KR20200099470A - Method and apparatus for configuration of reference signal in wirelss communication system - Google Patents

Abstract

The present invention relates to a communication technique for fusing a 5^th generation (5G) communication system with an Internet of things (IoT) technology to support a higher data transmission rate than that of a 4^th generation (4G) system and a system thereof. The present invention can be applied to an intelligent service (for example, smart home, smart building, smart city, smart car or connected car, healthcare, digital education, retail business, security and safety related services, etc.) based on a 5G communication technology and an IoT-related technology. According to the present invention, disclosed are a method for dynamically or quasi-statically setting a demodulation reference signal (DMRS) explicitly or implicitly and an apparatus thereof. According to the present invention, a control signal processing method in a wireless communication system comprises the steps of: receiving a first control signal transmitted from a base station; processing the first control signal received; and transmitting a second control signal generated based on the processing to the base station.

Description

Method and device for setting reference signal in wireless communication system {METHOD AND APPARATUS FOR CONFIGURATION OF REFERENCE SIGNAL IN WIRELSS COMMUNICATION SYSTEM}

The present disclosure proposes a method of configuring a demodulation reference signal (DMRS) that is a reference signal by a base station or a terminal in a wireless communication system.

Efforts are being made to develop an improved 5G communication system or a pre-5G communication system in order to meet the increasing demand for wireless data traffic after the commercialization of 4G communication systems. For this reason, the 5G communication system or the pre-5G communication system is called a communication system after a 4G network (Beyond 4G Network) or a system after an LTE system (Post LTE). In order to achieve a high data rate, the 5G communication system is being considered for implementation in the ultra-high frequency (mmWave) band (eg, 60 gigabyte (80 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the transmission distance of radio waves, in 5G communication systems, beamforming, massive MIMO, and Full Dimensional MIMO (FD-MIMO) ), array antenna, analog beam-forming, and large scale antenna technologies are being discussed. In addition, in order to improve the network of the system, in 5G communication systems, advanced small cells, advanced small cells, cloud radio access networks (cloud RAN), and ultra-dense networks. , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, CoMP (Coordinated Multi-Points), and interference cancellation And other technologies are being developed. In addition, in the 5G system, advanced coding modulation (ACM) methods such as Hybrid FSK and QAM Modulation (FQAM) and SWSC (Sliding Window Superposition Coding), advanced access technologies such as Filter Bank Multi Carrier (FBMC), NOMA (non-orthogonal multiple access), and sparse code multiple access (SCMA) have been developed.

On the other hand, the Internet is evolving from a human-centered network in which humans generate and consume information, to an Internet of Things (IoT) network that exchanges and processes information between distributed components such as objects. IoE (Internet of Everything) technology, which combines IoT technology with big data processing technology through connection with cloud servers, is also emerging. In order to implement IoT, technology elements such as sensing technology, wired/wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between objects, machine to machine , M2M), and MTC (Machine Type Communication) technologies are being studied. In the IoT environment, intelligent IT (Internet Technology) services that create new value in human life by collecting and analyzing data generated from connected objects can be provided. IoT is the field of smart home, smart building, smart city, smart car or connected car, smart grid, healthcare, smart home appliance, advanced medical service, etc. through the convergence and combination of existing IT (information technology) technology and various industries. Can be applied to.

Accordingly, various attempts have been made to apply a 5G communication system to an IoT network. For example, technologies such as sensor network, machine to machine (M2M), and machine type communication (MTC) are implemented by techniques such as beamforming, MIMO, and array antenna, which are 5G communication technologies. . The application of a cloud radio access network (cloud RAN) as the big data processing technology described above can be said as an example of the convergence of 3eG technology and IoT technology.

As described above and with the development of a wireless communication system, a variety of services can be provided, and thus a method for smoothly providing these services is required.

The present disclosure proposes a method and apparatus for transmitting/receiving a signal for supporting non-orthogonal multiple access (NOMA) in a wireless communication system. Specifically, in this case, a method of configuring and transmitting a DMRS is proposed, and the invention proposed in the present invention is not limited to the case of NOMA transmission.

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

By effectively performing channel estimation through a method in which a base station or a terminal proposed in the present disclosure sets a reference signal structure suitable for a transmission environment, overhead of a reference signal can be minimized and radio resources can be efficiently utilized.

1 is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource domain in which data or control channels are transmitted in a 5G system.
2 is a diagram illustrating a slot structure considered in a 5G system.
FIG. 3 is a diagram illustrating DMRS patterns (type1 and type2) used for communication between base station terminals in a 5G system.
4A is a flowchart illustrating an operation of a base station according to Method 1, Method 2, Method 3, and Method 4 according to the first embodiment.
4B is a flowchart illustrating an operation of a terminal according to Method 1, Method 2, Method 3, and Method 4 according to the first embodiment.
5A is a flowchart illustrating an operation of a base station according to Method 5 according to the first embodiment.
5B is a flowchart illustrating an operation of a terminal according to Method 5 according to the first embodiment.
6A is a flowchart illustrating an operation of a base station according to the second embodiment.
6B is a flowchart illustrating an operation of a terminal according to the second embodiment.
7 is a block diagram of a terminal according to an embodiment.
8 is a block diagram of a base station according to an embodiment.

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

In describing the embodiments, descriptions of technical contents that are well known in the technical field to which the present invention pertains and are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention by omitting unnecessary description.

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

Advantages and features of the present disclosure, and a method of achieving them will be apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments described below, but may be implemented in a variety of different forms, only the present embodiments make the disclosure of the present invention complete, and are common knowledge in the technical field to which the present disclosure belongs. It is provided to completely inform the scope of the technical idea to those who have, and the present disclosure is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification. In addition, in describing the present disclosure, when it is determined that a detailed description of a related function or configuration may unnecessarily obscure the subject matter of the present disclosure, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present disclosure and may vary according to the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

Hereinafter, the base station is a subject that performs resource allocation of the terminal, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a radio access unit, a base station controller, or a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. In the present disclosure, a downlink (DL) refers to a radio transmission path of a signal transmitted from a base station to a terminal, and an uplink (UL) refers to a radio transmission path of a signal transmitted from the terminal to the base station. In addition, the LTE or LTE-A system may be described below as an example, but the embodiments of the present disclosure may be applied to other communication systems having a similar technical background or channel type. For example, 5G mobile communication technology (5G, new radio, NR) developed after LTE-A may be included, and the following 5G may be a concept including existing LTE, LTE-A and other similar services. have. In addition, the present disclosure may be applied to other communication systems through some modifications without significantly departing from the scope of the present disclosure as a judgment of a person having skilled technical knowledge.

