

As shown in FIG. 2H , if one beam is not received, it may be impossible to re-receive the corresponding beam later, and accordingly, it is necessary to notify the base station that the corresponding beam has not been properly received. Furthermore, since the quality of the beam is different from that of not receiving it, if the quality is low, the corresponding beam need not be used for actual data transmission, but if it is not received, the corresponding beam may be an optimal beam. A signal notifying the base station that reception and generation of channel state information is impossible in the reference signal transmission is required. The operation of notifying the base station that channel state information generation is impossible is possible through the following method.

- Reference signal reception and channel information generation impossible indication method 1: Delivered through direct DCI signal

- Reference signal reception and channel information generation impossibility indication method 2: Transmits and delivers a specific bit promised in the channel status report

- Reference signal reception and channel information generation impossible indication method 3: Unmeasured channel status report information is transmitted by not transmitting

The first method is a method of transmitting through a direct DCI signal. For example, if the terminal did not correctly receive the reference signal from the base station by placing a 1-bit signal separately in the uplink control signal (PUCCH format 2, 2a, 3, 4, etc. in the case of LTE) through which the channel state information is transmitted to the base station, or This indicates that the channel state information has not been correctly generated. In addition, a plurality of bits may be used for a plurality of channel state information reporting assumptions (eg, CSI process of LTE) or a plurality of cells (eg, carrier aggregation of LTE). These plurality of bits may be arranged according to the order of the channel state information report ID, measurement setting ID, cell ID, etc. in the standard. For example, the MSB notifies whether a measurement with a low ID is received, and the LSB notifies whether a measurement with a high ID is received. As another example, the UE may check a CSI-RS resource having an optimal channel state through RSRP, RSRQ, CQI, etc., and may deliver it in the form of a CSI-RS resource indicator (CRI). At this time, a plurality of resources must be configured to report the CRI, and among them, specific resources may not be measured or channel state information may not be properly generated. Accordingly, the UE notifies the base station of which resource among the CSI-RS resources configured for the CRI for each CRI has not been properly measured. At this time, resources that are not measured among the configured CSI-RS resources may be processed as follows.

- Non-measurable CSI-RS resource processing method for CRI report 1: When selecting a CRI, selection is made based on the most recently created channel state report on the CSI-RS resource or RSRP, RSRQ, etc.

- Non-measurable CSI-RS resource processing method for CRI report 2: A resource that cannot be measured or for which channel state information is not generated is not included in CRI selection, and is selected based on resources for which channel state information is generated

Method 1 of processing non-measurable CSI-RS resources for CRI report is a method of selecting a CRI based on the most recently generated channel state report or RSRP, RSRQ, etc. in the corresponding CSI-RS resource. Even if the corresponding CSI-RS resource has not been measured, an approximate selection is possible by referring to the most recent measurement result of the corresponding resource, and through this, more accurate CRI selection may be possible. In this case, even in aperiodic CSI-RS transmission, it is more advantageous when precoding having the same or similar characteristics is transmitted in the corresponding resource.

Method 2 of processing non-measurable CSI-RS resources for CRI report is a method of selecting resources based on resources for which channel state information is generated without including resources for which measurement is not possible or for which channel state information is not generated in CRI selection. If the corresponding CSI-RS resource is not measured, the precoding applied to the corresponding CSI-RS resource may have completely different characteristics from the precoding in the previous transmission. can occur Therefore, it can be excluded to prevent such errors.

In addition, when the UE selects some ports among CSI-RS resources when reporting channel state information in addition to the CSI-RS resources required for CRI selection and reports channel state information to the base station, the measurement fails or the generation of channel state information fails. It is also possible to indicate the CSI-RS port.

The indicator indicating the CSI-RS unmeasurable resource processing method may be configured so that the base station reports to the terminal through RRC or MAC CE configuration. For example, in a low band such as 2 GHz or 4 GHz, there is less room for such a problem, and thus the usefulness of the above report may be low. Accordingly, by enabling the setting of such a report to be turned on and off, it is possible to configure the report according to the needs of the base station. In addition, it is possible to indirectly set whether the report is made or not made according to the frequency band used by the base station. For example, if the frequency to which the terminal is accessing is less than (or less than) 6 GHz, the indicator is not reported, and when the frequency exceeds (or greater than) 6 GHz, the indicator is reported. In addition, even when the synchronization signal of the corresponding system supports transmission of a plurality of synchronization signals or beam transmission, reporting of the corresponding indicator may be indirectly configured.

The indicator used in the non-measurable CSI-RS resource processing method 1 for the above-mentioned CRI report is a measurement failure indicator (Measurement failure indicator), an RF failure indicator (RF failure indicator), a beam measurement failure indicator (Beam measurement failure indicator) , a valid channel state information indicator (Valid CSI indicator), a valid CSI-RS resource indicator (Valid CSI-RS resource indicator), a valid CSI-RS port indicator (Valid CSI-RS port indicator) It can be expressed in various names such as.

The second method is to transmit and deliver a specific bit promised in the channel status report. The UE delivers information such as CRI, RI (Rank indicator), PMI (Precoder matrix indicator), and CQI (Channel quality indicator) to the base station through channel state information. At this time, since some or all of the channel state information is fixed and transmitted to a specific bit, the reference signal measurement and channel state report generation such as the cell, measurement setting, channel state report setting, reference signal setting, etc. were not accurately performed to the base station. can inform For example, in the case of CRI and RI information, there are not many corresponding bits and consumes a lot of resources for transmission, but in the case of PMI or CQI, because it consumes relatively few resources and uses many bits, report using one of the corresponding values. can make it For example, when PMI is 0, CQI is 0, or both PMI and CQI are 0, it indicates that measurement of a corresponding reference signal or generation of a channel state report has failed. Through this, it is possible to indicate the corresponding measurement failure and the generation failure of the channel state report without using additional UCI overhead.

The third method is a method in which the channel state report is not performed with respect to the reference signal resource, cell, CSI process, measurement configuration, channel state report configuration, etc. that fail to measure or generate a report. It is a natural operation for the UE to preferentially measure the first transmitted reference signal and then measure the transmitted reference signal when measuring the beam. Accordingly, the base station determines the number of channel state reports reported by the UE and the preset or transmitted reference signal. It may be assumed that the UE has measured according to the signal measurement order or the reference signal measurement priority. Therefore, it is possible to indirectly check the reference signal that the UE has not measured or the reference signal that does not generate the channel state information through the reported number. Also, a reference signal measurement priority may be set for the above operation. For example, when a reference signal requiring another beam is set at the same time, one reference signal having priority may be measured. The following method is possible as a method of setting such priorities.

- Reference signal measurement priority setting method 1: Judging through the priority set in advance in the standard

- Reference signal measurement priority setting method 2: Judgment based on the priority delivered through setting by the base station

- Reference signal measurement priority setting method 3: Judgment through priority through transmitted time

The reference signal measurement priority setting method 1 is a method of determining through the priority set in advance in the standard. For example, the UE indirectly determines the measurement priority of the reference signal through the cell ID, CSI-RS ID, or CSI-RS type (Type I, Type II, non-precoded, beamformed) set for the UE in the standard. It can be identified to generate measurement and channel state information, and can be used for channel state reporting.

The reference signal measurement priority setting method 2 is a method of determining based on the priority transmitted by the base station through RRC setting. Indirect priority setting can reduce signaling overhead, but limits the freedom of configuration. Therefore, the priorities can be set by setting such priorities through RRC or MAC CE.

The reference signal measurement priority setting method 3 is a method of determining the priority through the transmitted time. As mentioned above, the UE is measuring the first transmitted reference signal, and in this case, it may not be able to measure the transmitted reference signal or generate channel state information. Accordingly, it may be determined that the reference signal transmitted within k slots (or subframes or mini-slots) from time n at which the reference signal is transmitted has a lower measurement priority. At this time, this k may be transmitted by the terminal to the base station as UE capability, and the base station may be allowed to assume that this UE capability is actually k or set to the terminal as an integer having a value larger than this.

Although the above embodiment has been described on the assumption that the transmitter and the receiver are a base station and a terminal, respectively, in the case of an uplink, the transmitter and the receiver may be a terminal and a base station, respectively. In addition, when the side link is considered, it is possible that both the corresponding transmitter and the receiver are terminals.

2J is a flowchart illustrating an operation sequence according to an embodiment of the present invention.

In FIG. 2J , the terminal or the base station determines whether the beam switching capability of the corresponding terminal or base station can support the corresponding reference signal allocation in the entire reference signal pool used for beam sweeping. At this time, for such determination, OFDM symbol structure, CP length, subcarrier spacing, beam switching time that the terminal or base station can support through a phase shifter, precoding supportable unit, etc. may be considered. If the terminal or base station can support the corresponding reference signal pool in the corresponding step, the terminal or the base station performs beam sweeping using the entire reference signal pool in a later step. The base station supports the corresponding beam sweeping operation by measuring or allocating only the signals measurable by the corresponding terminal or the base station among the entire reference signal pool.

2K is a flowchart illustrating an operation sequence of a terminal according to an embodiment of the present invention.

Referring to FIG. 2K , the UE receives configuration information for configuration of a reference signal (CSI-RS, Mobility RS, Sychronization Signal, etc.) for beam sweeping in step 2k-10. In addition, the terminal based on the received configuration information, the number of ports for each reference signal, the number of antennas for each dimension N1 and N2, the oversampling factors for each dimension O1 and O2, one subframe for transmitting a plurality of reference signals It is possible to check at least one of a plurality of resource configs for setting config and location, codebook subset restriction related information, report related information, CSI-process index, and transmission power information. Thereafter, the terminal configures one piece of feedback configuration information based on at least one reference signal position in step 2k-20. In the corresponding information, PMI/CQI period and offset, RI period and offset, wideband/subband or not, submode, etc. may be set. When the terminal receives the reference signal based on the corresponding information in step 2k-40, the channel between the base station antenna and the reception antenna of the terminal is estimated based on this. In step 1040, the UE generates feedback information (rank, PMI and CQI or RSRP, RSRQ, etc.) using the received feedback configuration based on the estimated channel or signal reception quality. Thereafter, the terminal transmits the feedback information to the base station at a feedback timing determined according to the feedback setting of the base station in step 2k-50 to complete the feedback generation and reporting process.

2L is a flowchart illustrating an operation sequence of a base station according to an embodiment of the present invention.

