CN115134062A

CN115134062A - Method and apparatus for setting multiple DMRS structures in a wireless cellular communication system

Info

Publication number: CN115134062A
Application number: CN202210734150.XA
Authority: CN
Inventors: 申哲圭; 吕贞镐; 吴振荣; 郭莹宇; 金东汉; 金润善; 卢勳东; 金泰亨
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2016-07-21
Filing date: 2017-07-21
Publication date: 2022-09-30
Anticipated expiration: 2037-07-21
Also published as: WO2018016904A1; KR102589185B1; KR20220066238A; KR20180011022A; CN115134062B; KR102399616B1

Abstract

Disclosed are a communication technology for combining a 5G communication system for supporting a higher data transmission rate than a 4G system with an IoT technology, and a system thereof. The present disclosure may be applied to smart services (e.g., smart homes, smart buildings, smart cities, smart cars or networked cars, healthcare, digital education, retail, security and security related services, etc.) based on 5G communication technology and IoT related technology. Disclosed is a method by which a base station sets various demodulation reference signal (DMRS) structures and determines uplink and downlink transmission timings for reducing delay.

Description

Method and apparatus for setting multiple DMRS structures in a wireless cellular communication system

Technical Field

The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for a base station to set a plurality of demodulation reference signal (DMRS) structures and determine uplink and downlink transmission timings for reducing delay.

Background

In order to meet the increasing demand for radio data services after commercialization of 4G communication systems, efforts have been made to develop advanced 5G communication systems or pre-5G communication systems. Therefore, the 5G communication system or the pre-5G communication system is also referred to as a super 4G network communication system or a post-LTE system. In order to achieve higher data transfer rates, it is being considered to implement a 5G communication system on an ultra high frequency (millimeter wave) band (e.g., such as a 60GHz band). In order to avoid propagation loss of radio waves and increase transmission distance of radio waves in an ultra high frequency band, various techniques are being discussed, such as beamforming of a 5G communication system, massive MIMO, full-dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and massive antenna. Furthermore, in order to improve the 5G communication system, technological development is being performed in terms of advanced small cells, cloud radio access networks (cloud RANs), ultra dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), receiving-end interference cancellation, and the like. Furthermore, in 5G communication systems, hybrid FSK and QAM modulation (FQAM) and Sliding Window Superposition Coding (SWSC) are developed as Advanced Coding Modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and Sparse Code Multiple Access (SCMA) are also developed as advanced access technologies.

Meanwhile, the internet, a connected network in which human-centric humans generate and consume information, is now evolving towards the internet of things (IoT) where distributed entities, such as things, exchange and process information without human intervention. In addition, an internet of things (IOE) has emerged, which is a combination of internet of things technology and big data processing technology implemented through a connection with a cloud server. Since IoT implementations require technical elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology, sensor networks, machine-to-machine (M2M) communication, Machine Type Communication (MTC), and the like have been studied in recent years. Such IoT environments can provide intelligent internet technology services that create new value for human life by collecting and analyzing data generated between internet things. IoT is applicable in various fields including smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart appliances, advanced medical services, etc. through the fusion and integration of existing Information Technology (IT) and various industrial applications.

In line with this, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks, Machine Type Communication (MTC), and machine-to-machine (M2M) communication are being implemented based on 5G communication technologies such as beamforming, MIMO, and array antennas. Using a cloud radio access network (cloud RAN) for big data processing technology is an example of 5G technology and IoT technology convergence.

Further, unlike the LTE system, the 5G wireless communication considers a system operating in a higher frequency band and a 6GHz or lower frequency band. Since the channel characteristics depend on the frequency band, the 5G system needs to redesign the reference signal in consideration of this point. Furthermore, 5G wireless communication importantly allows for support of low latency and high mobility, and it is important to minimize the overhead of reference signals.

Disclosure of Invention

[ problem ] to provide a method for producing a semiconductor device

An object of the present disclosure is to support low delay and high mobility and minimize the overhead of reference signals by constructing a plurality of demodulation reference signal (DMRS) structures and providing a method of allowing a base station to set the DMRS structure in a 5G system operating in a higher frequency band as well as a 6GHz or lower frequency band.

Further, another object of the present disclosure is to minimize overhead of a reference signal by providing a method of allowing a terminal to configure necessary information and feed back the information so that a base station selects a DMRS suitable for a transmission environment from among a plurality of DMRS structures.

Further, it is still another object of the present disclosure to reduce a delay time of data transmission by providing a method for determining transmission timing such as HARQ ACK/NACK transmission timing or PUSCH transmission timing when time required for signal processing of a base station and a terminal is reduced in an LTE system using FDD or TDD.

[ MEANS FOR SOLVING PROBLEMS ] A method for producing a semiconductor device

In order to achieve the above object, a method of a base station according to an embodiment of the present disclosure may include: determining control information for transmitting a demodulation reference signal (DMRS), the control information including at least one of first information for the number of symbols and second information for positions of the symbols on a time axis; transmitting the control information to the terminal; and transmitting the DMRS to the terminal according to the determined control information.

A base station according to an embodiment of the present disclosure may include a transceiver and a controller configured to: determining control information for transmitting a demodulation reference signal (DMRS), the control information including at least one of first information for the number of symbols and second information for positions of the symbols on a time axis; controlling the transceiver to transmit the control information to the terminal; and controlling the transceiver to transmit the DMRS to the terminal according to the determined control information.

The method of the terminal according to the embodiment of the disclosure may include: receiving control information for transmitting a demodulation reference signal (DMRS) from a base station, the control information including at least one of first information for the number of symbols and second information for positions of the symbols on a time axis; and receiving the DMRS according to the control information.

A terminal according to an embodiment of the present disclosure may include a transceiver configured to: receiving control information for transmitting a demodulation reference signal (DMRS) from a base station, the control information including at least one of first information for the number of symbols and second information for positions of the symbols on a time axis; and controlling the transceiver to receive the DMRS according to the control information.

In another embodiment of the present disclosure, a method of a terminal may include receiving a first signal from a base station in an (n-k) th subframe, identifying a subframe for transmitting a second signal corresponding to the first signal in tables 3-7a below, and transmitting the second signal in the identified subframe.

[ tables 3 to 7a ]

In another embodiment of the present disclosure, wherein identifying the subframe for transmitting the second signal in tables 3-7a may include identifying a reception timing of the first signal in tables 3-7a, and determining a transmission timing of the second signal corresponding to the reception timing of the first signal.

In another embodiment of the present disclosure, the first signal may include a Physical Downlink Shared Channel (PDSCH), and the second signal may include ACK (acknowledgement)/NACK (negative acknowledgement) information of the PDSCH.

In another embodiment of the present disclosure, a method of a base station may include transmitting a first signal to a terminal in an (n-k) th subframe, identifying a subframe for receiving a second signal corresponding to the first signal in tables 3-7a below, and receiving the second signal in the identified subframe.

[ tables 3 to 7a ]

In another embodiment of the present disclosure, wherein identifying the subframe for receiving the second signal in tables 3-7a may include determining a transmission timing of the first signal in tables 3-7a, and identifying a reception timing of the second signal corresponding to the transmission timing of the first signal.

[ advantageous effects of the invention ]

According to an embodiment of the present disclosure, a method for constructing a plurality of demodulation reference signal (DMRS) structures and allowing a base station to set a DMRS structure suitable for a transmission environment is provided. This makes it possible to efficiently perform channel estimation according to support for low delay and high mobility in a channel environment of a 5G wireless communication system. DMRS transmission may also be performed environmentally adaptively, minimizing overhead of reference signals, and efficiently transmitting radio resources.

Further, according to another embodiment of the present disclosure, there is provided a method of allowing a terminal to configure necessary information and feed back the information so that a base station selects a DMRS suitable for a transmission environment from among a plurality of DMRS structures. Through the present disclosure, DMRS transmission may be performed environment-adaptively and overhead of reference signals may be minimized.

Further, according to still another embodiment of the present disclosure, a method for determining transmission timing such as HARQ ACK/NACK transmission timing or data transmission timing is provided to reduce a delay time.

Drawings

Fig. 1 is a diagram illustrating a downlink time-frequency domain transmission structure of an LTE or LTE-a system.

Fig. 2 is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-a system.

Fig. 3 is a diagram illustrating radio resources of a 1RB of a minimum unit scheduled via downlink in an LTE or LTE-a system.

Fig. 4, 5, 6, 7, 8, 9, and 10 are diagrams illustrating a plurality of DMRS structures according to 1-1 embodiments of the present disclosure.

Fig. 11 and 12 are diagrams illustrating an example of a method for orthogonally supporting MU transmission between terminals using different DMRS structures according to embodiments 1 to 3 of the present disclosure.

Fig. 13 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.

Fig. 14 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure.

Fig. 15 is a diagram illustrating a position of a preamble DMRS in the case where a slot length is 7 or 14 OFDM symbols.

Fig. 16, 17, 18, 19, 20, and 21 are diagrams illustrating transmission positions of extended/additional DMRSs in the case that a slot length is 7 or 14 OFDM symbols.

Fig. 22 is a diagram illustrating a DMRS structure according to an embodiment of the present disclosure.

Fig. 23 is a diagram illustrating a method for mapping antenna ports to the element DMRS structure proposed in fig. 22.

Fig. 24 is a diagram illustrating a method for mapping more antenna ports to the element DMRS structure proposed in fig. 22.

Fig. 25, 26, and 27 are diagrams showing radio resource configurations of the LTE system.

Fig. 28 is a diagram illustrating feedback timing of information required to select a reference signal according to embodiment 2-2 of the present disclosure.

Fig. 29 is a diagram illustrating a method for distinguishing reference signals based on feedback of information required to select the reference signals according to embodiments 2-3 of the present disclosure.

Fig. 30 is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present disclosure.

Fig. 31 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure.

Fig. 32 is a diagram showing a downlink time-frequency domain transmission structure of an LTE or LTE-a system.

Fig. 33 is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-a system.

Fig. 34 is a diagram showing data of eMBB, URLLC, and mtc allocated in frequency-time resources in a communication system.

Fig. 35 is a diagram showing data of eMBB, URLLC, and mtc allocated in frequency-time resources in a communication system.

Fig. 36 is a diagram showing a structure of dividing one transmission block into several code blocks and adding CRC according to one embodiment.

Fig. 37 is a diagram illustrating a transmission scheme using an outer code according to an embodiment.

Fig. 38 is a block diagram illustrating a communication system with or without application of an external code according to an embodiment.

Fig. 39 is a diagram illustrating the operation of the terminal according to the 3-1, 3-2, 3-3, and 3-4 embodiments.

Fig. 40 is a diagram illustrating the operation of the terminal according to the 3-5, 3-6, 3-7, and 3-8 embodiments.

Fig. 41 is a block diagram showing the structure of a terminal according to the embodiment.

Fig. 42 is a block diagram showing the structure of a base station according to the embodiment.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear. The following terms are defined in consideration of functions of the present disclosure, and may be changed according to the intention of a user, an operator, and the like. Therefore, the definitions should be based on the contents of the entire specification.

Advantages and features of the present disclosure and the manner of attaining them will become apparent with reference to the following detailed description of embodiments and the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. The present disclosure is to be limited only by the scope of the following claims. Like reference numerals refer to like elements throughout the specification.

Wireless communication systems, which originally provided voice-oriented services, are now evolving into broadband wireless communication systems that provide high-speed high-quality packet data services based on communication standards such as high-speed packet access (HSPA), long term evolution (LTE, or evolved universal terrestrial radio access (E-UTRA)), or third generation partnership project (3GPP) LTE-advanced (LTE-a), 3GPP 2 High Rate Packet Data (HRPD), Ultra Mobile Broadband (UMB), and Institute of Electrical and Electronics Engineers (IEEE) 802.16E. In addition, 5G or New Radio (NR) communication standards are being developed for fifth generation wireless communication systems.

< first embodiment >

In a wireless communication system, a base station should transmit a reference signal for terminal channel estimation. Using the reference signal, the terminal can perform channel estimation and demodulate the received signal. In addition, the terminal can know the channel state through the reference signal and feed it back to the base station.

Generally, for transmission of a reference signal, a transmission interval of the reference signal based on frequency and time 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 becomes narrower, the channel estimation performance is improved, and thus the demodulation performance of the signal is improved. However, this causes an increase in the overhead of the reference signal, thereby limiting the data transmission rate.

A typical 4G LTE system operating in a 2GHz band uses reference signals such as a cell-specific reference signal (CRS) and a demodulation reference signal (DMRS) in downlink. If the interval of the reference signal is represented in frequency by a subcarrier interval "m" of an Orthogonal Frequency Division Multiplexing (OFDM) signal and in time by a symbol interval "n" of the OFDM signal, the transmission interval (m, n) based on the frequency and time of the reference signal corresponding to the

antenna ports

1 and 2 is (3, 4) in the case of the CRS having a normal Cyclic Prefix (CP). Further, in case that the DMRS has a normal CP, a transmission interval (m, n) based on frequency and time of a reference signal is (5, 7).

Unlike the LTE system, the 5G wireless communication considers a system operating at a higher frequency band as well as a 6GHz or lower frequency band. Since the channel characteristics depend on the frequency band, the 5G system needs to redesign the reference signal in consideration of this point.

The LTE/LTE-a system is a representative example of a broadband wireless communication system, and employs an Orthogonal Frequency Division Multiplexing (OFDM) scheme in a Downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme in an Uplink (UL). The uplink refers to a radio link used by a terminal (also referred to as a User Equipment (UE) or a Mobile Station (MS)) to transmit data or control signals to a base station (BS, also referred to as an eNode B or an eNB), and the downlink refers to a radio link used by a base station to transmit data or control signals to a terminal. The multiple access scheme as described above distinguishes data or control information of each user by allocating and operating time-frequency resources such that the time-frequency resources for carrying data or control information do not overlap with respect to the respective users, i.e., orthogonality is established.

Fig. 1 is a diagram showing a basic structure of a time-frequency domain of a radio resource region transmitted as a data or control channel in a downlink of an LTE/LTE-a system.

In fig. 1, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is an OFDM symbol. N is a radical of _symb One OFDM symbol 102 constitutes one slot 106, and two slots constitute one subframe 105. The length of the slot is 0.5ms and the length of the subframe is 1.0 ms.

Further, the radio frame 114 is a time domain portion composed of ten subframes. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is composed of N in total _BW A number of subcarriers 104.

In the time-frequency domain, the basic unit of resources is a Resource Element (RE)112, which may be represented by an OFDM symbol index and a subcarrier index. Resource Blocks (RBs) 108 or Physical Resource Blocks (PRBs) are defined as consecutive N's in the time domain _symb One OFDM symbol 102 and consecutive N in the frequency domain _RB A number of subcarriers 110. Thus, one RB 108 is represented by N _symb ×N _RB And RE 112.

Generally, the minimum transmission unit of data is an RB unit. In LTE system, N _symb Is 7, N _RB Is 12, N _BW And N _RB In proportion to the bandwidth of the system transmission band. The data transmission rate increases in proportion to the number of RBs scheduled to the terminal. The LTE system defines and operates six transmission bandwidths. In an FDD system in which a downlink and an uplink are separated by frequency, a downlink transmission bandwidth and an uplink transmission bandwidth may be different from each other. The channel bandwidth means an RF bandwidth corresponding to a system transmission bandwidth.

Table 1-1 shows the relationship between the system transmission bandwidth and the channel bandwidth defined in the LTE system. For example, the LTE system having a channel bandwidth of 10MHz has a transmission bandwidth formed of 50 RBs.

[ Table 1-1]

Fig. 2 is a diagram showing a basic structure of a time-frequency domain of a radio resource region transmitted as a data or control channel in an uplink of an LTE/LTE-a system.

In fig. 2, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is an SC-FDMA symbol 202. N is a radical of _symb ^UL One SC-FDMA symbol constitutes one slot 206, and two slots constitute one subframe 205. The minimum transmission unit in the frequency domain is a subcarrier, and the entire system transmission bandwidth 204 is composed of N in total _BW One subcarrier. N is a radical of _BW Is proportional to the system transmission band.

In the time-frequency domain, a basic list of resourcesThe element is a Resource Element (RE)212, which may be defined by an SC-FDMA symbol index and a subcarrier index. Resource Block (RB) pairs 208 are defined as consecutive N in the time domain _symb ^UL One SC-FDMA symbol and consecutive N in frequency domain _SC ^RB And (4) a subcarrier. Thus, one RB is formed by N _symb ^UL x N _SC ^RB And RE. Generally, the minimum transmission unit of data or control information is an RB unit. In case of PUCCH, it is mapped to a frequency region corresponding to 1RB and transmitted during one subframe.

Fig. 3 is a diagram illustrating radio resources of a minimum unit 1RB scheduled via downlink in an LTE or LTE-a system. As described below, a plurality of different types of signals may be transmitted through the radio resources shown in fig. 3.

1. Cell-specific rs (crs): this is a reference signal periodically transmitted for all terminals belonging to one cell, and can be commonly used by a plurality of terminals.

2. Demodulation reference signal (DMRS): this is a reference signal transmitted for a specific terminal only in case data is transmitted to the terminal. The DMRS may consist of a total of 8 DMRS ports. In LTE/LTE-a, ports 7 to 14 correspond to DMRS ports, which maintain orthogonality so that they do not interfere with each other by using Code Division Multiplexing (CDM) or Frequency Division Multiplexing (FDM).

3. Physical Downlink Shared Channel (PDSCH): this is the data channel transmitted in the downlink, which is used by the base station to transmit traffic to the terminal. This is transmitted through REs in the data region of fig. 3 that are not used for transmitting the reference signal.

4. Channel state information reference signal (CSI-RS): this is a reference signal transmitted for a terminal belonging to one cell for measuring a channel state. Multiple CSI-RSs may be transmitted to one cell.

5. Other control channels (PHICH, PCFICH, and PDCCH): these channels provide control information required for a terminal to receive a PDSCH or transmit an ACK/NACK to operate a hybrid automatic repeat request (HARQ) for uplink data transmission.

Among the above signals, the CRS and DMRS are reference signals used to demodulate a signal received through channel estimation. Since the channel estimation performance directly affects the demodulation performance, a transmission interval based on the frequency and time of the reference signal is determined and maintained. For example, if the interval of the reference signal is represented in frequency by the subcarrier interval "m" of the OFDM signal and in time by the symbol interval "n" of the OFDM signal, the transmission interval (m, n) based on the frequency and time of the reference signal corresponding to the

antenna ports

1 and 2 is (3, 4) in the case of the CRS having the normal CP. Further, in case that the DMRS has a normal CP, a transmission interval (m, n) based on frequency and time of a reference signal is (5, 7).