In this case, it will be appreciated that each block of the flowchart diagrams and combinations of the flowchart diagrams may be executed by computer program instructions. Since these computer program instructions can be mounted on the processor of a general purpose computer, special purpose computer or other programmable data processing equipment, the instructions executed by the processor of the computer or other programmable data processing equipment are described in the flowchart block(s). It creates a means to perform functions. These computer program instructions can also be stored in computer-usable or computer-readable memory that can be directed to a computer or other programmable data processing equipment to implement a function in a particular way, so that the computer-usable or computer-readable memory It is also possible to produce an article of manufacture containing instruction means for performing the functions described in the flowchart block(s). Computer program instructions can also be mounted on a computer or other programmable data processing equipment, so that a series of operating steps are performed on a computer or other programmable data processing equipment to create a computer-executable process to create a computer or other programmable data processing equipment. It is also possible for instructions to perform processing equipment to provide steps for executing the functions described in the flowchart block(s).

In addition, each block may represent a module, segment, or part of code that contains one or more executable instructions for executing the specified logical function(s). In addition, it should be noted that in some alternative execution examples, functions mentioned in blocks may occur out of order. For example, two blocks shown in succession may in fact be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order depending on the corresponding function.

In this case, the term'~ unit' used in this embodiment refers to software or hardware components such as FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and'~ unit' performs certain roles. do. However,'~ part' is not limited to software or hardware. The'~ unit' may be configured to be in an addressable storage medium, or may be configured to reproduce one or more processors. Thus, as an example,'~ unit' refers to components such as software components, object-oriented software components, class components and task components, processes, functions, properties, and procedures. , Subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, database, data structures, tables, arrays, and variables. The components and functions provided in the'~ units' may be combined into a smaller number of elements and'~ units', or may be further divided into additional elements and'~ units'. In addition, components and'~ units' may be implemented to play one or more CPUs in a device or a security multimedia card. Also, in an embodiment, the'~ unit' may include one or more processors.

The wireless communication system deviated from the initial voice-oriented service, for example, 3GPP HSPA (High Speed Packet Access), LTE (Long Term Evolution or E-UTRA (Evolved Universal Terrestrial Radio Access)), LTE-Advanced (LTE-A), LTE-Pro, 3GPP2's High Rate Packet Data (HRPD), UMB (Ultra Mobile Broadband), and IEEE's 802.16e. It is developing into a communication system.

As a representative example of a broadband wireless communication system, the LTE system employs an Orthogonal Frequency Division Multiplexing (OFDM) scheme in downlink (DL), and Single Carrier Frequency Division Multiplexing (SC-FDMA) scheme in uplink (UL). ) Method is adopted. Uplink refers to a radio link through which a terminal (UE (User Equipment) or MS (Mobile Station)) transmits data or control signals to a base station (eNode B or base station (BS)), and downlink refers to a base station It refers to a wireless link that transmits data or control signals. In addition, the above-described multiple access method generally assigns and operates each user's data or control information so that the time-frequency resources for carrying data or control information for each user do not overlap each other, that is, orthogonality is established. Distinguish.

Since the 5G communication system, a communication system after LTE, must be able to freely reflect various requirements of users and service providers, services that simultaneously satisfy various requirements must be supported. Services considered for 5G communication systems include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliability low latency communication (URLLC). There is this.

eMBB aims to provide a more improved data rate than the data rate supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G communication system, eMBB must be able to provide a maximum transmission rate of 20 Gbps in downlink and 10 Gbps in uplink from the viewpoint of one base station. In addition, the 5G communication system must provide the maximum transmission rate and at the same time provide the increased user perceived data rate of the terminal. In order to satisfy such a requirement, it may be required to improve various transmission/reception technologies including a more advanced multi-antenna (Multi Input Multi Output, MIMO) transmission technology. In addition, in LTE, signals are transmitted using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, whereas in the 5G communication system, the data transmission speed required by the 5G communication system is increased by using a frequency bandwidth wider than 20 MHz in a frequency band of 3 to 6 GHz or 6 GHz or higher. Can be satisfied.

At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G communication systems. In mMTC, in order to efficiently provide the Internet of Things, it is required to support large-scale terminal access within a cell, improve terminal coverage, improved battery time, and reduce terminal cost. The IoT is attached to various sensors and various devices to provide a communication function, so it must be able to support a large number of terminals (for example, 1,000,000 terminals/km2) within a cell. In addition, the terminal supporting mMTC is highly likely to be located in a shaded area not covered by the cell, such as the basement of a building due to the nature of the service, and thus requires wider coverage compared to other services provided by the 5G communication system. A terminal supporting mMTC should be configured as a low-cost terminal, and since it is difficult to frequently exchange the battery of the terminal, a very long battery life time such as 10 to 15 years is required.

Finally, in the case of URLLC, it is a cellular-based wireless communication service used for a mission-critical purpose. For example, remote control of robots or machinery, industrial automation, unmaned aerial vehicles, remote health care, emergency situations. Services used for emergency alerts, etc. can be considered. Therefore, the communication provided by URLLC must provide very low latency and very high reliability. For example, a service supporting URLLC must satisfy air interface latency of less than 0.5 milliseconds, and at the same time, meet the requirements of a packet error rate of 10-5 or less. Therefore, for a service supporting URLLC, a 5G system must provide a smaller Transmit Time Interval (TTI) than other services, and at the same time allocate a wide resource in a frequency band to secure the reliability of a communication link.

The three services of 5G, namely eMBB, URLLC, and mMTC, can be multiplexed and transmitted in one system. In this case, different transmission/reception techniques and transmission/reception parameters may be used between services in order to satisfy different requirements of each service.

Hereinafter, the frame structure of the 5G system will be described in more detail with reference to the drawings.

1 is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource domain in which data or control channels are transmitted in a 5G system.