Referring to FIG. 2L, in step 2l-10, the base station transmits configuration information for reference signals (CSI-RS, Mobility RS, Sychronization Signal, etc.) for beam sweeping to the terminal. The configuration information includes the number of ports for each reference signal, N1 and N2 that are the number of antennas for each dimension, O1 and O2 that are oversampling factors for each dimension, one subframe config for transmitting the reference signal, and a plurality of resources for setting the location It may include at least one of config, codebook subset restriction related information, CSI report related information, CSI-process index, and transmission power information. Thereafter, the base station transmits feedback configuration information based on at least one reference signal to the terminal in steps 2l-20. In the corresponding information, PMI/CQI period and offset, RI period and offset, wideband/subband or not, submode, etc. may be set. Thereafter, the base station transmits the configured reference signal to the terminal. The terminal estimates a channel for each antenna port, generates PMI, RI, CQI, RSRP, RSRQ, etc. corresponding thereto and transmits the generated PMI, RI, CQI, RSRP, and RSRQ to the base station. Accordingly, the base station receives the feedback information from the terminal at the timing determined in steps 21-30, and uses it to determine the channel state between the terminal and the base station.

2M is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention.

Referring to FIG. 2M , the terminal includes a communication unit 2m-10 and a control unit 2m-20. The communication unit 2m-10 performs a function of transmitting or receiving data from the outside (eg, a base station). Here, the communication unit 2m-10 may transmit feedback information to the base station under the control of the control unit 2m-20. The control unit 2m-20 controls the state and operation of all components constituting the terminal. Specifically, the control unit 2m-20 generates feedback information according to information allocated from the base station. In addition, the control unit 2m-20 controls the communication unit 2m-10 to feed back the generated channel information to the base station according to timing information allocated from the base station. To this end, the controller 2m-20 may include a channel estimator 2m-30. The channel estimator 2m-30 determines necessary feedback information based on a reference signal received from the base station and feedback allocation information, and estimates a channel using the received reference signal based on the feedback information. In addition, based on the DCI transmitted by the base station, the size and rank of the PRG corresponding to the PDSCH transmission described in the embodiment of the present invention, and the reference signal mapping to which the precoder is applied to the DMRS port is applied to decode the PDSCH. In FIG. 2M , an example in which the terminal includes the communication unit 2m-10 and the control unit 2m-20 has been described, but the present invention is not limited thereto, and various configurations may be further provided according to functions performed in the terminal. For example, the terminal may further include a display unit for displaying the current state of the terminal, an input unit for receiving a signal such as performing a function from a user, a storage unit for storing data generated in the terminal, and the like. In addition, although it is illustrated that the channel estimator 2m-30 is included in the controller 2m-20, the present invention is not limited thereto. The control unit 2m-20 may control the communication unit 2m-10 to receive configuration information for each of at least one or more reference signal resources from the base station. In addition, the control unit 2m-20 may control the communication unit 2m-10 to measure the at least one reference signal and receive feedback setting information for generating feedback information according to the measurement result from the base station. have.

In addition, the control unit 2m-20 may measure at least one or more reference signals received through the communication unit 2m-10 and generate feedback information according to the feedback setting information. In addition, the control unit 2m-20 may control the communication unit 2m-10 to transmit the generated feedback information to the base station at a feedback timing according to the feedback setting information. In addition, the control unit 2m-20 receives a reference signal (CSI-RS, Mobility RS, Synchronization Signal, etc.) from the base station, generates feedback information based on the received reference signal, and uses the generated feedback information to the base station. can be sent to In this case, the control unit 2m-20 may select a precoding matrix, a beam index, an antenna port, a resource index, and the like according to the information of the base station.

2N is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention.

Referring to FIG. 2N , the base station includes a control unit 2n-10 and a communication unit 2n-20. The control unit 2n-10 controls the state and operation of all components constituting the base station. Specifically, the control unit 2n-10 allocates a reference signal (CSI-RS, Mobility RS, Synchronization Signal, etc.) resource for channel estimation of the UE to the UE, and allocates a feedback resource and a feedback timing to the UE. To this end, the controller 2n-10 may further include a resource allocator 2n-30. In addition, feedback setting and feedback timing are allocated so that feedback from multiple terminals does not collide, and feedback information set at the corresponding timing is received and interpreted. The communication unit 2n-20 performs a function of transmitting and receiving data, a reference signal, and feedback information to the terminal. Here, the communication unit 2n-20 transmits a reference signal to the terminal through the allocated resources under the control of the controller 2n-10, and receives feedback on channel information from the terminal. In the above description, the resource allocator 2n-30 is illustrated as being included in the controller 2n-10, but the present invention is not limited thereto. The controller 2n-10 may control the communication unit 2n-20 to transmit configuration information for each of the at least one or more reference signals to the terminal, or may generate the at least one or more reference signals. Also, the controller 2n-10 may control the communication unit 2n-20 to transmit feedback setting information for generating feedback information according to the measurement result to the terminal. In addition, the control unit 2n-10 controls the communication unit 2n-20 to transmit the at least one reference signal to the terminal and receive feedback information transmitted from the terminal at a feedback timing according to the feedback setting information. can do. In addition, the control unit 2n-10 may transmit feedback configuration information to the terminal, transmit a reference signal to the terminal, and receive feedback information generated based on the feedback configuration information and the reference signal information from the terminal. have. In this case, the controller 2n-10 may transmit feedback configuration information corresponding to each antenna port group of the base station and additional feedback configuration information based on the relationship between the antenna port groups. In addition, the controller 2n-10 may transmit a beamformed CSI-RS to the terminal based on the feedback information, and receive feedback information generated based on the reference signal from the terminal.

<Third embodiment>

A term for identifying an access node used in the following description, a term referring to network entities, a term referring to messages, a term referring to an interface between network objects, and a term referring to various identification information and the like are exemplified for convenience of description. Therefore, the present invention is not limited to the terms described below, and other terms referring to objects having equivalent technical meanings may be used.

For convenience of description, the present invention uses terms and names defined in the 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) standard. However, the present invention is not limited by the above terms and names, and may be equally applied to systems conforming to other standards.

3A is a diagram illustrating the structure of an existing LTE system.

Referring to FIG. 3A , the wireless communication system includes a plurality of base stations 3a-05, 3a-10. 3a-15, 3a-20, a Mobility Management Entity (MME, 3a-25), and a Serving S-GW (Serving). -Gateway, 3a-30). User Equipment (hereinafter referred to as UE or terminal, 3a-35) accesses an external network through base stations 3a-05, 3a-10, 3a-15, 3a-20 and S-GW 3a-30. .

The base stations 3a-05, 3a-10, 3a-15, and 3a-20 are access nodes of a cellular network and provide wireless access to terminals accessing the network. That is, the base stations 3a-05, 3a-10, 3a-15, and 3a-20 collect and schedule status information such as buffer status, available transmission power status, and channel status of terminals to service users' traffic. to support connection between the terminals and a core network (CN). The MME 3a-25 is a device in charge of various control functions as well as a mobility management function for the UE, and is connected to a plurality of base stations, and the S-GW 3a-30 is a device that provides a data bearer. In addition, the MME (3a-25) and the S-GW (3a-30) may further perform authentication (authentication), bearer management, etc. for the terminal accessing the network, and the base stations 3a-05 , 3a-10, 3a-15, 3a-20) or a packet to be delivered to the base stations 3a-05, 3a-10, 3a-15, 3a-20.

One base station can generally transmit and receive multiple carriers over several frequency bands. For example, when a carrier having a forward center frequency of f1 and a carrier having a forward center frequency of f2 are transmitted from the base station 3a-05, one terminal transmits and receives data using one of the two carriers in the prior art. did. However, a terminal having a carrier aggregation capability can transmit and receive data through multiple carriers at the same time. The base stations 3a-05, 3a-10, 3a-15, and 3a-20 can increase the transmission speed of the terminal by allocating more carriers according to the situation to the terminal 3a-35 having the carrier aggregation capability. have. As described above, aggregation of the forward and reverse carriers transmitted and received by one base station is called carrier aggregation (CA) within the base station. In a traditional sense, when one forward carrier transmitted by one base station and one reverse carrier received by the base station constitute one cell, carrier aggregation means that the terminal transmits and receives data through several cells at the same time. it could be Through this, the maximum transmission rate is increased in proportion to the number of aggregated carriers.

Hereinafter, in the present specification, that the terminal receives data through an arbitrary forward carrier or transmits data through an arbitrary reverse carrier means a control channel and a data channel provided by a cell corresponding to the center frequency and frequency band characterizing the carrier. It has the same meaning as sending and receiving data using In this specification, in particular, carrier aggregation will be expressed as 'a plurality of serving cells are configured', and with respect to the serving cell, a Primary Serving Cell (PCell) and a Secondary Serving Cell (hereinafter referred to as SCell), Or, a term such as an activated serving cell will be used. PCell and SCell are terms indicating the type of serving cell configured in the UE. There are some differences between the PCell and the SCell, for example, the PCell always maintains an active state, whereas the SCell repeats the active state and the inactive state according to the instruction of the base station. The mobility of the UE is controlled based on the PCell, and the SCell can be understood as an additional serving cell for data transmission and reception. PCell and SCell in the embodiments of the present invention mean PCell and SCell defined in LTE standards 36.331 or 36.321. The above terms have the meaning as they are used in the LTE mobile communication system. In the present invention, terms such as carrier, component carrier, and serving cell are used interchangeably.

In a typical CA in a base station, the UE through a Physical Uplink Control Channel (PUCCH) of the PCell, a Hybrid Automatic Repeat request (HARQ) feedback and channel state information (Channel) for the PCell State Information (hereinafter CSI) as well as HARQ feedback and CSI for the SCell are transmitted. This is in order to apply the CA operation even to a UE in which simultaneous uplink transmission is impossible. In LTE Rel-13 eCA (enhanced CA), an additional SCell having PUCCH is defined and up to 32 carriers can be aggregated. The PUCCH SCell is limited to a serving cell belonging to a Mast Cell Group (MCG). The MCG means a set of serving cells controlled by a base station (Master eNB, MeNB) that controls the PCell, and the SCG is a base station that is not a base station that controls the PCell, that is, a base station that controls only secondary cells (SCells). Secondary eNB, SeNB) refers to a set of serving cells. Whether a specific serving cell belongs to the MCG or the SCG, the base station informs the terminal in the process of setting the corresponding serving cell. In addition, the base station informs the UE whether each SCell belongs to the PCell group or the PUCCH SCell group.

3B is a diagram illustrating a radio protocol structure of an existing LTE system.

