KR20220066238A - Method and apparatus for configuration of multiple demodulation reference siganl structures in wireless cellular communication system - Google Patents

Abstract

The present disclosure relates to a communication method and system in which a 5G communication system for supporting a higher data transfer rate after a 4G system is fused with IoT technology. The present disclosure can be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retail business, security and safety related service, and the like) based on the 5G communication technology and IoT related technology. According to the present invention, disclosed is a method in which a base station configures a plurality of demodulation reference signal (DMRS) structures and determines uplink and downlink transmission timings for delay reduction. Accordingly, the present invention enables efficient transmission of radio resources.

Description

Setting method and apparatus for multiple DMRS structures in a wireless cellular communication system

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus in which a base station configures multiple demodulation reference signal (DMRS) structures and determines uplink and downlink transmission timings for delay reduction.

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 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 alleviate 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 radio access network: cloud RAN), 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, advanced coding modulation (ACM) methods such as FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), and advanced access technologies such as Filter Bank Multi Carrier (FBMC), 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/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 MTC (Machine Type Communication), 5G communication technology is implemented by techniques such as beam forming, MIMO, and array antenna. there will be The application of cloud radio access network (cloud RAN) as the big data processing technology described above can be said to be an example of convergence of 5G technology and IoT technology.

Also, unlike the LTE system, 5G wireless communication considers a system operating in a frequency band of 6 GHz or less as well as a high frequency band higher than that. Since the channel characteristics vary depending on the frequency band, it is necessary to newly design the reference signal in consideration of this in the 5G system. In addition, support for low latency and high mobility is important in 5G wireless communication, and it is important to minimize the overhead of the reference signal.

An object of the present invention is to configure a plurality of DMRS (Demodulation Reference Signal) structures in a 5G system operating in a frequency band of 6 GHz or less as well as a high frequency band higher than that by providing a method for the base station to set them, thereby providing low latency and high mobility This is to minimize the overhead of the reference signal while supporting

In addition, another object of the present invention is to minimize the overhead of a reference signal by providing a method for configuring and feeding back information necessary for a UE to select a DMRS suitable for a transmission environment from among a plurality of DMRS configurations.

In addition, another object of the present invention is a method of determining transmission timing such as HARQ ACK/NACK transmission timing or PUSCH transmission timing when the time required for signal processing between the base station and the terminal is reduced in an LTE system using FDD or TDD By providing , the delay time for data transmission is reduced.

In a base station method according to an embodiment of the present invention for solving the above problems, determining control information including at least one of symbol position information and symbol number information on a time axis in which a demodulation reference signal (DMRS) is transmitted , transmitting the control information to the terminal and transmitting a DMRS corresponding to the determined control information to the terminal.

A base station according to an embodiment of the present invention includes a transceiver and a control unit for determining control information including at least one of symbol position information and symbol number information on a time axis in which a demodulation reference signal (DMRS) is transmitted, the control unit comprising: may control the transceiver to transmit the control information to the terminal and transmit a DMRS corresponding to the determined control information to the terminal.

The terminal method according to an embodiment of the present invention comprises the steps of: receiving control information including at least one of symbol position information and symbol number information on a time axis in which a demodulation reference signal (DMRS) is transmitted from a base station; It may include receiving the corresponding DMRS.

The terminal according to an embodiment of the present invention includes a transceiver for receiving control information including at least one of symbol position information and symbol number information on a time axis in which a demodulation reference signal (DMRS) is transmitted from a base station, and the determined control information. It may include a control unit for controlling the transceiver to receive the corresponding DMRS.

In another embodiment of the present invention, the method of the terminal includes the steps of receiving a first signal in an n-k th subframe from a base station, and selecting a subframe for transmitting a second signal corresponding to the first signal in the following [Table] 3-7a] and transmitting the second signal in the confirmed subframe.

[Table 3-7a]

In addition, in another embodiment of the present invention, the step of checking the subframe in which the second signal is transmitted in [Table 3-7a] may include the reception timing of the first signal in [Table 3-7a] and determining the transmission timing of the second signal corresponding to the checked reception timing of the first signal.

In addition, in another embodiment of the present invention, the first signal may include a physical downlink shared channel (PDSCH), and the second signal may include ACK/NACK information for the PDSCH.

In addition, in another embodiment of the present invention, the base station method includes the steps of transmitting a first signal in an n-k-th subframe to a terminal, and a subframe for receiving a second signal corresponding to the first signal as follows. It may include confirming in [Table 3-7a] and receiving the second signal in the confirmed subframe.

[Table 3-7a]

In addition, in another embodiment of the present invention, the step of checking the subframe for receiving the second signal in [Table 3-7a] includes the transmission of the first signal in [Table 3-7a] The method may include determining a timing and confirming a reception timing of the second signal corresponding to the determined transmission timing of the first signal.

According to an embodiment of the present invention, there is provided a method for configuring a plurality of demodulation reference signals (DMRS) and for a base station to configure a DMRS structure suitable for a transmission environment. This makes it possible to effectively perform channel estimation according to the low latency support and high mobility support environment in the channel environment of the 5G wireless communication system. In addition, the DMRS transmission is performed adaptively to minimize the overhead of the reference signal and to enable efficient transmission of radio resources.

In addition, according to another embodiment of the present invention, there is provided a method for configuring and feeding back information necessary for a terminal to select a DMRS suitable for a transmission environment by a base station from among a plurality of configurations of a demodulation reference signal (DMRS). Through the present invention, it is possible to minimize the overhead of the reference signal by performing the transmission of the DMRS adaptively.

In addition, according to another embodiment of the present invention, a method for determining HARQ ACK/NACK transmission timing or data transmission timing is provided so that the delay time can be reduced.

1A is a diagram illustrating a downlink time-frequency domain transmission structure of an LTE or LTE-A system.
1B is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-A system.
1C is a diagram illustrating a radio resource of 1 RB, which is a minimum unit that can be scheduled in downlink in an LTE or LTE-A system.
1d, 1e, 1faa, 1fab, 1fba, 1fbb, and 1g are diagrams showing the structure of a plurality of DMRSs according to the 1-1 embodiment of the present invention.
1ha and 1hb are diagrams illustrating an example of a method of orthogonally supporting MU transmission between terminals using different DMRS structures according to embodiments 1-3 of the present invention.
1I is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention.
1J is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention.
1K is a diagram illustrating the position of the front-load DMRS when the slot length is 7 or 14 OFDM symbols.
11A, 11B, 1LC, 11D, 1LE, and 11F are diagrams illustrating positions at which the Extended/Additional DMRS is transmitted when the length of the slot is 7 or 14 OFDM symbols.
1M is a diagram for explaining a DMRS structure according to an embodiment of the present invention.
FIG. 1N is a diagram for explaining a method of mapping an antenna port to the unit DMRS structure proposed in FIG. 1M.
FIG. 1O is a diagram for explaining a method of mapping a larger number of antenna ports to the unit DMRS structure proposed in FIG. 1M.
2A, 2B and 2C are diagrams illustrating a radio resource configuration of an LTE system.
2D is an exemplary diagram illustrating a feedback timing of information required for selection of a reference signal according to a second embodiment of the present invention.
FIG. 2E is an exemplary diagram illustrating a method of classifying a reference signal based on feedback of information required for selection of a reference signal according to a second or third embodiment of the present invention.
2F is a block diagram illustrating an internal structure of a terminal according to embodiments of the present invention.
2G is a block diagram illustrating an internal structure of a base station according to embodiments of the present invention.
3A is a diagram illustrating a downlink time-frequency domain transmission structure of an LTE or LTE-A system.
3B is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-A system.
FIG. 3c is a diagram illustrating a state in which data for eMBB, URLLC, and mMTC are allocated from frequency-time resources in a communication system.
FIG. 3D is a diagram illustrating a state in which data for eMBB, URLLC, and mMTC are allocated from frequency-time resources in a communication system.
3E is a diagram illustrating a structure in which one transport block is divided into several code blocks and a CRC is added according to an embodiment.
3F is a diagram illustrating a structure in which an outer code is applied and coded according to an embodiment.
3G is a diagram illustrating a block diagram according to whether or not an outer code is applied according to an embodiment.
3H is a diagram showing the operation of a terminal according to the 3-1 embodiment, the 3-2 embodiment, the 3-3 embodiment, and the 3-4 embodiment.
3I is a diagram showing the operation of the terminal according to the 3-5th embodiment, the 3-6 embodiment, the 3-7 embodiment, and the 3-8 embodiment.
3J is a block diagram illustrating a structure of a terminal according to embodiments.
3K is a block diagram illustrating a structure of a base station according to embodiments.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, when it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. And, the terms to be described later 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.

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 technical field to which the present invention belongs 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.

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 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.

<First embodiment>

In order for the terminal to estimate a channel in a wireless communication system, the base station needs to transmit a reference signal for this. The terminal may perform channel estimation using the reference signal and demodulate the received signal. In addition, the terminal may determine the channel state through the reference signal and use it to feed back it to the base station.

In general, when a reference signal is transmitted, a frequency and time-based transmission interval of the reference signal is determined in consideration of a maximum delay spread and a maximum Doppler spread of a channel. As the transmission interval of the reference signal is narrower, the channel estimation performance is improved and the demodulation performance of the signal can be improved.

In the conventional 4G LTE system operating in a frequency band of 2 GHz, reference signals such as a cell-specific reference signal (CRS) and a demodulation reference signal (DMRS) are used in the downlink. When the interval of the reference signal in frequency is expressed as the subcarrier interval m of the OFDM (Orthogonal Frequency Division Multiplexing) signal, and the interval of the reference signal in time is expressed as the symbol interval n of the OFDM signal, the normal cyclic prefix; In the case of CRS assuming normal CP), the transmission interval based on the frequency and time of the reference signals corresponding to antenna ports 1 and 2 is (m, n) = (3,4). Also, in the case of DMRS assuming normal CP, the transmission interval based on the frequency and time of the reference signal is (m, n) = (5, 7).

Unlike the LTE system, 5G wireless communication considers a system operating in a frequency band of 6 GHz or less as well as a high frequency band higher than that. Since the channel characteristics vary according to the frequency band, it is necessary to newly design the reference signal in consideration of this in the 5G system.

As a representative example of the broadband wireless communication system, in the LTE/LTE-A system, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is employed in Downlink (DL), and SC-FDMA (Single) in Uplink (UL). Carrier Frequency Division Multiple 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 allocates and operates time-frequency resources so that time-frequency resources to which data or control information are to be transmitted for each user do not overlap each other, that is, orthogonality is established, so that each user's data or Identifies control information.

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/LTE-A 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 by 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 1-1] 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.

[Table 1-1]

1B is a diagram illustrating the 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/LTE-A system.

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.

1C illustrates a radio resource of 1 RB, which is the smallest unit that can be scheduled in downlink in the LTE/LTE-A system. A plurality of different types of signals as follows may be transmitted through the radio resource shown in FIG. 1C.

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 (ports). In LTE/LTE-A, port 7 to port 14 correspond to DMRS ports, and ports maintain orthogonality so as not to cause interference with each other using Code Division Multiplexing (CDM) or Frequency Division Multiplexing (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 terminal and is transmitted using REs in which a reference signal is not transmitted in the data region of FIG. 1C.

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. Other control channels (PHICH, PCFICH, PDCCH): Transmits ACK/NACK for providing control information necessary for the terminal to receive the PDSCH or operating HARQ (Hybrid Automatic Repeat request) for uplink data transmission.

In the signal, CRS and DMRS are reference signals used to demodulate a signal received through channel estimation. Since channel estimation performance directly affects demodulation performance, the transmission interval is determined based on the frequency and time of the reference signal in consideration of this. and is maintained. For example, if the interval of the reference signal in frequency is expressed as the subcarrier interval m of the OFDM signal and the interval of the reference signal in time is expressed as the symbol interval n of the OFDM signal, in the case of CRS assuming a normal CP, antenna port 1 and The transmission interval based on the frequency and time of the reference signal corresponding to 2 is (m, n) = (3,4). In addition, in the case of DMRS assuming a normal CP, the transmission interval based on the frequency and time of the reference signal is (m, n) = (5, 7).

Unlike the LTE system, 5G wireless communication considers a system operating in a frequency band of 6 GHz or less as well as a high frequency band higher than that. Since the channel characteristics vary according to the frequency band, it is necessary to design the reference signal in consideration of this in the 5G system. In addition, in 5G wireless communication, support for low latency of wireless signal transmission and support for high mobility of wireless signals are considered as important. Additionally, in the 5G system, it is important to minimize the overhead of the reference signal. Accordingly, the present invention provides a method for configuring a plurality of DMRS (Demodulation Reference Signal) structures and a method for a base station to set them to solve this problem.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, an embodiment of the present invention will be described using an LTE or LTE-A system as an example, but 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.

More specifically, the basic structure of a time-frequency domain in which signals are transmitted in downlink and uplink may be different from those shown in FIGS. 1A and 1B . In addition, types of signals transmitted in downlink and uplink may also be different. Accordingly, the embodiments of the present invention may 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.

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. And, the terms to be described later 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.

Demodulation reference signal (DMRS) described below is transmitted by applying UE-specific precoding to a reference signal, so that the UE performs demodulation without additionally receiving precoding information. It refers to a reference signal with possible characteristics, and the name used in the LTE system will be used as it is. However, the term for DMRS may be expressed in other terms depending on the intention of the user and the purpose of using the reference signal. More specifically, the term "DMRS" is merely to provide specific examples to easily explain the technical content of the present invention and to help the understanding of the present invention, and is not intended to limit the scope of the present invention. That is, it is apparent to those of ordinary skill in the art to which the present invention pertains that it can be implemented even with a reference signal based on the technical idea of the present invention.

In Embodiment 1-1 of the present invention, which will be described below, the structure of various DMRSs according to use cases will be described. In Embodiment 1-2 of the present invention, a method for the base station to configure and transmit a suitable DMRS structure among a plurality of DMRS structures according to a transmission environment is described. In addition, embodiments 1-3 of the present invention describe a method of orthogonally supporting multiple-user (MU) transmission between terminals using different DMRS structures when multiple DMRS structures are supported.

[Example 1-1]

Embodiment 1-1 describes a method of configuring the structure of the DMRS, which is the reference signal of the present invention, in various ways according to the transmission environment.

Referring to FIG. 1c , the LTE system has one fixed DMRS structure, and when the number of transport layers is 2 or less, 12 DMRS REs are transmitted per RB, and when the number of transport layers exceeds 2, 24 DMRSs per RB sent to the RE.

As described above, in the 5G wireless communication system, unlike the LTE system, a system operating not only in a frequency band of 6 GHz or less but also in a high frequency band higher than that is considered. Since the channel characteristics vary according to the frequency band, the DMRS in the 5G system needs to be designed differently from the DMRS of LTE. Also, in the 5G system, low latency support and high mobility support are being considered as important. Therefore, multiple DMRS structures are required according to the transmission environment.

For example, to support low latency, it is necessary to perform channel estimation quickly. For this, DMRS needs to be transmitted in a forward position on the transmission time axis. For high mobility support, tracking of a channel that changes rapidly in time This should be possible, and for this, the DMRS needs to be transmitted with high density based on one transmission time axis. Here, the density may mean the amount of resources (eg, the number of REs) through which the DMRS is transmitted in an arbitrary transmission unit.

Also, for example, a reference signal such as CRS may not be supported in the 5G system. In general, CRS guarantees channel estimation performance even in a low signal to interference plus noise ratio (SINR) region (eg, -10 to 0 dB) due to the high density of the reference signal. It may be difficult to guarantee the channel estimation performance in the domain.

Therefore, the present invention proposes a method of configuring the DMRS structure in various ways according to the transmission environment.

In order to configure the structure of the DMRS in various ways, first, it is necessary to set a position where the DMRS can be transmitted. When a transmittable DMRS location is set, the base station according to an embodiment of the present invention may determine and transmit a DMRS structure necessary for the set location. And the terminal according to an embodiment of the present invention needs to know the transmission possible position of the DMRS.

Unlike the LTE system, the 5G wireless communication system may have various frame structures and may be operated with a variable TTI (Transmission Time Interval), so the location setting for the DMRS needs to be separately specified as a terminal. Also, unlike LTE, in the 5G wireless communication system, the number of OFDM symbols in time constituting a subframe and the number of subcarriers in frequency may be different. In the present invention, in most drawings, the number of OFDM symbols in time constituting a subframe and the number of subcarriers in frequency constituting a resource block are set to be the same as in LTE, but this may be set differently. For example, as shown in FIGS. 1faa, 1fab, 1fba, and 1fb, one resource block may consist of 12 or 16 subcarriers in frequency.

* More specifically, the setting of the position where the DMRS can be transmitted can be divided into a position in time and a position in frequency, and can be set by a combination of position in time and position in frequency.

First, the position in time at which the DMRS can be transmitted can be considered in two ways as follows. The first method is to set the position in time at which the DMRS is transmitted based on the subframe. In general, this is a method considering that location setting for transmission resources is performed in units of subframes.

For example, assuming that the duration corresponding to one subframe is represented by x, a method in which the position of the DMRS is set in a unit of y=x/2 may be considered. As a more specific example, referring to FIGS. 1faa to 1fba, when x=14 (OFDM symbol), the position of the DMRS may be set in a unit of y=7, and the temporal position of the DMRS that can be set in one subframe is It may be the 3/6/9/12th OFDM symbol.

The second method is to set the position in time at which the DMRS is transmitted based on the start point of the allocated data channel (eg, PDSCH). This is a method considering that, unlike the LTE system, the period in which the data channel is transmitted in the subframe may be set in various ways in the 5G wireless communication system. For example, based on the start point of the data channel, the position in time of the configurable DMRS may be the 1/4/7/10th OFDM symbol.