(일례로 12)개의 연속된 RE들은 하나의 자원 블록(Resource Block, RB, 104)을 구성할 수 있다. 또한, 시간 영역에서

개의 연속된 OFDM 심볼들은 하나의 서브프레임(110)을 구성할 수 있다. In Fig. 1, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The basic unit of a resource in the time and frequency domain is a resource element (RE, 101), one Orthogonal Frequency Division Multiplexing (OFDM) symbol 102 on the time axis and one subcarrier 103 on the frequency axis. Can be defined as In the frequency domain

(For example, 12) consecutive REs may constitute one resource block (RB, 104). Also, in the time domain

Four consecutive OFDM symbols may constitute one subframe 110.

2 is a diagram illustrating a slot structure considered in a 5G system.

)=14). 1개의 서브프레임(201)은 하나 또는 다수 개의 슬롯(202, 203)으로 구성될 수 있으며, 1개의 서브프레임(201)당 슬롯(202, 203)의 개수는 부반송파 간격에 대한 설정 값 μ(204, 205)에 따라 다를 수 있다. 도 2의 일 예에서는 부반송파 간격 설정 값으로 μ=0(204)인 경우와 μ=1(205)인 경우의 슬롯 구조가 도시되어 있다. μ=0(204)일 경우, 1개의 서브프레임(201)은 1개의 슬롯(202)으로 구성될 수 있고, μ=1(205)일 경우, 1개의 서브프레임(201)은 2개의 슬롯(203)으로 구성될 수 있다. 즉 부반송파 간격에 대한 설정 값 μ에 따라 1개의 서브프레임 당 슬롯 수(

)가 달라질 수 있고, 이에 따라 1개의 프레임 당 슬롯 수(

)가 달라질 수 있다. 각 부반송파 간격 설정 μ에 따른

및

는 하기의 표 1로 정의될 수 있다.FIG. 2 shows an example of a structure of a frame 200, a subframe 201, and a slot 202. One frame 200 may be defined as 10 ms. One subframe 201 may be defined as 1 ms, and thus, one frame 200 may consist of a total of 10 subframes 201. In addition, one slot 202, 203 may be defined as 14 OFDM symbols (that is, the number of symbols per slot (

)=14). One subframe 201 may be composed of one or a plurality of slots 202, 203, and the number of slots 202, 203 per subframe 201 is a set value μ (204) for the subcarrier spacing. , 205). In the example of FIG. 2, slot structures in the case of μ=0 (204) and μ=1 (205) as subcarrier spacing setting values are shown. When μ=0 (204), one subframe 201 may consist of one slot 202, and if μ=1 (205), one subframe 201 may consist of two slots ( 203). In other words, the number of slots per subframe according to the setting value μ for the subcarrier spacing (

) May vary, and accordingly, the number of slots per frame (

) Can be different. According to each subcarrier spacing setting μ

And

May be defined in Table 1 below.

[Table 1]

Next, one of the reference signals in the 5G system, a DeModulation Reference Signal (DMRS) will be described in detail.

Demodulation reference signal (DMRS) described below refers to a reference signal having a characteristic of performing demodulation without additionally receiving precoding information by the UE by applying UE-specific precoding to the reference signal. The DMRS can consist of several DMRS ports, and each port maintains orthogonality so as not to cause interference with each other by using CDM or FDM. However, the term for DMRS may be expressed in other terms depending on the intention of the user and the purpose of using the reference signal. More specifically, the term DMRS is merely a specific example to easily explain the technical content of the present invention and to aid understanding of the present invention, and is not intended to limit the scope of the present invention. That is, it is apparent to those of ordinary skill in the art to which the present invention belongs to that it is possible to implement the reference signal based on the technical idea of the present invention.

3 is a diagram illustrating DMRS patterns (type1 and type2) used for communication between base station terminals in an NR system. In the NR system, two DMRS patterns are supported. In FIG. 3, two DMRS patterns are shown in detail. In FIG. 3, FIGS. 301 and 302 represent DMRS type1, FIG. 301 represents 1 symbol pattern, and FIG. 302 represents 2 symbol pattern. DMRS type 1 of FIGS. 301 and 302 is a comb 2 structure DMRS pattern, and may be composed of two CDM groups, and different CDM groups are FDM. Specifically, in FIGS. 301 and 302, a green portion represents CDM group0, and a red portion represents CDM group1. In the 1 symbol pattern of FIG. 301, the CDM is applied to the same CDM group in terms of frequency, so that two DMRS ports can be distinguished, and thus, a total of four orthogonal DMRS ports can be configured. FIG. 301 shows the DMRS port IDs mapped to each CDM group (in the case of a downlink, the DMRS port ID is +1000 to the illustrated number). In the 2-symbol pattern of FIG. 302, a time/frequency CDM is applied to the same CDM group to distinguish four DMRS ports, and thus, a total of eight orthogonal DMRS ports can be configured. FIG. 302 shows the DMRS port IDs mapped to each CDM group (in the case of a downlink, the DMRS port ID is +1000 to the illustrated number). In contrast, the DMRS type 2 of FIGS. 303 and 304 is a DMRS pattern in which FD-OCC is applied to a subcarrier adjacent to each other in frequency, and may be composed of three CDM groups, and different CDM groups are FDM. Specifically, in FIGS. 303 and 304, a part marked in blue indicates CDM group0, a part marked in green indicates CDM group1, and a part marked in red indicates CDM group2. In the 1 symbol pattern of FIG. 303, the CDM is applied to the same CDM group in terms of frequency, so that two DMRS ports can be distinguished, and thus, a total of 6 orthogonal DMRS ports can be configured. FIG. 303 shows the DMRS port IDs mapped to each CDM group (in the case of a downlink, the DMRS port ID is +1000 to the illustrated number). In the 2-symbol pattern of FIG. 304, the time/frequency CDM is applied to the same CDM group so that 4 DMRS ports can be distinguished, and thus a total of 12 orthogonal DMRS ports can be configured. FIG. 304 shows the DMRS port IDs mapped to each CDM group (in the case of a downlink, the DMRS port ID is +1000 to the illustrated number).