Unlike the LTE system, the 5G wireless communication considers a system operating at a higher frequency band as well as a 6GHz or lower frequency band. Since the channel characteristics depend on the frequency band, the 5G system needs to redesign the reference signal in consideration of this point. Furthermore, 5G wireless communication importantly allows for support of low latency and high mobility, and it is important to minimize the overhead of reference signals. Accordingly, the present disclosure provides methods for constructing a plurality of demodulation reference signal (DMRS) structures and methods for setting the structures at a base station.

Now, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although the embodiments of the present disclosure will be described below using an LTE or LTE-a system as an example, the embodiments may be applied to other communication systems having a similar technical background or channel form, for example, to a 5G (or New Radio (NR)) mobile communication technology that is being developed after LTE-a.

In particular, the basic structure of the time-frequency domain for transmitting signals in the downlink and uplink may be different from those shown in fig. 1 and 2. Further, the types of signals transmitted in the downlink and uplink may be different. Thus, it will be apparent to those skilled in the art that embodiments of the present disclosure may be applied to other communication systems with some modifications without departing from the scope of the present disclosure.

In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear. The following terms are defined in consideration of the functions of the present disclosure, and may be changed according to the intention of a user, an operator, or the like. Therefore, the definitions should be based on the contents of the entire specification. Hereinafter, a Base Station (BS), which is an entity that allocates resources to a terminal, may be at least one of an eNode B, a Node B, a radio access unit, a base station controller, or a Node on a network. A 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 communication functions. In the present disclosure, Downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and Uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station.

The demodulation reference signal (DMRS) described below refers to a reference signal to which UE-specific precoding is applied and thus allows a terminal to perform demodulation without receiving additional precoding information. Although the nomenclature will be named in the following according to usage in the LTE system, the term DMRS may be expressed as any other term according to the intention and purpose of a user to use a reference signal. In particular, the term DMRS is merely a specific example provided for ease of understanding the present disclosure, and is not intended to limit the scope of the present disclosure. That is, it is apparent to those skilled in the art that the embodiments of the present disclosure can be applied to any reference signal based on the subject matter of the present disclosure.

In embodiments 1 to 1 of the present disclosure, various DMRS structures according to use cases will be described. In embodiments 1 to 2 of the present disclosure, a method for a base station to set and transmit a DMRS structure suitable for a transmission environment among a plurality of DMRS structures will be described. In embodiments 1-3 of the present disclosure that support multiple DMRS structures, a method for a terminal that uses different DMRS structures to orthogonally support multi-user (MU) transmission will be described.

[ 1-1 example ]

The 1-1 embodiment describes a method for constructing a structure of a DMRS, which is a reference signal of the present disclosure, in different manners according to transmission environments.

Referring to fig. 3, the LTE system has a fixed DMRS structure. When the number of transmission layers is two or less, each RB is transmitted using 12 DMRS REs. When the number of transmission layers exceeds two, each RB transmits using 24 DMRS REs.

As described above, unlike the LTE system, the 5G wireless communication considers a system operating in a higher frequency band and a frequency band of 6GHz or lower. Since channel characteristics depend on a frequency band, DMRSs of a 5G system need to be designed differently from LTE. Furthermore, 5G systems place great importance on support for low latency and high mobility. Therefore, various DMRS structures according to transmission environments are required.

For example, to support low delay, channel estimation should be performed quickly. For this reason, DMRS needs to be transmitted in front of a transmission time axis and should allow fast-varying channel tracking over time to support high mobility. In addition, DMRSs need to be transmitted at high density on one transmission time axis. The density refers to an amount of resources (e.g., the number of REs) for DMRS transmitted in an arbitrary transmission element.

Also, for example, reference signals such as CRS may not be supported in a 5G system. In general, the CRS has a high reference signal density, and can guarantee channel estimation performance even in a low signal-to-noise ratio (SINR) region (e.g., -10 to 0 dB). When the CRS is not transmitted, only the DMRS may make it difficult to guarantee channel estimation performance in a low SINR region.

Accordingly, the present disclosure proposes a method for differently constructing a structure of a DMRS according to a transmission environment.

In order to construct various DMRS structures, it is first necessary to set positions where DMRSs can be transmitted. In an embodiment of the present disclosure, when a transmittable DMRS location is set, a base station may determine and transmit a DMRS structure required at the set location. Furthermore, in embodiments of the present disclosure, the terminal needs to know such transmittable DMRS locations.

Unlike the LTE system, the 5G wireless communication system may be configured into various frame structures and operate at variable Transmission Time Intervals (TTIs), and thus the location setting of the DMRS needs to be separately notified to the terminal. Further, in the 5G wireless communication system, the number of time-based OFDM symbols and the number of frequency-based subcarriers constituting a subframe may be different from the number of LTE systems. In most of the drawings of the present disclosure, the number of time-based OFDM symbols constituting a subframe and the number of frequency-based subcarriers constituting a resource block are shown to be set equal to the number of LTE, but these numbers may be set differently. For example, as shown in fig. 6, 7, 8, and 9, one resource block may consist of twelve subcarriers or sixteen subcarriers in frequency.

Specifically, the setting of the DMRS transmittable positions may be performed for each of the time position and the frequency position, and may be performed for a combination of the time position and the frequency position.

First, for a time location where DMRS is allowed to be transmitted, two methods may be considered. The first method is to set a time position of DMRS transmission based on a subframe. The method is generally performed in subframe units in consideration of the location setting of transmission resources.

For example, when a duration corresponding to one subframe is represented by x, a method of setting a DMRS position in units of y (═ x/2) may be considered. Referring to fig. 6 to 8 in particular, when the duration x is set to 14 OFDM symbols, DMRS positions may be set in units of 7(═ y), and settable time positions of DMRS in one subframe may be 3 rd, 6 th, 9 th and 12 th OFDM symbols.

The second method is to set a time position at which DMRS is transmitted based on a starting point of an allocated data channel (e.g., PDSCH). The method considers that a 5G wireless communication system (which is different from the LTE system) can set a data channel transmission interval differently in a subframe. For example, settable time positions of DMRSs may be 1 st, 4 th, 7 th and 10 th OFDM symbols based on a start point of a data channel.

Next, frequency positions allowing DMRSs to be transmitted may be set to have a density in consideration of a channel environment of a 5G communication system covering various digital processing (numerology). Here, the digital processing may refer to a subcarrier interval (e.g., a frequency difference between subcarriers), and the length of the subcarrier interval may be inversely proportional to the symbol length on the time axis.

For example, DMRS transmission positions on frequencies may be set such that DMRS is transmitted through at least two consecutive subcarriers. For example, part e and part f in fig. 7 show two frequency locations where DMRSs can be transmitted.

As described above, the DMRS transmittable position may be set to a combination of a time position and a frequency position. Indeed, for convenience, DMRS settings may be based on a subset of the available combinations. In addition, the transmission DMRS structure may be implicitly determined according to the above-described DMRS transmittable time position and number of transmission DMRS layers.

Specifically, the DMRS structures proposed in fig. 6 and 7 will be described.

As shown in parts a and b of fig. 7, when DMRSs are set for only one OFDM symbol located at the front of the time axis in one subframe to support low delay, a terminal can identify a DMRS structure according to the number of layers. For example, when the number of transmission layers is four layers or less, the reference signals may be more densely allocated in frequency as shown in part b of fig. 7. On the other hand, when the number of transmission layers is greater than four, reference signals having a low density can be allocated on frequencies as shown in part a of fig. 7. However, as shown in part a of fig. 7, it may be difficult to secure channel estimation performance by setting a reference signal to have a low density.

In another example, when DMRSs are set for two OFDM symbols in time in one subframe, as shown in part c and part d of fig. 7. As described above, when the number of transmission layers is four layers or less, the reference signals can be more densely allocated on the frequency as shown in part d of fig. 7. Further, when the number of transmission layers is greater than four, reference signals having a low density may be allocated on frequencies as shown in part c of fig. 7.

In yet another example, to supplement in an environment of a strong doppler effect (hereinafter, also referred to as high doppler), DMRSs may be set for four OFDM symbols on a time axis in one subframe, as shown in part e and part f of fig. 7. When the number of transmission layers is four layers or less, reference signals may be allocated as shown in part f of fig. 7. In this case, if the reference signals are more densely allocated in frequency, the overhead of the reference signals may become too large. When the number of transmission layers is greater than four, the reference signals may be allocated as shown in section e of fig. 7. However, in high-speed transmission, the probability that the number of transmission layers is greater than four is very low.

When the number of transmission layers is four or more, it is possible to operate with an Orthogonal Cover Code (OCC) of 4. When the number of transmission layers is two layers or less, the operation can be performed with the OCC of 2. The above examples may be similarly applied to other DMRS structures. In addition, the examples of the DMRS structures shown in fig. 8 and 9 may be similarly applied to the case where the number of frequency-based subcarriers in one resource block is sixteen.

Next, a method of performing operations such as doppler frequency measurement, phase noise compensation, and frequency offset correction using a DMRS is proposed. In an LTE system, the above operations may be performed using CRS. However, in a 5G communication system in which a signal such as a CRS is not transmitted on each subframe in the full frequency band, it may be difficult to perform the above-described operations such as doppler frequency measurement, phase noise compensation, and frequency offset correction.

In order to perform such operations, a reference signal with a high density in time is required. However, when the DMRS is set to, for example, only one previous OFDM symbol in time to support low delay, it is impossible to perform the above operation using only the DMRS. Accordingly, the base station may set the DMRS to a high density based on time as required, thereby performing operations such as doppler frequency measurement, phase noise compensation, and frequency offset correction. Specifically, in order to perform such an operation, the base station performs dynamic signaling, and the terminal performs operations such as doppler frequency measurement, phase noise compensation, and frequency offset correction by using the DMRS set through the dynamic signaling. For example, for signaling, the base station may add one bit to the Dynamic Control Information (DCI). The support of multiple DMRS structures in embodiments 1-1 may differ as follows, compared to the support of one fixed DMRS structure in an LTE system. First, unlike LTE, the number of DMRS Resource Elements (REs) allocated per antenna port may not be fixed. For example, although the number of DMRS REs allocated per antenna port is fixed to 12 in the LTE system, the number of DMRS REs allocated per antenna port may vary according to which of various DMRS structures is set.

In addition, the number of supported antenna ports may vary according to which DMRS structure is set. For example, in an environment where reference signal overhead needs to be reduced, it is difficult to support a high rank. Therefore, in this case, it is necessary to minimize the overhead of the reference signal by supporting only the minimum antenna port. Hereinafter, detailed examples of various proposed DMRS structures will be described.

For the above reasons, the 1 st-1 embodiment of the present disclosure proposes various DMRS structures according to transmission environments. Fig. 4 is a diagram illustrating one example of various DMRS structures. The structure of fig. 4 allows the DMRS to be transmitted through all subcarriers included in one OFDM symbol. However, DMRS locations proposed in this disclosure are not limited to the locations shown in fig. 4.

Specifically, as shown in part a of fig. 4, DMRS may be located in each of a third OFDM symbol and an eleventh OFDM symbol. For example, for time balance, the DMRS may be transmitted through each position of the third OFDM symbol and the eleventh OFDM symbol in one subframe, as shown in part a of fig. 4. However, when the 5G system has a basic structure different from that of the time-frequency domain of the LTE/LTE-a system, the DMRS location may change.

As another example, to support low delay, the DMRS may be transmitted only through the position of the third OFDM symbol in one subframe, as shown in part b of fig. 4. In this case, the terminal can rapidly demodulate the received signal because channel estimation is allowed in a state where the signal is received up to the third OFDM symbol.

As yet another example, to support high mobility, the DMRS may be transmitted through three positions of different OFDM symbols in one subframe, as shown in part c of fig. 4.

Meanwhile, DMRS signals may be generated based on a pseudo-random sequence similar to a downlink DMRS in LTE, or based on a Zadoff-chu (zc) sequence similar to an uplink DMRS in LTE. For example, when the uplink and downlink have the same DMRS structure, applying DMRS signal generation equally to the uplink and downlink allows orthogonal support of uplink/downlink DMRS ports.

In addition, in fig. 4, multiple DMRS ports may be supported by applying Orthogonal Cover Codes (OCC) on frequencies. When applying OCC in frequency, the advantage is that power imbalance problems that may occur when applying OCC in time do not occur. An example of this is shown in figure 5.

Fig. 5 shows an example of applying OCC when there are sixteen frequency-based subcarriers in one resource block. In fig. 5, DMRS ports are numbered from 7 th port to 14 th port based on the LTE system, but this is just an example for explanation. The port numbers used in the 5G system may be different.

Specifically, part a of fig. 5 shows an example of OCC applied when DMRS is transmitted using two ports (port 7, port 8). As shown in part a of fig. 5, an OCC of length 2 may be applied to the locations where

ports

7 and 8 are indicated. Therefore, when the DMRS is transmitted using two ports as shown in part a of fig. 5, the DMRS is not transmitted for all resources included in one OFDM symbol.

The sequences of OCCs are shown in tables 1-2. In the tables 1-2, the results of the test were,

indicating a sequence value according to the sequence length. When OCC size is 2, use

And

when OCC size is 4, all are used

As described above, based on the LTE system, tables 1-2 are also numbered from port 7 to port 14, but this is just an example for explanation. The port numbers used in 5G systems may be different.

Part b of fig. 5 shows an example of an OCC applied when four

ports

7, 8, 9 and 10 are transmitted. As shown in part b of fig. 5, an OCC of length 2 may be applied to the positions where the

ports

7, 8, 9, and 10 are indicated. When four or more ports are transmitted as shown, DMRS may be transmitted for all resources of an OFDM symbol. Next, part c of fig. 5 shows an example of OCC applied when eight ports are transmitted. When more than four ports are used, the OCC length is 4 as shown in section c of fig. 5.

Although fig. 5 shows an example of OCC applied to a case of transmitting two, four, or eight ports, applications of other numbers of ports less than eight can be easily extended from the example of fig. 5. For example, in the case of transmitting three ports, as shown in part a of fig. 5, only the

ports

7, 8, and 9 are transmitted. Thus,

ports

7 and 8 may be transmitted with a length-2 OCC applied to the corresponding location in section a of fig. 5, but a length-2 OCC is not applied to port 9 because there are no other ports at the corresponding location in section a of fig. 5.

[ tables 1-2]

Next, fig. 6, 7, 8, and 9 illustrate second examples of the proposed various DMRS structures. Fig. 6, 7, 8 and 9 show a structure modified from the form proposed in fig. 4 and 5. In particular, by considering the overhead of the reference signal, a structure capable of operating more efficiently than the methods proposed in fig. 4 and 5 is proposed by the DMRS location configuration and the antenna port mapping method on frequency.

The DMRS signals may be generated based on a pseudo-random sequence similar to a downlink DMRS in LTE, or may be generated based on a Zadoff-chu (zc) sequence similar to an uplink DMRS in LTE. Fig. 6 and 7 show configurations when the number of subcarriers in a frequency constituting a resource block is 12, and fig. 8 and 9 show configurations when the number of subcarriers in a frequency constituting a resource block is 16.

First, fig. 6 and 7 are described. The methods proposed in fig. 6 and 7 can flexibly use the method shown in part a of fig. 6 according to transmission conditionsDMRS location. The OCC and antenna port mapping method may be as shown in part b of fig. 6 and part c of fig. 6. In the tables 1-2, the results of the test were,

And

when OCC size is 4, all are used

In part b of fig. 6 and part c of fig. 6, DMRS ports are numbered from port 7 to port 14 based on the LTE system, but this is only an example for explanation. The port numbers used in the 5G system may be different.

Referring to part b of fig. 6, the reference signal is not transmitted at a position indicated by a lattice pattern, and may be transmitted only at a position indicated by a hatched pattern. In this case, two

ports

7 and 8 may transmit with OCC ═ 2 applied, and four

ports

7, 8, 11, and 13 may transmit with OCC ═ 4 applied. In contrast to this, when eight ports from port 7 to port 14 are transmitted,

ports

7, 8, 11, and 13 may transmit with OCC ═ 4 applied at positions indicated by a hatched pattern, and

ports

9, 10, 12, and 14 may transmit with OCC ═ 4 applied at positions indicated by a lattice pattern.

Referring to part c of fig. 6, two

ports

7 and 8 may transmit with OCC ═ 2 applied at a position indicated by a hatched pattern, and four

ports

7, 8, 11, and 13 may also transmit with OCC ═ 4 applied at a position indicated by a hatched pattern. Part b of fig. 6 shows a method of minimizing reference signal overhead in a good channel state, and part c of fig. 6 shows a method of improving channel estimation performance by further using a reference signal in a poor channel state. Although OCC is applied to the frequency domain in parts b and c of fig. 6, the method of applying OCC is not limited thereto.

As described above, the methods proposed in fig. 6 and 7 may flexibly use the DMRS locations shown in part a of fig. 6 according to transmission conditions. Part a of fig. 7, part b of fig. 7, part c of fig. 7, part d of fig. 7, part e of fig. 7, and part f of fig. 7 show examples of DMRS positions that are configurable according to transmission conditions. Related embodiments are as described above.

As described above, fig. 8 and 9 show the configuration in the case where the number of subcarriers constituting a resource block in frequency is 16. The related operation method is the same as that described in fig. 6 and 7, and thus a detailed description thereof will be omitted. The OCC and antenna port mapping method may be performed as shown in part b of fig. 8 and part c of fig. 8, and the detailed operation is the same as in part b of fig. 6 and part c of fig. 6. However, the method of applying OCC in the present disclosure is not limited thereto.

The methods proposed in fig. 8 and 9 may flexibly use the DMRS location shown in part a of fig. 8 according to transmission conditions, and part a of fig. 9, part b of fig. 9, part c of fig. 9, and part d of fig. 9 illustrate examples of configurable DMRS locations.

Finally, fig. 10 shows a third example of the proposed various DMRS structures. Fig. 10 is a structure in which DMRS has a form similar to that of the current LTE system. Therefore, the OCC and the antenna port mapping method applied in the DMRS of LTE may be applied as it is. However, in the present disclosure, other DMRS structures may be considered to meet next generation communication requirements according to channel environments. That is, the present disclosure proposes a method of constructing various DMRS structures in units of OFDM symbols according to a transmission environment by extending an existing DMRS structure of an LTE system.

Part a of fig. 10 shows DMRS positions that can be implemented in a conventional channel state. Part b of fig. 10 shows a structure in which an additional DMRS is mapped on a time axis in order to support high mobility. Part c of fig. 10 and part d of fig. 10 illustrate a method of reducing DMRS density on a frequency axis in order to minimize overhead of a reference signal in an environment having a small channel delay. Finally, to support low latency, DMRS structures as shown in part e of fig. 7 and part f of fig. 7 may be used. As shown in part e of fig. 10, when the position of DMRS transmission is located only in the first OFDM symbol, only 4-layer transmission can be supported at most.