Next, the position on the frequency at which the DMRS can be transmitted can be set to have a density in consideration of the channel environment of the 5G communication system covering various numerology. Here, the numerology may mean a subcarrier spacing (eg, a frequency difference between subcarriers), and the length of the spacing of the subcarriers on the frequency is the length of the symbol on the time axis. can be inversely proportional to

For example, a transmission position on a frequency of the DMRS may be configured so that the DMRS is transmitted through at least two or more consecutive subcarriers. As an example, as shown in FIGS. 1fa-4-1 and 1fa-4-2 in FIG. 1fab, positions on two frequencies at which DMRS can be transmitted are shown.

As described above, the setting of the position where the DMRS can be transmitted may be set as a combination of a position in time and a position in frequency, and the DMRS setting actually used may be set as a subset of possible combinations for convenience. . In addition, the transmitted DMRS structure may be implicitly determined according to the position in time in which the above-described DMRS can be transmitted and the number of transmitted DMRS layers.

More specifically, it will be described based on the DMRS structure proposed in FIGS. 1faa and 1fab.

As shown in FIGS. 1fa-2-1 and 1fa-2-2, when DMRS is set for only one OFDM symbol located at the front on the time axis within one subframe in order to support low latency, the UE transmits the layer ( The DMRS structure can be classified according to the number of layers). For example, when the number of transmitted layers is 4 or less, as shown in FIG. 1fa-2-2, the reference signal may be allocated more densely in terms of frequency. On the other hand, when the number of transmitted layers is greater than 4, as shown in FIG. 1fa-2-1, a reference signal having a low density in terms of frequency may be allocated. However, it may be difficult to guarantee channel estimation performance for a reference signal set to have a low density as shown in FIG. 1fa-2-1.

As another example, when DMRS is set for two OFDM symbols in time within one subframe as shown in FIGS. 1fa-3-1 and 1fa-3-2, as described above, when the number of transmitted layers is 4 or less, FIG. 1fa- As in 3-2, the reference signal can be assigned more densely in terms of frequency. In addition, when the number of transmitted layers is greater than 4, as shown in FIG. 1fa-3-1, a reference signal having a low density in terms of frequency may be allocated.

As another example, in an environment where the degree of Doppler effect is strong (hereinafter, it will be used interchangeably with the term High Doppler) as shown in FIGS. 1fa-4-1 and 1fa-4-2, DMRS is one When the number of transmitted layers is 4 or less when four OFDM symbols are set on the time axis in a subframe, a reference signal may be allocated as shown in FIG. 1fa-4-2. In this case, if the reference signal is allocated more densely in terms of frequency, the overhead of the reference signal may become too large. When the number of transmitted layers is greater than 4, a reference signal can be allocated as shown in FIG. 1fa-4-1, but in high-speed transmission, the probability that the number of transmitted layers is greater than 4 is very low.

Here, when the number of transmitted layers is 4 or more, OCC (Orthogonal Cover Code) = 4 may be operated, and if the number of transmitted layers is 2 or less, OCC = 2 may be operated. The above example may be similarly applied to other DMRS structures. In addition, the examples of the DMRS structure described in FIGS. 1fba and 1fbb can be equally applied to a case where the number of subcarriers on a frequency in one resource block is 16.

Next, a method for performing operations such as Doppler frequency measurement, phase noise compensation, and frequency offset correction using DMRS is proposed. In the existing LTE system, it was possible to perform such an operation using CRS, but in the case where there is no signal going out every subframe in the full band like CRS in the 5G communication system, the above-mentioned Doppler frequency measurement, phase noise compensation, and frequency It may be difficult to perform operations such as offset correction.

In order to perform such an operation, a reference signal having a high density in time is required. For example, when DMRS is set to only one OFDM symbol ahead in time to support low latency, it is impossible to perform the operation using only DMRS. . Therefore, the base station can perform operations such as Doppler frequency measurement, phase noise compensation, and frequency offset correction by setting a DMRS with high temporal density in an on-demand method provided upon request. More specifically, to perform this operation, the base station performs dynamic signaling, and the terminal performs operations such as Doppler frequency measurement, phase noise compensation, and frequency offset correction using the DMRS configured through this. For example, it may be signaled by adding 1 bit to dynamic control information (DCI). Supporting multiple DMRS structures in the 1-1 embodiment may have the following differentiation compared to supporting one fixed DMRS structure in the existing LTE system. First, unlike conventional LTE, the number of DMRS resource elements (REs) allocated per antenna port may not be fixed. For example, in the LTE system, the number of DMRS REs allocated per antenna port is fixed to 12, but when a plurality of DMRS structures are supported, the number of DMRS REs allocated per antenna port depends on which structure among various DMRS structures is set. may vary depending on

In addition, the number of supported antenna ports may vary according to which structure among various DMRS structures is configured. For example, since it is difficult to support a high rank in an environment in which the overhead of the reference signal must be reduced, in this case, the overhead of the reference signal must be minimized by supporting only the minimum antenna port. Hereinafter, specific examples of the above-described differentiation can be confirmed through various proposed DMRS structures.

For the above reasons, the 1-1 embodiment of the present invention proposes various DMRS structures according to the transmission environment. 1D is a diagram illustrating a first example of various DMRS structures. 1D, as an example, is a structure in which DMRS can be transmitted through all subcarriers included in one OFDM symbol. However, the location of the DMRS proposed in the present invention is not limited to that shown in FIG. 1D.

More specifically, as shown in FIG. 1d-1, the DMRS may be located in each of the 3rd OFDM symbol and the 11th OFDM symbol. For example, for time balance, the DMRS position may be transmitted through each of the 3rd OFDM symbol and the 12th OFDM symbol within one subframe, as shown in FIG. 1d-1. However, when the 5G system has a basic structure of a time-frequency domain different from that of the LTE/LTE-A system, the location of the DMRS may be different.

As another example, in the present invention, in order to support low latency, the DMRS location may be transmitted only through the third OFDM symbol in one subframe as shown in FIG. 1d-2. In this case, since the terminal can estimate the channel while receiving the signal up to the third OFDM symbol, it can quickly demodulate the received signal.

As another example, in the present invention, in order to support high mobility, the DMRS location may be transmitted through three different OFDM symbols in one subframe as shown in FIG. 1d-3.

On the other hand, the generation of the DMRS signal may be generated based on a pseudo-random sequence similar to downlink DMRS in LTE, or generated based on a ZC (Zadoff-Chu) sequence similar to uplink DMRS in LTE. have. For example, when the uplink/downlink has the same DMRS structure, DMRS signal generation may orthogonally support the DMRS port of the uplink/downlink if the uplink/downlink is equally applied.

In addition, in FIG. 1D , it is possible to support a plurality of DMRS ports by applying an orthogonal cover code (OCC) on a frequency. When OCC is applied in terms of frequency, there is an advantage in that a problem of power imbalance that may occur when applying OCC in terms of time does not occur. An example of this is shown in FIG. 1E .

FIG. 1E shows an example in which OCC is applied when the number of subcarriers on a frequency is 16 in one resource block. Although DMRS port numbers are numbered from port 7 to port 14 based on the LTE system in FIG. 1E, this is an example for description. For example, the port number used in the 5G system may be different from this.

More specifically, FIG. 1e-1 shows an example of OCC applied when DMRS is transmitted using two ports (port 7 and port 8). As shown in FIG. 1e-1, OCC having an OCC length of 2 may be applied at positions where ports 7 and 8 are indicated. Therefore, as in FIG. 1e-1, when DMRS is transmitted using two ports, DMRS may not be transmitted for all resources included in one OFDM symbol.

는 시퀀스 길이에 따른 시퀀스 값을 나타내며, OCC 크기가 2인 경우는

와

가 사용되며, OCC 크기가 4인 경우에는

가 모두 사용된다. 앞서 설명한 바와 같이 [표 1-2]도 LTE시스템을 기준으로 7번 포트부터 14번 포트로 넘버링을 하였지만, 이는 설명을 위한 예시이다. 예를 들어, 5G 시스템에서 사용되는 포트 넘버는 이와 다를 수 있다. [Table 1-2] shows the sequence for OCC. In [Table 1-2]

represents the sequence value according to the sequence length, and when the OCC size is 2,

Wow

is used, and when the OCC size is 4,

are all used As described above, [Table 1-2] also numbered port 7 to port 14 based on the LTE system, but this is an example for explanation. For example, the port number used in the 5G system may be different from this.

1e-2 shows an application example of OCC applied when four ports 7/8/9/10 are transmitted. An OCC having an OCC length of 2 may be applied at a position where ports 7/8/9/10 are indicated as shown in FIG. 1e-2. As shown, when four or more ports are transmitted, DMRS may be transmitted for all resources of an OFDM symbol. Next, FIG. 1e-3 shows an example of application of OCC when 8 ports are transmitted. When more than 4 ports are used as in FIG. 1e-3, OCC length 4 is used.

Although FIG. 1E shows an example of OCC application for a case where 2/4/8 ports are transmitted, the application of 8 or less other ports can be easily extended from the example of FIG. 1E. For example, if three ports are transmitted, since only ports 7/8/9 are transmitted in FIG. 1e-1 and ports 7/8/9, OCC of length 2 is applied and transmitted at the corresponding location in FIG. 1e-1. However, for port 9, the OCC of length 2 does not apply because other ports do not exist at the corresponding position in FIG. 1e-1.

[Table 1-2]

Next, FIGS. 1faa, 1fab, 1fba, and 1fbb show a second example of various proposed DMRS structures. 1faa, 1fab, 1fba, and 1fbb are modified structures of the form shown in FIGS. 1d and 1e. Specifically, we propose a structure that can operate more effectively in consideration of the overhead of a reference signal than the method shown in FIGS.

Generation of the DMRS signal may be generated based on a pseudo-random sequence similar to downlink DMRS in LTE, or generated based on a Zadoff-Chu (ZC) sequence similar to uplink DMRS in LTE. 1faa and 1fab show the structure when the number of subcarriers on frequency constituting the resource block is 12, and FIGS. 1fba and 1fbb show the structure when the number of subcarriers on frequency constituting the resource block is 16.

는 시퀀스 길이에 따른 시퀀스 값을 나타내며, OCC길이가 2인 경우는

와

가 사용되며, OCC 길이가 4인 경우에는

가 모두 사용된다. 도 1fa-1-2와 1fa-1-3에서 DMRS 포트 넘버를 LTE시스템을 기준으로 7번 포트부터 14번 포트로 넘버링을 하였지만, 이는 설명을 위한 예시이다. 예를 들어, 5G 시스템에서 사용되는 포트 넘버는 이와 다를 수 있다. First, FIGS. 1faa and 1fab will be described. In the method proposed in FIGS. 1faa and 1fab, the DMRS location shown in FIG. 1fa-1-1 can be flexibly used according to the transmission situation. The OCC and antenna port mapping method may be performed as shown in FIGS. 1fa-1-2 and 1fa-1-3. In [Table 1-2]

represents the sequence value according to the sequence length, and when the OCC length is 2,

Wow

is used, and when the OCC length is 4,

are all used Although DMRS port numbers are numbered from port 7 to port 14 based on the LTE system in FIGS. 1fa-1-2 and 1fa-1-3, this is an example for explanation. For example, the port number used in the 5G system may be different from this.

First, referring to FIG. 1fa-1-2, a reference signal may not be transmitted to a portion marked with a grid pattern, but a reference signal may be transmitted only to a portion marked with a hatched pattern. In this case, two ports 7/8 may be transmitted with OCC=2 applied, and four ports 7/8/11/13 may be transmitted with OCC=4 applied. On the other hand, when 8 ports from port 7 to 14 are transmitted, port 7/8/11/13 is transmitted with OCC=4 applied at the position indicated by the hatched pattern, and port 9 is transmitted from the position indicated by the grid pattern. /10/12/14 may be transmitted by applying OCC=4.

First, referring to FIG. 1fa-1-3, two ports 7/8 may be transmitted by applying OCC=2 to the portion indicated by the hatched pattern, and four ports 7/8/11 may be transmitted to the portion indicated by the hatched pattern. /13 may be transmitted by applying OCC=4. Here, FIG. 1fa-1-2 is a method for minimizing the overhead of the reference signal when the channel condition is good, and FIG. 1fa-1-3 shows the channel estimation performance by further using the reference signal when the channel condition is bad. way to improve it. Although the method in which the OCC is applied in terms of frequency has been described in FIGS. 1fa-1-2 and 1fa-1-3, the method in which the OCC is applied is not limited thereto.

As described above, in the method proposed in FIGS. 1faa and 1fab, the DMRS location shown in FIG. 1fa-1-1 may be flexibly used according to the transmission situation, and FIG. 1fa-2-1/1fa-2-2 /1fa-3-1/1fa-3-2/1fa-4-1/1fa-4-2 is a diagram showing examples of DMRS positions configurable according to transmission conditions. For an embodiment thereof, reference is made to the preceding description.

As described above, FIGS. 1fba and 1fbb show structures in the case where the number of subcarriers on a frequency constituting a resource block is 16. Since the operation method for this is the same as in FIGS. 1faa and 1fab, a detailed description thereof will be omitted. The OCC and antenna port mapping method may be performed as shown in FIGS. 1fb-1-2 and 1fb-1-3, and detailed operations are the same as in FIGS. 1fa-1-2 and 1fa-1-3. However, the method to which OCC is applied in the present invention is not limited thereto.

In the method proposed in FIGS. 1fba and 1fbb, the DMRS location shown in FIG. 1fb-1-1 can be flexibly used according to the transmission situation, and FIG. 1fb-2-1/1fb-3-1/1fb-3-2/ 1fb-4-1 is a diagram illustrating examples of configurable DMRS locations.

Finally, FIG. 1g shows a third example of various proposed DMRS structures. 1G is a structure in which DMRS has a form similar to that of the current LTE system. Therefore, the OCC and antenna port mapping method applied in DMRS of LTE may be applied as it is. However, in the present invention, rather than applying the DMRS structure of the existing LTE system as it is, a different DMRS structure may be considered according to a channel environment in order to satisfy next-generation communication requirements. That is, the present invention proposes a method of configuring various DMRS structures in units of OFDM symbols according to transmission environments by extending the DMRS structure of the existing LTE system.

1g-1 shows the positions of DMRSs that can be implemented in a general channel state. Also, FIG. 1G-2 shows a structure in which an additional DMRS is mapped on the time axis to support high mobility. 1g-3-1 and 1g-3-2 show a method of lowering the DMRS density on the frequency axis in order to minimize the overhead of the reference signal in an environment with a small channel delay. Finally, in order to support low latency, the DMRS structure shown in FIGS. 1g-4-1 and 1g-4-2 may be used. As in FIG. 1g-4-1, when the DMRS position is transmitted only in the front OFDM symbol, only 4-layer transmission can be supported.

1d, 1faa, 1fab, 1fba, 1fbb, and 1g show various DMRS structures according to transmission environments. However, in the present invention, the DMRS structure is not limited to the structure presented in the 1-1 embodiment. Accordingly, a DMRS structure different from that of FIGS. 1d, 1faa, 1fab, 1fba, 1fbb, and 1g may be applied to the following embodiments 1-2 and 1-3.

Also, although the structure of the DMRS has been described based on the downlink in embodiment 1-1, the same structure of the DMRS may be configured in the uplink in the 5G system. If the uplink/downlink has the same DMRS structure, the DMRS port of the uplink/downlink becomes orthogonal, so that more flexible operation is possible in an environment such as TDD (Time Division Duplex).

[Embodiment 1-1-1]

Embodiment 1-1-1 proposes another method for configuring the structure of DMRS proposed in embodiment 1-1. Note that in the 1-1-1 embodiment, a structure of a configurable DMRS can be divided into a front-loaded DMRS and an extended/additional DMRS. First, the front-loaded DMRS may be defined by the following two criteria.

One. The number of OFDM symbols for front-loaded DMRS

● Front-loaded DMRS is mapped over 1 or 2 adjacent OFDM symbol

■ Front-loaded DMRS is mapped on 1 OFDM symbol for low rank transmission.

■ Front-loaded DMRS is mapped on 2 adjacent OFDM symbols for high rank transmission.

2. The location of time for front-loaded DMRS

● Opt. 1: The first symbol of front-loaded DM-RS is fixed regardless of the first symbol of NR-PDSCH.

● Opt. 2: The first symbol of front-loaded DM-RS is no later than the first symbol of NR-PDSCH.

Specifically, the front-loaded DMRS may be configured in one or two adjacent OFDM symbols according to the number of transmission layers (rank). In addition, the front-loaded DMRS is located in front of the NR-PDSCH on the time axis, and the position may be fixed as described above, or the front-loaded RS may be located from the first symbol where the NR-PDSCH starts.

When explaining the advantages and disadvantages of Opt.1 and Opt.2, it can be assumed that, in the case of Opt.1, the DMRS location is fixed, so that the DMRS of the adjacent cell is always transmitted at the same location. However, in the case where the control channel region is set configurable or in the case of a subframe in which the control channel is not transmitted, the DMRS of the data channel cannot be positioned further, so a decoding latency problem may occur.

On the other hand, in the case of Opt.2, since the front-loaded DMRS is always located ahead of the data channel on the time axis, it has an advantage in terms of decoding latency. However, since the location of the front-loaded DMRS is diversified, that is, the DMRS location is not fixed, there may be problems in inter-cell interference control and operation of an advanced receiver. For this, a method of additionally introducing network signaling may be considered, but in general, a method in which the location of the DMRS is set to be fixed has an advantage more advantageous for system operation.

Therefore, for the above reasons, a specific method for setting the front-load DMRS to a fixed position is proposed. In FIG. 1K, the position of the front-load DMRS is shown for the case where the length of the slot is 7 or 14 OFDM symbols, respectively. Here, the location setting of the front-load DMRS may be determined by the area of the control channel. As an example, when the control channel region consists of up to two OFDM symbols, the front-load DMRS is located in the third OFDM symbol as shown in FIG. k-1. As another example, when the control channel region consists of up to three OFDM symbols, the front-load DMRS is located in the fourth OFDM symbol as shown in FIG. k-2.