As described above, in the NR system, two different DMRS patterns (FIGS. (301, 302) or (303, 304)) can be set, and whether the DMRS pattern is one symbol pattern (FIG. (301, 303)) or two adjacent A symbol pattern (Fig. 302, 304) may also be set. Also, not only the DMRS port number is scheduled, but also the number of CDM groups scheduled together for PDSCH rate matching can be set and signaled. In addition, in the case of CP-OFDM, both DMRS patterns described above in the DL and UL are supported, and in the case of DFT-S-OFDM, only DMRS type1 of the DMRS patterns described above in the UL is supported. In addition, it is supported so that additional DMRS can be set. Front-loaded DMRS refers to the first DMRS appearing in the first symbol in time, and additional DMRS refers to the DMRS appearing in the symbol after the front-loaded DMRS. In the NR system, the number of additional DMRSs can be set from a minimum of 0 to a maximum of 3. In addition, when additional DMRS is configured, the same pattern as the front-loaded DMRS is assumed. More specifically, information on whether the DMRS pattern type1 or type2 is described above for front-loaded DMRS, information on whether the DMRS pattern is a one symbol pattern or two adjacent symbol patterns, and information on the number of CDM groups used with the DMRS port are indicated. Then, when additional DMRS is additionally configured, DMRS information is configured in the same way as the front-loaded DMRS.

More specifically, the above-described downlink DMRS and uplink DMRS configurations may be configured through RRC signaling in Tables 2 and 3 below.

DMRS-DownlinkConfig ::= SEQUENCE {
dmrs-Type (DMRS type setting) ENUMERATED {type2} OPTIONAL, - Need S
dmrs-AdditionalPosition (Additional DMRS OFDM symbol setting) ENUMERATED {pos0, pos1, pos3} OPTIONAL, - Need S
maxLength (1 symbol or 2 symbol DMRS pattern related setting) ENUMERATED {len2} OPTIONAL, - Need S
scramblingID0 (scrambling ID0) INTEGER (0..65535) OPTIONAL, - Need S
scramblingID1 (scrambling ID1) INTEGER (0..65535) OPTIONAL, - Need S
phaseTrackingRS (PTRS setup) SetupRelease {PTRS-DownlinkConfig} OPTIONAL, - Need M
...
}

DMRS-UplinkConfig ::= SEQUENCE {
dmrs-Type (DMRS type setting) ENUMERATED {type2} OPTIONAL, - Need S
dmrs-AdditionalPosition (Additional DMRS OFDM symbol setting) ENUMERATED {pos0, pos1, pos3} OPTIONAL, - Need R
phaseTrackingRS (PTRS setup) SetupRelease {PTRS-UplinkConfig} OPTIONAL, - Need M
maxLength (1 symbol or 2 symbol DMRS pattern related setting) ENUMERATED {len2} OPTIONAL, - Need S

transformPrecodingDisabled SEQUENCE {
scramblingID0 (scrambling ID0) INTEGER (0..65535) OPTIONAL, - Need S
scramblingID1 (scrambling ID0) INTEGER (0..65535) OPTIONAL, - Need S
...
} OPTIONAL, - Need R
transformPrecodingEnabled SEQUENCE {
nPUSCH-Identity (cell ID for DFT-s-OFDM) INTEGER(0..1007) OPTIONAL, - Need S
sequenceGroupHopping (sequence group hopping) ENUMERATED {disabled} OPTIONAL, - Need S
sequenceHopping ENUMERATED {enabled} OPTIONAL, - Need S
...
} OPTIONAL, - Need R
...
}

Next, downlink control information (DCI) in the 5G system will be described in detail.

In the 5G system, scheduling information for uplink data (or physical uplink data channel (Physical Uplink Shared Channel, PUSCH)) or downlink data (or physical downlink data channel (Physical Downlink Shared Channel, PDSCH)) is provided through DCI. It can be transmitted from the base station to the terminal. The UE may monitor a DCI format for fallback and a DCI format for non-fallback for PUSCH or PDSCH. The countermeasure DCI format may be composed of a fixed field selected between the base station and the terminal, and the non-preparation DCI format may include a configurable field.

DCI may be transmitted through a physical downlink control channel (PDCCH) through a channel coding and modulation process. A Cyclic Redundancy Check (CRC) is attached to the DCI message payload, and the CRC can be scrambling with a Radio Network Temporary Identifier (RNTI) corresponding to the identity of the terminal. Different RNTIs may be used according to the purpose of the DCI message, for example, UE-specific data transmission, power control command, or random access response. That is, the RNTI is not explicitly transmitted, but may be included in the CRC calculation process and transmitted. When receiving the DCI message transmitted on the PDCCH, the terminal checks the CRC using the allocated RNTI, and if the CRC check result is correct, the terminal can know that the message has been transmitted to the terminal.

For example, DCI scheduling a PDSCH for system information (SI) may be scrambled with SI-RNTI. The DCI scheduling the PDSCH for a Random Access Response (RAR) message may be scrambled with RA-RNTI. The DCI scheduling the PDSCH for the paging message can be scrambled with P-RNTI. The DCI notifying the SFI (Slot Format Indicator) may be scrambled with SFI-RNTI. DCI notifying TPC (Transmit Power Control) can be scrambled with TPC-RNTI. The DCI for scheduling a UE-specific PDSCH or PUSCH may be scrambled with a Cell RNTI (C-RNTI).

DCI format 0_0 may be used as a countermeasure DCI for scheduling PUSCH, and in this case, CRC may be scrambled with C-RNTI. DCI format 0_0 in which CRC is scrambled with C-RNTI may include, for example, the following information.

] bits
- Time domain resource assignment (시간 도메인 자원 할당) - X bits
- Frequency hopping flag (주파수 호핑 플래그) - 1 bit.
- Modulation and coding scheme (변조 및 코딩 스킴) - 5 bits
- New data indicator (새로운 데이터 지시자) - 1 bit
- Redundancy version (리던던시 버전) - 2 bits
- HARQ process number (HARQ 프로세스 번호) - 4 bits
- TPC command for scheduled PUSCH (스케줄링된 PUSCH를 위한 전송 전력 제어(transmit power control) 명령 - [2] bits
- UL/SUL indicator (상향링크/추가적 상향링크(supplementary UL) 지시자) - 0 or 1 bit
-Identifier for DCI formats-[1] bit
-Frequency domain resource assignment -[

] bits
-Time domain resource assignment-X bits
-Frequency hopping flag-1 bit.
-Modulation and coding scheme-5 bits
-New data indicator-1 bit
-Redundancy version-2 bits
-HARQ process number-4 bits
-TPC command for scheduled PUSCH (transmit power control command for scheduled PUSCH-[2] bits
-UL/SUL indicator (uplink/supplementary UL indicator)-0 or 1 bit

DCI format 0_1 may be used as a non-preparative DCI for scheduling PUSCH, and in this case, CRC may be scrambled with C-RNTI. DCI format 0_1 in which CRC is scrambled by C-RNTI may include, for example, the following information.