Fig. 4, 6, 7, 8, 9, and 10 illustrate various DMRS structures according to transmission environments. However, the DMRS structure in the present disclosure is not limited to the structure set forth in the 1 st to 1 st embodiments. Accordingly, other DMRS structures different from fig. 4, 6, 7, 8, 9, and 10 may be applied to the 1 st-2 nd and 1 st-3 rd embodiments given below.

Although the 1 st-1 st embodiment relates to a downlink-based DMRS structure, the same DMRS structure may be set in an uplink in a 5G system. Uplink and downlink DMRS ports are orthogonal if the uplink and downlink have the same DMRS structure. Thus, flexible operation is possible in environments such as time division duplex, TDD.

[ examples 1-1-1 ]

1-1-1 embodiments propose another method of setting the DMRS structure proposed in the above-described 1-1 embodiments. In the 1-1-1 embodiments, it should be noted that DMRS structures that can be set may be divided into a preamble DMRS and an extension/additional DMRS. First, a preamble DMRS may be defined by the following two standards.

1. OFDM symbol number for preamble DMRS

● Pre-DMRS mapping on 1 or 2 adjacent OFDM symbols

■ preamble DMRS are mapped onto 1 OFDM symbol for low rank transmission.

■ pre-DMRS is mapped onto 2 adjacent OFDM symbols for high rank transmission.

2. Time position of preamble DMRS

● option 1: the first symbol of the preamble DM-RS is fixed regardless of the first symbol of the NR-PDSCH.

● option 2: the first symbol of the preamble DM-RS is no later than the first symbol of the NR-PDSCH.

Specifically, the preamble DMRS may be configured in one or two adjacent OFDM symbols according to the number of transmission layers (ranks). Further, on the time axis, the preamble DMRS is located before the NR-PDSCH and its location may be fixed as described above, or the preamble RS may be located at the first symbol from which the NR-PDSCH starts.

The advantages and disadvantages of option 1 and option 2 are as follows. In case of option 1, it may be assumed that DMRS locations are fixed, and thus DMRSs of neighboring cells are always transmitted at the same location. However, when the control channel region is set to be configurable, or in the case of a subframe in which the control channel is not transmitted, the DMRS of the data channel may not be located further forward, thereby causing a decoding delay problem.

On the other hand, in case of option 2, the preamble DMRS is always in front of the data channel on the time axis, and thus has an advantage in terms of decoding delay problem. However, the location of the preamble DMRS is varied, i.e., the location of the DMRS is not fixed, thereby causing problems in inter-cell interference control and advanced receiver operation. Therefore, further introduction of network signaling may be considered. However, in general, a method of fixedly setting a DMRS location is advantageous for system operation.

Therefore, for the above-described reason, a detailed method of setting the preamble DMRS to a fixed position is proposed. Fig. 15 shows the positions of the preamble DMRSs in the case where the slot length is 7 or 14 OFDM symbols. Here, a position where the preamble DMRS is set may be determined by a control channel region. For example, when the control channel region consists of two OFDM symbols at most, the preamble DMRS is located at the third OFDM symbol, as shown in part a of fig. 15. As another example, when the control channel region consists of three OFDM symbols at most, the preamble DMRS is located at the fourth OFDM symbol, as shown in part b of fig. 15.

As described above, when the position of the preamble DMRS is determined according to the maximum size of the settable control channel region, there may be a loss in reducing the decoding delay if some or all of the control channels are not set. Accordingly, the present disclosure proposes another method of setting the position of the preamble DMRS by the extension method of option 1.

For example, when the control channel region is composed of two OFDM symbols at most, the following may be used as an option: as shown in part a of fig. 15, a preamble DMRS is fixed to one setting of the third OFDM symbol, and as shown in part c of fig. 15, a preamble DMRS is fixed to another setting of the first OFDM symbol. The disadvantage of option 1 can be compensated if these two settings are selectively used according to circumstances.

In particular, the location setting of the plurality of preamble DMRSs may be performed in various ways. For example, a semi-static setup method through upper layer signaling (such as RRC) may be considered. Also, for example, the DMRS location may be set and transmitted through system information such as MIB or SIB. Also, for example, a method of dynamically setting a DMRS position through DCI may be considered. Alternatively, the location of the DMRS may be set by semi-persistent scheduling (SPS).

Next, extended/additional DMRS is explained. The aforementioned pre-DMRS is difficult to accurately estimate a channel because it is impossible to track a channel that rapidly changes over time in a high doppler case. Further, it is impossible to perform cross-correlation correction on frequency offset using only the preamble DMRS. Therefore, for this reason, it is necessary to transmit the additional DMRS at a later time than the transmission position of the preamble DMRS on the time axis in one slot.

Fig. 16 to 21 illustrate transmission positions of extended/additional DMRSs in the case where a slot length is 7 or 14 OFDM symbols. Fig. 16 to 21 illustrate extended/additional DMRSs with respect to part a of fig. 15, part b of fig. 15, and part c of fig. 15, wherein positions of preamble DMRSs are respectively set as illustrated in fig. 15.

Fig. 17, 18, and 19 illustrate embodiments in which extended/additional DMRS positions are set by avoiding CRS transmission positions in an LTE system. This has the advantage of reducing the impact of interference in LTE-NR coexistence scenarios. However, in the case of fig. 20 and 21, the position of the preamble DMRS overlaps with the position of the CRS transmission position in the LTE system as in the case of part c of fig. 15.

As shown in fig. 16 to 21, when the slot length is 7 OFDM symbols, the position of the extended/additional DMRS may be set to one. However, when the slot length is 14 OFDM symbols, the position of the extension/additional DMRS needs to be set to two according to the doppler case.

For example, referring to fig. 16 and 17, in an environment where a channel is rapidly changed, the location of the extended/additional DMRS may be set as shown in part b of fig. 16, and in an environment where a channel is rapidly changed, the location of the extended/additional DMRS needs to be set as shown in part a of fig. 17. In the above-described embodiments, fig. 15 and 16 to 21 show basic positions where DMRSs are set. If the DMRS transmission layer is increased, a transmission position of the DMRS may be further set. This will be described in detail by DMRS port multiplexing in fig. 24 below.

In addition, in case of the extended/additional DMRS, an overhead problem of the DMRS may occur because a plurality of DMRSs are disposed on a time axis. In this case, overhead of the DMRS may be reduced by setting the DMRS to have low density on a frequency axis. The aforementioned preamble DMRS and extended/additional DMRS may be more flexibly operated by a unit DMRS structure proposed below.

Specifically, the DMRS structure proposed by the present disclosure will be described with reference to fig. 22. In the present disclosure, a cell DMRS structure based on one OFDM symbol is proposed. Such a unit DMRS structure is advantageous for setting the position of reference signals with respect to various Transmission Time Intervals (TTIs), for supporting low latency, for setting the position of reference signals for ultra-reliable low latency communication (URLLC), and may also be advantageous in terms of scalability such as antenna port extension.

As shown in fig. 22, twelve subcarriers may be included in one OFDM symbol based on a PRB (PRB is a minimum transmission unit of data). As shown by reference numerals 3m10, 3m20, and 3m30, the density of DMRS Subcarriers (SC) in one OFDM symbol is variable (configurable). Reference numerals 3m10 and 3m20 denote DMRS structures when there are four and eight DMRS SCs in twelve subcarriers, respectively. Reference numeral 3m30 denotes a DMRS structure when the DMRS SC consists of all twelve subcarriers.

In the case of reference numerals 3m10 and 3m20, the use of an even number of DMRS SCs may be advantageous because isolated REs do not occur when space-frequency block coding (SFBC) is considered as a transmit diversity scheme. For example, if SFBC is transmitted through two antenna ports, and if REs for DMRS transmission on frequency are not multiples of two, the problem of not using one RE (isolated RE) can be solved.

In the case of reference numerals 3m10 and 3m20, SCs that are not used as DMRS SCs may be mapped to data or other reference signals or may be empty for DMRS power boosting. Here, a method of nulling SCs not used as DMRS SCs for DMRS power boosting may be used to improve the performance of DMRS channel estimation in low signal-to-noise ratio (SNR) regions. The DMRS structure of fig. 22 may be used not only for a data channel but also for other channels (e.g., a control channel).

In the case of reference numerals 3m10 and 3m20, some subcarriers that are not used for DMRS transmission may be used as Direct Current (DC) subcarriers. However, in the case of reference numeral 3m30, since the DMRS is transmitted in all subcarriers, in order to transmit DC, it is necessary to clear some subcarriers.

Further, the DMRS structure of reference numeral 3m10 may be replaced with a structure of reference numeral 3m40 in consideration of DC subcarriers. The DMRS SCs denoted by reference numerals 3m10 to 3m40 may be generated based on a pseudo-random (PN) sequence or based on a Zadoff-chu (zc) sequence. DMRS structures denoted by reference numerals 3m10 (or 3m40) and 3m20 (this is an example of a more detailed utilization method) may be used in the CP-OFDM system.

Furthermore, this structure can be used by setting the same time-frequency position in the uplink and the downlink. The DMRS ports of the uplink and downlink are orthogonal if the uplink and downlink have the same DMRS structure. This therefore allows better channel estimation in environments such as TDD, thereby improving interference cancellation performance.

In contrast, the DMRS structure of reference numeral 3m30 is based on Zadoff-chu (zc) sequences similar to LTE and can be used in DFT-s-OFDM systems on the uplink. This makes low peak-to-average power ratio (PAPR) operation similar to that of LTE. However, the present disclosure is not limited to the above-described DMRS structure utilization methods of reference numerals 3m10 to 3m 40. For example, the DMRS structure of reference numeral 3m30 may be used for both CP-OFDM and DFT-s-OFDM as well as both uplink and downlink.

Fig. 23 illustrates a method of mapping antenna ports to the element DMRS structure proposed in fig. 22. In fig. 23, antenna ports (p) are denoted by A, B, C and D. However, the antenna ports may be represented by numbers or other letters. The mapping of the antenna ports is to support multi-layer transmission and rank. Thus, the antenna port mapping may be replaced with other terms layer transmission or rank support.

Specifically, reference numerals 3n10 and 3n20 denote cases where two antenna ports are mapped to the DMRS structure of reference numeral 3m 10. Reference numeral 3n10 shows a method of mapping two antenna ports (p) a and B in Frequency Division Multiplexing (FDM)/Code Division Multiplexing (CDM) by applying an Orthogonal Cover Code (OCC) of length 2. Further, reference numeral 3n20 shows a method of mapping antenna ports (p) a and B without applying OCC in the FDM scheme. As will be described later, like 3n20, reference numerals 3n40 and 3n60 show examples of mapping antenna ports in the FDD scheme without applying OCC.

Next, reference numerals 3n30 and 3n40 denote cases where two antenna ports are mapped to the DMRS structure of reference numeral 3m 20. The DMRS of reference numeral 3m20 may improve channel estimation performance by increasing the density of reference signals, compared to reference numeral 3m 10. Reference numeral 3n30 shows a method of mapping two antenna ports (p) a and B in FDM/CDM by applying OCC of length 2, and reference numeral 3n40 shows a method of mapping such antenna ports a and B in FDM scheme without applying OCC.

Next, reference numerals 3n50 and 3n60 denote cases where four antenna ports are mapped to the DMRS structure of reference numeral 3m 20. In particular, if four antenna ports are supported, subcarriers that are not used for DMRS transmission in the DMRS structure at reference numeral 3m20 may be empty and used for DMRS power boosting in order to improve channel estimation performance. Reference numeral 3n50 shows a method of mapping four antenna ports (p) A, B, C and D in FDM/CDM by applying OCC of length 2, and reference numeral 3n60 shows a method of mapping such antenna ports A, B, C and D in FDM scheme without applying OCC.

In the case of reference numerals 3n10, 3n30, and 3n50, applying OCC on the frequency axis has an advantage that the power imbalance problem does not occur. In the case of the LTE system, applying OCC on the time axis causes a power imbalance problem, and there is a limitation in applying OCC differently in each of two PRBs.

Finally, reference numeral 3n70 denotes a DMRS structure of reference numeral 3m 30. Since all twelve subcarriers are used as DMRSs in the case of reference numeral 3m30, a method of supporting orthogonal DMRS antenna ports by using Zadoff-Chu may be considered. In this case, assuming that the subcarrier spacing is 15kHz as in LTE, a maximum of eight orthogonal antenna ports can be supported by applying eight Cyclic Shift (CS) fields. Another approach to utilizing the 3m30 DMRS structure is to support four orthogonal antenna ports in FDM with a spacing of four subcarriers.

The present disclosure is not limited to a method of mapping antenna ports to DMRS structures proposed by reference numerals 3n10 to 3n 70. For example, in case of reference numeral 3m30, FDM is applied to DMRS SC as shown by reference numeral 3n80, and up to eight orthogonal antenna ports may be supported by applying four cyclic shift fields. The operation method as shown in 3n80 uses all subcarriers in one OFDM symbol in the case of supporting high rank, but has an advantage that only some subcarriers in one OFDM symbol are used as reference signals and other subcarriers can be used for data transmission in the environment of using low rank. For example, in the case of transmission of rank 4 or less in 3n80, orthogonality may be supported by four CSs of a reference signal using only odd subcarriers, and the remaining six even subcarriers may be used for data transmission.

In fig. 24, a method of mapping a greater number of antenna ports to the proposed element DMRS structure than in fig. 22. In order to map a greater number of antenna ports than in fig. 23, TDM, FDM, and CDM may be further applied to the element DMRS structure.

First, reference numeral 3o10 shows that TDM is applied to reference numeral 3m20 to allow a maximum of eight antenna ports to be mapped. Reference numeral 3o20 shows an extension of the mapping of sixteen antenna ports by TDM using three OFDM symbols in time. In the case of using TDM-extended orthogonal antenna ports, RS density in frequency is maintained, but the density of DMRS is increased in a transmission unit. In order to maintain a low density of DMRSs in a transmission unit, it is considered that a higher rank is supported in an environment where channel conditions are very good and channel selectivity of a channel to frequency is low. Therefore, a method of spreading orthogonal antenna ports by using FDM or CDM can be considered.

Reference numeral 3o30 shows a method of mapping up to eight antenna ports by applying FDM to reference numeral 3m20 in frequency. Further, as shown by reference numeral 3o40, by applying an OCC of length 8 to reference numeral 3m20, up to eight antenna ports can be mapped.

Next, when all subcarriers are composed of DMRS SC as shown in 3m30, various antenna port extensions are possible according to the antenna port mapping method applied to 3m30 as described above. If the ZC sequence is CS by employing a subcarrier spacing of 15kHz in 3n30 to support eight orthogonal antenna ports, then spreading to sixteen orthogonal antenna ports is feasible by applying TDM as shown in 3o 10.

If FDM is used with four subcarrier spacings in 3m30, a maximum of four orthogonal antenna ports can be supported. However, considering FDM in 3o30 further, FDM is used with eight subcarrier spacings, and therefore can support up to eight orthogonal antenna ports.

The present disclosure is not limited to the antenna port expansion method shown in fig. 24. Any combination of TDM, FDM, and CDM may be applied, and orthogonal antenna ports may be spread in various ways. For example, when the number of antenna ports is extended only by using TDM in the case of 3o10 or 3o20 as described above, there is a disadvantage in that the density of DMRS increases in a transmission unit. To overcome this, TDM may be applied to two consecutive slots as shown in 3o50, or CDM with an OCC length of 4 may be applied to two consecutive slots as shown in 3o 60.

In the case of 3o50 and 3o60, the description has been made on the basis of two slots. However, a time unit to which TDM or CDM is applied is not limited to a slot. Further, unlike the method of mapping up to 8 antenna ports by applying OCC length 8 as in 3o40, if DMRS is generated with a ZC sequence, additional antenna ports may be supported by using CS as shown in 3o 70. In case CS is used instead of OCC as shown in 3o70, it is advantageous to maintain the RS density over frequency.

[ examples 1-2]

Embodiments 1-2 relate to a method of setting a DMRS structure suitable for a transmission environment among a plurality of DMRS structures. When various DMRS structures are supported as in the 1 st to 1 st embodiments of the present disclosure, and when a DMRS structure suitable for a transmission environment can be set as in the 1 st to 2 nd embodiments, a base station can optimize overhead of a reference signal by differently setting the DMRS structure according to the transmission environment.

In particular, it is necessary to improve channel estimation performance by setting a DMRS structure with high overhead of reference signals in a low-SNR or high-speed transmission environment. On the other hand, in a high SNR or low-speed transmission environment, it is necessary to improve transmission efficiency by setting a DMRS structure with low overhead of a reference signal. In this way, by adaptively transmitting the reference signal to the transmission environment, unnecessary overhead of the reference signal can be minimized, and thus system performance can be maximized.

Hereinafter, a method in which a base station sets a DMRS structure suitable for a transmission environment is described in detail. The DMRS structure applicable to the transmission environment proposed in the present disclosure may be semi-statically or dynamically set by the base station. Alternatively, a DMRS structure suitable for a transmission environment may be implicitly set.

First, a method of semi-statically setting a DMRS structure suitable for a transmission environment is described. The simplest method for semi-statically setting the DMRS structure is to set the DMRS structure through high-layer signaling.

Specifically, by setting DMRS-structure id in RRC as shown in tables 1-3 below, information on different DMRS structures may be signaled. In tables 1 to 3, maxDMRS-Structure indicates the number of settable DMRS structures, and each set value may indicate a different DMRS Structure. In this way, the DMRS structure may be semi-statically set via RRC, and a terminal according to an embodiment of the present disclosure may know the currently transmitted DMRS structure based on a value set in RRC.

[ tables 1 to 3]

For example, referring to the 1 st-1 st embodiments, the DMRS structure may be divided into two structures, i.e., a preamble DMRS and an extension/additional DMRS. In this case, the value of maxMRS-Structure in tables 1-3 may be set to 1. For example, it may be set that if the value of maxDMRS-Structure is 0, a preamble DMRS is indicated, and if the value of maxDMRS-Structure is 1, an extension/additional DMRS is indicated. In tables 1 to 3, DMRS-sturctureID may be changed to DMRS-configureID or other items.

In another example, when the Structure of the extended/additional DMRS exceeds one, the value of maxDMRS-Structure may increase by more than 1. Further, when the DMRS density on frequency is adjusted in the element DMRS Structure as described in embodiments 1-1-1, the maxDMRS-Structure value may be set to a larger value.

In yet another example, DMRS density in time/frequency may be set by an additional configuration, separate from setting a preamble DMRS and an extension/additional DMRS. Specifically, the settings can be made as shown in tables 1-4.

[ tables 1 to 4]

As another example, a method of dynamically setting, by a base station, a DMRS structure suitable for a transmission environment will be described. If information on DMRS is set in the MAC CE in a manner similar to the method of setting DMRS information in RRC, information on DMRS structure can be more dynamically set.