As described above, when the location of the front-load DMRS is determined by the maximum size of a configurable control channel area as described above, if some or all of the control channels are not configured, there may be a loss in reducing decoding latency. Therefore, the present invention proposes another method for setting the location of the Front-load DMRS by using the extended method of Opt.1.

For example, when the control channel region consists of up to two OFDM symbols, the front-load DMRS is set to be fixed to the third OFDM symbol as shown in FIG. k-1, and the front-load DMRS is configured as shown in FIG. k-3. A setting fixed to the first OFDM symbol may be set as one option. And by changing these two settings according to the situation, the disadvantage of Option 1 can be supplemented.

Specifically, setting the positions of a plurality of Front-load DMRSs may be performed in various ways. For example, a method of semi-statically setting through higher layer signaling such as RRC may be considered. Also, for example, the DMRS location may be set in system information such as MIB or SIB and transmitted. Also, for example, a method of dynamically setting the DMRS location through DCI may be considered. Alternatively, it is also possible to set the location of the DMRS through semi-persistent scheduling (SPS).

Next, Extended/Additional DMRS will be described. The front-loaded DMRS described above has difficulty in accurately estimating a channel because it is impossible to track a channel that changes rapidly in time in a High Doppler situation. In addition, it is impossible to perform cross-correlation with respect to a frequency offset using only the front-loaded DMRS. Therefore, for this reason, an additional DMRS needs to be transmitted later on the time axis than the position where the front-loaded DMRS is transmitted in one slot.

11A to 1LF show positions at which the Extended/Additional DMRS is transmitted when the slot length is 7 or 14 OFDM symbols, respectively. It is noted that FIGS. 1la to 1lf show Extended/Additional DMRSs respectively for FIGS. k-1, k-2, and k-3 in which the location of the front-loaded DMRS is set as described in FIG. 1k.

1-1 and 1-2 show an embodiment in which the Extended/Additional DMRS location is set avoiding the location where the CRS is transmitted in the LTE system. This has the advantage of reducing the influence of interference in the LTE-NR coexistence situation. However, in the case of Figure 1-3, like Figure k-3, the location of the front-loaded DMRS overlaps with the location where the CRS is transmitted in the LTE system.

As shown in FIGS. 1la to 1lf, when the length of the slot is 7 OFDM symbols, one position of the Extended/Additional DMRS can be set, whereas when the length of the slot is 14 OFDM symbols, the position of the Extended/Additional DMRS is The location needs to be set to two depending on the Doppler situation.

For example, referring to FIG. 1-1, the location of Extended/Additional DMRS can be set as shown in FIG. 1-2 in an environment in which the channel changes rapidly, and Extended/Additional DMRS in an environment in which the channel changes very quickly. It is necessary to set the location of the additional DMRS as shown in FIG. 1-1-3. In the above embodiment, FIGS. 1K and 1A to 1LF show a basic location where the DMRS is configured. If the DMRS transport layer is increased, the DMRS transmission position may be additionally configured. This will be described in more detail through the method of DMRS port multiplexing in FIG. 1o below.

In addition, in the case of the Extended/Additional DMRS, as a plurality of DMRSs are configured on the time axis, a DMRS overhead problem may occur. Therefore, in this case, it is possible to reduce the overhead of the DMRS by setting the DMRS to have a low density on the frequency axis. Front-load DMRS and Extended/Additional DMRS described above can be operated more flexibly through the Unit DMRS structure proposed below.

Specifically, the DMRS structure proposed by the present invention will be described with reference to FIG. 1m. The present invention proposes a unit DMRS structure configured based on one OFDM symbol. As such, the unit DMRS structure constructed based on one OFDM symbol is advantageous for setting the position of the reference signal for various transmission time intervals (TTI), as well as supporting low latency and a reference signal for URLLC (Ultra-Reliable Low Latency Communication). It is advantageous for positioning and may also be advantageous in terms of scalability such as antenna port expansion.

As shown in FIG. 1M, 12 subcarriers may be included in one OFDM symbol based on the PRB, which is the minimum data transmission unit. As in the identification numbers 3m10, 3m20, and 3m30, the density of the DMRS SC (subcarrier) in one OFDM symbol is configurable. Identification number 3m10 and identification number 3m20 indicate the DMRS structure for the case where there are 4 and 8 DMRS SCs in 12 subcarriers, respectively, and identification number 3m30 indicates the DMRS structure for the case where the DMRS SC consists of all 12 subcarriers. indicates

The configuration of an even number of DMRS SCs in identification numbers 3m10 and 3m20 may have an advantage in that orphan REs do not occur when Space Frequency Block Coding (SFBC) is considered as a transmit diversity technique. For example, when SFBC is transmitted through two antenna ports and an RE through which DMRS is transmitted does not exist in a multiple of 2 on a frequency, the problem that one orphan RE (RE) cannot be used can be solved.

In identification numbers 3m10 and 3m20, SCs not used as DMRS SCs may be mapped with data or other reference signals, or may be emptied for DMRS power boosting. Here, emptying an SC that is not used as a DMRS SC for DMRS power boosting may be used as a method of improving the performance of DMRS channel estimation in a low signal to noise ratio (SNR) region. The DMRS structure of FIG. 1M may be used not only in the data channel but also in other channels (eg, control channels).

In identification numbers 3m10 and 3m20, some of the subcarriers not transmitted by DMRS may be used as DC (Direct Current) subcarriers. However, in the case of ID number 3m30, since DMRS is transmitted in all subcarriers, it is necessary to vacate a part in order to transmit DC.

In addition, the DMRS structure of the identification number 3m10 may be replaced with the structure of the identification number 3m40 in consideration of the DC subcarrier. The DMRS SCs shown in FIGS. 3m10 to 3m40 may be generated based on a pseudo-random (PN) sequence or a Zadoff-Chu (ZC) sequence. DMRS structures of identification numbers 3m10 (or 3m40) and 3m20, which are examples of a more specific application method, may be used in the CP-OFDM system.

And it can be set and used at the same time-frequency position in the uplink/downlink. If the uplink/downlink has the same DMRS structure, since the DMRS port of the uplink/downlink becomes orthogonal, channel estimation can be performed better than in the TDD environment, and thus the interference cancellation capability can be improved.

Conversely, the DMRS structure of the identification number 3m30 is based on a ZC (Zadoff-Chu) sequence similar to LTE and can be used in the DFT-s-OFDM system in the uplink. This may enable operation for a low PAPR (Peak-to-Average Power Ratio) similar to LTE. However, the present invention is not limited to the method of utilizing the DMRS structure of FIGS. 3m10 to 3m40 presented above. For example, the DMRS structure of identification number 3m30 may be used for both CP-OFDM/DFT-s-OFDM and uplink/downlink.

In FIG. 1N, a method of mapping an antenna port to the unit DMRS structure proposed in FIG. 1M is described. In FIG. 1N , antenna ports are denoted as p=A, B, C, D, etc. for convenience. Note, however, that the antenna port number may be represented by other numbers. Also, here, the mapping of the antenna ports is to support multi-layer transmission and rank. Therefore, antenna port matching specified below may be replaced with the terms layer transmission or rank support.

Specifically, identification number 3n10 and identification number 3n20 show a case in which two antenna ports are mapped to the DMRS structure of identification number 3m10. Identification number 3n10 shows a method in which two antenna ports p=A and B are mapped to Frequency Division Multiplexing (FDM)/Code Division Multiplexing (CDM) by applying an Orthogonal Cover Code (OCC) of length 2 to each other. In addition, identification number 3n20 shows a method in which antenna ports p=A, B are mapped in the FDM scheme without applying OCC. As will be described later, 3n40 and 3n60 also show examples of mapping antenna ports by applying the FDD scheme without applying OCC like 3n20.

Next, identification number 3n30 and identification number 3n40 show a case in which two antenna ports are mapped to the DMRS structure of identification number 3m20. DMRS of identification number 3m20 can improve the channel estimation performance by increasing the density of the reference signal compared to identification number 3m10. Identification number 3n30 shows a method in which two antenna ports p=A, B are mapped by FDM/CDM by applying OCC of length 2, and identification number 3n40 is mapped by p=A, B in FDM method without applying OCC show how to become

Next, identification number 3n50 and identification number 3n60 show a case in which four antenna ports are mapped to the DMRS structure of identification number 3m20. In particular, in the case of supporting four antenna ports, in order to improve channel estimation performance, a subcarrier in which DMRS is not transmitted is emptied in the DMRS structure of identification number 3m20 to be used for DMRS power boosting. Identification number 3n50 shows how the four antenna ports p = A, B, C, D are mapped to FDM/CDM by applying OCC and FDM of length 2, and identification number 3n60 is p in FDM method without applying OCC Shows how =A, B, C, D are mapped.

When OCC is applied in frequency to the identification numbers 3n10, 3n30, and 3n50, a power imbalance problem does not occur. In the case of the LTE system, when OCC is applied in time, a power imbalance problem occurs, and there is a restriction that OCC is applied differently for each PRB within two PRBs.

Finally, identification number 3n70 shows the DMRS structure of identification number 3m30, and since identification number 3m30 uses all 12 subcarriers as DMRS, consider an orthogonal DMRS antenna port support method using ZC (Zadoff-Chu). can At this time, as in LTE, a subcarrier spacing of 15 kHz is assumed and 8 cyclic shift (CS) fields are applied to support up to 8 orthogonal antenna ports. As another method utilizing the DMRS structure of 3m30, it is possible to support 4 orthogonal antenna ports by performing FDM at intervals of 4 subcarriers.

The present invention is not limited to the method in which the antenna port is mapped to the DMRS structure proposed in FIGS. 3n10 to 3n70. For example, in the case of identification number 3m30, DMRS SC is FDMed as shown in FIG. 3n80 and 4 cyclic shift fields are applied to support up to 8 orthogonal antenna ports. 3n80, when a high rank is supported, all subcarriers in one OFDM symbol are used, but in an environment using a low rank, only some subcarriers in one OFDM symbol are used as reference signals, and the remaining has the advantage that it can be used for data transmission. For example, in case of transmission of rank 4 or lower in FIG. 3n80, orthogonality may be supported with 4 CSs using only the reference signal of odd subcarriers, and the remaining 6 even subcarriers may be used for data transmission.

In FIG. 1o, a method in which a larger number of antenna ports are mapped to the proposed unit DMRS structure than in FIG. 1m is presented. In order to map a larger number of antenna ports than in FIG. 1N, additional TDM, FDM, and CDM may be performed in the unit DMRS structure.

First, referring to FIG. 3m20, as shown in FIG. 3o10, FIG. 3m20 is TDMed in time, and it is possible to map up to 8 antenna ports. 3O20 shows a case in which a maximum of 16 antenna port mappings can be extended by performing TDM with 3 OFDM symbols in time. When extending the orthogonal antenna port using TDM, there is an advantage in that the RS density on the frequency is maintained as it is, but there is a disadvantage in that the density of the DMRS in the transmission unit is increased. In order to keep the density of DMRS low in the transmission unit, the higher rank extends the orthogonal antenna port by using FDM or CDM considering that the channel condition is very good and the selectivity of the channel on the frequency is supported in an environment that is low. you can consider how to do it.

As in FIG. 3o30, FIG. 3m20 is FDM on frequency to show a method of mapping up to 8 antenna ports. Also, as in FIG. 3o40, it is possible to map up to 8 antenna ports by applying OCC length 8 to FIG. 3m20.

Next, when all subcarriers are configured with DMRS SCs as shown in FIG. 3m30, various antenna ports may be extended according to the antenna port mapping method applied to FIG. 3m30 as described above. If 8 orthogonal antenna ports are supported by assuming a subcarrier interval of 15 kHz in FIG. 3m30 and ZC sequence is CS, 16 orthogonal antenna ports can be extended by applying TDM as shown in FIG. 3o10.

If FDM is used with an interval of 4 subcarriers in FIG. 3m30, up to 4 orthogonal antenna ports can be supported. However, when additional FDM is considered as shown in FIG. 3o30, when FDM is used with an interval of 8 subcarriers, a maximum of 8 orthogonal antenna ports support is possible

The present invention is not limited to the antenna port extension method shown in FIG. 1o. It can be applied by combining TDM, FDM, and CDM, and it is possible to extend the orthogonal antenna port in various ways. For example, as described above, when the number of antenna ports is extended using only TDM as in FIG. 3o10 or 3o20, there is a disadvantage in that the density of the DMRS in the transmission unit increases. As a method to compensate for this disadvantage, TDM based on two consecutive slots as in FIG. 3o50 or CDM of OCC length 4 based on two consecutive slots as in FIG. 3o60 may be applied.

3O50 and 3O60 have been described based on two slots, but the time unit to which TDM or CDM is applied in FIGS. 3O50 and 3O60 is not limited to the slot. In addition, unlike the method of mapping up to 8 antenna ports by applying OCC length 8 as shown in FIG. 3o40, if DMRS is generated as a ZC sequence, it is better to support additional antenna ports using CS as shown in FIG. 3o70. It is possible. In the case of using CS instead of OCC as in FIG. 3o70 , there is an advantage in that the RS density in frequency is maintained as it is.

[Embodiment 1-2]

Embodiment 1-2 describes a method for the base station to configure a DMRS structure suitable for a transmission environment among a plurality of DMRS structures. When multiple DMRS structures are supported as in the 1-1 embodiment of the present invention, and a DMRS structure suitable for the transmission environment can be set as in the 1-2 embodiment, the base station changes the DMRS structure according to the transmission environment. By setting the , it is possible to optimize the overhead of the reference signal.

More specifically, in an environment of low SNR or high-speed transmission, it is necessary to set a DMRS structure having high reference signal overhead to improve channel estimation performance. Conversely, in a high SNR or low-speed transmission environment, it is necessary to set a DMRS structure with a low reference signal overhead to improve transmission efficiency. In this way, when the reference signal is adaptively transmitted to the transmission environment, the overhead of the unnecessary reference signal can be minimized to maximize the system performance.

Hereinafter, a method for the base station to configure a DMRS structure suitable for a transmission environment will be described in more detail. The DMRS structure configuration suitable for the transmission environment of the base station proposed in the present invention may be configured semi-statically or dynamically. In addition, the DMRS structure suitable for the transmission environment may be implicitly set.

First, a method for semi-statically setting a DMRS structure suitable for a transmission environment by a base station will be described. The simplest way to semi-statically configure the DMRS structure is to set the DMRS structure through higher layer signaling.

More specifically, information on different DMRS structures may be signaled by setting DMRS-StructureId in RRC as shown in [Table 1-3] below. In [Table 1-3], maxDMRS-Structure indicates the number of configurable DMRS structures, and each set value may indicate a different DMRS structure. In this way, the DMRS structure may be semi-statically configured through the RRC, and the UE according to an embodiment of the present invention may determine the structure of the currently transmitted DMRS based on the value set in the RRC.

[Table 1-3]

For example, referring to the 1-1-1 embodiment, the DMRS structure may be divided into two structures: a front-loaded DMRS and an extended/additional DMRS. In this case, the value of maxDMRS-Structure in [Table 1-3] may be set to 1. For example, if the value of maxDMRS-Structure is 0, it may be set to indicate Front-loaded DMRS, and if the value of maxDMRS-Structure is 1, it may be set to indicate Extended/Additional DMRS. In Table 1-3, DMRS-sturctureID may be changed to DMRS-configureID or another term.

As another example, when there is more than one structure of Extended/Additional DMRS, the value of maxDMRS-Structure may increase to 1 or more. In addition, when adjusting the DMRS density in frequency in the unit DMRS structure as described in the 1-1-1 embodiment, the maxDMRS-Structure value may be set to a larger value.

As another example, it is also possible to set the time/frequency density of the DMRS through an additional configuration, separately from configuring the Front-loaded DMRS and the Extended/Additional DMRS. More specifically, it may be set in the same way as in [Table 1-4] below.

[Table 1-4]

As another example, a method in which the base station dynamically configures a DMRS structure suitable for a transmission environment will be described. If the DMRS information is set in the MAC CE in a method similar to the method of setting the DMRS information in the RRC above, it is possible to more dynamically configure the information on the DMRS structure.

As another example, the simplest way to dynamically configure the DMRS structure is to put information on the DMRS structure in DCI and transmit it. In this case, for a basic operation, a DCI format to which a field for dynamically operating the DMRS structure is not applied may be separately defined. If the DMRS structure is set using DCI, the DMRS structure can be dynamically changed, so there is an advantage in that transmission efficiency can be improved. On the other hand, there is a disadvantage in that DCI overhead occurs to operate it.

Hereinafter, a method of establishing a DMRS structure using DCI will be described in more detail. As various reference signal structures are supported, the number of bits required to signal the various reference signal structures to DCI increases, but in general, 1-2 bits as shown in [Table 1-5] or [Table 1-6] below can be used to include information on the structure of the DMRS in the DCI field. For example, [Table 1-5] shows an example of operating two structures of a reference signal using 1 bit.

[Table 1-5]

As another example, [Table 1-6] shows an example in which 4 structures of the reference signal are operated using 2 bits. The low density2 field of [Table 1-6] may be set as a field for not transmitting DMRS if necessary. The application of this will be described in the 1-3 embodiment. As described in Example 1-1, the DMRS structure may be determined by a combination of the signaling of [Table 1-5] or [Table 1-6] and the number of DMRS transmission layers used.

[Table 1-6]

In addition, unlike the method of signaling the RS density using [Table 1-5] or [Table 1-6] as described above as a method of transmitting information on the DMRS structure in DCI, the method described in Example 1-1 As described above, a position in time at which DMRS can be transmitted may be specifically signaled.

In Example 1-1, a method in which a position in time at which a DMRS is transmitted is set based on a subframe and a start point of an allocated data channel (ex, PDSCH) in the first for setting a position in time at which DMRS can be transmitted A method for setting the . In this case, it is possible to signal the information on the location in time at which the DMRS is transmitted to the DCI.