Referring to FIG. 3b, the radio protocol of the LTE system is PDCP (Packet Data Convergence Protocol 3b-05, 3b-40), RLC (Radio Link Control 3b-10, 3b-35), MAC (Medium Access) in the UE and the eNB, respectively. Control 3b-15, 3b-30). The PDCPs 3b-05 and 3b-40 are in charge of IP header compression/restore operations. The main functions of PDCP are summarized below.

- Header compression and decompression (ROHC only)

- Transfer of user data

- In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM

- Order reordering function (For split bearers in DC (only support for RLC AM): PDCP PDU routing for transmission and PDCP PDU reordering for reception)

- Duplicate detection of lower layer SDUs at PDCP re-establishment procedure for RLC AM)

- Retransmission function (Retransmission of PDCP SDUs at handover and, for split bearers in DC, of PDCP PDUs at PDCP data-recovery procedure, for RLC AM)

- Encryption and decryption function (Ciphering and deciphering)

- Timer-based SDU discard in uplink.

The radio link control (Radio Link Control, hereinafter referred to as RLC) 3b-10, 3b-35 reconfigures a PDCP PDU (Packet Data Unit) to an appropriate size to perform ARQ operation and the like. The main functions of RLC are summarized below.

- Data transfer function (Transfer of upper layer PDUs)

- ARQ function (Error Correction through ARQ (only for AM data transfer))

- Concatenation, segmentation and reassembly of RLC SDUs (only for UM and AM data transfer)

- Re-segmentation of RLC data PDUs (only for AM data transfer)

- Reordering of RLC data PDUs (only for UM and AM data transfer)

- Duplicate detection (only for UM and AM data transfer)

- Protocol error detection (only for AM data transfer)

- RLC SDU discard function (RLC SDU discard (only for UM and AM data transfer))

- RLC re-establishment function (RLC re-establishment)

The MACs 3b-15 and 3b-30 are connected to several RLC layer devices configured in one terminal, and perform operations of multiplexing RLC PDUs into MAC PDUs and demultiplexing RLC PDUs from MAC PDUs. The main functions of MAC are summarized below.

- Mapping function (Mapping between logical channels and transport channels)

- Multiplexing/demultiplexing of MAC SDUs belonging to one or different logical channels into/from transport blocks (TB) delivered to/from the physical layer on transport channels)

- Scheduling information reporting function (Scheduling information reporting)

- HARQ function (Error correction through HARQ)

- Priority handling between logical channels of one UE

- Priority handling between UEs by means of dynamic scheduling

- MBMS service identification

- Transport format selection

- Padding function

The physical layer (3b-20, 3b-25) channel-codes and modulates upper layer data, creates an OFDM symbol and transmits it over a radio channel, or demodulates and channel-decodes an OFDM symbol received through the radio channel and transmits it to an upper layer do the action

Although not shown in this figure, an RRC (Radio Resource Control, hereinafter referred to as RRC) layer exists above the PDCP layer of the terminal and the base station, and the RRC layer provides access and measurement related configuration control messages for radio resource control. can give and receive

3C is a diagram illustrating 2, 4, 8 antenna port CSI-RS transmission using radio resources of 1 subframe and 1 RB (Resourced Block), which are the minimum units that can be scheduled in downlink in the existing LTE system.

The radio resource shown in FIG. 3C consists of one subframe on the time axis and one RB on the frequency axis. Such radio resources consist of 12 subcarriers in the frequency domain and 14 OFDM symbols in the time domain to have a total of 168 unique frequencies and time positions. In LTE/LTE-A, each natural frequency and time position of FIG. 3C is referred to as a resource element (RE).

A plurality of different types of signals as follows may be transmitted to the radio resource shown in FIG. 3C .

1. CRS (Cell Specific Reference Signal): A reference signal transmitted for all terminals belonging to one cell

2. DMRS (Demodulation Reference Signal): A reference signal transmitted for a specific terminal and used to perform channel estimation for reconstructing information carried on the PDSCH. One DMRS port is transmitted by applying the same precoding as the PDSCH layer connected thereto. A UE desiring to receive a specific layer of the PDSCH receives a DMRS port connected to the layer, performs channel estimation, and then uses this to restore information carried on the layer.

3. PDSCH (Physical Downlink Shared Channel): This is a data channel transmitted through downlink, which is used by the base station to transmit traffic to the UE and uses REs in which a reference signal is not transmitted in the data area of FIG. 3c. sent

4. CSI-RS (Channel Status Information Reference Signal): A reference signal transmitted for terminals belonging to one cell and used to measure the channel state. A plurality of CSI-RSs may be transmitted to one cell.

5. ZP-CSI-RS (Zero Power CSI-RS): The actual signal is not transmitted at the location where the CSI-RS is transmitted.

6. IMR (Interference Measurement Resource): Corresponds to a location where CSI-RS is transmitted, and one or more of A, B, C, D, E, F, G, H, I, J can be set as IMR in FIG. 3C has exist. The UE assumes that all signals received in REs configured as IMR are interference and performs interference measurement.

7. Other control channels (PHICH (Physical Hybrid-ARQ Indicator Channel), PCFICH (Physical Control Format Indicator Channel), PDCCH (Physical Downlink Control Channel)): Provides control information necessary for the UE to receive the PDSCH or uplink data ACK/NACK transmission for operating HARQ (Hybrid automatic repeat request) for transmission

In addition to the above signals, in the LTE-A system, zero power CSI-RSs may be configured so that CSI-RSs transmitted by different base stations may be received without interference by UEs of the corresponding cells. The zero power CSI-RS (muting) may be applied at a position where the CSI-RS can be transmitted, and in general, the UE skips the corresponding radio resource and receives a traffic signal. In the LTE-A system, zero power CSI-RS (muting) is also called muting by another term. This is because zero power CSI-RS (muting) is applied to the location of the CSI-RS and transmit power is not transmitted.

In FIG. 3C , the CSI-RS may be transmitted using a portion of the positions indicated by A, B, C, D, E, F, G, H, I, and J according to the number of antennas transmitting the CSI-RS. Also, muting can be applied to some of the positions indicated by A, B, C, D, E, F, G, H, I, and J. In particular, the CSI-RS may be transmitted with 2, 4, or 8 REs according to the number of transmitting antenna ports. When the number of antenna ports is 2, the CSI-RS is transmitted in half of the specific pattern in FIG. 3c. When the number of antenna ports is 4, the CSI-RS is transmitted over the entire specific pattern, and when the number of antenna ports is 8, two patterns are used. CSI-RS is transmitted. On the other hand, muting is always done in one pattern unit. That is, muting can be applied to a plurality of patterns, but cannot be applied to only a part of one pattern when the CSI-RS and the position do not overlap. However, only when the position of the CSI-RS and the position of the muting overlap, it can be applied only to a part of one pattern.

In addition, the UE may be allocated CSI-IM (or IMR, interference measurement resources) together with the CSI-RS, and the resource of the CSI-IM has the same resource structure and location as the CSI-RS supporting 4port. CSI-IM is a resource for a terminal receiving data from one or more base stations to accurately measure interference from an adjacent base station. For example, if it is desired to measure the amount of interference when the neighboring base station transmits data and the amount of interference when it does not transmit data, the base station configures a CSI-RS and two CSI-IM resources, and one CSI-IM is The signal is always transmitted and the other CSI-IM prevents the neighboring base station from always transmitting the signal, so that the amount of interference of the neighboring base station can be effectively measured.

In the LTE-A system, the base station may notify the terminal of CSI-RS configuration information through higher layer signaling. The CSI-RS configuration includes an index of CSI-RS configuration information, the number of ports included in the CSI-RS, CSI-RS transmission period, transmission offset, CSI-RS resource configuration information, CSI-RS Includes scrambling ID, quasi co-location (QCL) information, and the like.

When CSI-RSs for two antenna ports are transmitted, signals of each antenna port are transmitted from two REs connected in the time axis, and the signals of each antenna port are classified by orthogonal codes and are subjected to code division multiplexing (CDM). In addition, when CSI-RSs for four antenna ports are transmitted, signals for the remaining two antenna ports are transmitted in the same manner by using two REs in addition to CSI-RSs for two antenna ports. The same is true when CSI-RSs for 8 antenna ports are transmitted. In the case of transmitting more than 8 CSI-RSs of 12 and 16, 12 and 16 CSI-RSs are transmitted by combining positions where the existing 4 and 8 CSI-RSs are transmitted in the RRC configuration. In other words, when 12 CSI-RSs are transmitted, three 4-port CSI-RS transmission locations are bundled and transmitted as one 12-port CSI-RS, and when 16 CSI-RSs are transmitted, 8-port CSI-RS The two transmission positions are bundled and transmitted as one 16-port CSI-RS. In addition, one additional difference between 12 and 16-port CSI-RS transmission compared to the existing 8-port or less CSI-RS transmission is that a CDM having a size of 4 is supported. Existing CSI-RS of 8 ports or less supports CDM2 and transmits 2 CSI-RS 2 ports on 2 time symbols to support power boosting up to 6 dB based on 8 ports, so that full power can be used for CSI-RS transmission. have. However, in the case of 12-port or 16-port CSI-RS, since full power cannot be used for CSI-RS transmission with a combination of CDM2 and 6dB, CDM4 is supported for this case so that full power can be used.

3D is a diagram for explaining periodic CSI-RS configuration and operation in an existing LTE system.

Referring to FIG. 3D , the base station configures periodic CSI-RSs through RRC messages to the terminals (3d-05). The CSI-RS configuration includes an index of CSI-RS configuration information, the number of antenna ports included in the CSI-RS, a transmission period of the CSI-RS, a transmission offset, CSI-RS resource configuration information, CSI-RS resource configuration. Includes RS scrambling ID, quasi co-location (QCL) information, and the like. Since the existing LTE terminal does not support aperiodic CSI-RS transmission, the base station must always transmit periodic CSI-RS to report channel state information to the terminal.

Table 9 below shows the RRC field constituting the CSI-RS configuration.

Table 9 RRC settings to support periodic CSI-RS in the CSI process

The CSI-RS process is required to deliver channel information of each base station to a serving cell when there are multiple base stations to support Coordinated MultiPoint (CoMP), and currently supports up to four. The configuration for reporting the channel state based on the periodic CSI-RS in the CSI process can be classified into four types as shown in Table 9. The CSI-RS config is for setting the frequency and time location of the CSI-RS RE. Here, the number of ports of the corresponding CSI-RS is set by setting the number of antennas. The resource config sets the RE location in the RB, and the subframe config sets the period (3d-15) and offset (3d-10) of the subframe.