As another example, the simplest method of dynamically setting the DMRS structure is to insert information on the DMRS structure in DCI to be transmitted. In this case, the DCI format may be separately defined, in which a field for dynamically operating the DMRS structure is not applied for basic operation. If the DMRS structure is set using DCI, the DMRS structure may be dynamically changed, which is advantageous to improve transmission efficiency. On the other hand, there is a disadvantage in that DCI overhead occurs to operate on it.

Hereinafter, a method of setting a DMRS structure by using DCI will be described in detail. The number of bits required to signal various reference signal structures in DCI may increase due to the support of the various reference signal structures. In general, as shown in tables 1 to 5 or tables 1 to 6, information on the DMRS structure may be contained in the DCI field by using one or two bits. For example, tables 1-5 show examples of two types of reference signal structures operating using one bit.

[ tables 1 to 5]

To represent	RS Density	Situation of use
			‘0’	Low density	Low delay/low Doppler/low delay/high SINR
‘1’	High density	High Doppler/high delay/low SINR

In addition, tables 1-6 show examples of four types of reference signal structures that operate using two bits. In tables 1 to 6, if necessary, the low density 2 field may be set to a field indicating that the DMRS is not transmitted. The related utilization will be described in the embodiments 1 to 3. As described in embodiments 1-1, the DMRS structure may be determined by a combination of the signaling of tables 1-5 or tables 1-6 and the number of DMRS transmission layers used.

[ tables 1 to 6]

To represent	RS Density	Situation of use
			‘00’	Low density 1	Low delay/low Doppler
‘01’	Low density 2	Low delay/high SINR [ other options: RS-free configuration]
			‘10’	Medium density	Moderate SINR
‘11’	High density	High Doppler/high delay/low SINR

As a method of inserting information on DMRS structure in DCI to be transmitted, unlike a method of signaling RS density by using tables 1 to 5 or tables 1 to 6, a time position at which DMRS can be transmitted may be specifically signaled as described in embodiments 1 to 1.

In the 1 st-1 st embodiment, a method of setting DMRS transmittable time positions based on a subframe and based on a starting point of an allocated data channel (e.g., PDSCH) is proposed for setting the time positions at which DMRS can be transmitted. In this case, information on a time position where DMRS may be transmitted may be signaled in DCI.

For example, in a method of setting a DMRS transmittable time position on a subframe basis, when a value representing a subframe duration is defined as x, the position of a DMRS may be set in the unit of y ═ x/2. In this case, it is possible to indicate whether DMRS density is high or low in units of y using only 1 or 2 bits.

Specifically, the lower DMRS density on the time axis may be a DMRS composed of one OFDM symbol, and the higher DMRS density on the time axis may be a DMRS composed of two OFDM symbols. Further, the DMRS structure may be determined by a combination of such a structure and the number of DMRS transmission layers used. Details are as described in examples 1-1.

On the other hand, inserting a field indicating a DMRS structure in DCI at each transmission may be inefficient. Therefore, a method of transmitting a field indicating a DMRS structure through DCI based on a predetermined time interval may be considered. However, in this case, since the structure of the reference signal may be changed only when the field indicating the DMRS structure is transmitted, more dynamic operation of the DMRS structure may be difficult compared to a method of indicating the DMRS structure every time of transmission.

Finally, another method of implicitly setting a DMRS structure suitable for a transmission environment at a base station will be described. The first method is to set different DMRS structures according to Transmission Modes (TM).

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 the time axis, and TM C may be set as a reference signal having a low density on the time axis. In this case, TM a may be set as a TM supporting high mobility, and TM C may be set as a TM supporting low latency.

Alternatively, two DCI formats may be defined in one TM. One of the two formats may be set to a structure for transmitting a reference signal of a TM characteristic, and the other may be set to a reference signal having high density by operating in a fallback mode similar to DCI format 1A in LTE. In this case, the terminal may determine which DMRS structure is applied according to the TM mode or DCI format information currently set.

The second method is to change the structure of a reference signal to be applied according to a Modulation and Coding Scheme (MCS). Specifically, reference signals having a high density may be mapped in an area where a low MCS is set to improve channel estimation performance, and reference signals having a low density may be mapped in an area where a high MCS is set. In this case, the terminal may implicitly know the structure of the transmitted reference signal from the received MCS information.

A third method is to set different DMRS structures according to frame structures. Specifically, in an independent frame structure, the DMRS is set to one OFDM symbol in an anterior portion in time as in part a of fig. 7 or part b of fig. 7, and in a general frame structure, the DMRS may be set to two OFDM symbols in time as in part c of fig. 7 or part d of fig. 7.

As another setting method, in the case where a PDCCH in a common search space is identified based on the LTE system, the structure of reference signals of a PDSCH connected thereto may be mapped to have a high density. Similarly, in case of identifying a PDCCH in a UE-specific search space, reference signals of the PDCCH connected to the UE-specific search space may be mapped to reference signals having a low density compared to the PDCCH connected to the common search space. This is to improve channel estimation performance because the common search space contains important information that all terminals should see. In this case, the terminal may implicitly recognize the structure of the reference signal from the search space.

[ examples 1 to 3]

When supporting various DMRS structures (unlike the existing LTE system), embodiments 1-3 propose a method of supporting transmission between terminals (multi-users (MUs)) using different DMRS structures while maintaining orthogonality of the DMRSs. Even in the 5G system, the terminal performing MU transmission needs to use a structure of a specific reference signal to prevent the above-described problem. In this case, the flexibility of MU transmission may be limited. Therefore, when MU transmission is performed between terminals using different DMRS structures, two methods are proposed to maintain orthogonality between MU terminals.

The first approach is to perform rate matching on overlapping portions in order to maintain orthogonality when different DMRS structures overlap. The method will be described in detail with reference to fig. 11 and 12. Part a of fig. 11 and part b of fig. 11 illustrate a method in which a base station performs rate matching with respect to region a in part a of fig. 11 when terminals using different DMRS structures perform MU transmission.

This method has a disadvantage in that the base station should additionally signal information on rate matching to the terminal. The number of bits required for signaling may vary depending on the number of supported DMRS structures. Basically, when several DMRS structures are supported, the number of signaling bits required to inform DMRS structures of other MU terminals increases. However, when the DMRS structure is simplified to two or four types described in tables 1 to 4 and tables 1 to 5 in embodiments 1 to 2, signaling of one or two bits is sufficient to inform the terminal about the DMRS structures of other MU terminals. In addition, by considering rate matching of other terminals in reference signal regions where different DMRS structures overlap, there is an advantage that power boosting can be performed on the reference signal. However, unlike the LTE system, this method does not cause transparent MU operation for the terminal.

A second method is to insert additional reference signals in the reference signal regions where DMRS structures overlap to maintain orthogonality. That is, the second method is to set and transmit the same DMRS structure.

Referring to fig. 11 and 12, when a terminal using different DMRS structures as shown in part a of fig. 11 and part b of fig. 11 performs MU transmission, a base station inserts a reference signal in region a of part a of fig. 11. This means that a base station using the DMRS structure of part a of fig. 11 performs transmission by using the DMRS structure of part b of fig. 11. Unlike the first method, this method has an advantage that it does not require additional signaling to be transmitted to a terminal using part a of fig. 11.

On the other hand, based on part a of fig. 11, it may be changed depending on implementation whether the terminal will additionally use or not additionally use the reference signal included in the area a. If a terminal using part a of fig. 11 is a terminal requiring low delay, the reference signal of the area a may not be used for fast signal processing. However, in this case, additional signaling may be required to indicate this. For example, the base station transmits information on ACK/NACK timing to the terminal through DCI so that the terminal can determine whether to use the reference signal of region a based on part a of fig. 11.

Part a of fig. 12, part b of fig. 12, and part c of fig. 12 illustrate a method of changing DMRS density when a variable transmission time interval (variable TTI) is applied. Further, a method of maintaining orthogonality of DMRSs of MU terminals is proposed.

Specifically, part a of fig. 12 shows a case where several TTIs are combined and transmitted. In this case, it can be assumed that the same precoding is applied to the DMRS during transmission of several TTIs. In particular, when the TTI duration is short, it may be inefficient to transmit DMRSs having the same density in frequency as shown in part a of fig. 12 in terms of overhead of reference signals. Accordingly, examples of changing DMRS density are shown in part b of fig. 12 and part c of fig. 12 as a method of reducing reference signal overhead.

First, as shown in part b of fig. 12, a method of setting DMRSs to reduce the overhead of reference signals in TTI-1 and TTI-2 is possible. In another approach, as shown in part c of fig. 12, the DMRS may not be transmitted in TTI-2. Thus, in TTIs where DMRS density changes, orthogonality may not be maintained when different terminals use different DMRS structures for MU transmission. In this case, when different DMRS structures overlap, the above-described two methods of maintaining orthogonality may be applied.

Specifically, in case of applying the rate matching method, the base station signals rate matching information to the terminal by using DCI before every TTI. In contrast, in case of applying the second method, the base station can set the same DMRS structure to different terminals in TTI-2 without additional signaling, for example, as in the case of MU transmission in TTI-2 of part b of fig. 12 and part c of fig. 12. For example, the DMRS structure in TTI-1 may be transmitted in TTI-2.

Further, a method of efficiently supporting MUs of terminals using different OCC lengths is proposed. For example, a case where a terminal using an OCC of length 2 and an OCC of length 4 performs MU transmission is described. For example, when layer 2 transmission is performed using an OCC of length 4 based on tables 1-2, layer 2 transmission may be performed through

ports

7 and 11 or through

ports

8 and 13. This enables more orthogonal MU pairing compared to layer 2 transmission

methods using ports

7 and 8 or

ports

11 and 13.

As described above, based on the LTE system in tables 1-2, the numbering from port 7 to port 14 is an example for explanation. The port numbers used in 5G systems may be different from this. Thus, the above method may be applied based on the OCC sequence corresponding to each port in tables 1-2.

Fig. 13 and 14 show a terminal and a base station, respectively, each having a transmitter, a receiver and a processor for implementing the above-described embodiments of the present disclosure. The above-described 1-1 to 1-3 embodiments show transmission/reception methods for a base station and a terminal that configure a plurality of DMRS structures and perform a correlation operation. The receiver, processor and transmitter in each of the base station and terminal should operate in accordance with such embodiments.

Specifically, fig. 13 is a block diagram showing an internal structure of a terminal according to an embodiment of the present disclosure. As shown in fig. 11 and 12, a terminal of the present disclosure may include a terminal receiver 1800, a terminal transmitter 1804, and a terminal processor 1802. In an embodiment of the present disclosure, the terminal receiver 1800 and the terminal transmitter 1804 may be collectively referred to as a transceiver.

The transceiver may transmit and receive signals to and from a base station. These signals 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 signal to be transmitted, an RF receiver for low-noise amplifying a received signal and down-converting the frequency, and the like. Further, the transceiver may receive a signal through a radio channel, output the received signal to the terminal processor 1802, and transmit the signal output from the terminal processor 1802 through the radio channel.

The terminal processor 1802 may control the terminal to operate in accordance with the above-described embodiments of the present disclosure. For example, the terminal receiver 1800 may receive reference signals from base stations, and the terminal processor 1802 may control to interpret the method of analyzing the reference signals. Further, terminal transmitter 1804 may transmit reference signals in this manner.

Fig. 14 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure. As shown in fig. 13, the base station of the present disclosure may include a base station receiver 1901, a base station transmitter 1905, and a base station processor 1903. In an embodiment of the present disclosure, the base station receiver 1901 and the base station transmitter 1905 may be collectively referred to as a transceiver.

The transceiver can transmit signals to and receive signals from the terminal. These signals 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 signal to be transmitted, an RF receiver for low-noise amplifying a received signal and down-converting the frequency, and the like.

Further, the transceiver may receive a signal through a radio channel, output the received signal to the base station processor 1903, and transmit the signal output from the base station processor 1903 through the radio channel. The base station processor 1903 may control the base station to operate according to the above-described embodiments of the present disclosure. For example, the base station processor 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. Then, the base station transmitter 1905 may transmit the reference signal and the configuration information to the terminal, and the base station receiver 1901 may receive the reference signal.

Further, according to an embodiment of the present disclosure, the base station processor 1903 may control a process for supporting orthogonal MU transmission between terminals using different DMRS structures. In addition, information required for control may be transmitted to the terminal through the base station transmitter 1905.

While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it will be clearly understood that this is done by way of illustration only and is not intended to be limiting of the present disclosure. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure. Further, the disclosed embodiments may be implemented in combination as desired. For example, the 1 st-1 st, 1 st-2 nd and 1 st-3 rd embodiments of the present disclosure may be combined with each other, at least in part, for the operation of the base station and the terminal. Furthermore, although the above embodiments are presented based on the FDD LTE system, these embodiments or modifications thereof based on the same technical idea may be implemented in other systems such as the TDD LTE system, the 5G or NR system, and the like.

< second embodiment >

In a wireless communication system, a base station should transmit a reference signal for terminal channel estimation. Using the reference signal, the terminal can perform channel estimation and demodulate the received signal. In addition, the terminal can know the channel state through the reference signal and feed it back to the base station. In general, for transmission of a reference signal, a transmission interval of the reference signal based on frequency and time 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 becomes narrower, the channel estimation performance is improved, and thus the demodulation performance of the signal can be improved. However, this causes an increase in the overhead of the reference signal, thereby limiting the data transmission rate.

A typical 4G LTE system operating in a 2GHz band uses reference signals such as a cell-specific reference signal (CRS) and a demodulation reference signal (DMRS) in downlink. If the interval of the reference signal is represented in frequency by a subcarrier interval "m" of an Orthogonal Frequency Division Multiplexing (OFDM) signal and in time by a symbol interval "n" of the OFDM signal, the transmission interval (m, n) based on the frequency and time of the reference signal corresponding to

antenna ports

1 and 2 is (3, 4) in the case of a CRS employing a normal Cyclic Prefix (CP). Further, in case of the DMRS employing the normal CP, the transmission interval (m, n) based on the frequency and time of the reference signal is (5, 7).

Unlike the LTE system, the 5G wireless communication considers a system operating in a higher frequency band and a 6GHz or lower frequency band. Since the channel characteristics depend on the frequency band, the 5G system needs to redesign the reference signal in consideration of this point. Furthermore, 5G wireless communication importantly allows for support of low latency and high mobility, and it is important to minimize the overhead of reference signals.

In a wireless communication system, a base station should transmit a reference signal to a terminal in order to measure a downlink channel state. In case of an advanced long term evolution (LTE-a) system of 3GPP, a terminal measures a channel state between a base station and the terminal by using a CRS or a channel state information reference signal (CSI-RS) transmitted by the base station.

As the channel state, some factors such as the amount of interference in the downlink should be considered. The amount of interference in the downlink includes an interference signal and thermal noise caused by an antenna included in each neighboring base station, and plays an important role in determining the channel condition of the downlink.

For example, when one transmission antenna included in a certain base station transmits a signal to one reception antenna included in a certain terminal, the terminal should determine the energy of each symbol receivable through a downlink and the amount of interference to be received together with the symbol in the interval of receiving the symbol using a reference signal received from the base station, and then determine Es/Io. The determined Es/Io is converted into a data transmission rate or a corresponding value and notified to the base station in the form of a Channel Quality Indicator (CQI), so that the base station can determine a transmission rate of data transmission to the terminal in downlink.

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

In LTE/LTE-a, there are three types of Channel State Information (CSI) provided by the terminal as feedback, as shown below.

● Rank Indicator (RI): the number of spatial layers that the terminal can receive in the current channel state.

● Precoder Matrix Indicator (PMI): a precoding matrix indicator preferred by the terminal in a current channel state.

● Channel Quality Indicator (CQI): the maximum data rate that the terminal can receive in the current channel state. The CQI may be replaced by SINR, maximum error correction code rate and modulation scheme, data efficiency per frequency, etc., each of which may be used similarly to the maximum data rate.

RI, PMI and CQI are interrelated. For example, the precoding matrix supported by LTE/LTE-a is defined differently for each rank. Therefore, even if the values are the same, the PMI value when the RI value is 1 and the PMI value when the RI value is 2 are interpreted differently.

Further, the terminal determines the CQI based on the assumption that the rank value and PMI value notified to the base station by the terminal are applied to the base station. For example, when the terminal informs the base station of RI _ X, PMI _ Y and CQI _ Z, which means that when the rank is RI _ X and the precoding is PMI _ Y, the terminal may receive data according to a data rate corresponding to CQI _ Z. Therefore, when calculating the CQI, the terminal assumes a transmission scheme to be performed by the base station, so that when the base station actually performs transmission with the transmission scheme, optimal performance can be obtained.

In LTE/LTE-a, the periodic feedback of the terminal is set to one of the following four feedback modes according to the contained information:

1. report modes 1-0: RI, wideband CQI (wCQI)

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

3. Report modes 2-0: RI, wCQI, sub-band CQI (sCQI)

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

The feedback timing of each information of the above four feedback modes is determined by N transmitted via a higher layer signal _pd 、N _OFFSET,CQI 、M _RI 、N _OFFSET,RI Etc. are determined. In feedback mode 1-0, the transmission period of wCQI is N _pd One sub-frame and feedback timing with N _OFFSET,CQI Is determined. In addition, the transmission period of RI is N _pd ×M _RI One subframe with an offset of N _OFFSET,CQI +N _OFFSET,RI 。

FIG. 25 is a diagram showing that when N is _pd ＝2、M _RI ＝2、N _OFFSET,CQI 1 and N _OFFSET,RI Graph of feedback timing of RI and wCQI at-1. In fig. 25, each timing represents one subframe index.

The feedback mode 1-1 has the same feedback timing as the mode 1-0, but differs from the case of one antenna port, two antenna ports, or four antenna ports in that wCQI and PMI are transmitted together at wCQI transmission timing.

In feedback mode 2-0, the feedback period of sCQI is N _pd A subframe, offset value is N _OFFSET,CQI . Feedback period of wCQI is H multiplied by N _pd A sub-frame with an offset value of N _OFFSET,CQI As in the case of the offset value of the sccqi. Here, H is defined as H · J · K +1, K is transmitted via a higher layer signal, and J is a value determined according to the system bandwidth. For example, the J value of a 10MHz system is defined as 3. As a result, the wCQI is transmitted once every H transmission of the sCQI. The period of RI is M _RI ×H×N _pd One subframe with an offset of N _OFFSET,CQI +N _OFFSET,RI 。

FIG. 26 is a diagram showing a case when N _pd ＝2、M _RI ＝2、J＝3(10MHz)、K＝1、N _OFFSET,CQI 1 and N _OFFSET,RI Graph of feedback timing of RI, sccqi, and wCQI at-1. The feedback mode 2-1 has the same feedback timing as in the mode 2-0, but the difference is that the PMIs are transmitted together at the wCQI transmission timing with respect to the case of one antenna port, two antenna ports, or four antenna ports.