As an example, when using a method in which a position in time at which a DMRS is transmitted is set based on a subframe, when a value indicating a subframe duration is defined as x, the position of the DMRS is set in a unit of y=x/2 can be considered. In this case, it is possible to indicate whether the DMRS density is high or low in y unit using only 1-2 bits.

More specifically, a low DMRS density on the time axis may be a DMRS composed of one OFDM symbol, and a high DMRS density on the time axis may be a DMRS composed of two OFDM symbols. In addition, the DMRS structure may be determined by a combination of the number of DMRS transport layers used together. For a specific example of this, refer to the above-described embodiment 1-1.

On the other hand, since it may be inefficient to include the field indicating the DMRS structure in DCI for every transmission and transmit it, the field indicating the DMRS structure is transmitted through DCI based on a preset time interval. may be considered. However, in this case, since the structure of the reference signal can be changed only when the field indicating the DMRS structure is transmitted, more dynamic operation of the DMRS structure may be difficult compared to the method of indicating the DMRS structure at every transmission.

Finally, another example of how the base station implicitly sets the DMRS structure suitable for the transmission environment will be described. The first method is a method of configuring different DMRS structures according to a transmission mode (TM).

More specifically, TM A may be set as a reference signal having a high density, TM B may be set as a reference signal having an average density on a time axis, and TM C may be set as a reference signal having a low density on a time axis. In this case, TM A may be configured as a TM for supporting high mobility and TM C may be configured as a TM for supporting low latency.

Another method is to define two DCI formats in one TM. One of the two formats is set as a structure of a reference signal for transmitting TM features, and the other is a reference signal having a high density by operating in a fallback mode similar to DCI format 1A in LTE. can be set to In this case, the UE may determine which DMRS structure is applied from the currently configured TM mode or DCI format information.

The second method is a method of varying the structure of a reference signal applied according to a modulation and coding scheme (MCS). More specifically, a reference signal having a high density may be mapped in an area in which a low MCS is set to improve channel estimation performance, and a reference signal having a low density may be mapped in an area in which a high MCS is set. In this case, the terminal can implicitly know the structure of the reference signal transmitted from the received MCS information.

The third method is a method in which different DMRS structures are configured according to the frame structure. More specifically, in the self-contained frame structure, DMRS is set in one OFDM symbol ahead in time as in FIG. 1fa-2-1/ FIG. 1fa-2-2, and in the general frame structure, FIG. 1fa-3-1/ FIG. 1fa As in -3-2, it can be assumed that DMRS is configured for two OFDM symbols in time.

As another setting method, when a PDCCH in a common search space is checked based on the LTE system, a structure of a reference signal for a PDSCH connected thereto may be mapped to have a high density. Similarly, when checking a PDCCH in a UE-specific search space, a reference signal for a PDSCH connected thereto may be mapped to a reference signal having a lower density compared to a PDCCH connected to the common search space. have. This is to improve the channel estimation performance for the common search space because it contains important information that all terminals must see. In this case, the terminal can implicitly know the structure of the reference signal from the search space.

[Example 1-3]

In the 1-3 embodiment, when multiple DMRS structures are supported, unlike the existing LTE system, multiple-user transmission may be supported between terminals using different DMRS structures, and MU transmission of each of the terminals We propose a method for DMRS to maintain orthogonality with each other. In the 5G system, there is also a method to prevent the above problem from occurring by allowing UEs that transmit MUs to use a specific reference signal structure, but in this case, the flexibility of MU transmission may be limited. Therefore, we propose two methods for maintaining orthogonality between MUs when MUs are transmitted between UEs using different DMRS structures.

The first method is to perform rate matching on the overlapping part in order to maintain orthogonality when different DMRS structures overlap. This method will be described in detail with reference to FIG. 1H. 1h-1 and 1h-2 are a method for transmitting by a base station performing rate matching on area A of FIG. 1h-1 when a terminal using a different DMRS structure transmits MU. .

This method has a disadvantage that the base station must additionally signal information on rate matching to the terminal. In this case, the number of bits required for signaling may be different depending on the number of supported DMRS structures. Basically, if multiple DMRS structures are supported, the number of signaling bits required to inform the DMRS structures of other MUs is increased. However, as described in [Table 1-4] and [Table 1-5] of the 1-2 embodiment, when the DMRS structure is simplified into 2-4 types and operated, other MUs that are MU The DMRS structure of the UE may be informed. At the same time, there is an advantage that power boosting can be performed on the reference signal in this part considering that other terminals perform rate matching in the reference signal region where different DMRS structures overlap. However, in this method, unlike the LTE system, the MU operation is no longer transparent to the UE.

The second method is a method of transmitting an additional reference signal in a reference signal region where the DMRS structures overlap in order to maintain orthogonality when different DMRS structures overlap. In other words, the second method is a method of setting and transmitting the same DMRS structure.

When this method is described in detail with reference to FIG. 1H, when a terminal using a different DMRS structure of FIGS. 1H-1 and 1H-2 transmits MU, the base station includes a reference signal in area A of FIG. 1H-1 to send In this case, it means that the base station using the DMRS structure of FIG. 1h-1 transmits using the DMRS structure of FIG. 1h-2. Unlike the first method, when this method is used, there is an advantage in that additional signaling is not required to the terminal using FIG. 1H-1.

Meanwhile, whether or not the terminal additionally uses the reference signal included in the region A part for channel estimation with reference to FIG. 1H-1 may vary depending on implementation. If the terminal using FIG. 1h-1 is a terminal requiring low latency, the reference signal for the region A portion may not be used for fast signal processing. However, in this case, additional signaling to indicate this may be required. For example, the base station transmits information on ACK/NACK timing to the terminal through DCI, so that the terminal determines whether to use the channel estimation of the reference signal for the area A part based on FIG. 1h-1 can decide

1h-3, 1h-4, and 1h-5 show a method of changing the DMRS density when a variable Transmission Time Interval (TTI) is applied. In addition, at this time, we propose a method for maintaining orthogonality of DMRSs of UEs that are MUs to each other.

More specifically, FIG. 1H-3 is a diagram illustrating a case in which a plurality of TTIs are combined and transmitted. In this case, it may be assumed that the same precoding is applied to the DMRS while a plurality of TTIs are transmitted. In particular, when the TTI duration is short, it may be inefficient in terms of overhead of the reference signal to transmit the DMRS at the same density in frequency as shown in FIG. 1h-3. Accordingly, examples of changing the DMRS density are shown in FIGS. 1h-4 and 1h-5 as a method of reducing the overhead of the reference signal.

First, in TTI-1 and TTI-2 of FIG. 1H-4, a method of setting the DMRS to lower the overhead of the reference signal is possible. Also, as another method, there may be a method in which DMRS is not transmitted in TTI-2 as in FIG. 1h-5. As described above, when MU transmission is attempted in TTI in which the DMRS density is changed, a situation in which orthogonality is not maintained may occur because different terminals use different DMRS structures. In this case, as described above, both methods for maintaining orthogonality can be applied when different DMRS structures overlap.

More specifically, when the method for rate matching is applied, the base station uses DCI to signal rate matching information to the terminal before every TTI. Contrary to this, when the second method is applied, for example, as in the case of MU transmission in TTI-2 of FIGS. 1H-4 and 1H-5, the base station provides information to different terminals in TTI-2 without additional signaling. The same DMRS structure can be configured and transmitted. For example, the DMRS structure in TTI-1 may be transmitted in TTI-2.

Additionally, a method for efficiently performing MU support between terminals using different OCC lengths is proposed. For example, a case in which terminals using OCC of length 2 and OCC of length 4 are transmitted to the MU will be described. For example, when 2-layer transmission is performed using OCC of length 4 based on [Table 1-2], 2-layer transmission is performed through ports 7 and 11 or 2-layer transmission is performed through ports 8 and 13. can This enables more orthogonal MU pairing compared to 2-layer transmission using ports 7 and 8 or 2-layer transmission using ports 11 and 13.

As described above, in [Table 1-2], port 7 to port 14 are numbered based on the LTE system, but this is an example for explanation. For example, the port number used in the 5G system may be different from this. Therefore, the proposed method can be applied based on the OCC sequence corresponding to each port in [Table 1-2].

In order to carry out the above embodiments of the present invention, the transmitting unit, receiving unit, and processing unit of the terminal and the base station are respectively shown in Figs. A method of transmitting and receiving a base station and a terminal is shown in order to configure and provide a method for the base station to set it. In order to perform this, a receiving unit, a processing unit, and a transmitting unit of the base station and the terminal must operate according to the embodiment, respectively.

Specifically, FIG. 1I is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 1H , the terminal of the present invention may include a terminal receiving unit 1800 , a terminal transmitting unit 1804 , and a terminal processing unit 1802 . In the embodiment of the present invention, the terminal receiving unit 1800 and the terminal collectively refer to the transmitting unit 1804 as a transceiver.

The transmitting/receiving unit of the terminal may transmit/receive a signal to/from the base station. The signal may include control information and data. To this end, the transceiver of the terminal may be composed of a radio frequency (RF) transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency. In addition, the transceiver of the terminal may receive a signal through a wireless channel and output it to the terminal processing unit 1802 , and transmit the signal output from the terminal processing unit 1802 through a wireless channel.

The terminal processing unit 1802 may control a series of processes so that the terminal can operate according to the above-described embodiment of the present invention. For example, when the terminal receiving unit 1800 receives the reference signal from the base station, the terminal processing unit 1802 may control to interpret the application method of the reference signal. Also, the terminal transmitter 1804 may transmit the reference signal in the same way.

1J is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 1I , the base station of the present invention may include a base station receiving unit 1901 , a base station transmitting unit 1905 , and a base station processing unit 1903 . The base station receiver 1901 and the base station transmitter 1905 may be collectively referred to as a transceiver in the embodiment of the present invention.

The transceiver of the base station may transmit and receive a signal to and from the terminal. The signal may include control information and data. To this end, the transceiver of the base station may include an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts a received signal.

In addition, the transceiver of the base station may receive a signal through a wireless channel and output it to the base station processing unit 1903 , and transmit the signal output from the base station processing unit 1903 through the wireless channel. The base station processing unit 1903 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 1903 may determine the structure of the reference signal and control to generate configuration information of the reference signal to be transmitted to the terminal. Thereafter, the reference signal and configuration information may be transmitted to the terminal using the base station transmitter 1905 , and the base station receiver 1901 may receive the reference signal.

Also, according to an embodiment of the present invention, the base station processing unit 1903 may control a process for supporting MU transmission orthogonally between terminals using different DMRS structures. In addition, information necessary for control may be transmitted to the terminal using the base station transmitter 1905 .

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 can be implemented based on the technical idea 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, 1-2, and 1-3 of the present invention with each other. 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 TDD LTE system, 5G or NR system.

<Second embodiment>

In order for the terminal to estimate the channel in the wireless communication system, the base station needs to transmit a reference signal for this. The terminal may perform channel estimation using the reference signal and demodulate the received signal. In addition, the terminal may determine the channel state through the reference signal and use it to feed back it to the base station. In general, when a reference signal is transmitted, a transmission interval of the reference signal based on the frequency and time of the reference signal is determined in consideration of a maximum delay spread and a maximum Doppler spread of a channel. As the transmission interval of the reference signal is narrower, the channel estimation performance is improved and the demodulation performance of the signal can be improved.

In the conventional 4G LTE system operating in a frequency band of 2 GHz, reference signals such as a cell-specific reference signal (CRS) and a demodulation reference signal (DMRS) are used in the downlink. When the interval of the reference signal in frequency is expressed as the subcarrier interval m of the OFDM (Orthogonal Frequency Division Multiplexing) signal, and the interval of the reference signal in time is expressed as the symbol interval n of the OFDM signal, the normal cyclic prefix; In the case of CRS assuming normal CP), the transmission interval based on the frequency and time of the reference signals corresponding to antenna ports 1 and 2 is (m, n) = (3,4). Also, in the case of DMRS assuming normal CP, the transmission interval based on the frequency and time of the reference signal is (m, n) = (5, 7).

Unlike the LTE system, 5G wireless communication considers a system operating in a frequency band of 6 GHz or less as well as a high frequency band higher than that. Since the channel characteristics vary according to the frequency band, it is necessary to newly design the reference signal in consideration of this in the 5G system. In addition, in 5G wireless communication, low latency support and high mobility support are being considered as important. Additionally, in the 5G system, it is important to minimize the overhead of the reference signal.

In a wireless communication system, a base station must transmit a reference signal to a terminal in order to measure a downlink channel state. In the case of 3GPP's LTE-A (Long Term Evolution Advanced) system, the terminal uses a CRS or Channel Status Information Reference Signal (CSI-RS) transmitted by the base station to determine the channel state between the base station and the terminal. measure

Several factors should be considered for the channel state. For example, the amount of interference in downlink may be considered. The amount of interference in the downlink includes an interference signal and thermal noise generated by antennas included in each of the adjacent base stations, and plays an important role in determining the downlink channel condition of the terminal.

For example, when one transmitting antenna included in one base station transmits a signal to one receiving antenna included in one terminal, the terminal uses a reference signal received from the base station per symbol that can be received through downlink. After determining the amount of interference to be received along with the energy and the corresponding symbol during the period in which the symbol is received, Es/Io must be determined. The determined Es/Io is converted into a data transmission 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 determines at which transmission rate data is transmitted to the terminal in the downlink. make it possible to judge

In the case of the LTE-A system, the terminal feeds back information on the downlink channel state to the base station so that the base station can use it for downlink scheduling. That is, the terminal measures the channel state using a reference signal transmitted by the base station through the downlink, and feeds back the measured channel state information to the base station in the form defined in the LTE/LTE-A standard.

In LTE/LTE-A, there are three types of channel state information (CSI) 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 UE can receive in the current channel state. CQI may be replaced with SINR, which can be utilized similarly to the maximum data rate, the maximum error-correcting code rate and modulation scheme, data efficiency per frequency, and the like.

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. Accordingly, a PMI value when RI has a value of 1 and a PMI value when RI has a value of 2 are interpreted differently even if the values are the same.

In addition, the terminal determines the CQI assuming that the rank value and the PMI value notified by the terminal to the base station are applied by the base station. For example, 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 data according to the data rate corresponding to CQI_Z. In this way, the terminal assumes which transmission method to perform to the base station when calculating the CQI, so that optimized performance can be obtained when the base station actually transmits in the corresponding transmission method.

In LTE/LTE-A, the periodic feedback of the UE is set to one of the following four feedback modes (feedback mode or reporting mode) depending on what information is included:

One. Reporting mode 1-0: RI, wideband CQI (wCQI)

2. Reporting mode 1-1: RI, wCQI, PMI

3. Reporting mode 2-0: RI, wCQI, narrowband (subband) CQI (sCQI)

4. Reporting mode 2-1: RI, wCQI, sCQI, PMI

서브프레임이며, 오프셋은 N_OFFSET,CQI + N_OFFSET,RI이다.The feedback timing of each information for the four feedback modes is determined by the values of N _pd , N _OFFSET,CQI , M _RI , and N _OFFSET,RI transmitted as a higher layer signal. In feedback mode 1-0, the transmission period of wCQI is N _pd subframes, and the feedback timing is determined with subframe offset values of N _OFFSET,CQI . In addition, the transmission period of the RI is

It is a subframe, and the offset is N _OFFSET,CQI + N is _OFFSET,RI .

2A is a diagram illustrating feedback timings of RI and wCQI in the case of N _pd =2, M _RI =2, N _{OFFSET, CQI} = 1, N _{OFFSET, RI} = -1. In FIG. 2A, each timing indicates a subframe index.

Feedback mode 1-1 has the same feedback timing as mode 1-0, but the difference is that wCQI and PMI are transmitted together in wCQI transmission timing for any one situation of one antenna port, two antenna ports, or four antenna ports have

서브프레임이며, 오프셋 값은 sCQI의 오프셋 값과 같이 N_OFFSET,CQI이다. 여기서,

로 정의되는데 K는 상위신호로 전달되며, J는 시스템 대역폭(bandwidth)에 따라 결정되는 값이다. 예를 들어, 10MHz 시스템에 대한 J 값은 3으로 정의된다. 결국, wCQI는 H번의 sCQI 전송마다 한번씩 이에 대체하여 전송된다. 그리고 RI의 주기는

서브프레임이며 오프셋은 N_OFFSET,CQI + N_OFFSET,RI이다. In feedback mode 2-0, the feedback period for sCQI is N _pd subframes, and the offset value is N _OFFSET,CQI . And the feedback period for wCQI is

It is a subframe, and the offset value is N _OFFSET,CQI like the offset value of sCQI. here,

It is defined as , where K is transmitted to the upper level signal, and J is a value determined according to the system bandwidth. For example, the J value for a 10 MHz system is defined as 3. As a result, the wCQI is transmitted instead of once for every H sCQI transmission. And the cycle of RI is

Subframe and offset is N _OFFSET,CQI + N is _OFFSET,RI .

Figure 2b shows RI, sCQI, wCQI feedback timing for the case of N _pd =2, M _RI =2, J = 3 (10 MHz), K = 1, N _{OFFSET, CQI} = 1, N _{OFFSET, RI} = -1. It is a drawing showing. Feedback mode 2-1 has the same feedback timing as mode 2-0, but with respect to any one situation of one antenna port, two antenna ports, or four antenna ports, the difference is that PMI is transmitted together in the wCQI transmission timing. have

The feedback timing described above is a case in which the number of CSI-RS antenna ports is one, two, or four, and as another example, CSI-RS for any one of four antenna ports or eight antenna ports In the case of the assigned terminal, two pieces of PMI information are fed back differently from the feedback timing. In this case, that is, when the UE is allocated CSI-RS for any one of 4 antenna ports or 8 antenna ports, feedback mode 1-1 may be divided into two submodes again.