○ For resource allocation type 0(자원 할당 타입 0의 경우),

bits

○ For resource allocation type 1(자원 할당 타입 1의 경우),

bits
- Time domain resource assignment - 1, 2, 3, or 4 bits
- VRB-to-PRB mapping (가상 자원 블록(virtual resource block)-to-물리 자원 블록(physical resource block) 매핑) - 0 or 1 bit, only for resource allocation type 1.

○ 0 bit if only resource allocation type 0 is configured;

○ 1 bit otherwise.
- Frequency hopping flag - 0 or 1 bit, only for resource allocation type 1.

○ 0 bit if only resource allocation type 0 is configured;

○ 1 bit otherwise.
- Modulation and coding scheme - 5 bits
- New data indicator - 1 bit
- Redundancy version - 2 bits
- HARQ process number - 4 bits
- 1st downlink assignment index (제1 하향링크 할당 인덱스) - 1 or 2 bits

○ 1 bit for semi-static HARQ-ACK codebook(준정적 HARQ-ACK 코드북의 경우);

○ 2 bits for dynamic HARQ-ACK codebook with single HARQ-ACK codebook(단일 HARQ-ACK 코드북과 함께 동적 HARQ-ACK 코드북이 사용되는 경우).
- 2nd downlink assignment index (제2 하향링크 할당 인덱스) - 0 or 2 bits

○ 2 bits for dynamic HARQ-ACK codebook with two HARQ-ACK sub-codebooks(2개의 HARQ-ACK 부코드북과 함께 동적 HARQ-ACK 코드북이 사용되는 경우);

○ 0 bit otherwise.
- TPC command for scheduled PUSCH - 2 bits
- SRS resource indicator (SRS 자원 지시자) -

or

bits

○

bits for non-codebook based PUSCH transmission(PUSCH 전송이 코드북 기반이 아닐 경우);

○

bits for codebook based PUSCH transmission(PUSCH 전송이 코드북 기반일 경우).
- Precoding information and number of layers (프리코딩 정보 및 레이어의 개수) - up to 6 bits
- Antenna ports (안테나 포트) - up to 5 bits
- SRS request (SRS 요청) - 2 bits
- CSI request (채널 상태 정보 요청) - 0, 1, 2, 3, 4, 5, or 6 bits
- CBG transmission information (코드 블록 그룹(code block group) 전송 정보) - 0, 2, 4, 6, or 8 bits
- PTRS-DMRS association (위상 트래킹 기준 신호-복조 기준 신호 관계) - 0 or 2 bits.
- beta_offset indicator (베타 오프셋 지시자) - 0 or 2 bits
- DMRS sequence initialization (복조 기준 신호 시퀀스 초기화) - 0 or 1 bit-Carrier indicator-0 or 3 bits
-UL/SUL indicator-0 or 1 bit
-Identifier for DCI formats-[1] bits
-Bandwidth part indicator-0, 1 or 2 bits
-Frequency domain resource assignment

○ For resource allocation type 0 (for resource allocation type 0),

bits

○ For resource allocation type 1 (for resource allocation type 1),

bits
-Time domain resource assignment-1, 2, 3, or 4 bits
-VRB-to-PRB mapping (virtual resource block-to-physical resource block mapping)-0 or 1 bit, only for resource allocation type 1.

○ 0 bit if only resource allocation type 0 is configured;

○ 1 bit otherwise.
-Frequency hopping flag-0 or 1 bit, only for resource allocation type 1.

○ 0 bit if only resource allocation type 0 is configured;

○ 1 bit otherwise.
-Modulation and coding scheme-5 bits
-New data indicator-1 bit
-Redundancy version-2 bits
-HARQ process number-4 bits
-1st downlink assignment index (1st downlink assignment index)-1 or 2 bits

○ 1 bit for semi-static HARQ-ACK codebook (for semi-static HARQ-ACK codebook);

○ 2 bits for dynamic HARQ-ACK codebook with single HARQ-ACK codebook (when a dynamic HARQ-ACK codebook is used together with a single HARQ-ACK codebook).
-2nd downlink assignment index (2nd downlink assignment index)-0 or 2 bits

○ 2 bits for dynamic HARQ-ACK codebook with two HARQ-ACK sub-codebooks (when a dynamic HARQ-ACK codebook is used with two HARQ-ACK sub-codebooks);

○ 0 bit otherwise.
-TPC command for scheduled PUSCH-2 bits
-SRS resource indicator (SRS resource indicator)-

or

bits

○

bits for non-codebook based PUSCH transmission (when PUSCH transmission is not based on codebook);

○

bits for codebook based PUSCH transmission (when PUSCH transmission is based on codebook).
-Precoding information and number of layers (precoding information and number of layers)-up to 6 bits
-Antenna ports-up to 5 bits
-SRS request (SRS request)-2 bits
-CSI request (Channel state information request)-0, 1, 2, 3, 4, 5, or 6 bits
-CBG transmission information (code block group transmission information)-0, 2, 4, 6, or 8 bits
-PTRS-DMRS association (phase tracking reference signal-demodulation reference signal relationship)-0 or 2 bits.
-beta_offset indicator (beta offset indicator)-0 or 2 bits
-DMRS sequence initialization (demodulation reference signal sequence initialization)-0 or 1 bit

DCI format 1_0 may be used as a countermeasure DCI for scheduling the PDSCH, and in this case, the CRC may be scrambled with C-RNTI. DCI format 1_0 in which CRC is scrambled with C-RNTI may include, for example, the following information.