The base station transmits the CSI-RS (3d-20) through the corresponding resource according to the configured subframe config, and the terminal receives the periodically transmitted CSI-RS. In addition, the UE reports the value of the CSI-RS measured according to the CSI-RS reporting condition set by the base station. As the reporting method, a periodic or aperiodic reporting method may be used.

The above process continues until the base station changes the setting value through RRC reconfiguration (3d-25).

[Example 3-1]

FIG. 3E is a diagram for explaining multi-transmission CSI-RS and aperiodic CSI-RS configuration and activation/deactivation operations considered in the present invention.

In the case of multi-transmission CSI-RS (hereinafter referred to as multi-shot CSI-RS), the base station configures a periodic CSI-RS through an RRC message to the UEs (3e-05). The CSI-RS configuration includes an index of the existing CSI-RS configuration information, the number of antenna ports included in the CSI-RS, a transmission period of the CSI-RS, a transmission offset, CSI-RS resource configuration information, CSI -RS includes scrambling ID, quasi co-location (QCL) information, and the like. In addition, an indicator indicating that the CSI-RS configuration is for multi-shot CSI-RS may be included. Thereafter, the base station indicates which of the CSI-RS resources configured with the MAC control signal (Control Element, hereinafter, CE) is actually activated (3e-15). As described with reference to FIG. 3C, the CSI-RS may be transmitted using a portion of 1 to 8 indicated positions according to the number of antennas transmitting it. When the UE is instructed to activate the CSI-RS through the MAC CE, the UE performs the CSI-RS activation operation (CSI-RS reception) after X ms (eg, 8 ms, 3e-15) (3e-20). Therefore, since the corresponding operation is performed X ms after the MAC CE is successfully received, the MAC transmits the MAC CE reception time information (subframe number at the time of MAC CE reception) to the physical layer. After receiving and measuring the CSI-RS according to period information set through RRC, the CSI-RS measurement value is reported from the base station according to the CSI-RS reporting method determined. In the reporting method, periodic or aperiodic reporting is possible. Thereafter, the UE receives the CSI-RS deactivation through the MAC CE (3e-35), and after Y ms (eg, 8 ms, 3e-40) has elapsed after receiving this, the CSI-RS reception and CSI-RS reporting are deactivated. do. If CSI-RS is received for Y ms, the information is valid.

On the other hand, in the case of an aperiodic CSI-RS (hereinafter, Aperiodic CSI-RS), the base station configures the aperiodic CSI-RS through an RRC message to the UEs (3e-45). The CSI-RS configuration may or may not include the existing subframe config information, and an indicator indicating that the CSI-RS configuration is for aperiodic CSI-RS may be included. Thereafter, the base station indicates which of the CSI-RS resources configured for the MAC CE is actually activated (3e-50). As described with reference to FIG. 3C, the CSI-RS may be transmitted using a portion of 1 to 8 indicated positions according to the number of antennas transmitting it. When the UE is instructed to activate the CSI-RS through the MAC CE, the UE performs the CSI-RS activation operation (CSI-RS reception) after X ms (eg, 8 ms, 3e-55) (3e-60). Therefore, since the corresponding operation is performed after X ms (3e-65) from the time when the MAC CE is successfully received, the MAC transmits the MAC CE information (subframe number when MAC CE is received) to the physical layer. forward to The difference between the operation and the existing CSI-RS reception operation is that the CSI-RS transmission from the base station is transmitted together in a subframe in which DCI is transmitted aperiodically (3e-60). The UE receives DCI, receives and measures CSI-RS transmitted in the same subframe, and reports the CSI-RS measurement value according to the CSI-RS reporting method determined by the base station. Aperiodic reporting is possible in the reporting method. Afterwards, the UE receives CSI-RS deactivation through the MAC CE (3e-60), and after Y ms (eg, 8 ms, 3e-70) has elapsed after receiving this, CSI-RS reception and CSI-RS reporting are deactivated. do. If CSI-RS is received for Y ms, the information is valid.

In addition, in the CSI-RS configuration through the RRC message, the following method may be used to distinguish different configurations.

1. A method of including identification information indicating Multi-shot CSI-RS and Aperiodic CSI-RS in the existing CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used.

2. A method of including identification information indicating Multi-shot CSI-RS in the existing CSI-RS config IE, and introducing a new Aperiodic CSI-RS config IE for additional Aperiodic CSI-RS. The Aperiodic CSI-RS config IE does not include subframe config information.

3. A method of introducing a new New CSI-RS config IE in addition to the existing CSI-RS config IE. The New CSI-RS config IE includes an identifier that distinguishes the Multi-shot CSI-RS and the Aperiodic CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used

If one or more aperiodic/multi-shot CSI-RS resources are configured in the UE, the base station may use a newly defined MAC CE to indicate activation and deactivation of the CSI-RS resources. Through this, activation and deactivation of the CSI-RS resource can be determined more quickly and adaptively. In addition, the configured aperiodic/multi-shot CSI-RS resource may be initialized in an inactive state after initial configuration and handover. In the present invention, two design methods are proposed according to the signal structure of the MAC CE. The first MAC CE design method is that one MAC CE transmitted by the base station includes activation and deactivation commands for all serving cells, and the second method of MAC CE design is that one MAC CE includes activation and deactivation for a corresponding serving cell. to include only commands.

3F is a diagram illustrating a first method of a MAC control signal instructing activation and deactivation of a CSI-RS resource, proposed by the present invention.

As described above, in the first method of designing MAC CE, one MAC CE transmitted by the base station includes activation and deactivation commands for all serving cells. model can be distinguished. In the first model, the number of serving cells (serving cells having a high index in ServCellIndex) having the configured CSI-RS resource is 8 or less, and a 1-byte field (Ci, 3f-05) is used to indicate this. do. In the second model, the number of serving cells (serving cells having a high index in ServCellIndex) having set CSI-RS resources is greater than 8, and to indicate this, 4-byte fields (Ci, 3f-25) are used This is to support up to 32 serving cells. In the above design, it is a great feature to determine the format based on the index of the serving cell in which the CSI-RS resource is configured or the CSI process is configured.

In addition, fields indicating which CSI-RS resources are activated and deactivated for each CSI process of the serving cell (Ri, 3f-10, 3f-15, 3f-30, 3f-30, 3f-35, 3f-40) is used The CSI-RS resource command is characterized in that it is indicated only for activated serving cells, and consists of fields (Ri) of 1 byte like 3f-45.

MAC CE for activation and deactivation of CSI-RS may be defined as follows.

- Ci: this field indicates the presence of Activation/Deactivation CSI-RS command(s) for the serving cell with ServCellIndex i. The Ci field set to "1" indicates that Activation/Deactivation CSI-RS command(s) for the serving cell with ServCellIndex i are included. The Ci field set to "0" indicates that no Activation/Deactivation CSI-RS command for the serving cell with ServCellIndex i is included. The number of Activation/Deactivation CSI-RS command for a serving cell is same as the number of configured CSI-RS processes for the serving cell;

- Ri: this field indicates the activation/deactivation status of the CSI-RS resource associated with CSI-RS-ConfigNZPId i for the CSI-RS process.

In the above, Ri corresponds to CSI-RS-ConfigNZPId. That is, it means a CSI-RS resource in which the transmission power allocated to the same frequency in the same CSI process is not 0.

3G is a diagram illustrating a second method of a MAC control signal indicating activation and deactivation of a CSI-RS resource, proposed by the present invention.

The second method of designing the MAC CE is such that one MAC CE transmitted by the base station is defined as serving cell specific and includes only activation and deactivation commands for the corresponding serving cell. In the above design, it is characterized in that only the command for the serving cell from which the MAC CE for CSI-RS activation and deactivation is received is included. That is, since the MAC CE design second method is configured to be serving cell specific, there is no need to indicate the index of the serving cell, but only fields (Ri) indicating which CSI-RS resources are activated and deactivated for each CSI process of the serving cell. , 3g-05, 3g-10) are used. The CSI-RS resource command is characterized in that it is indicated only for activated serving cells, and consists of fields (Ri) of 1 byte as shown in 3f-15.

MAC CE for activation and deactivation of CSI-RS may be defined as follows.

- Ri: this field indicates the activation/deactivation status of the CSI-RS resource associated with CSI-RS-ConfigNZPId i for the CSI-RS process.

In the above, Ri corresponds to CSI-RS-ConfigNZPId. That is, it means a CSI-RS resource in which the transmission power allocated to the same frequency in the same CSI process is not 0.

The second method of designing the MAC CE may have an advantage because the structure is simple if the MAC CE can be transmitted in multiple cells. However, if the MAC CE cannot be transmitted in multiple cells, the first method of designing the MAC CE is a valid method.

3H is a diagram for explaining the entire operation in the multi-shot CSI-RS mode to which the present invention is applied.

The terminal 3h-01 receives system information from the base station 3h-03 (3h-05) and performs an RRC connection (3h-10). Thereafter, the terminal receives an RRC message for configuring a CSI-RS resource from the base station. The CSI-RS configuration includes an index of the existing CSI-RS configuration information, the number of antenna ports included in the CSI-RS, a transmission period of the CSI-RS, a transmission offset, CSI-RS resource configuration information, CSI -RS includes scrambling ID, quasi co-location (QCL) information, and the like. In addition, an indicator indicating that the CSI-RS configuration is for multi-shot CSI-RS may be included, and the following method may be used for CSI-RS configuration through the RRC message to distinguish different configurations. .

1. A method of including identification information indicating Multi-shot CSI-RS and Aperiodic CSI-RS in the existing CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used.

2. A method of including identification information indicating Multi-shot CSI-RS in the existing CSI-RS config IE, and introducing a new Aperiodic CSI-RS config IE for additional Aperiodic CSI-RS. The Aperiodic CSI-RS config IE does not include subframe config information.