와 N_OFFSET,CQI + N_OFFSET,RI로 정의된다. For example, in the first submode, the RI is transmitted together with the first PMI information, and the second PMI information is transmitted along with the wCQI. Here, the period and offset of the feedback for wCQI and the second PMI are defined as N _pd and N _OFFSET,CQI , and the feedback period and offset values for the RI and the first PMI information are respectively

with N _OFFSET,CQI + It is defined as N _OFFSET,RI .

When both the first PMI (i1) and the second PMI (i2) are reported from the terminal to the base station, the terminal and the base station correspond to the combination of the first PMI and the second PMI in the set (codebook) of precoding matrices shared by each other It is confirmed that the precoding matrix W(i1, i2) is the preferred precoding matrix of the terminal.

In other words, when the precoding matrix corresponding to the first PMI is W1 and the precoding matrix corresponding to the second PMI is W2, the terminal and the base station determine that the precoding matrix preferred by the terminal is W1W2, the product of the two matrices. share information

서브프레임이며 오프셋은 N_OFFSET,CQI + N_OFFSET,RI로 정의된다. When the feedback mode for the eight CSI-RS antenna ports is 2-1, precoding type indicator (PTI) information is added to the feedback information. At this time, the PTI is fed back together with the RI, and the period is

Subframe, offset is N _OFFSET,CQI + It is defined as N _OFFSET,RI .

이며 오프셋은 N_OFFSET,CQI이다. 여기서 H'은 상위신호로 전달된다. Specifically, when the PTI is 0, the first PMI, the second PMI, and the wCQI are all fed back. At this time, wCQI and the second PMI are transmitted together at the same timing, the period is N _pd , and the offset is given as N _OFFSET,CQI . The cycle of the first PMI is

and the offset is N _OFFSET,CQI . Here, H' is transmitted as an upper-order signal.

의 주기와 N_OFFSET,CQI의 오프셋을 가지고 피드백되며 H는 CSI-RS 안테나 포트 개수가 2인 경우와 같이 정의된다. On the other hand, when the PTI is 1, wCQI is transmitted together with the wideband second PMI, and the sCQI is fed back together with the narrowband second PMI at a separate timing. In this case, the first PMI is not transmitted, and is reported after the second PMI and CQI are calculated assuming the most recently reported first PMI when the PTI is 0. Periods and offsets of PTI and RI are the same as in the case where PTI is 0. The period of sCQI is defined as N _pd subframes, and the offset is defined as N _OFFSET,CQI . The wCQI and the second PMI are

It is fed back with a period of N _{OFFSET and an offset of CQI} , and H is defined as in the case where the number of CSI-RS antenna ports is 2.

2c-1 and 2c-1 show N _pd =2, M _RI =2, J=3 (10MHz), K=1, H'=3, N _OFFSET,CQI =1, N _OFFSET,RI =-1 It is a diagram showing feedback timing in the case of PTI=0 and PTI=1, respectively, for the case of .

LTE/LTE-A supports not only periodic feedback of the terminal but also aperiodic feedback. When the base station wants to obtain aperiodic feedback information of a specific terminal, the base station performs specific aperiodic feedback with an aperiodic feedback indicator included in downlink control information (DCI) for uplink data scheduling of the corresponding terminal uplink data scheduling of the corresponding terminal is performed by setting it to

In this case, when the terminal receives an indicator configured to perform aperiodic feedback in the n-th subframe, the terminal performs uplink transmission including aperiodic feedback information in data transmission in the n+k-th subframe. Here, k is a parameter defined in the 3GPP LTE Release 11 standard and is 4 in frequency division duplexing (FDD), and is defined as in [Table 2-1] in time division duplexing (TDD). [Table 2-1] shows the k value for each subframe number n in the TDD UL/DL configuration.

[Table 2-1]

When the aperiodic feedback is configured, the feedback information includes RI, PMI, and CQI as in the case of periodic feedback, and the RI and PMI may not be fed back according to the feedback configuration. And, the CQI may include both wCQI and sCQI or may include only wCQI information.

As described above, unlike the LTE system, 5G wireless communication considers a system operating in a frequency band of 6 GHz or less as well as a high frequency band higher than that of the LTE system. Also, in 5G wireless communication, low latency support and high mobility support are being considered as important. Additionally, in the 5G system, it is important to minimize the overhead of the reference signal. Therefore, in the 5G system, unlike the LTE system, a plurality of reference signals suitable for the transmission environment may be supported.

In this way, when a plurality of reference signals are supported, the UE may need additional feedback information for selecting a reference signal suitable for the transmission environment as well as RI, PMI, and CQI. Accordingly, the present invention provides a method in which the terminal feeds back information necessary for the selection of the reference signal to the base station so that the adaptive transmission of the reference signal is possible.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, an embodiment of the present invention will be described using an LTE or LTE-A system as an example, but 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. More specifically, a method of periodically or aperiodically feedbacking channel information may be different from the method in LTE described above. In addition, although the present invention has been described with reference to DMRS, it can be applied to other reference signals as well. Accordingly, the embodiments of the present invention may 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.

In addition, when it is determined that a detailed description of a function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. And, the terms to be described later 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 the terminal to a flag station.

Feedback information for selecting a reference signal suitable for a transmission environment to be described below is expressed in terms of a pilot density indicator (PDI). However, the term for PDI may be expressed in other terms depending on the intention of the user and the purpose of using the reference signal. For example, it may be replaced by a term such as a reference-signal density indicator (RDI), a Doppler frequency indicator (DFI), a delay spread indicator (DSI), or an SINR indicator (SI). The abbreviation defined as PDI is merely to provide specific examples to easily explain the technical content of the present invention and to help the understanding of the present invention, and is not intended to limit the scope of the present invention. That is, it is apparent to those of ordinary skill in the art to which the present invention pertains that it can be implemented even with a reference signal based on the technical idea of the present invention.

In Embodiment 2-1 of the present invention, which will be described below, feedback information that may be included in PDI will be described. In Embodiment 2-2 of the present invention, a method of feeding back PDI will be described. And in Embodiment 2-3 of the present invention, a method of operating a base station using PDI will be described.

[Embodiment 2-1]

Embodiment 2-1 describes information that can be included in PDI, which is feedback information proposed by the present invention. As described above, a plurality of structures of the reference signal required according to the transmission environment may be supported.

More specifically, in an environment where the degree of the Doppler effect is strong, it is necessary to increase the density of the reference signal on the transmission time axis to increase the channel estimation performance. On the other hand, in an environment in which the degree of the Doppler effect is small (hereinafter, the term Low Doppler will be used interchangeably), it is necessary to reduce the reference signal overhead by lowering the density of the reference signal on the transmission time axis. And in a high delay environment, it is necessary to increase the density of the reference signal on the transmission frequency axis to increase the channel estimation performance. On the other hand, in the low delay environment, it is necessary to reduce the overhead of the reference signal by lowering the density of the reference signal on the transmission frequency axis. In addition, in a low SNR (Signal to interference plus noise ratio) environment, a structure of a reference signal having a high density is required to ensure channel estimation performance, and in a high SNR environment, the reference signal overhead is reduced by lowering the density of the reference signal. need to reduce

As described above, Doppler information that determines the structure of the reference signal, channel delay information, and SINR information are all information that the UE can grasp through measurement. Accordingly, PDI, which is feedback information proposed by the present invention, may include Doppler information, channel delay information, and SINR information. However, the information that can be included in the PDI of the present invention is not limited to the above information.

The UE may inform information about a preferred reference signal structure in a channel environment by feeding back the measured Doppler information, channel delay information, and SINR information. In the present invention, the PDI may include all of Doppler information, channel delay information, and SINR information, or only some information.

More specifically, based on the information included in the PDI, the structure of which reference signal is suitable according to the situation will be described below.

First, when Doppler information is included in the PDI, the UE can determine the structure of a reference signal suitable for a channel environment through Doppler frequency measurement. For example, the terminal may measure the Doppler frequency by performing temporal correlation based on the reference signal. And as shown in Equation 1 below, when the Doppler frequency (Hz) is greater than X, it may indicate that transmission of a reference signal having a high density is required on the transmission time axis.

[Equation 1]

Doppler frequency > X

를 나타낸다. 따라서, Doppler frequency는 캐리어 주파수(carrier frequency)와 단말 속도에 영향을 받음을 알 수 있다. In Equation 1, X (Hz) represents a threshold for the Doppler frequency. And the Doppler frequency can be expressed as Doppler frequency = f*v/c. Here, f represents carrier frequency (Hz), v(m/s) represents the speed of the terminal, and c represents the speed of light.

indicates Accordingly, it can be seen that the Doppler frequency is affected by the carrier frequency and the terminal speed.

For example, when f = 2.5 GHz and v = 350 km/h, the Doppler frequency becomes 810 Hz. As an example, when the Doppler frequency is 800 Hz or more, the threshold X=800 Hz for the Doppler frequency may be set when it is considered as a High Doppler environment.

Unlike the LTE system, since the 5G system considers the terminal speed up to 500 km/h, the method of adaptively changing the structure of the reference signal in consideration of the terminal speed can be very effective. In the present invention, as in Equation 1, when the Doppler frequency is greater than X, a one bit indicator may be fed back to indicate that transmission of a reference signal having a high density on the time axis is required.

Next, when channel delay information is included in the PDI, the terminal can determine the structure of a reference signal suitable for the channel environment through channel delay measurement. For example, the terminal may measure the channel delay information through various methods based on the reference signal.

For example, the terminal may measure a power delay profile (PDP) by performing frequency correlation based on a reference signal. Delay spread information such as root mean square (RMS) delay spread or maximum delay spread may be obtained from the PDP information. And as shown in Equation 2 below, when Delay spread (sec) is greater than Y, it may indicate that transmission of a reference signal having a high density on the transmission frequency axis is required.

[Equation 2]

Delay spread > Y

In Equation 2, Y(sec) represents a threshold for Delay spread. And the delay spread may be an RMS delay spread or a maximum delay spread. If the RMS delay spread is the basis, Y is set based on the RMS delay spread value, and may be set differently based on the maximum delay spread value.

In general, since the reference signal in the existing LTE system is designed assuming the worst case for the channel delay, it is possible to improve the transmission efficiency by using a reference signal having a lower frequency density in an environment with a low channel delay. can

In addition, in the 5G system, the system is considered not only in the frequency band below 6 GHz but also in the higher frequency band, and accordingly, support for various subcarrier spacing is considered. need to design

In the present invention, when the delay spread is greater than Y as in [Equation 2], one bit indicator may be fed back to indicate that transmission of a reference signal having a high density on the frequency axis is required. However, even in the 5G system, if the reference signal is designed assuming the worst case for channel delay, additional indication for delay information may not be needed.

Finally, when channel SINR information is included in the PDI, the UE may determine the structure of a reference signal suitable for the channel environment through SINR measurement. For example, the terminal may measure the SINR through various methods based on the received signal. And as shown in Equation 3 below, when the SINR is greater than Z, the structure of the reference signal having a high density may be indicated.

[Equation 3]

SINR > Z

In Equation 3, Z represents a threshold for SNR. In general, in a low SINR region (-10 to 0 dB), it is important to maintain system performance by improving channel estimation performance using a reference signal having a high density. As an embodiment, the threshold Z=0dB for SINR may be set.

In the present invention, when the SINR is greater than Z as in Equation 3, a one bit indicator may be fed back to indicate preference for a reference signal having a high density. However, in [Equation 3], the SINR is to be replaced by the CQI index defined in Table 7.2.3-1 of the 3GPP LTE standard TS.36.213 or the maximum error correction code rate and modulation method, data efficiency per frequency, etc. may be

If, in [Equation 3], the SINR is replaced with the CQI index and used, there is an advantage that the structure information of the preferred reference signal can be implicitly fed back through the CQI feedback without using an additional bit. . As an embodiment, when the lowest CQI index is fed back, it may be indicated that a reference signal having a high density is preferred.

Based on the information that can be included in the PDI, which is the feedback information proposed by the present invention from Embodiment 2-1, and each information included in the PDI, the UE prefers which reference signal structure, that is, what reference signal structure in the current situation. A method of determining whether transmission of is required has been described through Equations 1 to 3 above. According to the above situation, information required for the terminal to feed back to the base station may be set to 1 to 3 bits.

However, when a plurality of threshold values are set in Equations 1 to 3 as needed, the structure of a reference signal preferred by the UE may be further subdivided and set according to the threshold values. Also, in this case, the number of bits of information required for the terminal to feed back to the base station may increase.

For example, if two thresholds X1 and X2 for the Doppler frequency are set as in [Equation 4], the structure of the reference signal preferred by the terminal can be divided into three types.

[Equation 4]

Doppler frequency > X1 (4-1)

X2 ≤ Doppler frequency ≤ X1 (4-2)

Doppler frequency < X2 (4-3)

In [Equation 4], when there are three reference signal structures according to the density on the transmission time axis, Equation 4-1 indicates that the reference signal having the highest density is preferred on the transmission time axis, and Equation 4-2 is the transmission time axis indicates that a reference signal having a medium density is preferred in the above figure, and Equation 4-3 may indicate that a reference signal having a low density is preferred on the transmission time axis. The above method can be equally applied to Equations 2 and 3.

[Embodiment 2-2]

Embodiment 2-2 describes a method in which the terminal feeds back a pilot density indicator (PDI), which is feedback information proposed by the present invention, to the base station. As described above, a case in which the UE feeds back PDI along with RI, PMI, and CQI, which are channel state information fed back to the base station in LTE/LTE-A, is considered.

First, when aperiodic feedback is used, the base station sets the aperiodic feedback indicator included in downlink control information for uplink data scheduling of the corresponding terminal to perform PDI feedback, thereby providing PDI information to uplink data of the corresponding terminal. can be transmitted including

Next, consider the case of using aperiodic feedback. In the case of aperiodic feedback, since the number of bits usable for feedback may be limited, information required for feedback may be limited to 1 to 3 bits using Equations 1 to 3 of the 2-1 embodiment. The PDI feedback method proposed in the present invention may be classified as follows based on the CQI feedback in the LTE system.

One. When feedback is based on wideband CQI (wCQI)

2. When feedback is based on narrowband (subband) CQI (sCQI)

3. When separately fed back to wCQI and sCQI

Based on the assumption of FIG. 2A, FIG. 2D-1 is a diagram illustrating a case in which the PDI feedback method is fed back based on wCQI. 2d-1 shows that PDI is transmitted together whenever wCQI is fed back. In this case, a reference signal suitable for the channel state may be determined based on the entire band.

Based on the assumption of FIG. 2B, FIG. 2D-2 is a diagram illustrating a case in which the PDI feedback method is fed back based on sCQI. In this case, the reference signal suitable for the channel state may be determined based on the narrowband.

Based on the assumption of FIG. 2B, FIG. 2D-3 is a diagram illustrating a case in which the PDI feedback is separately fed back to wCQI and sCQI. In this case, the reference signal suitable for the channel state of the base station may be determined based on the wideband or the narrowband.

[Embodiment 2-3]

Embodiment 2-3 describes an operation of a base station when PDI, which is feedback information proposed by the present invention, is fed back from the terminal to the base station. The base station can distinguish which environment the supportable reference signal is suitable for as shown in [Table 2-2] or [Table 2-3] below.

[Table 2-2] shows an example of a case where two types of reference signal structures are operated, and [Table 2-3] shows an example of a case of operating four types of reference signal structures. For example, when there are two supportable reference signal structures, it is possible to distinguish which environment each of the two reference signals is suitable for through [Table 2-2].

[Table 2-2]

As another example, in a case where there are four types of supportable reference signal structures, it is possible to classify which environment each reference signal is suitable for through [Table 2-3].

[Table 2-3]

More specifically, the structure of the reference signal for [Table 2-3] is shown in FIG. 2E. When the transmission environment requires low latency or is a Low Doppler environment, it is possible to use a structure of a reference signal having a low density on the time axis as shown in FIG. 2e-1. On the contrary, in an environment where the transmission environment is low delay, it is possible to use a structure of a reference signal having a low frequency density as shown in FIG. 2e-2. Contrary to this, in a high delay environment, it is possible to use a structure of a reference signal having a high frequency density as shown in FIG. 2E-3. And in a high Doppler environment or a low SINR environment, it is possible to use a reference signal structure having a high density as shown in FIG. 2e-4.

In other words, it is possible to interpret as follows. The structure of FIG. 2E-1 shows the structure of a reference signal corresponding to low latency/Low Doppler. The structure of FIG. 2e-2 shows the structure of a reference signal corresponding to low delay/high SINR. The structure of FIG. 2E-3 shows the structure of a reference signal corresponding to high delay / high SINR. And the structure of FIG. 2e-4 shows the structure of a reference signal corresponding to High Doppler/Low SINR.

A method of determining the structure of a reference signal suitable for the current environment when the base station receives the PDI, which is the feedback information proposed in the present invention, from the terminal from the above embodiment 2-3 has been described through an example. However, as described above, the method of determining the structure of the reference signal suitable for the transmission environment through PDI reception may vary according to the structure of the reference signal supported by the base station.

[Example 2-4]

In the present invention, when a plurality of reference signals are supported, a method of feeding back information on a reference signal preferred by the terminal is proposed. Embodiment 2-4 proposes a method of setting the type or number of reference signals that can be supported to a specific terminal as UE capability when a plurality of reference signals are supported.

More specifically, the base station can inform the terminal of the type of reference signal that can be set through UE capability signaling, and the terminal can feed back information on the reference signal preferred by the terminal within the type of reference signal that can be set through this. . When the base station notifies the terminal of the type of reference signal that can be set through UE capability signaling, there is an advantage in that it is easy for the terminal to select a reference signal preferred by the terminal from within the type of the reference signal.