] bits
- Time domain resource assignment - X bits
- VRB-to-PRB mapping - 1 bit
- Modulation and coding scheme - 5 bits
- New data indicator - 1 bit
- Redundancy version - 2 bits
- HARQ process number - 4 bits
- Downlink assignment index - 2 bits
- TPC command for scheduled PUCCH - [2] bits
- PUCCH resource indicator (물리 상향링크 제어 채널(physical uplink control channel, PUCCH) 자원 지시자- 3 bits
- PDSCH-to-HARQ feedback timing indicator (PDSCH-to-HARQ 피드백 타이밍 지시자) - [3] bits-Identifier for DCI formats-[1] bit
-Frequency domain resource assignment-[

] bits
-Time domain resource assignment-X bits
-VRB-to-PRB mapping-1 bit
-Modulation and coding scheme-5 bits
-New data indicator-1 bit
-Redundancy version-2 bits
-HARQ process number-4 bits
-Downlink assignment index-2 bits
-TPC command for scheduled PUCCH-[2] bits
-PUCCH resource indicator (physical uplink control channel (PUCCH) resource indicator-3 bits
-PDSCH-to-HARQ feedback timing indicator (PDSCH-to-HARQ feedback timing indicator)-[3] bits

DCI format 1_1 may be used as a non-preparative DCI for scheduling the PDSCH, and in this case, the CRC may be scrambled with C-RNTI. DCI format 1_1 in which CRC is scrambled with C-RNTI may include, for example, the following information.

○ For resource allocation type 0,

bits

○ For resource allocation type 1,

bits
- Time domain resource assignment - 1, 2, 3, or 4 bits
- VRB-to-PRB mapping - 0 or 1 bit, only for resource allocation type 1.

○ 0 bit if only resource allocation type 0 is configured;

○ 1 bit otherwise.
- PRB bundling size indicator (물리 자원 블록 번들링 크기 지시자) - 0 or 1 bit
- Rate matching indicator (레이트 매칭 지시자) - 0, 1, or 2 bits
- ZP CSI-RS trigger (영전력 채널 상태 정보 기준 신호 트리거) - 0, 1, or 2 bits
For transport block 1(제1 전송 블록의 경우):
- Modulation and coding scheme - 5 bits
- New data indicator - 1 bit
- Redundancy version - 2 bits
For transport block 2(제2 전송 블록의 경우):
- Modulation and coding scheme - 5 bits
- New data indicator - 1 bit
- Redundancy version - 2 bits
- HARQ process number - 4 bits
- Downlink assignment index - 0 or 2 or 4 bits
- TPC command for scheduled PUCCH - 2 bits
- PUCCH resource indicator - 3 bits
- PDSCH-to-HARQ_feedback timing indicator - 3 bits
- Antenna ports - 4, 5 or 6 bits
- Transmission configuration indication (전송 설정 지시, TCI) - 0 or 3 bits
- SRS request - 2 bits
- CBG transmission information - 0, 2, 4, 6, or 8 bits
- CBG flushing out information (코드 블록 그룹 플러싱 아웃 정보) - 0 or 1 bit
- DMRS sequence initialization - 1 bit-Carrier indicator-0 or 3 bits
-Identifier for DCI formats-[1] bits
-Bandwidth part indicator-0, 1 or 2 bits
-Frequency domain resource assignment

○ For resource allocation type 0,

bits

○ For resource allocation type 1,

bits
-Time domain resource assignment-1, 2, 3, or 4 bits
-VRB-to-PRB mapping-0 or 1 bit, only for resource allocation type 1.

○ 0 bit if only resource allocation type 0 is configured;

○ 1 bit otherwise.
-PRB bundling size indicator (physical resource block bundling size indicator)-0 or 1 bit
-Rate matching indicator-0, 1, or 2 bits
-ZP CSI-RS trigger (zero power channel status information reference signal trigger)-0, 1, or 2 bits
For transport block 1 (for the first transport block):
-Modulation and coding scheme-5 bits
-New data indicator-1 bit
-Redundancy version-2 bits
For transport block 2 (for the second transport block):
-Modulation and coding scheme-5 bits
-New data indicator-1 bit
-Redundancy version-2 bits
-HARQ process number-4 bits
-Downlink assignment index-0 or 2 or 4 bits
-TPC command for scheduled PUCCH-2 bits
-PUCCH resource indicator-3 bits
-PDSCH-to-HARQ_feedback timing indicator-3 bits
-Antenna ports-4, 5 or 6 bits
-Transmission configuration indication (TCI)-0 or 3 bits
-SRS request-2 bits
-CBG transmission information-0, 2, 4, 6, or 8 bits
-CBG flushing out information (code block group flushing out information)-0 or 1 bit
-DMRS sequence initialization-1 bit

Hereinafter, embodiments of the present disclosure will be described in detail together with the accompanying drawings. Hereinafter, an exemplary embodiment of the present disclosure will be described using a 5G wireless communication system as an example, but the exemplary embodiment of the present disclosure may be applied to other communication systems having a similar technical background or channel type. An embodiment of the present disclosure may be applied not only to a 5G communication system but also to a communication system after LTE and LTE-A or 5G. In addition, the embodiments of the present disclosure may be applied to other communication systems through some modifications without significantly departing from the scope of the present disclosure, as determined by a person having skilled technical knowledge.

In describing the present disclosure, when it is determined that a detailed description of a related function or configuration may unnecessarily obscure the subject matter of the present disclosure, a detailed description thereof will be omitted. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary depending on the intention or custom of users or operators. Therefore, the definition should be made based on the contents throughout this specification.

<First Example>

In the first embodiment of the present disclosure, a method for the base station to set the number of OFDM symbols of the DMRS as a reference signal will be described. In the 5G system, the DMRS structure can be changed according to the transmission environment, and the overhead of the reference signal can be optimized according to the transmission environment. More specifically, it is necessary to improve the channel estimation performance by setting a large number of OFDM symbols to be used as DMRSs in a low SNR or high speed environment. On the contrary, in an environment of high SNR or low speed, it is necessary to improve transmission efficiency by reducing the reference signal overhead by using a small number of OFDM symbols as DMRS. When the reference signal is adaptively transmitted to the transmission environment as described above, unnecessary overhead of the reference signal can be minimized to maximize system performance.

As described above, the number of OFDM symbols of the DMRS can be set to be semi-static through higher layer signaling (RRC signaling), but when the transmission environment changes dynamically or the cell edge ), since the RRC signaling is transmitted by being included in a data channel having a lower coverage than the control channel, there may be a case in which the terminal cannot receive the RRC signaling, so L1 signaling transmitted through the control channel ( DCI signaling), it is necessary to dynamically set the number of OFDM symbols of the DMRS. Accordingly, an embodiment of the present disclosure proposes a method of dynamically setting the number of OFDM symbols of the DMRS, which is a reference signal, using L1 signaling (DCI signaling).