3. A method of introducing a new New CSI-RS config IE in addition to the existing CSI-RS config IE. The New CSI-RS config IE includes an identifier that distinguishes the Multi-shot CSI-RS and the Aperiodic CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used

Thereafter, the base station indicates which of the CSI-RS resources configured through the MAC CE is actually activated (3h-20). As described with reference to FIG. 3C, the CSI-RS may be transmitted using a portion of 1 to 8 indicated positions according to the number of antennas transmitting it. When the UE is instructed to activate the CSI-RS through the MAC CE, the UE performs the CSI-RS activation operation (CSI-RS reception) after X ms (eg, 8 ms) (3e-25). That is, since the corresponding operation proceeds X ms after the MAC CE is successfully received, the MAC transmits the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer, Prepares CSI-RS configuration such as configured antenna port and subframe configuration, prepares for interference measurement, prepares to report CSI-RS measurement value according to the CSI-RS reporting method determined by the base station for the measured CSI-RS . In the reporting method, periodic or aperiodic reporting is possible. In step 3h-35, the terminal receives the CSI-RS from the base station according to a preset period. Thereafter, the UE receives CSI-RS deactivation through the MAC CE (3h-35), and the MAC transmits the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer. In addition, CSI-RS reception and CSI-RS reporting are inactivated after Y ms (eg, 8 ms) have elapsed since the reception thereof (3h-40). If CSI-RS is received for Y ms, the information is valid.

3I is a diagram for explaining the entire operation in the aperiodic CSI-RS mode to which the present invention is applied.

The terminal 3i-01 receives system information from the base station 3i-03 (3i-05), and performs an RRC connection (3i-10). Thereafter, the terminal receives an RRC message for configuring a CSI-RS resource from the base station. The CSI-RS configuration may or may not include the existing subframe config information, and an indicator indicating that the CSI-RS configuration is for aperiodic CSI-RS may be included. In addition, an indicator indicating that the CSI-RS configuration is for an Aperiodic CSI-RS may be included, and the following method may be used for CSI-RS configuration through the RRC message to distinguish different configurations.

1. A method of including identification information indicating Multi-shot CSI-RS and Aperiodic CSI-RS in the existing CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used.

2. A method of including identification information indicating Multi-shot CSI-RS in the existing CSI-RS config IE, and introducing a new Aperiodic CSI-RS config IE for additional Aperiodic CSI-RS. The Aperiodic CSI-RS config IE does not include subframe config information.

3. A method of introducing a new New CSI-RS config IE in addition to the existing CSI-RS config IE. The New CSI-RS config IE includes an identifier that distinguishes the Multi-shot CSI-RS and the Aperiodic CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used

Thereafter, the base station indicates which of the CSI-RS resources configured through the MAC CE is actually activated (3i-20). As described with reference to FIG. 3C, the CSI-RS may be transmitted using a portion of 1 to 8 indicated positions according to the number of antennas transmitting it. When the UE is instructed to activate the CSI-RS through the MAC CE, the UE performs the CSI-RS activation operation (CSI-RS reception) after X ms (eg, 8 ms) (3e-25). That is, since the corresponding operation proceeds X ms after the MAC CE is successfully received, the MAC transmits the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer, It monitors CSI-RS reception in a subframe for receiving DCI, prepares for interference measurement, and prepares to report the CSI-RS measurement value according to the CSI-RS reporting method determined by the base station for the measured CSI-RS. Aperiodic reporting is possible in the reporting method. Thereafter, the UE receives CSI-RS deactivation through the MAC CE (3i-35), and the MAC transmits the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer. In addition, CSI-RS reception and CSI-RS reporting are inactivated after Y ms (eg, 8 ms) have elapsed since the reception thereof (3i-40). If CSI-RS is received for Y ms, the information is valid.

FIG. 3j is a diagram illustrating the entire UE operation of CSI-RS activation and deactivation using MAC CE proposed in the present invention.

The UE in the RRC connection state receives the CSI-RS configuration from the base station (3j-05). According to the type of the CSI-RS configuration, since the base station varies the CSI-RS resource and transmission operation, the operation of the terminal is also changed. In addition, the configured aperiodic/multi-shot CSI-RS resource may be initialized in an inactive state after initial configuration and handover. In the CSI-RS configuration through the RRC message, the following method may be used to distinguish different configurations.

1. A method of including identification information indicating Multi-shot CSI-RS and Aperiodic CSI-RS in the existing CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used.

2. A method of including identification information indicating Multi-shot CSI-RS in the existing CSI-RS config IE, and introducing a new Aperiodic CSI-RS config IE for additional Aperiodic CSI-RS. The Aperiodic CSI-RS config IE does not include subframe config information.

3. A method of introducing a new New CSI-RS config IE in addition to the existing CSI-RS config IE. The New CSI-RS config IE includes an identifier that distinguishes the Multi-shot CSI-RS and the Aperiodic CSI-RS config IE. If the Aperiodic CSI-RS is indicated, the subframe config information set in the CSI-RS config IE is not used

In step 3j-10, the UE analyzes the CSI-RS configuration information received from the base station and determines which type it is. Type 1 is the existing periodic CSI-RS reception operation, and it can be determined based on the identification method according to the CSI-RS config method.

If the Type 2 operation is determined by the UE analyzing the CSI-RS configuration information received from the base station in step 3j-10, the UE performs the operation shown in FIG. 3H. That is, the operation is performed in the multi-shot CSI-RS mode. That is, it receives which of the CSI-RS resources configured through the MAC CE is actually activated (3j-20). Since the corresponding operation is performed after X ms from the time when the MAC CE is successfully received, the MAC transfers the information (subframe number when receiving the MAC CE) to the physical layer when the MAC CE is received (3j- 25), prepare CSI-RS configuration such as configured antenna port and subframe configuration, prepare for interference measurement, report the CSI-RS measurement value according to the CSI-RS reporting method determined by the base station for the measured CSI-RS. Prepare (3j-30). In step 3h-35, the terminal receives the CSI-RS from the base station according to a preset period, and reports the measurement value to the base station. In the reporting method, periodic or aperiodic reporting is possible. Thereafter, the UE receives CSI-RS deactivation through the MAC CE (3h-40), and the MAC transfers the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer (3h-45). . In addition, CSI-RS reception and CSI-RS reporting are inactivated after Y ms (eg, 8 ms) have elapsed since the reception thereof (3h-50). If CSI-RS is received for Y ms, the information is valid.

If the UE analyzes the CSI-RS configuration information received from the base station in step 3j-10 and the Type 3 operation is determined, the UE performs the operation in FIG. 3i. That is, the operation is performed in aperiodic CSI-RS mode. That is, the UE checks which of the CSI-RS resources configured through MAC CE reception is actually activated (3j-55). When the UE is instructed to activate the CSI-RS resource through the MAC CE, the UE performs the CSI-RS activation operation (CSI-RS reception) after X ms (eg, 8 ms). That is, since the corresponding operation is performed X ms after the MAC CE is successfully received, the MAC transmits the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer ( 3j-60), preparation for interference measurement, preparing to report the measured CSI-RS according to the CSI-RS reporting method determined from the base station (3j-65), and a subframe for receiving DCI CSI-RS reception is monitored in (3j-70). Aperiodic reporting is possible in the reporting method. Thereafter, the UE receives CSI-RS deactivation through the MAC CE (3j-75), and the MAC transfers the MAC CE reception time information (subframe number upon MAC CE reception) to the physical layer (3j-80). ,. In addition, CSI-RS reception and CSI-RS reporting are inactivated after Y ms (eg, 8 ms) have elapsed since the reception thereof (3j-85). If CSI-RS is received for Y ms, the information is valid.

3K is a diagram illustrating a method of using a counter in the operation of CSI-RS activation and deactivation using MAC CE proposed in the present invention.

As another embodiment of performing the entire operation of the terminal in FIG. 3J, the operation when a timer such as sCellDeactivationTimer is introduced may be specified. The UE in the RRC connection state receives the CSI-RS configuration from the base station (3k-05). According to the type of the CSI-RS configuration, since the base station varies the CSI-RS resource and transmission operation, the operation of the terminal is also changed. In step 3k-10, the UE analyzes the CSI-RS configuration information received from the base station and determines which type it is. Type 1 is the existing periodic CSI-RS reception operation (3k-15), and it can be determined based on the identification method according to the CSI-RS config method. If the operation of Type 2 or 3 is confirmed through the CSI-RS configuration information, the UE may check the activated CSI-RS resource by receiving the MAC CE (3k-20). Upon receiving the above time point, that is, MAC CE, the UE starts CSIRSDeactivationTimer. That is, the CSIRSDeactivationTimer is driven for each cell in which the CSI-RS resource is configured or the CSI process is configured (or driven for each CSI process), and start/restart is at the time when the MAC CE that activates the resource is received, and when the timer expires Deactivate the resource (3k-35). In addition, a timer may be managed for each CSI-RS resource.

[Example 3-2]

3ka is a diagram illustrating an aperiodic CSI-RS and multi-shot CSI-RS transmission procedure according to the first embodiment. First, the base station may configure K CSI-RSs through RRC signaling (3ka-05). In this case, the K CSI-RSs may be configured for each CSI process in the case of LTE or by a CSI resource setting in the case of a new radio (NR) access network (or 5G network). Thereafter, the UE determines activation/deactivation settings for N≤K CSI-RS resources among the K CSI-RS resources. If the configured K is less than or equal to 4, the UE considers that the K CSI-RS resources are always activated (3ka-10). That is, in this case, it means that N=K. On the other hand, when K is greater than 4, the base station signals activation/deactivation for N=4 CSI-RS resources out of K through MAC CE according to Example 3-1 (3ka-15). Afterwards, if there is SubframeConfig information in the CSI-RS IE set to RRC, the base station and the UE promise this as a multi-shot CSI-RS to perform CSI-RS transmission/reception for the N CSI-RS resources (3ka-20 ). On the other hand, when there is no SubframeConfig information in the CSI-RS IE configured as RRC, the base station and the UE promise this as an aperiodic CSI-RS. The base station may announce one CSI-RS resource aperiodically transmitted among the N CSI-RS resources configured as the MAC CE to the terminal through DCI (3ka-25). At this time, the 'aperiodic transmission/measurement for a single CSI-RS resource' may indicate a single DCI code point to a plurality of CSI-RS resources, but in this case, each CSI-RS resource is connected to an individual CSI reporting. It means that only one aperiodic CSI-RS transmission can be performed per CSI reporting. Thereafter, the base station and the terminal perform aperiodic transmission/reception for the selected CSI-RS resource (3ka-30).