For example, the type or number of settable reference signal structures may vary depending on the slot structure. More specifically, a case in which 14 symbols are used as one slot and a structure in which 7 symbols are used as one slot may use different types of reference signals. In addition, in the structure of the mini-slot, a structure or type of a reference signal different from the above-described slot structure may be used.

Also, in terms of the terminal, the types of usable reference signals may be limited depending on the implementation of the terminal. Specifically, a specific terminal may not support all reference signal structures because a method for implementing channel estimation for a reference signal is limited.

Therefore, as in the proposed method, the base station informs the terminal of the types of reference signals that can be set through UE capability signaling, and the terminal selects the reference signals preferred by the terminal from among the types of available reference signals. Required in a supported environment. Here, the UE capability signaling may be set in RRC (Radio Resource Control) signaling, which is a higher layer signal.

* 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. 2F and 2G, respectively. In the 2-1 to 2-3 embodiments, a method of transmitting and receiving a base station and a terminal is shown in order to perform an operation of transmitting and receiving a pilot density indicator (PDI), which is feedback information proposed by the present invention. For this, the receiving unit, processing unit, and transmitting unit of the base station and the terminal must operate according to each embodiment.

Specifically, FIG. 2F is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 2F , the terminal of the present invention may include a terminal receiving unit 1800 , a terminal transmitting unit 1804 , and a terminal processing unit 1802 .

The terminal receiving unit 1800 and the terminal transmitting unit 1804 may be collectively referred to as a transceiver in the embodiment of the present invention. The transmitting/receiving unit of the terminal may transmit/receive a signal to/from the base station. The signal may include control information and data. To this end, the transceiver of the terminal may be composed of a radio frequency (RF) transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies a received signal and down-converts the frequency.

In addition, the transceiver of the terminal may receive a signal through a wireless channel and output it to the terminal processing unit 1802 , and transmit the signal output from the terminal processing unit 1802 through a wireless channel.

The terminal processing unit 1802 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 processing unit 1802 measures and interprets information that may be included in the PDI. Also, the terminal processing unit 1802 may control the terminal transmitting unit 1804 to transmit PDI information to the base station. Also, according to an embodiment of the present invention, the terminal processing unit 1802 may periodically or aperiodically determine the PDI transmission timing and control it.

2G is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 2G , the base station of the present invention may include a base station receiving unit 1901 , a base station transmitting unit 1905 , and a base station processing unit 1903 . The base station receiver 1901 and the base station transmitter 1905 may be collectively referred to as a transceiver in the embodiment of the present invention.

The transceiver of the base station may transmit and receive a signal to and 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 of the base station may receive a signal through a wireless channel and output it to the base station processing unit 1903 , and transmit the signal output from the base station processing unit 1903 through the wireless channel.

The base station processing unit 1903 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 receiving unit 1901 receives the PDI fed back from the terminal. The base station processing unit 1903 may interpret the PDI information received from the terminal and determine which reference signal structure is suitable for the transmission environment. Thereafter, the base station processing unit 1903 controls the base station transmitter 1905 to transmit the corresponding reference signal based on the structure of the reference signal selected based on the PDI. Also, according to an embodiment of the present invention, the base station processing unit 1903 may perform a setting for periodically or aperiodically receiving a PDI and control it.

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 is apparent to those of ordinary skill in the art to which the present invention pertains that other modifications can be implemented 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, parts of embodiments 2-1, 2-2, and 2-3 of the present invention may be combined with each other and operated through a base station and a terminal. 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 TDD LTE system, 5G or NR system.

<Third embodiment>

In a wireless communication system, particularly, in a conventional LTE system, after 3 ms after receiving downlink data, HARQ (Hybrid Automatic Repeat reQuest) ACK (Acknowledgement) or NACK (Negative Acknowledgment) information that informs whether data transmission is successful in uplink transmitted to the base station. For example, HARQ ACK / NACK information of a physical downlink shared channel (PDSCH) received in subframe n from the base station to the terminal is a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) in subframe n+4 transmitted to the base station.

In addition, in a frequency division duplex (FDD) LTE system, the base station transmits downlink control information (DCI) including uplink resource allocation information to the terminal, or may request retransmission through a physical hybrid ARQ indicator channel (PHICH), the terminal When the above uplink data transmission scheduling is received in subframe n, the UE performs uplink data transmission in subframe n+4. That is, PUSCH transmission is performed in subframe n+4. The above example is a description in an LTE system using FDD, and in an LTE system using Time Division Duplex (TDD), HARQ ACK/NACK transmission timing or PUSCH transmission timing varies depending on the uplink-downlink subframe configuration, , this is done according to predetermined rules.

* In the LTE system using the FDD or TDD, the HARQ ACK/NACK transmission timing or the PUSCH transmission timing is a predetermined timing according to the case where the time required for signal processing between the base station and the terminal is about 3 ms. However, if the LTE base station and the terminal reduce the signal processing time to about 1 ms or 2 ms, the delay time for data transmission may be reduced. Reducing the signal processing time to 1 ms or 2 ms may be achieved by limiting the number of allocated Physical Resource Blocks (PRBs), Modulation and Coding Scheme (MCS), Transport Block Size (TBS), and the like.

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 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 (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 alleviate 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), an ultra-dense network (ultra-dense network) ), Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP) and reception interference cancellation Technology development is underway.

In addition, in the 5G system, the advanced coding modulation (ACM) methods FQAM (Hybrid FSK and QAM Modulation) and SWSC (Sliding Window Superposition Coding), and advanced access technologies FBMC (Filter Bank Multi Carrier), 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 information between distributed components such as objects and processes them. 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, technologies such as sensor network, machine to machine (M2M), and MTC (Machine Type Communication) are implemented by 5G communication technologies such as beamforming, MIMO, and array antenna. will be. The application of cloud radio access network (cloud RAN) as the big data processing technology described above can be said to be an example of convergence of 5G technology and IoT technology.

As described above, a plurality of services can be provided to a user in a communication system, and in order to provide such a plurality of services to a user, a method and an apparatus using the same are required to provide each service within the same time period according to characteristics. .

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

In the present specification, it will be understood that each block of the flowchart diagrams and combinations of flowchart diagrams may be executed 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 be performed substantially simultaneously, or the blocks may sometimes be performed in the reverse order according to a 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. '~' may be configured to reside on an addressable storage medium or may be configured to refresh one or more processors. Accordingly, as an example, '~' indicates 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. Also, in an embodiment, '~ part' may include one or more processors.

In a wireless communication system including the 5th generation, at least one service of enhanced mobile broadband (eMBB), massive machine type communications (mmTC), and ultra-reliable and low-latency communications (URLLC) may be provided to the terminal. The services may be provided to the same terminal during the same time period. In an embodiment, eMBB may be a high-speed transmission of high-capacity data, mMTC may be a service that minimizes terminal power and accesses multiple terminals, and URLLC may be a service that aims for high reliability and low latency, but is not limited thereto. The three services may be major scenarios in a system such as an LTE system or 5G/NR (new radio, next radio) after LTE. In the embodiment, a method for coexistence of eMBB and URLLC or a coexistence method between mMTC and URLLC and an apparatus using the same will be described.

When the base station schedules data corresponding to the eMBB service to a certain terminal in a specific transmission time interval (TTI), when a situation occurs to transmit URLLC data in the TTI, the eMBB data is scheduled and transmitted In a frequency band that exists, the generated URLLC data may be transmitted without transmitting a part of the eMBB data. Here, the UE scheduled for the eMBB and the UE scheduled for URLLC may be the same UE or different UEs.

In this case, the possibility that the eMBB data is damaged increases because a part of the eMBB data that has already been scheduled and transmitted is not transmitted. In this case, it is necessary to determine a method for processing a signal received by a UE scheduled for eMBB or a UE scheduled for URLLC and a method for receiving a signal.

Therefore, in an embodiment of the present invention, when information according to eMBB and URLLC is scheduled by sharing part or all frequency bands, when information according to mMTC and URLLC are scheduled at the same time, or when information according to mMTC and eMBB is scheduled at the same time It describes a coexistence method between heterogeneous services that can transmit information according to each service when the information according to each service is scheduled or when information according to eMBB, URLLC, and mMTC is scheduled at the same time.

Hereinafter, the base station, as a subject performing resource allocation of the terminal, 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 the terminal to a flag station. In addition, although an embodiment of the present invention will be described below using an 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.

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 terminal (terminal or user equipment, UE) or mobile station (MS) transmits data or control signals to a base station (eNode B, or base station (BS)), and downlink is a base station Refers to a radio link that transmits data or control signals to this terminal In the multiple access method as described above, time-frequency resources for transmitting data or control information for each user do not overlap each other, that is, orthogonality is By allocating and operating so as to be established, each user's data or control information can be distinguished.

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 data, it is possible to transmit an acknowledgment (ACK) informing the transmitter of decoding success so that the transmitter can transmit new data.

3A 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 or a similar system.

Referring to FIG. 3A , 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. However, such specific numerical values may be variably applied.

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) may be 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 in one slot may include N _symb x N _RB REs 112 .

In general, the minimum allocation unit in the frequency domain of data is the RB. In general, in the LTE system, N _symb = 7, N _RB = 12, N _BW and N _RB may be 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 can operate by defining 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 indicates a radio frequency (RF) bandwidth corresponding to the system transmission bandwidth.

[Table 3-1] below 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 may be configured with a transmission bandwidth of 50 RBs.

[Table 3-1]

In the case of downlink control information, it may be transmitted within the first N OFDM symbols in the subframe. In an embodiment, generally N = {1, 2, 3}. Accordingly, the N value may be variably applied to each subframe according to the amount of control information to be transmitted in the subframe. The transmitted control information may include 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, and information about HARQ ACK/NACK.

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 is defined according to various formats, and whether it is scheduling information for uplink data (UL grant) or scheduling information for downlink data (DL grant) according to each format, whether it is a compact DCI with a small size of control information , whether spatial multiplexing using multiple antennas is applied, whether DCI for power control, etc. can be indicated. For example, DCI format 1, which is scheduling control information (DL grant) for downlink data, may include at least one of the following control information.

- Resource allocation type 0/1 flag: indicates 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 to allocate a specific RB within an RBG.

- Resource block assignment: indicates an 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): It indicates the modulation scheme used for data transmission and the size of the transport block that is the data to be transmitted.

- HARQ process number (HARQ process number): indicates the process number of HARQ.

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

- Redundancy version: indicates a redundancy version of HARQ.

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

The DCI is a physical downlink control channel (PDCCH) that is a downlink physical 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 should be mixed and used).

In general, the DCI is independently scrambled with a specific RNTI (Radio Network Temporary Identifier) (or UE identifier) for each UE, a cyclic redundancy check (CRC) is added, and after channel coding, each consists of an independent PDCCH. is sent 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 may be transmitted spread over the entire system transmission band.

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

The base station notifies the PDSCH to be transmitted to the terminal through the MCS among the control information constituting the DCI, the applied modulation scheme and the size of the data to be transmitted (transport block size; TBS). In an embodiment, the MCS may consist of 5 bits or more or fewer 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, 2 bits per symbol in the case of QPSK modulation, 4 bits per symbol in the case of 16QAM modulation, and 6 bits per symbol in the case of 64QAM modulation may be transmitted. In addition, a modulation scheme of 256QAM or higher may be used according to system modification.

3B 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.

Referring to FIG. 3B , 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 may be 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 may have 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) may be 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, PDSCH, which is a physical channel for downlink data transmission, or PUCCH or PUSCH, which is an uplink physical channel, through which HARQ ACK/NACK corresponding to PDCCH/EPDDCH including semi-persistent scheduling release (SPS release) is transmitted. A timing relationship of can be defined. 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 n-4 th subframe is PUCCH or PUSCH in n th subframe. can be transmitted to

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 the HARQ operation, the UE may perform buffering on data determined to be an error as a result of decoding the received data, and then perform combining with the next retransmission data.

HARQ ACK / NACK information of the PDSCH transmitted in subframe n-k is transmitted from the terminal to the base station through PUCCH or PUSCH in subframe n, where k is the FDD or TDD (time division duplex) of the LTE system and its sub It may be defined differently according to the frame setting.

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. In addition, when data is transmitted through a plurality of carriers, a value of k may be applied differently according to the TDD setting of each carrier. In the case of the TDD, the value of k is determined according to the TDD UL/DL configuration as shown in Table 3-2 below.

[Table 3-2]

Unlike downlink HARQ in the LTE system, 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 can be transmitted/received according to the following rules.

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 may be defined differently according to the FDD or time division duplex (TDD) of the LTE system and its settings. For example, in the case of an FDD LTE system, k may be 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. In addition, when data is transmitted through a plurality of carriers, a value of k may be applied differently according to the TDD setting of each carrier. In the case of the TDD, the value of k is determined according to the TDD UL/DL configuration as shown in Table 3-3 below.

[Table 3-3]

Meanwhile, HARQ-ACK information of PHICH transmitted in subframe i is related to PUSCH transmitted in subframe i-k. In the case of an FDD system, k is given as 4. That is, HARQ-ACK information of PHICH transmitted in subframe i in the FDD system is related to PUSCH transmitted in subframe i-4. In the case of a TDD system, when a UE for which Enhanced Interference Mitigation and Traffica Adaptation (EIMTA) is not configured, only one serving cell is configured or when all of them have the same TDD UL/DL configuration, when TDD UL/DL configurations 1 to 6 , k value can be given according to the following [Table 3-4].

[Table 3-4]

That is, for example, in TDD UL/DL configuration 1, PHICH transmitted in subframe 6 may be HARQ-ACK information of PUSCH transmitted in subframe 2 that is 4 subframes before.

If the TDD UL/DL configuration is 0, if HARQ-ACK is received with the PHICH resource corresponding to I _PHICH = 0, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe ik, and the k value is the [ It is given according to Table 3-4]. When the TDD UL/DL configuration is 0, if HARQ-ACK is received with the PHICH resource corresponding to I _PHICH = 1, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe i-6.

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. In addition, when applied to another wireless communication system in an embodiment, the value of k may be changed and applied to a system using a modulation scheme corresponding to FDD.

3c and 3d show how data for eMBB, URLLC, and mMTC, which are services considered in a 5G or NR system, are allocated from frequency-time resources.

Referring to FIGS. 3C and 3D , it can be seen how frequency and time resources are allocated for information transmission in each system.

First, in FIG. 3C , data for eMBB, URLLC, and mMTC are allocated in the entire system frequency band 300 . When the URLLC data 303, 305, 307 is generated and transmission is required while the eMBB 301 and the mMTC 309 are allocated in a specific frequency band and transmitted, the eMBB 301 and the mMTC 309 have already been allocated for the eMBB 301 and the mMTC 309. The URLLC data 303 , 305 , 307 may be transmitted without emptying the part or transmitting the eMBB 301 and the mMTC 309 .

Among the above services, since it is necessary to reduce the delay time of URLLC, URLLC data may be allocated (303, 305, 307) to a part of the resource 301 to which the eMBB is allocated and transmitted. 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. 3D , the entire system frequency band 400 is divided into subbands 402 , 404 , and 406 , and each subband 402 , 404 , and 406 can be used to transmit services and data. Information related to the subband configuration may be predetermined, and this information may be transmitted from the base station to the terminal through higher level signaling.

Alternatively, the information related to the subband may be arbitrarily divided by a base station or a network node to provide services to the terminal without transmission of additional subband configuration information. In FIG. 3D , 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.

In all embodiments, a length of a transmission time interval (TTI) used for URLLC transmission may be shorter than a TTI length used for eMBB or mMTC transmission. In addition, a response of information related to URLLC can be transmitted faster than eMBB or mMTC, and thus information can be transmitted and received with low delay.

3E is a diagram illustrating a process in which one transport block is divided into several code blocks and a CRC is added.

Referring to FIG. 3E , a cyclic redundancy check (CRC) 503 may be added to the last or front part of one transport block 501 to be transmitted in uplink or downlink. The CRC may have 16 bits or 24 bits, a predetermined number of bits, or a variable number of bits according to channel conditions, and may be used to determine whether or not channel coding is successful.

Blocks 501 and 503 to which TB and CRC are added may be divided into several codeblocks (CB) 507 , 509 , 511 and 513 ( 505 ). The code block may be divided based on a preset maximum size. In this case, the last code block 513 is smaller in size than other code blocks, or 0, a random value, or 1 is added to determine the length with other code blocks. can be adjusted to be the same.

CRCs 517, 519, 521, and 523 may be added to the divided code blocks, respectively (515). The CRC may have 16 bits or 24 bits or a predetermined number of bits, and may be used to determine whether channel coding succeeds. However, the CRC 503 added to the TB and the CRCs 517 , 519 , 521 , and 523 added to the code block may be omitted depending on the type of channel code to be applied to the code block. For example, when a low-density parity-check (LDPC) code rather than a turbo code is applied to a code block, CRCs 517, 519, 521, and 523 to be inserted for each code block may be omitted. However, even when LDPC is applied, the CRCs 517 , 519 , 521 , and 523 may be added to the code block as it is. In addition, even when a polar code is used, a CRC may be added or omitted.

3F is a diagram illustrating a method in which an outer code is used and transmitted, and FIG. 3G is a block diagram illustrating a structure of a communication system in which the outer code is used.

Referring to FIGS. 3F and 3G , a method of transmitting a signal using an outer code can be viewed.

In FIG. 3F, after one transport block is divided into several code blocks, bits or symbols 604 at the same position in each code block are encoded with a second channel code to generate parity bits or symbols 606. can be (602). Thereafter, CRCs may be added to each of the code blocks and the parity code blocks generated by the second channel code encoding ( 608 and 610 ). Whether to add the CRC may vary depending on the type of the channel code. For example, when the turbo code is used as the first channel code, the CRCs 608 and 610 are added, but later, each code block and parity code blocks may be encoded by the first channel code encoding.