The following methods may be considered as a method of setting the number and location of OFDM symbols of the DMRS.

[Method 1]

The base station may explicitly set the number of uplink DMRS OFDM symbols to the terminal by using a new parameter of up to 2 bits in DCI. The number of bits set in the new parameter may be set based on other settings (DMRS symbol pattern, PUSCH mapping type, frequency hopping setting, etc.). More specifically, when the new parameter is set to “00”, the DMRS is transmitted at the OFDM symbol position ( ₁₀ ) of the first DMRS set in RRC signaling regardless of the number of symbols of the PUSCH or PDSCH allocated to one slot. When the new parameter is set to "01", "10", "11", it is related to the PUSCH mapping type determined through RRC signaling, the number of symbols of the PUSCH allocated to one slot determined by L1 signaling, and whether or not frequency hopping. The location of the OFDM symbol through which DMRS is transmitted is changed.

Specifically, when DMRS 1 symbol pattern, PUSCH mapping type A, and frequency hopping is not set, a new parameter of 2 bits is set in DCI. According to the set value, the number of OFDM symbols of the DMRS and the transmission location are as shown in [Table 8]. Is determined. In Table 8 below, l ₀ is the position of the first OFDM symbol of the DMRS set through higher signaling (RRC signaling) in the time resource in which the PUSCH is transmitted. For example, when l ₀ = 0, DMRS is transmitted in the first OFDM symbol among OFDM symbols set for PUSCH transmission. Specifically, if l ₀ =3, the new parameter represents 10, and the number of OFDM symbols set for PUSCH transmission is 11, among the OFDM symbols set for PUSCH transmission, as 3 and 9 are determined based on the following table. DMRS is transmitted in the 4th and 10th OFDM symbols.

[Table 8]

If it is a DMRS 1 symbol pattern, PUSCH mapping type B, and frequency hopping is not set, a new parameter of 2 bits is set in DCI, and the number of OFDM symbols in the DMRS and a transmission location are determined according to the set value as shown in [Table 9] below.

[Table 9]

When the DMRS 2 symbol pattern is PUSCH mapping type A and frequency hopping is not set, a new parameter is set to 1 bit in DCI, and the number of OFDM symbols of the DMRS and the transmission location are determined according to the set value as shown in [Table 10].

[Table 10]

If it is a DMRS 2 symbol pattern, PUSCH mapping type B, and frequency hopping is not set, a new parameter is set to 1 bit in DCI, and the number of OFDM symbols of the DMRS and a transmission location are determined according to the set value as shown in [Table 11].

[Table 11]

When the DMRS 1 symbol pattern, PUSCH mapping type A, and frequency hopping is set, a new parameter of 1 bit is set in DCI, and the number of OFDM symbols of the DMRS and the transmission location are determined according to the set value as shown in Table 12 below.

[Table 12]

When the DMRS 1 symbol pattern, PUSCH mapping type B, and frequency hopping is set, a new parameter is set to 1 bit in DCI, and the number of OFDM symbols of the DMRS and the transmission location are determined according to the set value as shown in [Table 13].

[Table 13]

The above method is simple and clear because the number of DMRS OFDM symbols is explicitly set, but by adding a new parameter, the total number of DCI bits may increase, thereby increasing overhead.

[Method 2]

Since Method 1 uses a maximum of 2 bits, the overhead of DCI increases, and thus a method of reducing the overhead of DCI that increases through a maximum of 1 bit is proposed.

In dynamically changing the number of OFDM symbols of the DMRS, the overhead of the reference signal may not be optimized, but one of the preset number of OFDM symbols can be selected through RRC signaling through 1 bit of DCI. However, in the environment corresponding to Tables 10, 11, 12 and 13 in [Method 1], only 1 bit is required, so it can be matched as it is. In the case of Tables 8 and 9, the base station sets the number of additional OFDM symbols of the DMRS to 1 and 3, for example, through RRC signaling (all combinations of selecting two from 0 to 3 are possible. In the case of Tables 8 and 9, if the new 1bit of DCI is "0", it corresponds to "01" in Method 1 and is "1" This may correspond to "11" in Method 1.

[Method 3]

Methods 1 and 2 are implicit based on the parameter values existing in the DCI because the total number of bits of the DCI may increase by adding a new parameter of the DCI in setting the number of OFDM symbols of the DMRS. We propose a method of setting the number of symbols in DMRS.

An environment requiring a large number of DMRS OFDM symbols generally corresponds to an environment in which the UE is moving at high speed or the UE is located at the cell edge and the base station has a low reception SNR as described above. Conversely, an environment in which performance can be guaranteed even with a small number of DMRS OFDM symbols corresponds to an environment in which the terminal moves at a low speed or the base station has a high reception SNR because the terminal is located in the cell center. Similar to the above environment, the MCS (modulation and coding scheme) value, which is one of the parameters of DCI, is suitable for the base station to set a high MCS index to the terminal at high reception SNR, and the base station to set a low MCS index to the terminal at low reception SNR It is appropriate to do it. Accordingly, the number of OFDM symbols of the DMRS can be changed according to the MCS index among the parameters of the DCI. Specifically, in a region in which a low MCS is set, a large number of DMRS OFDM symbols may be set to improve channel estimation performance, and in a region in which a high MCS is configured, a large number of DMRS OFDM symbols may be set. For example, the DMRS symbol may be determined by the number of OFDM symbols of the DMRS according to the MCS index as shown in Table 14 below, and may be determined by a corresponding value according to any of Tables 8 to 13 above. For example, if the MCS index is 0 and corresponds to Table 8 (DMRS 1 symbol pattern, PUSCH mapping type A, and frequency hopping is not set), the DMRS symbol according to the case where the value of DCI 2 bits in Table 8 is 11 Can be set.

[Table 14]

Method 3 is not limited to the above Table 14, and various combinations may appear within the basic principles of Method 3.