The above feedback timing is a case where the number of CSI-RS antenna ports is one, two, or four. As another example, in the case where the terminal is allocated for four or eight antenna ports CSI-RS, two pieces of PMI information are fed back, unlike the feedback timing. In this case, i.e., in the case where CSI-RSs for four or eight antenna ports are allocated to the terminal, the feedback mode 1-1 may be divided into two sub-modes.

For example, in the first sub-mode, RI is transmitted together with the first PMI information, and the second PMI information is transmitted together with the wCQI. Here, feedback periods and offsets of wCQI and the second PMIEach shift is defined as N _pd And N _OFFSET,CQI And a feedback period and an offset value of the RI and the first PMI information are respectively defined as M _RI ×N _pd And N _OFFSET,CQI +N _OFFSET,RI 。

If the first PMI (i1) and the second PMI (i2) are reported from the terminal to the base station, the terminal and the base station confirm that a precoding matrix W (i1, i2) corresponding to a combination of the first and second PMIs in a precoding matrix codebook shared with each other is a precoding matrix preferred by the terminal.

In other words, assuming that a precoding matrix corresponding to the first PMI is W1 and a precoding matrix corresponding to the second PMI is W2, the terminal and the base station share information that a precoding matrix preferred by the terminal is determined as a product of two matrices, W1W 2.

When the feedback pattern of the eight CSI-RS antenna ports is 2-1, Precoding Type Indicator (PTI) information is added to the feedback information. In this case, PTI is fed back together with RI with a period of M _RI ×H×N _pd A sub-frame and an offset defined as N _OFFSET,CQI +N _OFFSET,RI 。

Specifically, when the PTI is 0, the first PMI, the second PMI, and the wCQI are all fed back. In this case, wCQI and the second PMI are transmitted together at the same timing with a period of N _pd The offset is given as N _OFFSET,CQI . The period of the first PMI is H' × N _pd Offset is N _OFFSET,CQI . Here, H' is transmitted through a higher layer signal.

On the other hand, if the PTI is 1, wCQI is transmitted together with the second wideband PMI, and sccqi is fed back together with the second subband PMI at separate timing. In this case, the first PMI is not transmitted and then reported after the second PMI, and the CQI is calculated assuming the first PMI that is reported most recently with a PTI of 0. The period and offset of PTI and RI are the same as in the case where PTI is 0. The period of sCQI is defined as N _pd One sub-frame, offset is defined as N _OFFSET,CQI . wCQI and second PMI with period H × N _pd And offset N _OFFSET,CQI Fed together, and the number of H-like CSI-RS antenna ports is 2Are defined as such.

Part a of fig. 27 and part b of fig. 27 are graphs showing feedback timings in the case where PTI ═ 0 and PTI ═ 1, respectively, where N is _pd ＝2、M _RI ＝2、J＝3(10MHz)、K＝1、H’＝3、N _OFFSET,CQI 1 and N _OFFSET,RI ＝1。

LTE/LTE-a supports not only cyclic feedback but also aperiodic feedback for terminals. When the base station desires to acquire aperiodic feedback information of a specific terminal, the base station performs uplink data scheduling of the terminal by setting an aperiodic feedback indicator included in Downlink Control Information (DCI) for performing uplink data scheduling for the terminal to perform the specific aperiodic feedback.

If the terminal receives an indicator set to perform aperiodic feedback in the nth subframe, the terminal inserts aperiodic feedback information in data transmission of the (n + k) th subframe and performs uplink transmission. Here, the parameter k defined in the 3GPP LTE release 11 standard is 4 in the case of Frequency Division Duplex (FDD) and is defined as in table 2-1 in the case of Time Division Duplex (TDD). Table 2-1 shows k values for each subframe number n in the TDD UL/DL configuration.

[ Table 2-1]

If aperiodic feedback is set, the feedback information includes RI, PMI, and CQI as in the case of periodic feedback, and RI and PMI may not be fed back according to the feedback setting. The CQI may include both wCQI and sccqi or may include only wCQI information.

Unlike the LTE system, 5G wireless communication considers a system operating at a higher frequency band as well as a 6GHz or lower frequency band. Since the channel characteristics depend on the frequency band, the 5G system needs to redesign the reference signal in consideration of this point. Furthermore, 5G wireless communication importantly allows for support of low latency and high mobility, and it is important to minimize the overhead of reference signals. Therefore, unlike the LTE system, the 5G system can support a plurality of reference signals suitable for a transmission environment.

When many reference signals are supported, the terminal may need additional feedback information to select a reference signal suitable for a transmission environment as well as RI, PMI, and CQI. Accordingly, the present disclosure provides a method for a terminal to transmit feedback information necessary for selecting a reference signal to a base station to enable environment adaptive transmission of the reference signal.

Now, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although the embodiments of the present disclosure will be described below using an LTE or LTE-a system as an example, the embodiments may be applied to other communication systems having a similar technical background or channel form, for example, to a 5G (or New Radio (NR)) mobile communication technology that is being developed after LTE-a. Specifically, the method of periodic or aperiodic feedback of channel information may be different from the method in LTE described above. Although the present disclosure is described with reference to DMRS, the present disclosure may be applied to other reference signals. Thus, it will be apparent to those skilled in the art that embodiments of the present disclosure may be applied to other communication systems with some modifications without departing from the scope of the present disclosure.

Feedback information for selecting a reference signal suitable for a transmission environment to be described below is represented by the term Pilot Density Indicator (PDI). However, the term of PDI may be denoted as any other term depending on the user's intention and the intended use of the reference signal. For example, the PDI may be replaced with terms such as reference signal density indicator (RDI), Doppler Frequency Indicator (DFI), Delay Spread Indicator (DSI), or SINR Indicator (SI). In particular, the term PDI is merely a specific example provided to facilitate understanding of the present disclosure and is not intended to limit the scope of the present disclosure. That is, it is apparent to those skilled in the art that the embodiments of the present disclosure can be applied to any reference signal based on the subject matter of the present disclosure.

In the 2 nd-1 st embodiment of the present disclosure, feedback information that may be included in the PDI will be described. In embodiments 2-2 of the present disclosure, a feedback method of the PDI will be described. In embodiments 2 to 3 of the present disclosure, an operation method of a base station using a PDI will be described.

[ 2-1 example ]

In the 2 nd-1 th embodiment, information that can be included in the PDI, which is feedback information proposed in the present disclosure, will be described. As described above, several structures of reference signals required according to transmission environments can be supported.

In particular, in an environment where the degree of doppler effect is high, it is necessary to enhance the channel estimation performance by increasing the density of reference signals on the transmission time axis. On the other hand, in an environment where the degree of doppler effect is low (hereinafter, also referred to as low doppler), it is necessary to reduce the overhead of the reference signal by reducing the density of the reference signal on the transmission time axis. Further, in a high delay environment, it is necessary to improve channel estimation performance by increasing the density of reference signals on the transmission frequency axis. On the other hand, in a low delay environment, it is necessary to reduce the overhead of the reference signal by reducing the density of the reference signal on the transmission frequency axis. In addition, in a low SNR (signal to interference plus noise ratio) environment, in order to secure channel estimation performance, a structure having a high density of reference signals is required. In a high SNR environment, overhead needs to be reduced by reducing the density of reference signals.

The terminal can find all doppler information, channel delay information, and SINR information determining the reference signal structure through measurement. Therefore, in the PDI as feedback information proposed in the present disclosure, doppler information, channel delay information, and SINR information may be included. However, information that may be included in the PDI of the present disclosure is not limited to the above information.

The terminal can report information on a preferred reference signal structure in a channel environment by providing feedback of measured doppler information, channel delay information, and SINR information. In the present disclosure, the PDI may include all or some of doppler information, channel delay information, and SINR information.

Specifically, the following description describes which reference signal structure is suitable for a certain case based on information included in the PDI.

First, when the PDI includes doppler information, the terminal can determine the structure of a reference signal suitable for a channel environment by measuring a doppler frequency. For example, the terminal may measure the doppler frequency by performing time correlation based on the reference signal. If the doppler frequency (Hz) is greater than X, as shown in equation 1 below, it may indicate that a reference signal having a high density on the transmission time axis needs to be transmitted.

[ equation 1]

Doppler frequency > X

In equation 1, x (hz) represents a threshold value of the doppler frequency. Further, the doppler frequency may be expressed as doppler frequency ≈ f × v/c, where f is a carrier frequency (Hz), v (m/s) is a terminal velocity, and c is an optical velocity (≈ 3 × 10) ⁸ m/s). Therefore, it can be seen that the doppler frequency is affected by the carrier frequency and the velocity of the terminal.

For example, when f is 2.5GHz and v is 350km/h, the doppler frequency is 810 Hz. For example, when the doppler frequency is 800Hz or higher, which is considered as a high doppler environment, the threshold value X of the doppler frequency may be set to 800 Hz.

Unlike the LTE system, the 5G system considers terminal speeds up to 500 km/h. Therefore, the above-described method of adaptively changing the reference signal structure in consideration of the terminal speed may be very effective. In the present disclosure, when the doppler frequency is greater than X, a one-bit indicator may be fed back to indicate that a reference signal having a high density on the time axis needs to be transmitted, as shown in equation 1.

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

For example, the terminal may measure a Power Delay Profile (PDP) by performing correlation on frequencies based on a reference signal. From the PDP information, delay spread information, such as Root Mean Square (RMS) delay spread or maximum delay spread, may be obtained. If the delay spread (sec) is greater than Y, as shown in equation 2 below, it may indicate that a reference signal having a high density at the transmission frequency needs to be transmitted.

[ equation 2]

Delay spread > Y

In equation 2, y (sec) represents a threshold value of delay spread. Further, the delay spread may be an RMS delay spread or a maximum delay spread. If RMS delay spread is used as a reference, Y is set based on the RMS delay spread value and may be set differently based on the maximum delay spread value.

In general, reference signals in existing LTE systems are designed assuming the worst case of channel delay. Therefore, in a low channel delay environment, the transmission efficiency is improved using a reference signal having a lower density in frequency.

Further, the 5G system considers not only a band of 6GHz or less but also a band of higher, thereby considering various subcarrier spacings. Therefore, unlike the conventional LTE system, the density of the reference signals in frequency needs to be redesigned.

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

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

[ equation 3]

SINR>Z

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

In the present disclosure, when the SINR is greater than Z as in equation 3, a one-bit indicator may be fed back to indicate that it is preferable to have a high density of reference signals. However, in equation 3, the SINR may be replaced with a CQI index or a maximum error correction code rate and modulation scheme, data efficiency per frequency, etc., as defined in table 7.2.3-1 of 3GPP LTE standard ts.36.213.

If the SINR is replaced by the CQI index in equation 3, there is an advantage in that the structure information of the reference signal can be implicitly fed back through CQI feedback without using additional bits. In one embodiment, in case of feeding back the lowest CQI index, it may be indicated that reference signals with high density are preferred.

In the 2-1 embodiment, some types of information included in the PDI as feedback information proposed by the present disclosure are described by equations 1 to 3, and a method of determining which reference signal structure is preferred by a terminal, i.e., which reference signal structure needs to be transmitted in the current case, through each type of information included in the PDI. According to this case, information required for the terminal to feed back to the base station may be set with 1 to 3 bits.

However, in case that several thresholds are set in equations 1 to 3 as necessary, the reference signal structure preferred by the terminal may be further subdivided according to the thresholds. In this case, the number of information bits required for the terminal to feed back to the base station can be increased.

For example, if two thresholds X1 and X2 of the doppler frequency are set as shown in equation 4, the reference signal structure preferred by the terminal can be classified into three types.

[ equation 4]

Doppler frequency > X1 (4-1)

X2 Doppler frequency X1 (4-2)

Doppler frequency < X2 (4-3)

When there are three reference signal structures according to the density on the transmission time axis in equation 4, equation 4-1 indicates that the reference signal having the highest density on the transmission time axis is preferable, equation 4-2 indicates that the reference signal having the medium density on the transmission time axis is preferable, and equation 4-3 indicates that the reference signal having the low density on the transmission time axis is preferable. This method can also be applied to

equations

2 and 3.

[ examples 2 to 2]

In the 2 nd-2 nd embodiment, a method in which a terminal feeds back a Pilot Density Indicator (PDI), which is feedback information proposed by the present disclosure, to a base station will be described. Considering the case where the PDI is fed back together with the RI, PMI, and CQI, which are channel state information fed back to the base station by the terminal in LTE/LTE-a.

First, in case of using aperiodic feedback, the base station can perform uplink data scheduling for the terminal to perform PDI feedback by setting an aperiodic feedback indicator included in downlink control information, thereby inserting PDI information in uplink data of the terminal.

Next, consider the case of using aperiodic feedback. In the case of aperiodic feedback, the number of bits available for feedback may be limited. Thus, by using equations 1 through 3 of the 2-1 embodiment described above, the information required for feedback can be limited to 1 through 3 bits. Based on CQI feedback of the LTE system, the PDI feedback method proposed by the present disclosure may be classified as follows.

1. Wideband CQI (wCQI) -based feedback

2. Subband CQI (sCQI) -based feedback

3. Separate feedback for wCQI and sCQI

Based on the assumption of fig. 25, part a of fig. 28 shows a case of feedback based on wCQI in the PDI feedback method described above. Part a of fig. 28 shows that PDIs are transmitted together whenever wCQI is fed back. In this case, a reference signal suitable for a channel state may be determined based on the entire frequency band.

Based on the assumption of fig. 26, part b of fig. 28 shows a case of feedback based on the sCQI in the PDI feedback method described above. In this case, a reference signal suitable for a channel state may be determined based on the subband.

Based on the assumption of fig. 26, part c of fig. 28 shows a case where PDI feedback is performed for wCQI and sCQI, respectively. In this case, the reference signal suitable for the channel state may be determined based on the wideband or the subband.

[ examples 2 to 2]

In the 2 nd-2 nd embodiment, an operation of the base station when the PDI as the feedback information proposed in the present disclosure is fed back from the terminal to the base station will be described. As shown in table 2-2 or table 2-3 below, the base station can distinguish which environment the supportable reference signal is suitable for.

Table 2-2 shows the case of operating the structure of the reference signal in two types, and table 2-3 shows the case of operating the structure of the reference signal in four types. For example, if two structures of reference signals are supportable, an environment suitable for each of the two reference signals can be known through table 2-2.

[ tables 2-2]

RS Density	Situation of use
		Low density	Low delay/low Doppler/low delay/high SINR
High density	High Doppler/high delay/low SINR

As another example, when there are four supportable reference signal structures, the environment suitable for each reference signal can be known through tables 2 to 3.

[ tables 2 to 3]

To represent	RS Density	Situation of use
			‘00’	Low density 1	Low delay/low Doppler
‘01’	Low density 2	Low delay/high SINR
			‘10’	Medium density	Medium SINR
‘11’	High density	High Doppler/high delay/low SINR

Specifically, the structure of the reference signals of tables 2-3 is shown in fig. 29. When a low delay or a low doppler environment is required for a transmission environment, a structure of a reference signal having a low density on a time axis may be used, as shown in part a of fig. 29. In contrast, when the transmission environment is a low delay environment, a structure having a low density of reference signals in frequency may be used, as shown in part b of fig. 29. On the other hand, in a high delay environment, a structure having a high density of reference signals in frequency may be used, as shown in part c of fig. 29. In a high doppler environment or a low SINR environment, a structure having a high density of reference signals may be used, as shown in part d of fig. 29.

In other words, it can be explained as follows. The structure of part a of fig. 29 shows the structure of a reference signal corresponding to low delay/low doppler. The structure of part b of fig. 29 shows the structure of the reference signal corresponding to low delay/high SINR. The structure of part c of fig. 29 shows the structure of a reference signal corresponding to high delay/high SINR. The structure of part d of fig. 29 shows the structure of the reference signal corresponding to high doppler/low SINR.

In embodiments 2 to 3, a method of determining a structure of a reference signal suitable for a current environment when a base station receives a PDI, which is feedback information proposed by the present disclosure, from a terminal is described. However, as described above, the method of determining the structure of the reference signal suitable for the transmission environment through the PDI reception may vary according to the structure of the reference signal supported by the base station.

[ examples 2 to 4]

In the present disclosure, a method of feeding back information on a terminal-preferred reference signal when several reference signals are supported has been proposed. In embodiments 2-4, when there are several supportable reference signals, a method of setting the type or number of reference signals supportable by a specific terminal through UE capability is proposed.

Specifically, the base station may inform the terminal of the type of the settable reference signal through UE capability signaling, and the terminal may feed back information on the reference signal preferred by the terminal from the settable reference signal type. Since the base station informs the terminal of the types of the settable reference signals through UE capability signaling, there is an advantage in that the terminal can easily select a preferred reference signal from the types of the settable reference signals.

For example, the type or number of settable reference signal structures may vary according to the slot structure. Specifically, different types of reference signals may be used for a structure using 14 symbols as one slot and a structure using 7 symbols as one slot. Further, in the structure of the micro slot, a structure or type of the reference signal different from the above-described slot structure may be used.

Furthermore, with respect to a terminal, the types of available reference signals may be limited depending on the terminal implementation. In particular, in the case of a specific terminal in which a channel estimation method of a reference signal is limited, not all reference signal structures are supported.

Therefore, as with the above-described method, in an environment supporting various reference signals, a method is required in which the base station notifies the terminal of the types of the settable reference signals through UE capability signaling, and the terminal selects a preferred reference signal from among the available reference signal types. Here, the UE capability signaling may be provided in Radio Resource Control (RRC) signaling, which is a higher layer signal.

Fig. 30 and 31 show a terminal and a base station, respectively, having a transmitter, a receiver and a processor, respectively, for implementing the above-described embodiments of the present disclosure. The above-described 2-1 to 2-3 embodiments illustrate methods for a base station and a terminal to transmit or receive a Pilot Density Indicator (PDI), which is feedback information proposed therein. The receiver, processor and transmitter in each of the base station and terminal should operate in accordance with such embodiments.

Specifically, fig. 30 is a block diagram showing an internal structure of a terminal according to an embodiment of the present disclosure. As shown in fig. 30, a terminal of the present disclosure may include a terminal receiver 1800, a terminal transmitter 1804, and a terminal processor 1802.

In an embodiment of the present disclosure, the terminal receiver 1800 and the terminal transmitter 1804 may be collectively referred to as a transceiver. The transceiver may transmit and receive signals to and from a base station. These signals 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 signal to be transmitted, an RF receiver for low-noise amplifying a received signal and down-converting the frequency, and the like.

Further, the transceiver may receive a signal through a radio channel, output the received signal to the terminal processor 1802, and transmit the signal output from the terminal processor 1802 through the radio channel.