When the outer code is used, the data to be transmitted passes through the second channel coding encoder 709 . The channel code used for the second channel coding may be, for example, a Reed-Solomon code, a Bose-Chaudhuri-Hocquenghem (BCH) code, a Raptor code, or a parity bit generation code. In this way, the bits or symbols that have passed through the second channel coding encoder 709 pass through the first channel coding encoder 711 . The channel code used for the first channel coding includes a convolutional code, an LDPC code, a Turbo code, a polar code, and the like.

When the channel-coded symbols are received by the receiver through the channel 713, the receiver may sequentially operate the first channel coding decoder 715 and the second channel coding decoder 717 based on the received signal. . The first channel coding decoder 715 and the second channel coding decoder 717 may perform operations corresponding to the first channel coding encoder 711 and the second channel coding encoder 709 , respectively.

On the other hand, in the channel coding block diagram in which the outer code is not used, only the first channel coding encoder 711 and the first channel coding decoder 705 are used in the transceiver, respectively, and the second channel coding encoder and the second channel coding decoder are used. doesn't happen Even when the outer code is not used, the first channel coding encoder 711 and the first channel coding decoder 705 may be configured in the same way as when the outer code is used.

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 second type data is not limited to URLLC, and may correspond to other systems requiring low delay or high reliability transmission or when low delay 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 a 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, wide coverage, or low power is required. Also, when describing the embodiment, it may be understood that the first type service includes or does not include the third type service.

The structure of a physical layer channel used for each type to transmit the three services or data may be different. For example, at least one of a length of a transmission time interval (TTI), an allocation unit of a frequency resource, a structure of a control channel, and a data mapping method 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 order to describe the method and apparatus proposed in the embodiment, the terms physical channel and signal in the conventional LTE or LTE-A system may be used. 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 embodiment 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 service 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. In an embodiment, the first type terminal, the second type terminal, and the third type terminal may be the same terminal or different terminals.

In the following embodiment, at least one of a PHICH, an uplink scheduling grant signal, and a downlink data signal is referred to as a first signal. Also, in the present invention, at least one of an uplink data signal for uplink scheduling grant and HARQ ACK/NACK for a downlink data signal is referred to as a second signal. In an embodiment, among the signals transmitted by the base station to the terminal, if a signal is expected to receive a response from the terminal, it may be the first signal, and the response signal of the terminal corresponding to the first signal may be the second signal. Also, in an embodiment, the service type of the first signal may be at least one of eMBB, URLLC, and mMTC, and the second signal may also correspond to at least one of the services.

For example, in LTE and LTE-A systems, PUCCH format 0 or 4 and PHICH may be a first signal, and a corresponding second signal may be PUSCH. Also, for example, in LTE and LTE-A systems, a PDSCH may be a first signal, and a PUCCH or PUSCH including HARQ ACK/NACK information of the PDSCH may be a second signal.

In the following embodiment, the TTI length of the first signal is a time value related to the first signal transmission and may indicate the length of the time during which the first signal is transmitted. In addition, in the present invention, the TTI length of the second signal is a time value related to the transmission of the second signal, and may indicate the length of the time during which the second signal is transmitted, and the TTI length of the third signal is related to the transmission of the third signal. The time value may indicate the length of time the third signal is transmitted. Also, in the present invention, the second signal transmission timing is information on when the terminal transmits the second signal and when the base station receives the second signal, and may be referred to as the second signal transmission/reception timing.

In addition, in the following embodiment, assuming that the terminal transmits the second signal in the n+k-th TTI when the base station transmits the first signal in the n-th TTI, the base station informs the terminal of the timing to transmit the second signal is the same as telling the value of k. Alternatively, if it is assumed that the terminal transmits the second signal in the n+4+a-th TTI when the base station transmits the first signal in the nth TTI, the fact that the base station informs the terminal of the timing to transmit the second signal is an offset It is equivalent to giving the value a. The offset may be defined in various ways, such as n+3+a, n+5+a, etc. instead of n+4+a, and the n+4+a value referred to in the present invention is also the offset a value in various ways in the same way. could be defined.

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

Hereinafter, in the present invention, upper signaling is a signal transmission method in which a base station uses a downlink data channel of a physical layer to a terminal or from a terminal to a base station using an uplink data channel of a physical layer, and RRC (Radio Resource Control) Signaling, or Packet Data Convergence Protocol (PDCP) signaling, or MAC (Medium Access Control) may also be referred to as a control element (MAC control element; MAC CE).

Although the present invention describes a method for determining the timing at which the terminal or the base station transmits the second signal after receiving the first signal, the method for transmitting the second signal may be possible in various ways. As an example, the timing of transmitting HARQ ACK/NACK information corresponding to the PDSCH to the base station after the terminal receives the PDSCH as downlink data follows the method described in the present invention, but selection of a PUCCH format to be used, selection of PUCCH resources Alternatively, a method of mapping HARQ ACK/NACK information to PUSCH may follow a method determined by another method. For example, selection of the PUCCH format to be used, selection of PUCCH resources, or a method of mapping HARQ ACK/NACK information to PUSCH may be determined based on the content of the LTE standard.

In the present invention, a terminal with reduced delay, or a terminal with reduced delay, or a terminal with a reduced processing time, or a terminal with a reduced processing time may be used interchangeably.

[Example 3-1]

Embodiment 3-1 describes a method of determining a timing for transmitting a related PUSCH when the UE receives a PHICH or a PDCCH/EPDCCH including a DCI transmitting uplink scheduling information. If the delay reduction is transmitted to the terminal with reduced delay, the PHICH may not be used, and in this case, it may be applied when DCI carrying uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with reduced delay is not received on the PHICH, it will be possible for the UE to omit PHICH decoding in the corresponding subframe.

When the TDD UL/DL configuration is one of 1 to 6, when the UE receives a PHICH or a PDCCH/EPDCCH including a DCI carrying uplink scheduling information in subframe n, the related PUSCH is set to subframe n+k is transmitted by the terminal, and k is given in [Table 3-5] below.

[Table 3-5]

When the TDD UL/DL configuration is 0, the PDCCH/EPDCCH in which the Most Significant Bit (MSB) of the uplink index of the uplink DCI format is 1 is received, or the PHICH is received in subframes 1 or 6, When the PHICH is received in subframe 0 or 5 where the I _PHICH resource is 0, the k value may be determined according to [Table 3-5]. When the TDD UL/DL configuration is 0, a PDCCH/EPDCCH having a LSB (Least Signigicant Bit) of 1 of the UL index of the uplink DCI format is received, or the I _PHICH resource is 1 in subframe 0 or 5 for PHICH. Upon reception, the k value may be determined to be 7. And if both the MSB and the LSB of the UL index of the uplink DCI format are 1, the PUSCH can be transmitted in both subframes n+k when k is 7 and when k follows [Table 3-5]. .

The method when the TDD UL/DL configuration is 0 is not only possible with the above method and may be applied through slight modifications. For example, when the TDD UL/DL configuration is 0, the PDCCH/EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received, or the PHICH is received in subframe 1 or 6, or the PHICH is received in subframe 0 or 5 When the I _PHICH resource is received at 1, the k value may be determined according to [Table 3-5].

When the TDD UL/DL configuration is 0, the PDCCH/EPDCCH having the LSB of the UL index of the uplink DCI format is 1, or when the PHICH is received in subframe 0 or 5 where the I _PHICH resource is 0, the k You can decide the value to be 7. As another example, when the TDD UL/DL configuration is 0, the PDCCH/EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received, or the PHICH is received in subframe 0 or 5, or the PHICH is received in subframe 1 or In 6, when the I _PHICH resource is 1, when received, the k value can be determined according to [Table 3-5].

When the TDD UL/DL configuration is 0, the PDCCH/EPDCCH having the LSB of the UL index of the uplink DCI format is 1, or when the PHICH is received in subframe 1 or 6 where the I _PHICH resource is 0, the k You can decide the value to be 6.

[Example 3-2]

Embodiment 3-2 describes a method for determining a timing for transmitting a related PUSCH when the UE receives a PHICH or a PDCCH/EPDCCH including a DCI carrying uplink scheduling information. If the delay reduction is transmitted to the terminal with reduced delay, the PHICH may not be used, and in this case, it may be applied when DCI carrying uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with reduced delay is not received on the PHICH, it will be possible for the UE to omit PHICH decoding in the corresponding subframe.

In subframe n, when the UE receives a PHICH or a PDCCH/EPDCCH including a DCI carrying uplink scheduling information, among k values greater than 2, the subframe of n+k is a subframe in which uplink transmission is possible. , the UE transmits the PUSCH in subframe n+k. For example, a UE receiving uplink DCI in subframe n transmits a PUSCH in a subframe in which uplink transmission is possible from n+3. If n+3 is a downlink subframe and n+4 is uplink transmission possible, PUSCH is transmitted in subframe n+4.

[Example 3-3]

Embodiment 3-3 describes a method for determining a timing for transmitting a related PUSCH when the UE receives a PHICH or a PDCCH/EPDCCH including a DCI carrying uplink scheduling information. If the delay reduction is transmitted to the terminal with reduced delay, the PHICH may not be used, and in this case, it may be applied when DCI carrying uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with reduced delay is not received on the PHICH, it will be possible for the UE to omit PHICH decoding in the corresponding subframe.

When the TDD UL/DL configuration is one of 1 to 6, when the UE receives a PHICH or a PDCCH/EPDCCH including a DCI carrying uplink scheduling information in subframe n, the related PUSCH is set to subframe n+k is transmitted by the terminal, and k is given in [Table 3-6] below.

[Table 3-6]

When the TDD UL/DL configuration is 0, the PDCCH/EPDCCH having the MSB of the UL index of the uplink DCI format of 1 is received, the PHICH is received in subframe 0 or 5, or the PHICH is received in subframe 1 or 6 I _PHICH When the resource is received from 0, the k value can be determined according to [Table 3-6].

When the TDD UL/DL configuration is 0, when the PDCCH/EPDCCH having the LSB of the UL index of the uplink DCI format is 1, or when the PHICH is received in the place where the I _PHICH resource is 1 in subframe 1 or 6, the k The value can be determined to be 3. And if both the MSB and the LSB of the UL index of the uplink DCI format are 1, the PUSCH may be transmitted in both subframes n+k when k is 3 and when k follows [Table 3-5]. .

The method when the TDD UL/DL configuration is 0 is not only possible with the above method and may be applied through slight modifications.

[Example 3-4]

Embodiments 3-4 describe a method for determining a timing for transmitting a PUSCH related to a terminal when receiving a PHICH or a PDCCH/EPDCCH including a DCI carrying uplink scheduling information. If the delay reduction is transmitted to the terminal with reduced delay, the PHICH may not be used, and in this case, it may be applied when DCI carrying uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with reduced delay is not received on the PHICH, it will be possible for the UE to omit PHICH decoding in the corresponding subframe.

When the UE receives PHICH or PDCCH / EPDCCH including DCI carrying uplink scheduling information in subframe n, among values where k is greater than 1, subframe of n+k is a subframe in which uplink transmission is possible , the UE transmits the PUSCH in subframe n+k. For example, the UE receiving the uplink DCI in subframe n transmits the PUSCH in a subframe in which uplink transmission is possible from n+2. If n+2 is a downlink subframe and n+3 is uplink transmission possible, PUSCH is transmitted in subframe n+3.

Embodiments 3-1 and 3-3 may be used according to the configuration of the base station to the terminal, or may be used according to information transmitted from DCI. In addition, the 3-2 embodiment and the 3-4 embodiment may be used according to the configuration of the base station to the terminal, or may be used according to information transmitted from DCI. Also, in the 3-1 to 3-4 embodiments, the base station may try to decode the PUSCH in a subframe in which the UE transmits the PUSCH.

3H illustrates the operation of the terminal. When the UE receives the PHICH or the PDCCH/EPDCCH containing uplink scheduling information, the UE checks at least one of the higher signaling configuration, the PHICH resource location, and DCI information (804). In FIG. 3h, the first timing setting 806 refers to a case when the minimum signal processing time of the terminal is about 3 ms including the TA value by using the conventional PUSCH transmission timing in LTE/LTE-A. . Therefore, when the UE confirms the first timing setting 806, it is the same as the PUSCH transmission timing in the conventional LTE/LTE-A. For example, in FDD, if uplink scheduling information is received from subframe n to PDCCH, the sub A PUSCH is transmitted in frame n+4 (808).

The second timing setting 810 in FIG. 3H may refer to a case when the minimum signal processing time of the terminal is about 2 ms including the TA value. Accordingly, when the UE confirms the second timing setting 810, the timing is determined according to the 3-1 embodiment or the 3-2 embodiment. For example, in FDD, uplink scheduling information is transmitted from subframe n to PDCCH. If received, the PUSCH is transmitted in subframe n+3 (812).

The third timing setting 814 in FIG. 3H may refer to a case where the minimum signal processing time of the terminal is about 1 ms including the TA value. Therefore, when the terminal confirms the third timing setting 814, the timing is determined according to the 3-3 embodiment or the 3-4 embodiment. For example, in FDD, uplink scheduling information is transmitted from subframe n to PDCCH. If received, the PUSCH is transmitted in subframe n+2 (816). In the above description, it may be possible to support only one of the second timing configuration 810 and the third timing configuration 814 depending on the terminal or the base station.

In addition, it will be possible for the 3-1 embodiment and the 3-3 embodiment to be implemented in combination. For example, when the UE receives the DCI in which the PDCCH/EPDCCH carries uplink scheduling information, the PUSCH transmission timing is determined as in the 3-1 embodiment, and the UE receives the PHICH, It may be possible to determine the transmission timing of , as in the 3-3 embodiment. That is, when uplink scheduling is performed in subframe n using DCI, the UE transmits PUSCH in subframe n+3 or later, and when uplink retransmission is indicated using PHICH, the UE transmits subframe n +2 or later, PUSCH can be transmitted.

In embodiments 3-1 to 3-4, PHICH means information corresponding to HARQ NACK for uplink transmission. Therefore, the meaning of receiving the PHICH may be interpreted as meaning that the terminal needs retransmission.

[Example 3-5]

The 3-5th embodiment describes a method for determining the timing at which a terminal receives downlink data PDSCH transmission and transmits HARQ ACK/NACK for the PDSCH through an uplink channel such as PUCCH or PUSCH.

HARQ ACK/NACK information of PDSCH transmitted in subframe n-k is transmitted in subframe n, and k may vary according to TDD UL/DL configuration and subframe position as shown in [Table 3-7] below. In this embodiment, the PDSCH may be a PDSCH scheduled by PDCCH/EPDCCH or a PDSCH configured with SPS.

[Table 3-7]

The order of the numbers written in each column of the table may be modified and applied differently.

In [Table 3-7], when there are several k values, it means that HARQ ACK/NACK information for one or more PDSCHs can be transmitted together in subframe n. For example, in UL/DL configuration 1, in subframe 2, HARQ ACK/NACK information corresponding to PDSCHs transmitted before 6 subframes and before 3 subframes are transmitted.

The [Table 3-7] will be modified to the following [Table 3-7a] and it will be possible to use it.

[Table 3-7a]

The order of the numbers written in each column of the table may be modified and applied differently.

[Example 3-6]

Embodiments 3-6 describe a method for determining a timing at which a UE receives downlink data PDSCH transmission and transmits HARQ ACK/NACK for the PDSCH through an uplink channel such as PUCCH or PUSCH.

If the base station transmits the PDSCH to the terminal in subframe n, the terminal transmits HARQ ACK/NACK information related to the PDSCH to a value in which k is greater than 2, when a subframe of n+k is a subframe in which uplink transmission is possible , the UE transmits PUCCH or PUSCH in subframe n+k. For example, the terminal receiving the PDSCH in subframe n transmits HARQ ACK/NACK information for the PDSCH to the base station as PUCCH or PUSCH in a subframe in which uplink transmission is possible from n+3. If n+3 is a downlink subframe and n+4 is uplink transmission possible, HARQ ACK/NACK information is transmitted through PUCCH or PUSCH in subframe n+4.

[Example 3-7]

Embodiment 3-7 describes a method for determining a timing at which a UE receives downlink data PDSCH transmission and transmits HARQ ACK/NACK for the PDSCH through an uplink channel such as PUCCH or PUSCH.

HARQ ACK/NACK information of PDSCH transmitted in subframe n-k is transmitted in subframe n, and k may vary according to TDD UL/DL configuration and subframe position as shown in [Table 3-8] below. In this embodiment, the PDSCH may be a PDSCH scheduled by PDCCH/EPDCCH or a PDSCH configured with SPS.

[Table 3-8]

The order of the numbers written in each column of the table may be modified and applied differently.

When there are multiple k values in [Table 3-8], it means that HARQ ACK/NACK information for one or more PDSCHs can be transmitted together in subframe n. For example, in UL/DL configuration 1, in subframe 2, HARQ ACK/NACK information corresponding to PDSCHs transmitted before 3 subframes and 2 subframes are transmitted.

The [Table 3-8] may be modified to the following [Table 3-8a] and used.

[Table 3-8a]

The order of the numbers written in each column of the table may be modified and applied differently.

[Example 3-8]

Embodiments 3-8 describe a method for determining a timing at which a UE receives downlink data PDSCH transmission and transmits HARQ ACK/NACK for the PDSCH through an uplink channel such as PUCCH or PUSCH.

If the base station transmits the PDSCH to the terminal in subframe n, the terminal transmits HARQ ACK/NACK information related to the PDSCH to a value in which k is greater than 1, when a subframe of n+k is a subframe in which uplink transmission is possible , the UE transmits PUCCH or PUSCH in subframe n+k. For example, the terminal receiving the PDSCH in subframe n transmits HARQ ACK/NACK information for the PDSCH to the base station as PUCCH or PUSCH in a subframe in which uplink transmission is possible from n+2. If n+2 is a downlink subframe and n+3 is uplink transmission possible, HARQ ACK/NACK information is transmitted through PUCCH or PUSCH in subframe n+3.