In NR, the CSI-RS and reporting can be configured as in the example of FIG. 3kaa. In the case of LTE, one or more CSI processes are configured, and at least one or more CSI-RS resource configuration information and CSI reporting information are included in each CSI process, and the UE generates and reports CSI based on this. On the other hand, in the case of NR, the UE checks information on at least one CSI-RS resource through N resource settings (3ka-1-05, 3ka-1-10), and M CSI reporting settings (3ka-1-10) 15, 3ka-1-20), it is possible to check configuration information for at least one or more CSI reporting. At this time, one resource setting (3ka-1-40) may include at least one CSI-RS resource set (3ka-1-45) consisting of at least one CSI-RS resource (3ka-1-50). . In addition, the terminal can check information about L links (3ka-1-30, 3ka-1-35) that provide a relationship between one resource setting and one reporting setting through the measurement setting (3ka-1-25). have. In order to refer to the frequency/time resource for the aperiodic CSI-RS transmission, it is possible to use an indicator related to the resource setting or an indicator related to the link of the measurement setting. Therefore, in the description below, 'selecting/indicating a CSI-RS resource' can be expressed as selecting or indicating a 'resource setting index' or selecting or indicating a 'link index'.

Embodiment 3-2 provides methods for extending aperiodic transmission/measurement for a single CSI-RS resource in Embodiment 3-1 to aperiodic transmission/measurement for multiple CSI-RS resources. In order to support aperiodic transmission / measurement of multiple CSI-RS resources, it is necessary to specify a plurality of CSI-RS resources that are aperiodically transmitted, and if L1 signaling capability (or DCI payload) for this is not sufficient In this case, methods are needed to alleviate it. In the following description, a part about multi-shot CSI-RS other than aperiodic CSI-RS will be omitted for convenience of description.

The first method is a plurality of aperiodic CSI-RS resources having the same transmission timing or the same L1 signaling timing (eg, transmitted within the same slot or transmission is designated by the same DCI) through MAC CE signaling. To set up a subgroup composed of The CSI-RS resource subgroup may be variously expressed according to circumstances such as a resource subgroup and a link subgroup. The detailed procedure of the first method is as follows. First, the base station may configure K CSI-RSs through RRC signaling (3kb-05). If K is greater than a specific constant, the base station signals activation/deactivation for N CSI-RS resource subgroups out of K through MAC CE (3kb-10). At this time, each CSI-RS resource subgroup includes at least one CSI-RS resource among the K CSI-RS resources set to the RRC. Thereafter, the base station may notify the UE of one CSI-RS resource subgroup transmitted aperiodically among the N CSI-RS resource subgroups configured as the MAC CE through DCI (3kb-15). In this case, one DCI code point in the 'aperiodic transmission/measurement for a single CSI-RS resource subgroup' may refer to a plurality of CSI-RS resource subgroups including a plurality of CSI-RS resources, but at this time each CSI-RS resource Subgroups are linked to individual CSI reporting. Thereafter, the base station and the terminal perform aperiodic transmission/reception for CSI-RS resources included in the selected CSI-RS resource subgourp (3kb-20).

In the first method, it is possible to configure the CSI-RS resource subgroup through the MAC CE through the following options. Option 1a is to have as many two-dimensional bitmaps as the number of subgroups. For example, the first dimension of the bitmap means selection of K CSI-RS resources configured for RRC as in Example 1, and the second dimension of the bitmap is N CSI activated/deactivated with the MAC CE. - It may mean selection for the RS resource subgroup. Option 1b is a method of designating a CSI-RS resource subgroup through a bitmap group or an alphabet sequence. For example, suppose that when K = 8 CSI-RS resources are set to RRC, N = 3 resource subgroups can be set through alphabets A, B, and C. In this case, the UE through the MAC CE setting such as [AABBC 0 0 0], the first and second resources are in subgroup A, the third and fourth resources are in subgroup B, the fifth resource is in subgroup C, and the sixth, It can be recognized that the seventh and eighth resources are not activated.

3kba is a diagram illustrating one detailed example of signaling for activation and deactivation of a CSI-RS resource subgroup through MACE CE in the first method. In this method, one MAC CE transmitted by the base station includes activation and deactivation commands for all serving cells, and can be divided into two models according to the number of serving cells having set CSI-RS resources. In the above, the first model is a case in which the number of serving cells (serving cells having a high index in ServCellIndex) having the configured CSI-RS resources is 8 or less, and to indicate this, a 1-byte field (Ci, 3kb-1-05) is used In the second model, the number of serving cells (serving cells having a high index in ServCellIndex) having the configured CSI-RS resources is greater than 8, and to indicate this, 4-byte fields (Ci, 3k-1-20) ) is used. This is to support up to 32 serving cells. In the above design, it is a great feature to determine the format based on the index of the serving cell in which the CSI-RS resource is configured.

In addition, fields (Ri, 3kb-1-10, 3kb-1-15, 3kb-1-25, 3kb-1-30) indicating which CSI-RS resource is activated and deactivated for each serving cell are used. The CSI-RS resource subgroup command is characterized in that it is indicated only for activated serving cells, and is composed of one-dimensional fields (Rij) such as 3kb-1-45 or {3kb-1-60, 3kb-1-65 , 3kb-1-70} may be composed of two-dimensional fields (Rij). In 3kb-1-45, a one-dimensional field may consist of a total of KN bits. This is to indicate whether the K CSI-RS resources for the N CSI-RS resource subgroups are included. For example, when K CSI-RS resources are set to RRC and N CSI-RS resource subgroups are configured based on these, the i-th N bit group {Ri1, ... , Rij, … , RiN} can be used to indicate activation / deactivation of the i-th CSI-RS resource. 3kb-1-50 is an example of 1-byte MAC CE signaling in the case of {K=4, N=2} in this example, and 3kb-1-55 is an example of {K=2, N=4} in this example. This is an example of 1-byte MAC CE signaling. In {3kb-1-60, 3kb-1-65, 3kb-1-70}, the 2D field may consist of N bitmaps composed of K bits. This is to indicate whether the K CSI-RS resources for the N CSI-RS resource subgroups are included. For example, if K = 8, 1-byte signaling 3kb-1-60, 3kb-1-65, 3kb-1-70 is a CSI-RS resource for the first, second, and Nth CSI-RS subgroup, respectively. Can be used to indicate activation/deactivation.

MAC CE for activation and deactivation of CSI-RS may be defined as follows.

- Ci: this field indicates the presence of Activation/Deactivation CSI-RS command(s) for the serving cell with ServCellIndex i. The Ci field set to "1" indicates that Activation/Deactivation CSI-RS command(s) for the serving cell with ServCellIndex i are included. The Ci field set to "0" indicates that no Activation/Deactivation CSI-RS command for the serving cell with ServCellIndex i is included.

- Ri: this field indicates the activation/deactivation status of the CSI-RS resource associated with CSI-RS-ConfigNZPId i

In the above, Ri corresponds to CSI-RS-ConfigNZPId. That is, it means a CSI-RS resource in which the transmission power allocated to the corresponding serving cell is not 0.

If one MAC CE transmitted by the base station is defined as serving cell specific, the MAC CE may be promised to include only activation and deactivation commands for the corresponding serving cell. In the above design, it is characterized in that only the command for the serving cell from which the MAC CE for CSI-RS activation and deactivation is received is included. In this case, there is no need to indicate the index of the serving cell as shown in FIG. 3kb-1 (that is, 3kb-1-05 or 3kb-1-20 is omitted) and only a certain CSI-RS resource is activated for each CSI process of the serving cell. and fields (Ri, 3kb-1-10, 3kb-1-15, 3kb-1-25, 3kb-1-30) indicating whether or not to be deactivated may be used.

In the first method, the resource selection relation by RRC/MAC CE/DCI configuration is equal to 3kb-30.

The second method is to select a CSI-RS resource subgroup for the aperiodic CSI-RS transmission through DCI based on a rule predetermined by a standard or subgroup configuration information predetermined by RRC. The detailed procedure of the second method is as follows. First, the base station may configure K CSI-RSs through RRC signaling (3kc-05). If K is greater than a specific constant, the base station signals activation/deactivation for N CSI-RS resources out of K through MAC CE (3kc-10). Thereafter, the base station transfers one CSI-RS resource subgroup aperiodically transmitted among a plurality of CSI-RS resource subgroups including at least one CSI-RS resource among the N CSI-RS resources set to the MAC CE through DCI to the terminal. (3kc-15). In this case, one DCI code point in the 'aperiodic transmission/measurement for a single CSI-RS resource subgroup' may refer to a plurality of CSI-RS resource subgroups including a plurality of CSI-RS resources, but at this time each CSI-RS resource Subgroups are linked to individual CSI reporting. Thereafter, the base station and the terminal perform aperiodic transmission/reception for CSI-RS resources included in the selected CSI-RS resource subgourp (3kc-20).

In the second method, the CSI-RS resource subgroup consisting of at least one CSI-RS resource among the CSI-RS resources activated/deactivated through MAC CE is to be set through the following options. Option 2a is to designate the subgroup setting method in advance according to the standard. For example, when N=2, it is possible to indicate aperiodic CSI-RS transmission for a CSI-RS resource subgroup with 2-bit DCI by specifying a rule as shown in <Table 10>. According to <Table 10>, DCI code point '00' means that aperiodic CSI-RS transmission is not performed, and '01' is the first (having the lowest RRC configuration order or the lowest CSI-RS activated by MAC CE). CSI-RS with /link ID is transmitted aperiodically, '10' indicates that the second (having the second RRC configuration order or having the second CSI-RS/link ID) CSI-RS activated with MAC CE is Aperiodic transmission, and '11' may be promised to mean that all CSI-RSs activated by MAC CE are aperiodically transmitted.

DCI bits for N=2 Contents 00 No aperiodic CSI-RS transmission 01 Aperiodic CSI-RS in config #1 10 Aperiodic CSI-RS in config #2 11 Aperiodic CSI-RS in config #1 and #2

Option 2a can be extended according to possible DCI payloads, DCI signaling methods, and the number of activated/deactivated resources. For example, if an independent 3-bit DCI payload is available and the number of activated/deactivated CSI-RS/links is N=4, specify a rule as shown in <Table 11> to use 3-bit DCI aperiodic for CSI-RS resource subgroup It is possible to indicate CSI-RS transmission. According to <Table 11>, DCI code point '00' means that aperiodic CSI-RS transmission is not performed, and subsequent DCI code points are RRC configuration order or CSI-RS among CSI-RS resources activated by MAC CE. /link ID may be promised to select a CSI-RS resource transmitted aperiodically according to ascending/descending order.