The terminal processor 1802 may control the terminal to operate in accordance with the above-described embodiments of the present disclosure. For example, the terminal processor 1802 measures and interprets information that may be included in the PDI. Further, terminal processor 1802 can control terminal transmitter 1804 to transmit the PDI information to the base station. Further, according to one embodiment, the terminal processor 1802 may periodically or aperiodically determine and control the transmission timing of the PDIs.

Fig. 31 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure. As shown in fig. 31, the base station of the present disclosure may include a base station receiver 1901, a base station transmitter 1905, and a base station processor 1903. In an embodiment of the present disclosure, the base station receiver 1901 and the base station transmitter 1905 may be collectively referred to as a transceiver.

Further, the transceiver may receive a signal through a radio channel, output the received signal to the base station processor 1903, and transmit the signal output from the base station processor 1903 through the radio channel.

The base station processor 1903 may control the base station to operate according to the above-described embodiments of the present disclosure. For example, the base station receiver 1901 receives PDI fed back by the terminal. The base station processor 1903 may analyze PDI information received from the terminal and determine which reference signal structure is suitable for a transmission environment. Then, the base station processor 1903 controls the base station transmitter 1905 to transmit a reference signal corresponding to the reference signal structure selected based on the PDI. Further, according to an embodiment of the present disclosure, the base station processor 1903 may perform and control setting for receiving PDI periodically or aperiodically.

While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure.

Furthermore, the disclosed embodiments can be implemented in combination as desired. For example, the 2-1, 2-2, and 2-3 embodiments of the present disclosure may be combined, at least in part, with each other for operation of the base station and the terminal. Further, although the above embodiments are presented based on the FDD LTE system, these embodiments or modifications thereof based on the same technical idea may be implemented in other systems such as the TDD LTE system, the 5G or NR system, and the like.

< third embodiment >

In a wireless communication system, particularly in a conventional LTE system, hybrid automatic repeat request (HARQ) Acknowledgement (ACK) or Negative Acknowledgement (NACK) information indicating success or failure of data transmission is transmitted to a base station on an uplink 3ms after reception of downlink data. For example, in response to a Physical Downlink Shared Channel (PDSCH) received from the base station to the terminal in subframe n, HARQ ACK/NACK information is transmitted to the base station through a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH) in subframe n + 4.

Also, in a frequency division duplex (LTE) system, a base station may transmit Downlink Control Information (DCI) including uplink resource allocation information to a terminal or request retransmission through a physical hybrid ARQ indicator channel (PHICH). When the terminal receives such uplink data transmission schedule in subframe n, the terminal performs uplink data transmission, i.e., PUSCH transmission, in subframe n + 4. This example is the case 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 an uplink-downlink subframe configuration performed according to a predetermined rule.

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

In order to meet the increasing demand for radio data services after commercialization of 4G communication systems, efforts have been made to develop advanced 5G communication systems or pre-5G communication systems. Therefore, the 5G communication system or the pre-5G communication system is also referred to as a super 4G network communication system or a post-LTE system.

In order to achieve higher data transfer rates, it is being considered to implement a 5G communication system on an ultra high frequency (millimeter wave) band (e.g., such as a 60GHz band). In order to avoid propagation loss of radio waves and increase transmission distance of radio waves in the ultra high frequency band, various techniques for 5G communication systems, such as beam forming, massive MIMO, full-dimensional MIMO (FD-MIMO), array antenna, analog beam forming, and massive antenna, are under discussion.

In addition, in order to improve the 5G communication system, technological development is being performed in terms of advanced small cells, cloud radio access networks (cloud RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, mobile networks, cooperative communication, coordinated multipoint (CoMP), reception-side interference cancellation, and the like.

Further, in the 5G communication system, hybrid FSK and QAM modulation (FQAM) and Sliding Window Superposition Coding (SWSC) have been developed as Advanced Coding Modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and Sparse Code Multiple Access (SCMA) have also been developed as advanced access techniques.

Meanwhile, the internet, which is a human-centric connected network in which humans generate and consume information, is now evolving towards the internet of things (IoT) where distributed entities, such as things, exchange and process information without human intervention. Furthermore, internet of everything (IOE) has emerged, which is a combination of IoT technology and big data processing technology through a connection with a cloud server. As IoT implementations require technical elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology, sensor networks, machine-to-machine (M2M) communication, Machine Type Communication (MTC), etc. have recently been studied.

The IoT environment can provide intelligent Internet technology services, and creates new value for human life by collecting and analyzing data generated among interconnected things. IoT can be applied to various fields including smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart appliances, advanced medical services, etc. through the fusion and combination of existing Information Technology (IT) and various industrial applications.

In line with this, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor networks, Machine Type Communication (MTC), and machine-to-machine (M2M) communication are being implemented based on 5G communication technologies such as beamforming, MIMO, and array antennas. Using a cloud radio access network (cloud RAN) for big data processing technology is one example of a convergence of 5G technology and IoT technology.

In this way, a variety of services may be provided to users in the communication system. To this end, a method and apparatus for providing each service in the same time interval according to service characteristics.

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

It will be understood that each block of the flowchart illustrations, and combinations of blocks in the flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart block or blocks. These computer program instructions may also be stored in a computer usable or computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer usable or computer-readable memory produce an article of manufacture including instruction means that implement the function specified in the flowchart block or blocks. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks.

Further, each block of the flowchart illustrations may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of order. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

The term "unit" as used herein may refer to a software or hardware component or device, such as a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC), which performs certain tasks. A unit may be configured to reside on the addressable storage medium and configured to execute on one or more processors. Thus, a module or unit may include, by way of example, components such as software components, object-oriented software components, class components and task components, procedures, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functionality provided for in the components and units may be combined into fewer components and units or further separated into additional components and modules. Further, the components and units may be implemented as one or more Central Processing Units (CPUs) in an operating device or a secure multimedia card. Further, in an embodiment, the means may comprise one or more processors.

In a wireless communication system including the fifth generation, a terminal may be provided with at least one of enhanced mobile broadband (eMBB), large-scale machine type communication (mtc), and ultra-reliable and low-latency communication (URLLC). These services may be provided to the same terminal in the same time interval. In non-limiting embodiments, the eMBB may be a service for high-speed transmission of high-capacity data, the mtc may be a service for terminal power minimization and multi-terminal access, and the URLLC may be a service for high reliability and low latency. The three services described above may be the main scenarios in LTE systems or 5G/NR (new radio, next radio) systems after LTE. In embodiments, methods and apparatus for eMBB and URLLC coexistence or mtc and URLLC coexistence will be described.

When the base station has scheduled data corresponding to the eMBB service to the terminal in a specific Transmission Time Interval (TTI), and when a situation occurs in which URLLC data must be transmitted in the above TTI, the URLLC data may be transmitted without transmitting a part of the eMBB data in a frequency band in which the eMBB data is scheduled to be transmitted. In this case, the terminal scheduled for the eMBB and the terminal scheduled for the URLLC may be the same terminal or different terminals.

In this case, since a part of the already scheduled eMBB data is not transmitted, there is a possibility that the eMBB data is damaged. In this case, a method of receiving signals and processing the received signals at a terminal scheduled for the eMBB or a terminal scheduled for the URLLC is required.

Therefore, in the embodiment of the present disclosure, when information according to the eMBB and the URLLC is simultaneously scheduled by sharing some or all frequency bands, when information according to the mtc and the URLLC is simultaneously scheduled, when information according to the mtc and the eMBB is simultaneously scheduled, or when information according to the eMBB, the URLLC, and the mtc is simultaneously scheduled, a method of coexistence between heterogeneous services by transmitting information according to each service will be described.

Hereinafter, a Base Station (BS), which is an entity that allocates resources to a terminal, may be at least one of an eNode B, a Node B, a radio access unit, a base station controller, or a Node on a network. A 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 communication functions.

In the present disclosure, Downlink (DL) refers to a wireless transmission path of a signal transmitted from a base station to a terminal, and Uplink (UL) refers to a wireless transmission path of a signal transmitted from a terminal to a base station. Although the embodiments of the present disclosure will be described below using an LTE or LTE-a system as an example, the embodiments may be applied to other communication systems having a similar technical background or channel form, for example, to a 5G (or New Radio (NR)) mobile communication technology that is being developed after LTE-a. Further, it will be apparent to those skilled in the art that embodiments of the present disclosure may be applied to other communication systems with some modifications without departing from the scope of the present disclosure.

The LTE/LTE-a system is a representative example of a broadband wireless communication system, and employs an Orthogonal Frequency Division Multiplexing (OFDM) scheme in a Downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme in an Uplink (UL).

The uplink refers to a radio link used by a terminal (also referred to as a User Equipment (UE) or a Mobile Station (MS)) to transmit data or control signals to a base station (BS, also referred to as an eNode B or an eNB), and the downlink refers to a radio link used by a base station to transmit data or control signals to a terminal. The multiple access scheme as described above distinguishes data or control information of each user by allocating and operating time-frequency resources such that the time-frequency resources for carrying data or control information do not overlap with respect to the respective users, i.e., orthogonality is established.

The LTE system employs a hybrid automatic repeat request (HARQ) scheme in which, when a decoding failure occurs in initial transmission, a physical layer retransmits corresponding data. In the HARQ scheme, if a receiver fails to correctly decode data, the receiver transmits information indicating a decoding failure (i.e., Negative Acknowledgement (NACK)) to a transmitter so that the transmitter can retransmit the corresponding data in a physical layer. The receiver combines the data retransmitted by the transmitter with the previously decoded data to improve data reception performance. Further, when data is correctly decoded, the receiver sends information indicating successful decoding (i.e., Acknowledgement (ACK)) to the transmitter so that the transmitter can send new data.

Fig. 32 is a diagram showing a basic structure of a time-frequency domain of a radio resource region transmitted as a data or control channel in the downlink of an LTE system or the like.

In fig. 32, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is an OFDM symbol. N is a radical of _symb One OFDM symbol 102 constitutes one slot 106, and two slots constitute one subframe 105. The length of the slot is 0.5ms and the length of the subframe is 1.0 ms. Further, the radio frame 114 is a time domain portion composed of ten subframes. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is composed of N in total _BW A number of subcarriers 104. However, such specific values may be variably applied.

Generally, the minimum transmission unit of data is an RB unit. In LTE system, N _symb Is 7, N _RB Is 12, N _BW And N _RB Proportional to the bandwidth of the system transmission band. The data transmission rate increases in proportion to the number of RBs scheduled to the terminal. The LTE system defines and operates six transmission bandwidths. In the case of an FDD system in which the downlink and uplink are separated by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth may be different from each other. The channel bandwidth denotes a Radio Frequency (RF) bandwidth corresponding to a system transmission bandwidth.

Table 3-1 shows the relationship between the system transmission bandwidth and the channel bandwidth defined in the LTE system. For example, the LTE system having a channel bandwidth of 10MHz has a transmission bandwidth formed of 50 RBs.

[ Table 3-1]

The downlink control information is transmitted within the first N OFDM symbols in the subframe. Typically, N ═ {1, 2, 3 }. Thus, for each subframe, the value of N varies according to the amount of control information to be transmitted in the current subframe. The control information includes a control channel transmission interval indicator indicating how many OFDM symbols are used to transmit the control information, scheduling information of downlink data or uplink data, an HARQ ACK/NACK signal, and the like.

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

Resource allocation type 0/1 flag: this informs whether the resource allocation type is type 0 or type 1. Type 0 is to allocate resources in units of Resource Block Groups (RBGs) by applying a bitmap method. In the LTE system, a basic scheduling unit is an RB represented by time and frequency domain resources, and an RBG composed of a plurality of RBs becomes a basic scheduling unit in type 0. Type 1 allocates a specific RB in the RBG.

-resource block allocation: this informs the RB allocated to data transmission. The resources to be represented are determined according to the system bandwidth and the resource allocation type.

Modulation and Coding Scheme (MCS): this indicates a modulation scheme used for data transmission and a size of a transport block as data to be transmitted.

-HARQ process number: this indicates the HARQ process number.

-new data indicator: this indicates whether the HARQ transmission is an initial transmission or a retransmission.

-redundancy version: this represents a redundancy version of HARQ.

-Transmit Power Control (TPC) commands of the Physical Uplink Control Channel (PUCCH): this represents the TPC command of the PUCCH as an uplink control channel.

After being processed by channel coding and modulation, DCI is transmitted through a Physical Downlink Control Channel (PDCCH) (hereinafter, also referred to as control information) or an enhanced PDCCH (epdcch) (hereinafter, also referred to as enhanced control information).

In general, DCI is scrambled with a specific Radio Network Temporary Identifier (RNTI) (or terminal identifier) independently for each terminal, and Cyclic Redundancy Check (CRC) is added and channel-coded. Then, each DCI is configured as an independent PDCCH and transmitted. In the time domain, the PDCCH is mapped and transmitted during a control channel transmission interval. The frequency domain mapping position of the PDCCH is determined by an Identifier (ID) of each terminal and is extended to the entire system transmission band.

Downlink data is transmitted through a Physical Downlink Shared Channel (PDSCH), which is a physical channel for downlink data transmission. The PDSCH is transmitted after the control channel transmission interval. Scheduling information, such as a specific mapping position in a frequency domain, a modulation scheme, etc., is determined based on DCI transmitted through the PDCCH.

The base station notifies the terminal of a modulation scheme applied to the PDSCH to be transmitted and a data size (transport block size (TBS)) to be transmitted through the MCS in the control information constituting the DCI. In embodiments, the MCS may be formed of 5 bits or more or less. 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.

The modulation schemes supported by the LTE system are Quadrature Phase Shift Keying (QPSK), 16 quadrature amplitude modulation (16QAM), and 64QAM, and the respective modulation orders correspond to 2, 4, and 6. That is, 2 bits are transmitted per symbol for QPSK modulation, 4 bits are transmitted per symbol for 16QAM modulation, and 6 bits are transmitted per symbol for 64QAM modulation. Furthermore, other modulation schemes beyond 256QAM may be used, depending on system modifications.

Fig. 33 is a diagram showing a basic structure of a time-frequency domain of a radio resource region transmitted as a data or control channel in an uplink of an LTE-a system.

In fig. 33, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The smallest transmission unit in the time domain is an SC-FDMA symbol 202. N is a radical of _symb ^UL One SC-FDMA symbol constitutes one slot 206, and two slots constitute one subframe 205. The minimum transmission unit in the frequency domain is a subcarrier, and the entire system transmission bandwidth 204 is composed of N in total _BW One subcarrier. N is a radical of _BW Is proportional to the system transmission band.

In the time-frequency domain, a basic unit of resources is a Resource Element (RE)212, which may be defined by an SC-FDMA symbol index and a subcarrier index. Resource Block (RB) pairs 208 are defined as consecutive N in the time domain _symb ^UL One SC-FDMA symbol and consecutive N in frequency domain _SC ^RB And (4) a subcarrier. Thus, one RB is formed by N _symb ^UL ×N _SC ^RB And RE. Generally, the minimum transmission unit of data or control information is an RB unit. In case of PUCCH, it is mapped to a frequency region corresponding to 1RB and transmitted during one subframe.

In the LTE system, a timing relationship between a PDSCH or a PDCCH/EPDDCH including a semi-persistent scheduling release (SPS release) as a physical channel for downlink data transmission and a PUCCH or PUSCH as an uplink physical channel for transmitting a corresponding HARQ ACK/NACK is defined. For example, in an LTE system operating with Frequency Division Duplex (FDD), HARQ ACK/NACK corresponding to PDSCH or PDCCH/EPDCCH including SPS release transmitted in the n-4 th subframe is transmitted as PUCCH or PUSCH in the n-th subframe.

In the LTE system, the downlink HARQ employs an asynchronous HARQ scheme in which a data retransmission time point is not fixed. That is, when the base station receives HARQ NACK from the terminal as feedback for the initial transmission data, the base station freely determines a transmission time point of retransmission data through a scheduling operation. The terminal decodes the received data for the HARQ operation, buffers the data determined to be erroneous, and then performs a combination with the retransmission data.

The HARQ ACK/NACK information of the PDSCH transmitted in subframe n-k is transmitted from the terminal to the base station via the PUCCH or PUSCH in subframe n. Here, k is defined differently according to FDD or TDD of the LTE system and subframe setting thereof.

For example, in the case of the FDD LTE system, k is fixed to 4. On the other hand, in case of the TDD LTE system, k may vary according to subframe settings and subframe numbers. Also, in case of data transmission through a plurality of carriers, the k value may be differently applied according to the TDD configuration of each carrier. In case of TDD, the k value is determined according to TDD UL/DL configuration, as shown in Table 3-2 below.

[ tables 3-2]

In the LTE system, unlike the downlink HARQ, the uplink HARQ employs a synchronous HARQ scheme in which a data transmission time point is fixed. That is, an uplink/downlink timing relationship among a Physical Uplink Shared Channel (PUSCH), which is a physical channel for uplink data transmission, a downlink control channel (PDCCH) preceding the PUSCH, and a Physical Hybrid Indicator Channel (PHICH), which is a physical channel for transmitting downlink HARQ ACK/NACK corresponding to the PUSCH, may be transmitted and received according to the following rule.

When receiving a PDCCH including uplink scheduling control information or a PHICH for transmitting downlink HARQ ACK/NACK from the base station in subframe n, the terminal transmits uplink data corresponding to the control information in subframe n + k through a PUSCH. Here, k is defined differently according to FDD or TDD of the LTE system and its setting. For example, in the case of the FDD LTE system, k is fixed to 4. On the other hand, in case of the TDD LTE system, k may vary according to subframe settings and subframe numbers. In addition, in case of data transmission through a plurality of carriers, the k value may be differently applied according to the TDD configuration of each carrier. In the case of TDD, the k value is determined according to TDD UL/DL configuration, as shown in Table 3-3 below.

[ tables 3 to 3]

Meanwhile, HARQ-ACK information of the PHICH transmitted in subframe i is related to a PUSCH transmitted in subframe i-k. In case of an FDD system, k is given as 4. That is, HARQ-ACK information of the PHICH transmitted in subframe i in the FDD system is related to the PUSCH transmitted in subframe i-4. In case of a TDD system, if a terminal without enhanced interference mitigation and service adaptation (EIMTA) configuration is configured for only one serving cell or has the same TDD UL/DL configuration, the value of k may be given as shown in tables 3-4 when the TDD UL/DL configuration is 1 to 6.

[ tables 3 to 4]

That is, for example, in TDD UL/DL configuration 1, the PHICH transmitted in subframe 6 may be HARQ-ACK information of PUSCH transmitted in subframe 2, subframe 2 being four subframes earlier than subframe 6.

In case of TDD UL/DL configuration 0, if corresponding to I _PHICH The PUSCH indicated by the HARQ-ACK information is transmitted in subframes i-k, and the value of k is given according to tables 3-4, if HARQ-ACK is received in PHICH resource of 0. Further, in case of TDD UL/DL configuration 0, if corresponding to I _PHICH When HARQ-ACK is received in PHICH resource of 1, PUSCH indicated by HARQ-ACK information is transmitted in subframe i-6.