The 3-5th and 3-7th embodiments may be used according to the configuration of the base station to the terminal, or may be used according to information transmitted from DCI. In addition, the 3-6 embodiment and the 3-8 embodiment may be used according to the configuration of the base station to the terminal, or may be used according to information transmitted in DCI. In addition, in the 3-5th to 3-8 embodiments, the base station attempts to decode PUCCH or PUSCH in a subframe in which the UE transmits PUCCH or PUSCH including HARQ ACK/NACK information for PDSCH. There will be.

3I describes the operation of the terminal. When the UE receives the PDSCH, the UE checks at least one of higher signaling configuration, DCI information, and the like (903). In FIG. 3i, the first timing setting 905 refers to using the HARQ ACK/NACK information transmission timing as PUCCH or PUSCH in the conventional LTE/LTE-A, and the minimum signal processing time of the terminal is about 3 ms including the TA value. It can refer to a case when Therefore, when the UE confirms the first timing setting 905, it is the same as the conventional HARQ ACK/NACK information transmission timing in LTE/LTE-A. For example, in FDD, if the PDSCH is received in subframe n, subframe In n+4, HARQ ACK/NACK information is transmitted through PUCCH or PUSCH (907).

The second timing setting 909 in FIG. 3I may refer to a case where the minimum signal processing time of the terminal is about 2 ms including the TA value. Therefore, when the terminal confirms the second timing setting 909, the timing is determined according to the 3-5th embodiment or the 3-6 embodiment. For example, in FDD, if the PDSCH is received in subframe n, the subframe In n+3, HARQ ACK/NACK information is transmitted through PUCCH or PUSCH (911).

The third timing setting 913 in FIG. 3I may refer to a case where the minimum signal processing time of the terminal is about 1 ms including the TA value. Therefore, when the terminal confirms the third timing setting 913, the timing is determined according to the 3-7 embodiment or the 3-8 embodiment. For example, in FDD, if the PDSCH is received in subframe n, the subframe In n+2, HARQ ACK/NACK information is transmitted through PUCCH or PUSCH (915). In the above, it may be possible to support only one of the second timing setting 909 and the third timing setting 913 depending on the terminal or the base station.

[Example 3-9]

Embodiments 3-9 describe timing for controlling power used by the terminal for uplink transmission.

A UE that cannot simultaneously transmit PUCCH and PUSCH may calculate the power P _PUSCH,c (i) used for PUSCH transmission to be transmitted in subframe i in a specific serving cell c as follows.

A UE capable of simultaneously transmitting PUCCH and PUSCH may calculate the power P _PUSCH,c (i) used for PUSCH transmission to be transmitted in subframe i in a specific serving cell c as follows.

는 P_CMAX,c(i)의 선형 변화된 값이며,

는 PUCCH 전송 전력인 P_PUCCH(i)의 선형변화된 값이다. M_PUSCH,c(i)는 서빙셀 c에서 서브프레임 i에 PUSCH 전송에 사용하도록 할당된 PRB 수이다.

는 상위 시그널링으로 전달된 파라미터들로 만들어지는 값이다. α_c는

값들 중에 하나로 상위에서 전달될 수 있다. P_Lc는 하향링크 패스로스(pathloss) 추정값으로 단말이 계산할 수 있다. In the above equations, P _CMAX,c (i) is the configured power that the UE can transmit to subframe i in the serving cell c.

is the linearly changed value of P _CMAX,c (i),

is a linearly changed value of P _PUCCH (i), which is the PUCCH transmission power. M _PUSCH,c (i) is the number of PRBs allocated to use for PUSCH transmission in subframe i in the serving cell c.

is a value made with parameters passed to higher level signaling. α _c is

One of the values can be passed from the parent. P _Lc may be calculated by the UE as a downlink pathloss estimation value.

는 PUSCH에서 전송되는 제어신호 부분에 따라 결정될 수 있는 값이다. δ_PUSCH.c는 PDCCH 또는 EPDCCH의 DCI 포맷 0/4 혹은 DCI 포맷 3/3A에 포함된 TPC(Transmission Power Control) 명령에 따라 설정될 수 있는 값이며, 이는 하기와 같은 수식에 따라 적용될 수 있다. 누적 전력 계산이 가능하도록 설정된다면

, 누적 설정이 되어있지 않다면

와 같이 계산한다.

is a value that can be determined according to the part of the control signal transmitted in the PUSCH. δ _PUSCH.c is a value that can be set according to a transmission power control (TPC) command included in DCI format 0/4 or DCI format 3/3A of the PDCCH or EPDCCH, and can be applied according to the following equation. If it is set to enable cumulative power calculation

, if accumulation is not set

Calculate as

In the above, the K _PUSCH for determining the timing may be transmitted through higher signaling. For example, if the delay reduction terminal is configured to have a minimum signal processing time of 1 ms, the terminal may assume that the K _PUSCH is 2. In the above description, the K _PUSCH of 2 may mean that the power of the PUSCH to be transmitted in subframe i is determined according to the power control command transmitted in i-2.

Alternatively, an indicator indicating the K _PUSCH value may be included in the DCI format in which the power control command is transmitted. For example, when the indicator is 0, it can be assumed that the K _PUSCH is 2, and when the indicator is 1, it can be assumed that the K _PUSCH is 3. Information on the K _PUSCH value indicated by the indicator of the DCI format may be mapped in various ways.

Although the above example is based on the FDD system, the value indicated in TDD may be provided as the following [Table 3-9].

[Table 3-9]

In TDD UL/DL configurations 1 to 6, the K _PUSCH may be determined according to subframe i based on the table above. In the case of TDD UL/DL configuration 0, a method of determining the K _PUSCH value may vary according to the 3-1 to 3-4 embodiments.

For example, in the 3-1 embodiment, when the TDD UL/DL configuration is 0, the PDCCH/EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received, or the PHICH is received in subframes 1 or 6, When the PHICH is received in subframe 0 or 5 where the I _PHICH resource is 0, the k value may be determined according to [Table 3-5]. In addition, when a PDCCH/EPDCCH having an LSB of 1 of the UL index of the uplink DCI format is received or a PHICH is received in subframe 0 or 5 where the I _PHICH resource is 1, the k value may be determined to be 7. In addition, when both the MSB and the LSB of the UL index of the uplink DCI format are 1, in the method of transmitting the PUSCH in both subframes n+k when k is 7 and when k follows [Table 3-5] Determination of the K _PUSCH value may be as follows.

In an example of the 3-1 embodiment, DCI information for scheduling a PUSCH that can be transmitted in subframes 3 or 8 may be transmitted in subframe 0 or 5 of the corresponding frame, or subframe 5 or It may be passed from 0. Therefore, it is necessary to specify in which subframe the PUSCH that can be transmitted in subframes 3 or 8 is scheduled for power control.

In the above example, if i is subframe 3 or 8, that is, when PUSCH transmission is transmitted in subframe 3 or 8, DCI format 0 or 4 provided in the PDCCH or EPDCCH or the LSB of the UL index part of other DCI formats is In the case of 1, it may be determined as 7.

[Example 3-10]

Embodiments 3-10 describe at which timing a PHICH including HARQ-ACK information according to PUSCH transmission is transmitted. Alternatively, it may be to explain when the PHICH including the HARQ-ACK information received by the UE is related to the transmitted PUSCH.

The UE configured to reduce delay may determine that HARQ-ACK information of PHICH transmitted in subframe i is related to PUSCH transmitted in subframe i-k. In the case of an FDD system, k is given as 3. That is, HARQ-ACK information of PHICH transmitted in subframe i in the FDD system is related to PUSCH transmitted in subframe i-3. In the case of a TDD system, when only one serving cell is configured for a UE to which EIMTA is not configured or when all of them have the same TDD UL/DL configuration, in TDD UL/DL configurations 1 to 6, the following [Table 3-10] A value of k can be given according to

[Table 3-10]

That is, for example, in TDD UL/DL configuration 1, PHICH transmitted in subframe 6 may be HARQ-ACK information of PUSCH transmitted in subframe 2 that is 4 subframes before.

If the TDD UL/DL configuration is 0, if HARQ-ACK is received with the PHICH resource corresponding to I _PHICH = 0, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe ik, and the k value is the [ It is given according to Table 3-4]. When the TDD UL/DL configuration is 0, if HARQ-ACK is received with the PHICH resource corresponding to I _PHICH = 1, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe i-6. The method as described above will be mixed as a method of applying the n+3 possible delay reduction terminal.

Or, it may be implemented with a modification as follows.

The UE configured to reduce delay may determine that HARQ-ACK information of PHICH transmitted in subframe i is related to PUSCH transmitted in subframe i-k. In the case of an FDD system, k is given as 2. That is, HARQ-ACK information of PHICH transmitted in subframe i in the FDD system is related to PUSCH transmitted in subframe i-2. In the case of a TDD system, when only one serving cell is configured for a UE to which EIMTA is not configured, or when all of them have the same TDD UL/DL configuration, in TDD UL/DL configurations 1 to 6, the following [Table 3-11] A value of k can be given according to

[Table 3-11]

That is, for example, in TDD UL/DL configuration 1, PHICH transmitted in subframe 6 may be HARQ-ACK information of PUSCH transmitted in subframe 3 that is 3 subframes before.

If the TDD UL/DL configuration is 0, if HARQ-ACK is received with the PHICH resource corresponding to I _PHICH = 0, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe ik, and the k value is 4 is given according to When the TDD UL/DL configuration is 0, if HARQ-ACK is received with the PHICH resource corresponding to I _PHICH = 1, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe i-3.

The operation methods corresponding to [Table 3-10] and [Table 3-11] may be selectively operated according to higher-order signaling from the base station.

When referring to subframe i-k or n-k in the present invention, if i-k or n-k is less than 0, subframe i-k or n-k may mean subframe 10+i-k or 10+n-k of the previous radio frame.

In the above, the 3-10 embodiment is set and used as the 3-1 embodiment, the 3-2 embodiment, or the 3-3 embodiment, or the 3-4 embodiment, so that it is used for uplink data transmission. Therefore, it can be used to reduce the retransmission delay time.

[Example 3-11]

Embodiment 3-11 describes a method for determining a timing at which a terminal receives downlink data PDSCH transmission and transmits HARQ ACK/NACK for the PDSCH through an uplink channel such as PUCCH or PUSCH. In the case of carrier aggregation, this embodiment may be particularly applied to a case where a primary cell (Pcell) is a TDD system and a secondary cell (Scell) is an FDD system. The above FDD may correspond to frame structure 1 of LTE, and TDD may correspond to frame structure 2 of LTE.

HARQ ACK/NACK information of PDSCH transmitted in subframe n-k is transmitted in subframe n, and k may vary according to TDD UL/DL configuration and subframe position as shown in [Table 3-12] below. In this embodiment, the PDSCH may be a PDSCH scheduled by PDCCH/EPDCCH or a PDSCH configured with SPS.

[Table 3-12]

The order of the numbers written in each column of the table may be modified and applied differently.

In [Table 3-12], when there are several k values, it means that HARQ ACK/NACK information for one or more PDSCHs can be transmitted together in subframe n.

Instead of using [Table 3-12], the following [Table 3-13] or [Table 3-14] may be applied.

[Table 3-13]

[Table 3-14]

[Table 3-13] can be applied for the purpose of minimizing the delay time, and [Table 3-14] can allow the number of HARQ-ACK bits transmitted in one subframe to be maintained similarly. In [Table 3-13] and [Table 3-14], they can be mixed and applied according to the UL-DL configuration as a standard, and in UL-DL configuration 6, the following [Table 3-15] and [Table 3-16] ] can be modified and applied by the method provided in

[Table 3-15]

[Table 3-16]

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. 3J and 3K, respectively. From the 3-1 embodiment to the 3-9 embodiment, the transmission/reception method between the base station and the terminal is shown in order to determine the transmission/reception timing and the terminal transmission power of the second signal and perform an operation according thereto. The receiving unit, processing unit, and transmitting unit of the terminal should each operate according to the embodiment.

Specifically, FIG. 3J is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 3J , the terminal of the present invention may include a terminal receiving unit 1200 , a terminal transmitting unit 1204 , and a terminal processing unit 1202 . In the embodiment of the present invention, the terminal receiving unit 1200 and the terminal collectively refer to the transmitting unit 1204 as a transceiver.

The transmitting/receiving unit of the terminal may transmit/receive a signal to/from the base station. The signal may include control information and data. To this end, the transceiver of the terminal may include an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts a received signal.

In addition, the transceiver of the terminal may receive a signal through a wireless channel and output it to the terminal processing unit 1202 , and transmit the signal output from the terminal processing unit 1202 through the wireless channel. The terminal processing unit 1202 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 1200 may receive a signal including the second signal transmission timing information from the base station, and the terminal processing unit 1202 may control to interpret the second signal transmission timing. Thereafter, the second signal is transmitted according to the timing using the terminal transmitter 1204 .

3K is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 3K , the base station of the present invention may include a base station receiving unit 1301 , a base station transmitting unit 1305 , and a base station processing unit 1303 . The base station receiving unit 1301 and the base station transmitting unit 1305 may be collectively referred to as a transceiver in the embodiment of the present invention.

The transceiver of the base station may transmit and receive a signal to and from the terminal. The signal may include control information and data. To this end, the transceiver of the base station may include an RF transmitter that up-converts and amplifies the frequency of a transmitted signal, and an RF receiver that low-noise amplifies and down-converts a received signal.

In addition, the transceiver of the base station may receive a signal through a wireless channel and output it to the base station processing unit 1303 , and transmit the signal output from the terminal processing unit 1303 through the wireless channel. The base station processing unit 1303 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 1303 may determine the second signal transmission timing and control to generate the second signal transmission timing information to be transmitted to the terminal. Thereafter, the base station transmitter 1305 transmits the timing information to the terminal, and the base station receiver 1301 receives the second signal based on the timing.

Also, according to an embodiment of the present invention, the base station processing unit 1303 may control to generate downlink control information (DCI) including the second signal transmission timing information. In this case, the DCI may indicate the second signal transmission timing information.

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 can be implemented based on the technical idea 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 3-1, 3-2, and 3-3 of the present invention with each other. In addition, although the above embodiments have been presented based on the LTE/LTE-A system, other modifications based on the technical idea of the embodiment may be implemented in other systems such as 5G and NR systems.

Claims (20)

In the method of a terminal of a communication system,
Receiving information related to a start symbol position of a demodulation reference signal (DMRS) from a base station within a transmission time interval;
checking a start symbol position of the DMRS; and
Receiving the DMRS from the base station at the confirmed starting symbol position of the DMRS,
The start symbol position of the DMRS is characterized in that it is defined in relation to the start of the transmission time interval based on the information. According to claim 1,
The start symbol position of the DMRS is a method, characterized in that the third or fourth symbol with respect to the start of the transmission time interval. According to claim 1,
The number of consecutive symbols of the DMRS is one or two. According to claim 1,
checking information related to a symbol position of an additional DMRS within the transmission time interval; and
The method further comprising the step of receiving the additional DMRS from the base station at the symbol position of the additional DMRS. According to claim 1,
The information related to the position of the start symbol of the DMRS within the transmission time interval is characterized in that it is received through downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). A method for a base station of a communication system, comprising:
transmitting information related to a start symbol position of a demodulation reference signal (DMRS) to a terminal within a transmission time interval;
Transmitting the DMRS to the terminal at the start symbol position of the DMRS,
The start symbol position of the DMRS is characterized in that it is defined in relation to the start of the transmission time interval based on the information. 7. The method of claim 6,
The start symbol position of the DMRS is a method, characterized in that the third or fourth symbol with respect to the start of the transmission time interval. 7. The method of claim 6,
The number of consecutive symbols of the DMRS is one or two. 7. The method of claim 6,
According to information related to the symbol position of the additional DMRS within the transmission time interval, the method further comprising the step of transmitting the additional DMRS to the terminal at the symbol position of the additional DMRS. 7. The method of claim 6,
The information related to the position of the start symbol of the DMRS within the transmission time interval is characterized in that it is transmitted through downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). In the terminal of a communication system,
transceiver; and
Receive information related to the start symbol position of a demodulation reference signal (DMRS) from the base station within the transmission time interval, confirm the start symbol position of the DMRS, and receive the DMRS from the base station at the confirmed start symbol position of the DMRS comprising a control unit that becomes
The start symbol position of the DMRS is defined in relation to the start of the transmission time interval based on the information. 12. The method of claim 11,
The start symbol position of the DMRS is the terminal, characterized in that the third or fourth symbol with respect to the start of the transmission time interval. 12. The method of claim 11,
The terminal, characterized in that the number of consecutive symbols of the DMRS is one or two. 12. The method of claim 11,
The controller is further configured to check information related to a symbol position of an additional DMRS within the transmission time interval, and receive the additional DMRS from the base station at the symbol position of the additional DMRS. 12. The method of claim 11,
The information related to the position of the start symbol of the DMRS within the transmission time interval is a terminal, characterized in that it is received through downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH). In a base station of a communication system,
transceiver; and
A control unit configured to transmit information related to a start symbol position of a demodulation reference signal (DMRS) to the terminal within a transmission time interval, and to transmit the DMRS to the terminal at the start symbol position of the DMRS,
The start symbol position of the DMRS is a base station, characterized in that it is defined in relation to the start of the transmission time interval based on the information. 17. The method of claim 16,
The start symbol position of the DMRS is a base station, characterized in that the third or fourth symbol with respect to the start of the transmission time interval. 17. The method of claim 16,
The number of consecutive symbols of the DMRS is one or two base stations. 17. The method of claim 16,
The control unit is further configured to transmit the additional DMRS to the terminal at the symbol position of the additional DMRS according to information related to the symbol position of the additional DMRS within the transmission time interval. 17. The method of claim 16,
The information related to the start symbol position of the DMRS within the transmission time interval is a base station, characterized in that it is transmitted through downlink control information (DCI) for scheduling a physical downlink shared channel (PDSCH).

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