DCI bits for N=4 Contents 000 No aperiodic CSI-RS transmission 001 Aperiodic CSI-RS in config #1 010 Aperiodic CSI-RS in config #2 011 Aperiodic CSI-RS in config #3 100 Aperiodic CSI-RS in config #4 101 Aperiodic CSI-RS in config #1 and #2 110 Aperiodic CSI-RS in config #2 and #3 111 Aperiodic CSI-RS in config #3 and #4

Option 2b is to pre-designate subgroup configuration information through RRC. For example, when N=2, it is possible to indicate aperiodic CSI-RS transmission for a CSI-RS resource subgroup with 2-bit DCI by specifying a rule as shown in <Table 12>. According to <Table 12>, DCI code point '00' means that aperiodic CSI-RS transmission is performed for CSI-RS resource subgroup #1 set as RRC, and '01' is CSI-RS resource subgroup set as RRC. It means that aperiodic CSI-RS transmission for #2 is performed, '10' means that aperiodic CSI-RS transmission is performed for CSI-RS resource subgroup #3 set as RRC, and '11' is set as RRC It may be promised to mean that aperiodic CSI-RS transmission for the CSI-RS resource subgroup #4 is performed. In this case, it is possible to define each CSI-RS resource subgroup information configured as RRC in a relative configuration order for CSI-RS resources activated/deactivated by MAC CE. It is also possible that a specific RRC setting value for the CSI-RS resource subgroup (eg, such as '00...0') is promised to mean that aperiodic CSI-RS transmission is not performed.

DCI bits for N=2 Contents 00 Aperiodic CSI-RS in subgroup #1 01 Aperiodic CSI-RS in subgroup #2 10 Aperiodic CSI-RS in subgroup #3 11 Aperiodic CSI-RS in subgroup #4

Option 2b can be extended according to possible DCI payloads, DCI signaling methods, and the number of activated/deactivated resources. According to <Table 13>, DCI code point '000' means that aperiodic CSI-RS transmission for CSI-RS resource subgroup #1 of the first serving cells set to RRC is performed, and '001' is set to RRC. It may be promised to mean that aperiodic CSI-RS transmission for CSI-RS resource subgroup #2 of the second serving cells is performed. The description of the remaining DCI code points is similar to this and thus will be omitted. In this case, it is possible to define each CSI-RS resource subgroup information configured as RRC in a relative configuration order for CSI-RS resources activated/deactivated by MAC CE.

DCI bits for N=3 Contents 000 Aperiodic CSI-RS in subgroup #1 for a 1st set of serving cells configured by higher layers 001 Aperiodic CSI-RS in subgroup #2 for a 2nd set of serving cells configured by higher layers 010 Aperiodic CSI-RS in subgroup #3 for a 3rd set of serving cells configured by higher layers 011 Aperiodic CSI-RS in subgroup #4 for a 4th set of serving cells configured by higher layers 100 Aperiodic CSI-RS in subgroup #5 for a 5th set of serving cells configured by higher layers 101 Aperiodic CSI-RS in subgroup #6 for a 6th set of serving cells configured by higher layers 110 Aperiodic CSI-RS in subgroup #7 for a 7th set of serving cells configured by higher layers 111 Aperiodic CSI-RS in subgroup #8 for a 8th set of serving cells configured by higher layers

In the second method, the CSI-RS subgroup configuration through RRC can be signaled through the relationship as shown in FIG. 3kca. According to FIG. 3kca, it is possible for the base station to map possible CSI-RS subgroup combinations through a total of E RRC code points. It is possible for the UE to identify the relationship between Ue and CSI-RS/link IDs signaled by RRC through the mapping.

In the second method, the resource selection relation by RRC/MAC CE/DCI configuration is equal to 3kc-30.

The third method is to directly designate two or more CSI-RS resources through DCI to indicate aperiodic CSI-RS transmission. The detailed procedure of the third method is as follows. First, the base station may configure K CSI-RSs through RRC signaling (3kd-05). If K is greater than a specific constant, the base station signals activation/deactivation for N CSI-RS resources out of K through MAC CE (3kd-10). Thereafter, the base station determines whether aperiodic transmission of a plurality of CSI-RS resources including up to X (eg, 2 or 3) CSI-RS resources among the N CSI-RS resources set to the MAC CE DCI It can be notified to the terminal through (3kd-15). Thereafter, the base station and the terminal perform aperiodic transmission/reception for CSI-RS resources included in the selected CSI-RS resource subgroup (3kd-20). In the case of the third method, a large amount of DCI payload may be required. For example, when N=6 and X=2, 4 bits may be required to represent the number of 6C2=15 cases, which may be a heavy burden for DCI transmission. Thus, it is possible to promise down-selection for some code points. Alternatively, when N=4 or less, corresponding DCI signaling may be promised as a bitmap for aperiodic transmission of each CSI-RS resouce activated/deactivated by MAC CE.

In the third method, the resource selection relation by RRC/MAC CE/DCI configuration is equal to 3kd-30.

A fourth method is to support activation/deactivation of individual CSI-RS resources and CSI-RS resource subgroup configuration through MAC CE, respectively. In the fourth method, the number of activated/deactivated CSI-RS resources N' and the number N of CSI-RS subgroups selected by DCI may be different. According to FIG. 3ke, first, the base station may configure K CSI-RSs through RRC signaling (3ke-05). If K is greater than a specific constant, the base station signals activation/deactivation for N' CSI-RS resources out of K through MAC CE (3ke-10). Thereafter, the base station configures N CSI-RS resource (or link) subgroups including at least one of N' CSI-RS resources activated/deactivated with the MAC CE (3ke-15). Thereafter, the base station may notify the terminal of one CSI-RS resource subgroup transmitted aperiodically among the N CSI-RS resource subgroups configured as the MAC CE through DCI (3ke-20). Thereafter, the base station and the terminal perform aperiodic transmission/reception of CSI-RS resources included in the selected CSI-RS resource subgroup (3ke-20).

For the fourth method, the base station may provide two types of MAC CE signaling. First, activation/deactivation signaling for K CSI-RS resources is provided through a bitmap consisting of K bits, such as 3ke-30. The UE can know that N' CSI-RS resources are activated/deactivated through this. Based on this, the base station sets up N CSI-RS subgroups including at least one of the N' activated CSI-RS resources. For example, the base station transmits N CSI-RS subgroup configuration information to the terminal through a one-dimensional bitmap consisting of N'N bits (Dij) like 3ke-35, or an N two-dimensional bitmap consisting of N' bits. can be notified to In this example, Dij indicates whether the j-th activated CSI-RS is included in the CSI-RS subgroup from i=1 to i=N. In this case, j may be understood as a relative value determined according to the RRC configuration order or CSI-RS/link ID ascending/descending order among CSI-RS resources activated by the MAC CE.

3L is a block diagram illustrating the configuration of a terminal according to an embodiment of the present invention.

Referring to FIG. 3L, the terminal includes a transceiver 3l-05, a controller 3l-10, a multiplexer and demultiplexer 31-15, a control message processor 3l-30, and various upper layer processing units 3l. -20, 3l-25), EPS bearer manager (3l-35) and NAS layer devices (3l-40).

The transceiver 31-05 receives data and a predetermined control signal through a forward channel of a serving cell and transmits data and a predetermined control signal through a reverse channel. When a plurality of serving cells are configured, the transceiver 31-05 performs data transmission/reception and control signal transmission/reception through the plurality of serving cells.

The multiplexing and demultiplexing unit 3l-15 multiplexes the data generated by the upper layer processing units 3l-20 and 3l-25 or the control message processing unit 3l-30, or transmits data received from the transceiver 31-05. After demultiplexing, it serves to transmit to the appropriate upper layer processing units 3l-20 and 3l-25 or the control message processing unit 3l-30.

The control message processing unit 31-30 is an RRC layer device and processes a control message received from the base station to take necessary operations. For example, if RRC CONNECTION SETUP message is received, SRB and temporary DRB are set.

The upper layer processing units 31-20 and 31-25 refer to DRB devices and may be configured for each service. It processes data generated from user services such as FTP (File Transfer Protocol) or VoIP (Voice over Internet Protocol) and transmits it to the multiplexing and demultiplexing unit 3l-15 or from the multiplexing and demultiplexing unit 3l-15. It processes the transmitted data and delivers it to the service application of the upper layer. One service may be mapped one-to-one with one EPS bearer and one upper layer processing unit.

The control unit 31-10 checks the scheduling command received through the transceiver 31-05, for example, reverse grants, and multiplexes it with the transceiver 31-05 so that the reverse transmission is performed with an appropriate transmission resource at an appropriate time. and the demultiplexing unit 3l-15. Also, the controller 31-10 may measure at least one or more reference signals received through the transceiver 31-05 and generate feedback information according to the feedback setting information. The controller 31-10 may control the transceiver 31-05 to transmit the generated feedback information to the base station at a feedback timing according to the feedback setting information. In addition, the control unit 31-10 receives a CSI-RS (Channel Status Indication-Reference Signal) from the base station, generates feedback information based on the received CSI-RS, and transmits the generated feedback information to the base station. can At this time, the control unit 31-10 selects a precoding matrix for each antenna port group of the base station, and adds one additional precoding matrix based on the relationship between the antenna port groups of the base station. You can choose.

Also, the controller 31-10 may receive a CSI-RS from the base station, generate feedback information based on the received CSI-RS, and transmit the generated feedback information to the base station. In this case, the controller 31-10 may select one precoding matrix for all antenna port groups of the base station. In addition, the control unit 31-10 receives feedback configuration information from the base station, receives the CSI-RS from the base station, generates feedback information based on the received feedback configuration information and the received CSI-RS, and The generated feedback information may be transmitted to the base station. In this case, the control unit 31-10 may receive feedback setting information corresponding to each antenna port group of the base station and additional feedback setting information based on the relationship between the antenna port groups.

3M is a block diagram illustrating the configuration of a base station, an MME, and an S-GW according to an embodiment of the present invention.

The base station apparatus of FIG. 3m includes a transceiver unit 3m-05, a control unit 3m-10, a multiplexing and demultiplexing unit 3m-20, a control message processing unit 3m-35, various upper layer processing units 3m-25, 3m-30), a scheduler (3m-15), EPS bearer devices (3m-40, 3m-45) and NAS layer devices (3m-50). The EPS bearer device is located in the S-GW, and the NAS layer device is located in the MME.

The transceiver 3m-05 transmits data and a predetermined control signal on a forward carrier and receives data and a predetermined control signal on a reverse carrier. When multiple carriers are configured, the transceiver 3m-05 performs data transmission/reception and control signal transmission/reception through the multiple carriers.