The description of the wireless communication system is based on the LTE system, but the present disclosure is not limited to the LTE system and can be applied to various wireless communication systems such as NR and 5G. Further, in the case of being applied to other wireless communication systems, the value may be changed even in a system using a modulation scheme corresponding to FDD.

Fig. 34 and 35 show data of eMBB, URLLC, and mtc allocated in frequency-time resources, which are services considered in a 5G or NR system.

Referring to fig. 34 and 35, frequency and time resources are allocated for information transmission in each system.

First, fig. 34 shows data of eMBB, URLLC, and mtc allocated in the entire system frequency band 300. If

URLLC data

303, 305, and 307 are generated and need to be transmitted while eMBB 301 and mtc 309 are allocated and transmitted in a particular frequency band, the already allocated portions of eMBB 301 and mtc 309 may be emptied, or

URLLC data

303, 305, and 307 may be transmitted without transmitting eMBB 301 and mtc 309.

Since URLLC needs to reduce delay time,

URLLC data

303, 305, and 307 may be allocated to the portion of the resource to which the eMBB 301 is allocated. Of course, when URLLC is further allocated and transmitted in resources to which eMBB is allocated, eMBB data may not be transmitted in overlapping frequency-time resources, and thus transmission performance of eMBB data may be degraded. That is, in the above case, a failure in the eMBB data transmission may occur due to URLLC allocation.

In fig. 35, the entire system frequency band 400 may be divided into

sub-bands

402, 404, and 406, each of which may be used to transmit services and data. Information related to the configuration of such a subband may be predetermined or transmitted to the terminal by the base station through upper layer signaling.

Alternatively, the base station or network node may arbitrarily configure the subbands and provide service to the terminal without separately transmitting subband configuration information. In fig. 35, subband 402 is used for eMBB data transmission, subband 404 is used for URLLC data transmission, and subband 406 is used for mtc data transmission.

In an embodiment, the length of the Transmission Time Interval (TTI) used in URLLC transmissions may be shorter than the TTI length used in eMBB or mtc transmissions. Further, an information response related to URLLC can be transmitted faster than eMBB or mtc, so that information can be transmitted and received with low delay.

Fig. 36 is a diagram illustrating a structure of dividing one transport block into several code blocks and adding CRC according to an embodiment.

Referring to fig. 36, a Cyclic Redundancy Check (CRC)503 may be added to the last or first portion of one Transport Block (TB)501 to be transmitted in uplink or downlink. The CRC may have 16 bits, 24 bits, a predetermined number of bits, or a variable number of bits depending on channel conditions, and may be used to determine whether the channel coding is successful.

The TB 501 to which the CRC 503 is added may be divided (505) into a plurality of Code Blocks (CBs) 507, 509, 511, and 513. The code blocks may have a predetermined maximum size. In this case, the last code block 513 may be smaller than other code blocks or may be adjusted to have the same length by adding 0, 1, or a random value.

CRCs

517, 519, 521, and 523 may be respectively added (515) to the divided code blocks. The CRC may have 16 bits, 24 bits, or a predetermined number of bits, and may be used to determine whether the channel coding was successful. However, the CRC 503 added to the TB and the

CRCs

517, 519, 521, and 523 added to the code block may be omitted according to the type of channel code to be applied to the code block. For example, when a Low Density Parity Check (LDPC) code is applied to code blocks instead of a turbo code,

CRCs

517, 519, 521, and 523 to be inserted into the respective code blocks may be omitted. Alternatively,

CRCs

517, 519, 521, and 523 may be added to code blocks even when LDPC is applied. Further, when a polar code is used, such a CRC may be added or omitted.

Fig. 37 is a diagram showing a transmission scheme using an external code, and fig. 38 is a block diagram showing a configuration of a communication system using an external code.

Referring to fig. 37 and 38, a method of transmitting a signal by using an outer code is as follows.

In fig. 37, a transport block is divided into code blocks, and bits or symbols 604 located at the same positions in the respective code blocks are encoded with a second channel code to generate (602) parity bits or symbols 606. Thereafter, CRCs may be added to the respective code blocks and parity code blocks generated by encoding with the second channel code, respectively (608, 610). Whether or not CRC is added may be determined according to the type of channel code. For example, if a turbo code is used as the first channel code,

CRCs

608 and 610 are added, but then the corresponding code blocks and parity code blocks may be encoded with the first channel code.

When the outer code is used, 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 code, a Raptor code, or a parity-check bit generation code. The bits or symbols passed through the second channel coding encoder 709 pass through the first channel coding encoder 711. The channel codes for the first channel coding include convolutional codes, LDPC codes, turbo codes, and polar codes.

When the receiver receives the channel-encoded symbols through the channel 713, the receiver may sequentially operate the first channel codec 715 and the second channel codec 717 based on the received signal. The first channel codec 715 and the second channel codec 717 may perform operations corresponding to the first channel codec 711 and the second channel codec 709, respectively.

On the other hand, in the case where the outer code is not used, only the first channel codec 711 and the first channel codec 705 are used in the transmitter and the receiver, respectively, and the second channel codec are not used. Even when the outer code is not used, the first channel codec 711 and the first channel codec 705 may be configured in the same manner as the case of using the outer code.

Hereinafter, the eMBB service will be referred to as a first type service, and the eMBB data will be referred to as first type data. The first type service or the first type data is not limited to the eMBB, and may be applicable to a case where high-speed data transmission is required or broadband transmission is performed. Further, the URLLC service will be referred to as a second type service, and URLLC data will be referred to as second type data. The second type of service or second type of data is not limited to URLLC and may be applicable in situations where low latency or high reliability transmission is required, or in other systems where low latency and high reliability are required.

Further, the mtc service will be referred to as a third type service, and the mtc data will be referred to as a third type data. The third type service or the third type data is not limited to mtc, and may be applied to a case where low speed, wide coverage, or low power is required. Further, in describing the embodiments, it will be understood that the first type of service may or may not include the third type of service.

The structure for each type of physical layer channel in order to transmit the above three services or data may be different. For example, at least one of a Transmission Time Interval (TTI) length, a frequency resource allocation unit, a control channel structure, and a data mapping method may be different.

Although three services and three data are described above, there may be more types of services and corresponding data. Even in this case, the present disclosure can be applied.

To describe the methods and apparatuses proposed in the embodiments, the terms physical channel and signal used in the conventional LTE or LTE-a system may be used. However, the present disclosure may be applied to wireless communication systems other than LTE and LTE-a systems.

In an embodiment, transmission and reception operations of a terminal and a base station are defined to transmit first, second and third types of services or data, and a method for operating a scheduled terminal that receives different types of services or data in the same system is proposed. In the present disclosure, the first, second and third types of terminals are referred to as scheduled terminals receiving the first, second and third types of services or data, respectively. In an embodiment, the first, second and third type terminals may be the same terminal or different terminals.

In the following embodiments, at least one of the PHICH, the uplink scheduling grant signal, and the downlink data signal is referred to as a first signal. Also, at least one of an uplink data signal for the uplink scheduling grant and HARQ ACK/NACK for the downlink data signal is referred to as a second signal. Among signals transmitted from the base station to the terminal, a signal that expects a response from the terminal may be a first signal, and such a response signal of the terminal in response to the first signal may be a second signal. Further, in an embodiment, the service type of the first signal may be at least one of eMBB, URLLC, and mtc, and the second signal may also correspond to at least one of these services.

For example, in LTE and LTE-a systems,

PUCCH format

0 or 4 and PHICH may be a first signal, and the corresponding second signal may be PUSCH. 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 embodiments, the TTI length of the first signal may indicate a length of time for transmitting the first signal as a time value related to the transmission of the first signal. Further, the TTI length of the second signal may indicate a length of time for transmitting the second signal as a time value related to transmission of the second signal, and the TTI length of the third signal may indicate a length of time for transmitting the third signal as a time value related to transmission of the third signal. Further, 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 second signal transmission/reception timing.

In the following description, it is assumed that when the base station transmits the first signal in the nth TTI, the terminal transmits the second signal in the (n + k) th TTI, and the base station notifies the terminal of the timing of transmitting the second signal means to notify the k value. Further, it is assumed that when the base station transmits the first signal in the nth TTI, the terminal transmits the second signal in the (n +4+ a) th TTI, and the base station notifies the terminal of the timing of transmitting the second signal, which means notifying the offset value of a. The offset may be defined by various methods, such as replacing n +4+ a with n +3+ a and n +5+ a.

The disclosure is also applicable to FDD and TDD systems.

In the present disclosure, upper layer signaling refers to a method of transmitting a signal from a base station to a terminal through a downlink data channel of a physical layer or transmitting a signal from a terminal to a base station through an uplink data channel of a physical layer. The upper layer signaling may also be referred to as Radio Resource Control (RRC) signaling, Packet Data Convergence Protocol (PDCP) signaling, or Medium Access Control (MAC) control element (MAC CE).

Although the present disclosure describes a method of determining a timing of transmitting a second signal after a terminal or a base station receives a first signal, there may be various methods of transmitting a second signal. For example, after receiving PDSCH (downlink data), the timing at which the terminal transmits HARQ ACK/NACK information corresponding to the PDSCH to the base station follows the method described in the present disclosure, but the method for selecting a PUCCH format, selecting a PUCCH resource, or mapping HARQ ACK/NACK information to a PUSCH may be determined in another manner. For example, a method for selecting a PUCCH format, selecting a PUCCH resource, or mapping HARQ ACK/NACK information to a PUSCH may be determined based on an LTE standard.

In the present disclosure, a terminal with reduced latency (or delay), a terminal configured with reduced latency, a terminal with reduced processing time, or a terminal configured with reduced processing time may be used interchangeably.

[ 3-1 example ]

In the 3-1 embodiment, a method for determining timing of transmitting a relevant PUSCH when a terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information will be described. The PHICH may not be used if there is a delay reduction in transmission to a terminal configured with the delay reduction, and this case may be applied when DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission with reduced latency is not received via the PHICH, the terminal may omit PHICH decoding in the corresponding subframe.

In case of TDD UL/DL configuration of one of 1 to 6, if the terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information in subframe n, the terminal transmits the relevant PUSCH in subframe n + k, where k is given in tables 3-5.

[ tables 3 to 5]

In case of TDD UL/DL configuration 0, if PDCCH/EPDCCH with Most Significant Bit (MSB) of UL index of uplink DCI format of 1 is received, if PHICH is received in

subframe

1 or 6, or if I in

subframe

0 or 5 _PHICH The PHICH is received at the location of resource 0, the value of k can be determined according to tables 3-5. In case of TDD UL/DL configuration 0, PDCCH/EPDCCH is received with Least Significant Bit (LSB) of UL index of uplink DCI format being 1, or if I in

subframe

0 or 5 _PHICH The location of resource 1 receives the PHICH, the value of k may be determined to be 7. If the MSB and LSB of the UL index of the uplink DCI format are both 1, the PUSCH may be transmitted in subframe n + k in both cases where k is 7 and k follows tables 3-5.

The method in the case of TDD UL/DL configuration 0 is not limited to the above-described method, and may be applied by slight modification. For example, in case of TDD UL/DL configuration 0, if PDCCH/EPDCCH whose MSB of UL index of uplink DCI format is 1 is received, if PHICH is received in

subframe

1 or 6, or if I in

subframe

0 or 5 _PHICH The PHICH is received at the location of resource 1, the value of k can be determined according to tables 3-5.

In case of TDD UL/DL configuration 0, PDCCH/EPDCCH with LSB of UL index 1 if uplink DCI format is received, or if I in

subframe

0 or 5 _PHICH The PHICH is received at a location of resource 0, the value of k may be determined to be 7. As another example, in case of TDD UL/DL configuration 0, if PDCCH/EPDCCH with MSB of UL index of uplink DCI format of 1 is received, if PHICH is received in

subframe

0 or 5, or if I in

subframe

1 or 6 _PHICH The location with resource 1 receives the PHICH, the value of k can be determined according to tables 3-5.

In case of TDD UL/DL configuration 0, PDCCH/EPDCCH with LSB of UL index of uplink DCI format of 1 is received, or if I in

subframe

1 or 6 _PHICH The PHICH is received at a location with resource 0, the value of k can be confirmedWas designated as 6.

[ 3-2 examples ]

In the 3-2 embodiment, a method for determining timing of transmitting a relevant PUSCH when a terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information will be described. The PHICH may not be used if there is a delay reduction in transmission to a terminal configured with the delay reduction, and this case may be applied when DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission with reduced latency is not received via the PHICH, the terminal may omit PHICH decoding in the corresponding subframe.

When the terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information in subframe n, the terminal transmits PUSCH in subframe n + k if subframe n + k is an uplink transmittable subframe, where the value of k is greater than 2. For example, a terminal receiving uplink DCI in subframe n transmits PUSCH in a subframe in which uplink transmission is possible from n + 3. If n +3 is a downlink subframe, and if n +4 is capable of uplink transmission, the PUSCH is transmitted in subframe n + 4.

[ examples 3 to 3]

In the 3 rd to 3 rd embodiments, a method for determining timing of transmitting a relevant PUSCH when a terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information will be described. The PHICH may not be used if there is a delay reduction in transmission to a terminal configured with the delay reduction, and this case may be applied when DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission with reduced latency is not received via the PHICH, the terminal may omit PHICH decoding in a corresponding subframe.

In case of TDD UL/DL configuration of one of 1 to 6, if a terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information in subframe n, the terminal transmits a relevant PUSCH in subframe n + k, where k is given in tables 3-6.

[ tables 3 to 6]

In case of TDD UL/DL configuration 0, if PDCCH/EPDCCH with MSB of UL index of uplink DCI format of 1 is received, if PHICH is received in

subframe

0 or 5, or if I in

subframe

1 or 6 _PHICH The PHICH is received at the location of resource 0, the value of k can be determined according to tables 3-6.

subframe

1 or 6 _PHICH The PHICH is received at a location of resource 1, the value of k may be determined to be 3. If the MSB and LSB of the UL index of the uplink DCI format are both 1, the PUSCH may be transmitted in subframe n + k in both cases where k is 3 and k follows tables 3-6.

The method in the case of TDD UL/DL configuration 0 is not limited to the above-described method, and may be applied by slight modification.

[ examples 3 to 4]

In the 3 rd to 4 th embodiments, a method for determining timing of transmitting a relevant PUSCH when a terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information will be described. The PHICH may not be used if there is a delay reduction in transmission to a terminal configured with the delay reduction, and this case may be applied when DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission with reduced latency is not received via the PHICH, the terminal may omit PHICH decoding in the corresponding subframe.

When the terminal receives PHICH or PDCCH/EPDCCH including DCI for transmitting uplink scheduling information in subframe n, the terminal transmits PUSCH in subframe n + k if subframe n + k is an uplink transmittable subframe, where the value of k is greater than 1. For example, a terminal receiving uplink DCI in subframe n transmits PUSCH in a subframe in which uplink transmission is possible from n + 2. If n +2 is a downlink subframe, and if n +3 enables uplink transmission, the PUSCH is transmitted in subframe n + 3.

The 3-1 and 3-3 embodiments may be used according to the configuration of a terminal provided by a base station or according to information transmitted in DCI. Also, the 3-2 embodiment and the 3-4 embodiment may be used according to the configuration of the terminal provided by the base station or according to information transmitted in DCI. Furthermore, in the 3-1 to 3-4 embodiments, the base station may attempt PUSCH decoding in a subframe in which the terminal transmits PUSCH.

Fig. 39 shows the operation of the terminal. When the terminal receives the PHICH or PDCCH/EPDCCH including UL scheduling information, the terminal identifies at least one of an upper layer signaling setting, a PHICH resource location, and DCI information in step 804. In fig. 39, the first timing setting 806 is to use the PUSCH transmission timing of the conventional LTE/LTE-a, and may indicate a case where the minimum signal processing time of the terminal is about 3ms, including the TA value. Thus, when the terminal recognizes the first timing setting 806, it is equal to the PUSCH transmission timing of the legacy LTE/LTE-a. For example, in FDD, if uplink scheduling information is received via PDCCH in subframe n, PUSCH is transmitted in subframe n +4 in step 808.

In fig. 39, the second timing setting 810 may indicate a case where the minimum signal processing time of the terminal is about 2ms, including a TA value. Thus, when the terminal recognizes the second timing setting 810, the timing is determined according to the 3-1 or 3-2 embodiment. For example, in FDD, uplink scheduling information is received via PDCCH in subframe n, and PUSCH is transmitted in subframe n +3 in step 812.

In fig. 39, the third timing setting 814 may indicate a case where the minimum signal processing time of the terminal is about 1ms, including a TA value. Thus, when the terminal recognizes the third timing setting 814, the timing is determined according to the 3 rd-3 or 3-4 th embodiment. For example, in FDD, uplink scheduling information is received via PDCCH in subframe n, and PUSCH is transmitted in subframe n +2 in step 816. In this case, the terminal or the base station may support only one of the second timing setting 810 and the third timing setting 814.

Further, the 3 rd-1 and 3 rd-3 embodiments may be implemented in combination. For example, when the terminal receives PDCCH/EPDCCH having DCI for transmitting uplink scheduling information, the transmission timing of PUSCH is determined as in the 3 rd-1 embodiment. When the terminal receives the PHICH, the transmission timing of the PUSCH is determined as in the 3 rd-3 rd embodiment. That is, in case of uplink scheduling using DCI in subframe n, the terminal may transmit PUSCH in subframe n +3 or later, and in case of uplink retransmission using PHICH, the terminal may transmit PUSCH in subframe n +2 or later.

In the 3-1 to 3-4 embodiments, the PHICH denotes information corresponding to HARQ NACK for uplink transmission. Thus, the reception of PHICH can be interpreted to mean that the terminal needs retransmission.

[ examples 3 to 5]

In the 3 rd to 5 th embodiments, a method of determining a timing at which a terminal receiving downlink data PDSCH transmission transmits HARQ ACK/NACK for PDSCH via an uplink channel (such as PUCCH or PUSCH).

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

[ tables 3 to 7]

The numerical order written in the above table may be modified and applied differently.

In tables 3-7, multiple values of k mean that HARQ ACK/NACK information for one or more PDSCHs may be transmitted together in subframe n. For example, in case of UL/DL configuration 1, HARQ ACK/NACK information corresponding to a PDSCH transmitted 6 subframes before and 3 subframes before is transmitted in subframe 2.

Tables 3-7 may be modified to the following tables 3-7 a.

[ tables 3 to 7a ]

The numerical order written in the above table may be variously modified and applied.

[ examples 3 to 6]

In the 3 rd to 6 th embodiments, a method of determining a timing at which a terminal receiving downlink data PDSCH transmission transmits HARQ ACK/NACK for PDSCH via an uplink channel (such as PUCCH or PUSCH).

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

[ examples 3 to 7]

In the 3 rd to 7 th embodiments, a method of determining a timing at which a terminal receiving downlink data PDSCH transmission transmits HARQ ACK/NACK for PDSCH via an uplink channel (such as PUCCH or PUSCH).

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

[ tables 3 to 8]

In tables 3-8, multiple values of k mean that HARQ ACK/NACK information for one or more PDSCHs may be transmitted together in subframe n. For example, in case of UL/DL configuration 1, HARQ ACK/NACK information corresponding to a PDSCH transmitted 3 subframes before and 2 subframes before is transmitted in subframe 2.

Tables 3-8 may be modified to tables 3-8a below.

[ tables 3 to 8a ]

[ examples 3 to 8]

In the 3 rd to 8 th embodiments, a method of determining a timing at which a terminal receiving downlink data PDSCH transmission transmits HARQ ACK/NACK for PDSCH via an uplink channel (such as PUCCH or PUSCH).

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

The 3-5 and 3-7 embodiments may be used according to the configuration of the terminal provided by the base station or according to information transmitted in DCI. Also, the 3 rd to 6 th embodiments and the 3 rd to 8 th embodiments may be used according to the configuration of the terminal provided by the base station or according to information transmitted in DCI. Further, in the 3-5 to 3-8 embodiments, the base station may attempt PUCCH or PUSCH decoding in a subframe in which the terminal transmits a PUCCH or PUSCH including HARQ ACK/NACK information for the PDSCH.

Fig. 40 shows the operation of the terminal. When the terminal receives the PDSCH, the terminal identifies at least one of upper layer signaling setup and DCI information in step 903. In fig. 40, a first timing setting 905 is to use HARQ ACK/NACK information timing via PUCCH or PUSCH of legacy LTE/LTE-a, and may indicate a case where the minimum signal processing time of a terminal is about 3ms (including a TA value). Thus, when the terminal recognizes the first timing setting 905, it is equal to HARQ ACK/NACK information of the legacy LTE/LTE-a. For example, in FDD, if a PDSCH is received in subframe n, HARQ ACK/NACK information is transmitted through a PUCCH or a PUSCH in subframe n +4 in step 907.

In fig. 40, the second timing setting 909 may indicate a case where the minimum signal processing time of the terminal is about 2ms (including the TA value). Thus, when the terminal recognizes the second timing setting 909, the timing is determined according to the 3-5 or 3-6 embodiments. For example, in FDD, a PDSCH is received in subframe n, and HARQ ACK/NACK information is transmitted through a PUCCH or PUSCH in subframe n +3 in step 911.

In fig. 40, the third timing setting 913 may indicate a case where the minimum signal processing time of the terminal is about 1ms (including the TA value). Thus, when the terminal recognizes the third timing setting 913, the timing is determined according to the 3-7 or 3-8 embodiments. For example, in FDD, the PDSCH is received in subframe n, and HARQ ACK/NACK information is transmitted through the PUCCH or PUSCH in subframe n +2 in step 915. In this case, the terminal or the base station may support only one of the second timing setting 909 and the third timing setting 913.

[ examples 3 to 9]

In embodiments 3 to 9, the timing for controlling the power used by the terminal for uplink transmission will be described.

A terminal incapable of simultaneously transmitting PUCCH and PUSCH may calculate power P for PUSCH transmission in subframe i of a specific serving cell c as follows _PUSCH,c (i)。

A terminal capable of simultaneously transmitting PUCCH and PUSCH may calculate in subframe i in a specific serving cell c as followsPower P for PUSCH transmission _PUSCH,c (i)。

In the above equation, P _CMAX,c (i) Denotes the power used for the transmission setting of the terminal in subframe i in the serving cell c.

Represents P _CMAX,c (i) The value of the linear change of (c),

denotes P as PUCCH transmit power _PUCCH (i) A linear change value of (c). M is a group of _PUSCH,c (i) Indicates the number of PRBs allocated to subframe i for PUSCH transmission in serving cell c.

Indicating a value formed by parameters transmitted through upper layer signaling. Alpha is alpha _c Can be taken as the value alpha _c E {0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1} is transmitted from higher layers. The terminal can calculate P _Lc As a downlink path loss estimate.

Is a value that can be determined from the control signal portion transmitted in the PUSCH. Delta _PUSCH,c Is a value that can be set according to a Transmit Power Control (TPC) command included in DCI format 0/4 or DCI format 3/3a of PDCCH or EPDCCH, which can be applied according to the following equation. If set to enable cumulative power calculation, then equation f is used _c (i)＝f _c (i-1)+δ _PUSCH.c (i-K _PUSCH ). If not, then use equation f _c (i)＝δ _PUSCH，c (i-K _PUSCH )。

K for determining timing as described above _PUSCH Can be transmitted through higher signaling. For exampleIf the minimum signal processing time of the delay reducing terminal is set to 1ms, the terminal may assume K _PUSCH Is 2. K _PUSCH Being 2 means that the power of the PUSCH to be transmitted in subframe i is determined according to the power control command conveyed in i-2.

Alternatively, indicate K _PUSCH An indicator of the value may be included in a DCI format conveying the power control command. For example, if the indicator is 0, K _PUSCH Is 2, if the indicator is 1, then K _PUSCH Is 3. K indicated by indicator of DCI format _PUSCH The information of the value may be mapped by various methods.

Although the above example is based on an FDD system, the values indicated in TDD may be provided in tables 3-9, as shown below.

[ tables 3 to 9]

In TDD UL/DL configurations 1 to 6, K _PUSCH May be determined from subframe i based on the above table. In case of TDD UL/DL configuration 0, the determination K may be changed according to the 3-1 rd to 3-4 th embodiments _PUSCH Method of value.

For example, in case of TDD UL/DL configuration 0 in 3-1 embodiment, if PDCCH/EPDCCH whose Most Significant Bit (MSB) of UL index of uplink DCI format is 1 is received, if PHICH is received in

subframe

1 or 6, or if I in

subframe

0 or 5 _PHICH The PHICH is received at the location of resource 0, the value of k can be determined according to tables 3-5. In case of TDD UL/DL configuration 0, if PDCCH/EPDCCH with Least Significant Bit (LSB) of UL index of uplink DCI format of 1 is received, or if I in

subframe

0 or 5 _PHICH The PHICH is received at a location of resource 1, the value of k may be determined to be 7. If MSB and LSB of UL index of uplink DCI format are both1, the PUSCH may be transmitted in subframe n + k in both cases where k is 7 and k follows tables 3-5. In this case, the determination of the KPUSCH value may be as follows.

In the example of the above-described 3-1 embodiment, DCI information for scheduling PUSCH that may be transmitted in

subframe

3 or 8 may be transmitted in

subframe

0 or 5 of the same frame or in

subframe

0 or 5 of the previous frame. Therefore, a subframe in which the PUSCH that can be transmitted in

subframe

3 or 8 is scheduled for power control needs to be specified.

In the above example, if i is subframe 3 or 8, i.e., when PUSCH transmission is performed in

subframe

3 or 8, when LSB of UL index of

DCI format

0 or 4 or other DCI format provided in PDCCH or EPDCCH is 1, it may be determined to be 7.

[ examples 3 to 10]

In the 3 rd to 10 th embodiments, the timing of transmitting PHICH including HARQ-ACK information after PUSCH transmission is described. That is, a temporal relationship between a PUSCH involved in transmission and a PHICH including HARQ-ACK information received by a terminal is described.

A terminal configured with reduced latency may determine that HARQ-ACK information for the PHICH sent in subframe i is associated with the PUSCH sent in subframe i-k. In case of an FDD system, k is given as 3. That is, in the FDD system, HARQ-ACK information of the PHICH transmitted in subframe i is associated with the PUSCH transmitted in subframe i-3. In case of a TDD system, a terminal not configured with EIMTA is configured only for one serving cell, or has the same TDD UL/DL configuration, and when the TDD UL/DL configuration is 1 to 6, the value of k may be given as shown in tables 3-10.

[ tables 3 to 10]

In case of TDD UL/DL configuration 0, ifIn the corresponding to I _PHICH The PUSCH indicated by the HARQ-ACK information is transmitted in sub-frames i-k, and the value of k is given according to tables 3-10, if HARQ-ACK is received in PHICH resource of 0. Further, in case of TDD UL/DL configuration 0, if corresponding to I _PHICH Upon receiving HARQ-ACK in PHICH resource of 1, PUSCH indicated by HARQ-ACK information is transmitted in subframe i-6. The above method can be applied to a terminal capable of reducing the delay of n + 3.

Alternatively, the implementation may be modified as follows.

A terminal configured with reduced latency may determine that HARQ-ACK information for the PHICH sent in subframe i is associated with the PUSCH sent in subframe i-k. In case of an FDD system, k is given as 2. That is, in the FDD system, HARQ-ACK information of the PHICH transmitted in subframe i is associated with the PUSCH transmitted in subframe i-2. In case of a TDD system, a terminal not configuring EIMTA is configured only for one serving cell, or has the same TDD UL/DL configuration, and when the TDD UL/DL configuration is 1 to 6, the value of k may be given as shown in tables 3-11.

[ tables 3 to 11]

That is, for example, in TDD UL/DL configuration 1, the PHICH transmitted in subframe 6 may be HARQ-ACK information of PUSCH transmitted in subframe 3, subframe 3 being three subframes earlier than subframe 6.

In case of TDD UL/DL configuration 0, if corresponding to I _PHICH The PUSCH indicated by the HARQ-ACK information is transmitted in subframes i-k, and the value of k is given according to tables 3-11, if HARQ-ACK is received in PHICH resource of 0. Further, in case of TDD UL/DL configuration 0, if corresponding to I _PHICH When HARQ-ACK is received in PHICH resource of 1, PUSCH indicated by HARQ-ACK information is transmitted in subframe i-3.

The operation methods corresponding to tables 3 to 10 and tables 3 to 11 may be selected according to upper layer signaling from the base station.

In the present disclosure, a subframe i-k or n-k may indicate a subframe 10+ i-k or 10+ n-k of a previous radio frame if i-k or n-k is less than zero.

The 3-10 th embodiment can be arranged as the 3-1 rd to 3-4 th embodiments, thereby serving to reduce the retransmission delay time in data transmission.

[ examples 3 to 11]

In the 3 rd to 11 th embodiments, a method of determining a timing at which a terminal receiving a downlink data PDSCH transmits HARQ ACK/NACK for the PDSCH to an uplink channel (such as PUCCH or PUSCH) will be described. This embodiment may be applied to the case of carrier aggregation, in particular, the case where the primary cell (Pcell) is a TDD system and the secondary cell (Scell) is FDD. FDD may correspond to frame structure 1 of LTE, and TDD may correspond to frame structure 2 of LTE.

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

[ tables 3 to 12]

The numerical order written in the above table can be modified and applied differently.

In tables 3-12, multiple values of k mean that HARQ ACK/NACK information for one or more PDSCHs may be transmitted together in subframe n.

Instead of tables 3 to 12, the following tables 3 to 13 or tables 3 to 14 may be applied.

[ tables 3 to 13]

[ tables 3 to 14]

Tables 3-13 may be applied for the purpose of minimizing delay time, and tables 3-14 may keep the same number of HARQ-ACK bits transmitted in one subframe. Tables 3-13 and tables 3-14 may be applied in combination according to the UL-DL configuration. In case of UL-DL configuration 6, tables 3-15 and tables 3-16 may be applied.

[ tables 3 to 15]

[ tables 3 to 16]

Fig. 41 and 42 show a terminal and a base station, respectively, having a transmitter, a receiver and a processor, respectively, for implementing the above-described embodiments of the present disclosure. The above-described 3-1 to 3-9 embodiments show transmission/reception methods of a base station and a terminal for determining a second signal transmission/reception timing and a terminal transmission power and performing a correlation operation. The receiver, processor and transmitter in each of the base station and terminal should operate in accordance with such embodiments.

Specifically, fig. 41 is a block diagram showing an internal structure of a terminal according to an embodiment of the present disclosure. As shown in fig. 41, a terminal of the present disclosure may include a terminal receiver 1200, a terminal transmitter 1204, and a terminal processor 1202. In an embodiment of the present disclosure, the terminal receiver 1200 and the terminal transmitter 1204 may be collectively referred to as a transceiver.

The transceiver may transmit and receive signals to and from a base station. These signals may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the frequency of a signal to be transmitted, an RF receiver for low-noise amplifying a received signal and down-converting the frequency, and the like.

Further, the transceiver can receive a signal through a radio channel, output the received signal to the terminal processor 1202, and transmit the signal output from the terminal processor 1202 through the radio channel. Terminal processor 1202 may control the terminal to operate in accordance with the above-described embodiments of the present disclosure. For example, terminal receiver 1200 can receive a signal including second signal timing information from a base station, and terminal processor 1202 can control to analyze second signal transmission timing. Further, the terminal transmitter 1204 may transmit a second signal according to the timing.

Fig. 42 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure. As shown in fig. 42, the base station of the present disclosure may include a base station receiver 1301, a base station transmitter 1305, and a base station processor 1303. In embodiments of the present disclosure, base station receiver 1301 and base station transmitter 1305 may be collectively referred to as a transceiver.

The transceiver may transmit and receive signals to and from the terminal. These signals may include control information and data. To this end, the transceiver may include an RF transmitter for up-converting and amplifying the frequency of a signal to be transmitted, an RF receiver for low-noise amplifying a received signal and down-converting the frequency, and the like.

Further, the transceiver may receive a signal through a radio channel, output the received signal to the base station processor 1303, and transmit the signal output from the base station processor 1303 through the radio channel. The base station processor 1303 may control the base station to operate according to the above-described embodiments of the present disclosure. For example, the base station processor 1303 may determine the second signal transmission timing and control to generate second signal transmission timing information to be transmitted to the terminal. Base station transmitter 1305 may then transmit timing information to the terminal, and base station receiver 1301 may receive a second signal based on the timing.

Further, according to an embodiment of the present disclosure, the base station processor 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.

While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it will be clearly understood that the same is by way of illustration and example only and is not intended to be taken by way of limitation. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure. Further, the disclosed embodiments may be implemented in combination as desired. For example, 3-1, 3-2, and 3-3 embodiments of the present disclosure may be combined, at least in part, with one another for operation of the base station and the terminal. Further, although the above embodiments are presented based on the LTE/LTE-a system, these embodiments or modifications thereof based on the same technical idea may be implemented in other systems such as the 5G or NR system.

Claims

1. A method performed by a base station in a wireless communication system, the method comprising:

transmitting first information associated with a number of symbols of a demodulation reference signal, DMRS, and second information associated with an additional DMRS location to a terminal, wherein the number of symbols of the DMRS is 1 or 2;

identifying a symbol position of the DMRS based on the first information, the second information, and a start of a slot identified between the start of the slot and a start of a scheduled Physical Downlink Shared Channel (PDSCH); and

transmitting the DMRS to the terminal at the identified symbol position of the DMRS.

2. The method of claim 1, wherein a symbol position of the DMRS is identified based on the first information, the second information, and a start of the scheduled PDSCH identified between a start of the time slot and a start of the scheduled PDSCH.

3. The method of claim 1, wherein a start of the slot between the start of the slot and a start of the scheduled PDSCH is identified by downlink control information, DCI.

4. The method of claim 1, wherein a first symbol of the DMRS and a second symbol of the DMRS are adjacent in a case that the number of the symbols of the DMRS is 2.

5. The method of claim 2, wherein the first symbol of the DMRS is identified as being the same as the start of the scheduled PDSCH where the symbol position of the DMRS is identified based on the first information, the second information, and the start of the scheduled PDSCH.

6. A base station in a wireless communication system, comprising:

a transceiver; and

a controller configured to:

transmitting, via the transceiver, first information associated with a number of symbols of a demodulation reference signal, DMRS, and second information associated with an additional DMRS location to a terminal, wherein the number of symbols of the DMRS is 1 or 2,

identifying a symbol position of the DMRS based on the first information, the second information, and a start of a slot identified between the start of the slot and a start of a scheduled Physical Downlink Shared Channel (PDSCH), an

7. The base station of claim 6, wherein a symbol position of the DMRS is identified based on the first information, the second information, and a start of the scheduled PDSCH identified between a start of the time slot and a start of the scheduled PDSCH.

8. The base station of claim 6, wherein a start of the slot between the start of the slot and the start of the scheduled PDSCH is identified by Downlink Control Information (DCI).

9. The base station of claim 6, wherein, where the number of symbols of the DMRS is 2, the first symbol of the DMRS and the second symbol of the DMRS are adjacent.

10. The base station of claim 7, wherein, in the event that a symbol position of the DMRS is identified based on the first information, the second information, and a start of the scheduled PDSCH, the first symbol identification of the DMRS is the same as the start of the scheduled PDSCH.

11. A method performed by a terminal in a wireless communication system, the method comprising:

receiving, from a base station, first information associated with a number of symbols of a demodulation reference signal, DMRS, and second information associated with an additional DMRS location, wherein the number of symbols of the DMRS is 1 or 2;

receiving, from the base station, the DMRS on the identified symbol position of the DMRS.

12. The method of claim 11, wherein a symbol position of the DMRS is identified based on the first information, the second information, and a start of the scheduled PDSCH identified between a start of the time slot and a start of the scheduled PDSCH.

13. The method of claim 11, wherein a start of the slot between the start of the slot and a start of the scheduled PDSCH is identified by downlink control information, DCI.

14. The method of claim 11, wherein, where the number of symbols of the DMRS is 2, a first symbol of the DMRS and a second symbol of the DMRS are adjacent.

15. The method of claim 12, wherein the first symbol of the DMRS is identified as being the same as the start of the scheduled PDSCH where the symbol position of the DMRS is identified based on the first information, the second information, and the start of the scheduled PDSCH.

16. A terminal in a wireless communication system, comprising:

a transceiver; and

a controller configured to:

receiving, via the transceiver, first information associated with a number of symbols of a demodulation reference signal, DMRS, and second information associated with an additional DMRS location from a base station, wherein the number of symbols of the DMRS is 1 or 2,

17. The terminal of claim 16, wherein a symbol position of the DMRS is identified based on the first information, the second information, and a start of the scheduled PDSCH identified between a start of the time slot and a start of the scheduled PDSCH.

18. The terminal of claim 16, wherein a start of the slot between the start of the slot and the start of the scheduled PDSCH is identified by downlink control information, DCI.

19. The terminal of claim 16, wherein, in a case that the number of the symbols of the DMRS is 2, the first symbol of the DMRS and the second symbol of the DMRS are adjacent.

20. The terminal of claim 17, wherein in the event that a symbol position of the DMRS is identified based on the first information, the second information, and a start of the scheduled PDSCH, the first symbol identification of the DMRS is the same as the start of the scheduled PDSCH.