The multiplexing and demultiplexing unit 3m-20 multiplexes the data generated by the upper layer processing unit 3m-25, 3m-30 or the control message processing unit 3m-35, or transmits data received from the transceiver 3m-05. After demultiplexing, it plays a role in delivering to the appropriate upper layer processing unit (3m-25, 3m-30), control message processing unit (3m-35), or control unit (3m-10). The control message processing unit 3m-35 processes the control message transmitted by the terminal to take a necessary action, or generates a control message to be transmitted to the terminal and transmits it to a lower layer.

The upper layer processing units (3m-25, 3m-30) can be configured for each EPS bearer, and the data transmitted from the EPS bearer device is configured as RLC PDUs and delivered to the multiplexing and demultiplexing unit (3m-20) or multiplexed and demultiplexed. The RLC PDU delivered from the unit 3m-20 is configured as a PDCP SDU and delivered to the EPS bearer device.

The scheduler allocates transmission resources to the terminal at an appropriate time in consideration of the buffer state and channel state of the terminal, and processes the signal transmitted by the terminal to the transceiver or transmits a signal to the terminal to the transceiver.

The EPS bearer device is configured for each EPS bearer, processes the data transmitted from the upper layer processing unit, and delivers it to the next network node.

The upper layer processing unit and the EPS bearer device are interconnected by the S1-U bearer. The upper layer processing unit corresponding to the common DRB is connected by the EPS bearer for the common DRB and the common S1-U bearer.

The NAS layer device processes the IP packet contained in the NAS message and delivers it to the S-GW.

In addition, the control unit 3m-10 controls the state and operation of all components constituting the base station. Specifically, the control unit 3m-10 allocates a CSI-RS resource for channel estimation of the UE to the UE, and allocates a feedback resource and a feedback timing to the UE. In addition, feedback setting and feedback timing are allocated so that feedback from multiple terminals does not collide, and feedback information set at the corresponding timing is received and interpreted. The transceiver 3m-05 performs a function of transmitting and receiving data, a reference signal, and feedback information to the terminal. Here, the transceiver 3m-05 transmits the aperiodic CSI-RS to the UE through the allocated resources under the control of the control unit 3m-10, and receives feedback on channel information from the UE. The controller 3m-10 may control the transceiver 3m-05 to transmit configuration information for each of the at least one or more reference signals to the terminal, or may generate the at least one or more reference signals. Also, the controller 3m-10 may control the transceiver 3m-05 to transmit feedback setting information for generating feedback information according to the measurement result to the terminal. In addition, the control unit 3m-10 transmits the at least one reference signal to the terminal, and configures the transceiver 3m-05 to receive feedback information transmitted from the terminal at a feedback timing according to the feedback setting information. can be controlled In addition, the control unit 3m-10 transmits feedback configuration information to the terminal, transmits an aperiodic CSI-RS to the terminal, and receives the feedback configuration information and feedback information generated based on the CSI-RS from the terminal. can receive In this case, the control unit 3m-10 may transmit feedback setting information corresponding to each antenna port group of the base station and additional feedback setting information based on the relationship between the antenna port groups. Also, the control unit 3m-10 may transmit a beamformed CSI-RS to the UE based on the feedback information, and receive feedback information generated based on the CSI-RS from the UE.

The present invention is entitled to the following claims.

CSI-RS activation and deactivation method and apparatus using MAC control signal

Multi-shot CSI-RS resource and aperiodic CSI-RS resource setting, activation and deactivation operation

- Three operations are classified according to the identifier included in the RRC message or the type of CSI-RS config IE in the RRC message (periodic CSI-RS, aperiodic CSI-RS, multi-transmission CSI-RS)

- The MAC does not directly perform the operation indicated by the MAC CE, but only transmits the relevant information to the PHY (because the operation proceeds 8 ms after the MAC CE is successfully received, the time information is transmitted).

- Determine the format based on the index of the serving cell in which the CSI-RS resource is configured or the CSI process is configured.

- Two design methods are proposed according to the signal structure of MAC CE.

- MAC CE design The first method includes activation and deactivation commands for all serving cells in one MAC CE transmitted by the base station.

- In the first method, the Ci field indicates a serving cell having a configured CSI-RS resource.

- CSI-RS command is indicated only for serving cells activated in the first method.

- In the second method of MAC CE design, one MAC CE includes only activation and deactivation commands for the corresponding serving cell.

- In the second method, a command to the serving cell from which the MAC CE was received is included. Activation/deactivation of CSI-RS only for the corresponding serving cell.

- The number of activation/deactivation resources in the CSI-RS command is the same as the number of configured CSI-RS processes for the serving cell.

- Ri corresponds to CSI-RS-ConfigNZPId.

- Timers like sCellDeactivationTimer

CSIRSDeactivationTimer is driven for each cell in which the CSI-RS resource is configured or the CSI process is configured (or for each CSI process)

Start/restart is when MAC CE that activates the resource is received

Deactivate the resource when the timer expires.

It is also possible to manage the timer for each CSI-RS resource.

- The configured aperiodic/multi-shot CSI-RS resources are deactivated first after configuration and handover.

On the other hand, the embodiments of the present invention disclosed in the present specification and drawings are merely presented as specific examples to easily explain the technical contents of the present invention and help 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 of ordinary skill in the art to which the present invention pertains that other modifications are possible based on the technical spirit of the present invention. In addition, each of the above embodiments may be operated in combination with each other as needed.

Claims (16)

A method of a terminal of a communication system, comprising:
Receiving SRS configuration information for configuring a plurality of semi-persistent SRS resources for semi-persistent sounding reference signal (SRS) transmission from a base station;
receiving activation information included in a medium access control (MAC) control element and indicating activation of at least one semi-persistent SRS resource among the plurality of semi-persistent SRS resources;
periodically transmitting an SRS corresponding to at least one activated semi-persistent SRS resource based on the activation information from a first timing determined as a timing at which a preset time has elapsed after receiving the activation information;
receiving deactivation information included in the MAC control element and indicating deactivation of at least one semi-persistent SRS resource among the plurality of semi-persistent SRS resources; and
Stopping SRS transmission corresponding to at least one deactivated semi-persistent SRS resource based on the deactivation information from a second timing determined as a timing at which a preset time has elapsed after receiving the deactivation information. .
According to claim 1,
The SRS configuration information comprises information on a channel state information reference signal (CSI-RS) resource corresponding to each semi-persistent SRS resource.
According to claim 1,
The method of claim 1, further comprising: checking uplink precoding information for data transmission based on the SRS configuration information.
According to claim 1,
The SRS configuration information comprises information on an SRS transmission band, the number of antenna ports, a transmission comb, and a cyclic shift.
In the method of a base station of a communication system,
Transmitting SRS configuration information for configuring a plurality of semi-persistent SRS resources for semi-persistent sounding reference signal (SRS) transmission to the terminal;
transmitting activation information included in a medium access control (MAC) control element and indicating activation of at least one semi-persistent SRS resource among the plurality of semi-persistent SRS resources;
periodically receiving an SRS corresponding to at least one activated semi-persistent SRS resource based on the activation information from a first timing determined as a timing at which a preset time has elapsed after transmitting the activation information; and
Transmitting deactivation information included in the MAC control element and indicating deactivation of at least one semi-persistent SRS resource among the plurality of semi-persistent SRS resources,
SRS reception corresponding to at least one deactivated semi-persistent SRS resource based on the deactivation information is not performed from a second timing determined as a timing when a preset time has elapsed after receiving the deactivation information Way.
6. The method of claim 5,
The SRS configuration information comprises information on a channel state information reference signal (CSI-RS) resource corresponding to each semi-persistent SRS resource.
6. The method of claim 5,
Uplink precoding information for data reception is confirmed based on the SRS configuration information.
6. The method of claim 5,
The SRS configuration information comprises information on an SRS transmission band, the number of antenna ports, a transmission comb, and a cyclic shift.
In the terminal of a communication system,
transceiver; and
Receives SRS configuration information for configuring a plurality of semi-persistent SRS resources for semi-persistent sounding reference signal (SRS) transmission from a base station, is included in a medium access control (MAC) control element, and includes the plurality of semi-persistent SRS resources. Receive activation information indicating activation of at least one semi-persistent SRS resource among persistent SRS resources, and based on the activation information from a first timing determined as a timing at which a preset time elapses after receiving the activation information Periodically transmit an SRS corresponding to at least one activated semi-persistent SRS resource, and receive deactivation information included in the MAC control element and indicating deactivation of at least one semi-persistent SRS resource among the plurality of semi-persistent SRS resources and a control unit configured to stop SRS transmission corresponding to at least one deactivated semi-persistent SRS resource based on the deactivation information from a second timing determined as a timing at which a preset time has elapsed after receiving the deactivation information A terminal comprising a.
10. The method of claim 9,
The SRS configuration information comprises information on a channel state information reference signal (CSI-RS) resource corresponding to each semi-persistent SRS resource.
10. The method of claim 9,
The controller is further configured to check uplink precoding information for data transmission based on the SRS configuration information.
10. The method of claim 9,
The SRS configuration information comprises information on an SRS transmission band, the number of antenna ports, a transmission comb, and a cyclic shift.
In a base station of a communication system,
transceiver; and
Transmits SRS configuration information for configuring a plurality of semi-persistent SRS resources for semi-persistent sounding reference signal (SRS) transmission to the terminal, is included in a medium access control (MAC) control element, and includes the plurality of semi-persistent SRS resources. Transmitting activation information indicating activation of at least one semi-persistent SRS resource among persistent SRS resources, and from a first timing determined as a timing at which a preset time elapses after transmitting the activation information, based on the activation information Periodically receives an SRS corresponding to at least one activated semi-persistent SRS resource, is included in the MAC control element, and transmits deactivation information indicating deactivation of at least one semi-persistent SRS resource among the plurality of semi-persistent SRS resources comprising a control unit configured to
SRS reception corresponding to at least one deactivated semi-persistent SRS resource based on the deactivation information is not performed from a second timing determined as a timing when a preset time has elapsed after receiving the deactivation information base station.
14. The method of claim 13,
The SRS configuration information includes information on a channel state information reference signal (CSI-RS) resource corresponding to each semi-persistent SRS resource.
14. The method of claim 13,
Base station, characterized in that the uplink precoding information for data reception is confirmed based on the SRS configuration information.
14. The method of claim 13,
The SRS configuration information includes information on an SRS transmission band, the number of antenna ports, a transmission comb, and a cyclic shift.

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