[Method 4]

As in Method 3, we propose a method of implicitly setting the number of DMRS symbols based on an existing parameter value of DCI. As described above, an environment requiring a large number of DMRS OFDM symbols corresponds to an environment in which the UE is moving at high speed or the UE is located at a cell edge and the base station has a low reception SNR. In such an environment, use a lower modulation order (1:pi/2 BPSK, 2:QPSK, 4:16QAM, etc.) than increasing the data rate by using a high modulation order (4:16 QAM, 6:64QAM, 8:256QAM). Thus, it is effective to increase the reliability. As existing MCS tables are divided into modulation orders 1, 2, 4, 6, and 8 as described above, MCS indexes not used in the environment with low reception SNR described above (e.g., modulation orders 4, 6, Since there are many MCS indexes corresponding to 8), it is possible to create a new MCS index table that is associated with the number of OFDM symbols of the DMRS while being composed of only modulation orders 1 and 2.

Considerations for designing a new MCS index table

One. Correspondence between the number of OFDM symbols in the DMRS and the MCS index

2. Composed of only low modulation order

For example, by designing a new MCS table, the following [Table 15] in which the MCS index corresponds only to modulation orders 1 and 2 may be designed.

[Table 15]

As an additional method, since the target coding rate and spectral efficiency are different for each MCS index, not only a low modulation order and many DMRS OFDM symbols are set at a low MCS index, but a new MCS table that is formed by mixing modulation order and DMRS OFDM symbols .

Considerations for designing a new MCS index table

One. Correspondence between the number of OFDM symbols in the DMRS and the MCS index

2. Composed of only low modulation order

3. Correspondence of modulation orders according to various target coding rates or spectral efficiency and the number of OFDM symbols of DMRS

For example, by designing a new MCS table, the following [Table 16] in which the MCS index corresponds only to modulation orders 1 and 2 may be designed.

[Table 16]

In addition, the existing MCS index table may be interpreted differently to lower the modulation order. More specifically, when the UE receives a setting to interpret the MCS index table differently through RRC signaling or DCI signaling, the Modulation order of the existing MCS index table can be lowered according to an equation or condition and analyzed. If the modulation order is analyzed by matching the number of OFDM symbols of the DMRS, even if a new MCS index table is not used as shown in [Table 15] or [Table 16], the same effects as in Tables 15 and 16 may be obtained.

Method 4 is not limited to the above [Tables 15 and 16], and various combinations may appear within the basic principles of Method 4.

4A is a flowchart illustrating an operation of a base station according to Method 1, Method 2, Method 3, and Method 4 according to the first embodiment.

First, the base station procedure is described, the base station may set the number of OFDM symbols of the DMRS through higher layer signaling or L1 signaling in step 401. The base station may set a resource for PUSCH transmission through higher layer signaling or L1 signaling in step 402. In this case, the number of OFDM symbols of the actually transmitted DMRS is determined according to the set number of OFDM symbols of the DMRS and resources for PUSCH transmission. Meanwhile, steps 401 and 402 are sequentially described for convenience of description, and the corresponding steps may be performed simultaneously or may be performed by changing the order of each step.

The base station can additionally set the number of OFDM symbols of the DMRS to the terminal through L1 signaling in step 403.

In step 404, the base station may determine the position of the OFDM symbol of the DMRS transmitted by the actual terminal and may perform channel estimation based on this.

The base station may decode and receive uplink data transmitted on the PUSCH in step 405.

4B is a flowchart illustrating an operation of a terminal according to Method 1, Method 2, Method 3, and Method 4 according to the first embodiment. The terminal may receive information on setting the number of OFDM symbols of the DMRS in step 406. The terminal may receive resource information for transmitting uplink data information in step 407. In step 408, the UE may receive a PDCCH including information for setting the number of OFDM symbols of the DMRS. In step 409, the terminal may determine the number of symbols and the location of the DMRS based on the number of OFDM symbols of the DMRS and resource information for transmitting the uplink data information received through the PDCCH in step 409. The terminal may transmit the DMRS in the resource designated in step 409.

[Method 5]

As described above, the environment in which the number of DMRS OFDM symbols needs to be dynamically changed corresponds to an environment in which a user wants to improve a decoding performance of data by improving a channel estimation performance when the terminal exists at a cell edge or when the reception SNR of the base station is low. The most important factor in the following environment is the transmit power of the terminal. When the terminal exists at the cell edge or the reception SNR of the base station is low, the base station may first be set to use the maximum transmission power of the terminal.

Even when the terminal uses the maximum transmission power, if the reception SNR of the base station is low, the base station can dynamically change the number of DMRS OFDM symbols to improve channel estimation performance and improve data decoding performance. When the UE uses the maximum transmission power, it means that a positive value is not used in the TPC command field included in the downlink control information DCI. That is, when both the base station and the terminal know that the terminal uses the maximum transmission power in the uplink, the base station does not set a positive TPC command field value to the terminal, so this value is meaningless. Based on this, when both the terminal and the base station know that the terminal uses the maximum transmission power, the number of OFDM symbols of the DMRS can be implicitly informed by using the positive value of the TPC command field.

As shown in Table 17 below, the base station may implicitly inform the number of OFDM symbols of the DMRS by using the positive value of the TPC command field.

[Table 17]

5A is a flowchart illustrating an operation of a base station according to Method 5 according to the first embodiment.

First, the base station procedure is described, the base station may set the number of OFDM symbols of the DMRS through higher layer signaling or L1 signaling in step 501. The base station may receive a power headroom report from the terminal in step 502. Meanwhile, steps 501 and 502 are sequentially described for convenience of description, and the corresponding steps may be performed simultaneously or may be performed by changing the order of each step. In step 503, the base station determines how much PUSCH transmission power the terminal is currently using relative to the maximum transmission power based on the power headroom report. When the base station determines that the terminal transmits the PUSCH with transmission power less than the maximum transmission power, the base station may determine that the terminal determines the number and location of OFDM symbols of the DMRS through RRC signaling in step 504 and transmits it. When the base station determines that the terminal transmits the PUSCH with the maximum transmission power, the base station sets the number of OFDM symbols of the DMRS to the terminal in step 505 by using the TPC command field included in the DCI as in Method 5. Then, the base station may determine that the terminal has determined and transmitted the number and position of OFDM symbols of the DMRS through L1 signaling in step 506. In step 507, the base station estimates a channel based on the number and position of OFDM symbols of the DMRS determined in steps 504 and 506. Finally, the base station may perform decoding and reception of the PUSCH based on the channel estimated in step 508.

5B is a flowchart illustrating an operation of a terminal according to Method 5 according to the first embodiment.

The UE may receive information on setting the number of OFDM symbols of the DMRS in step 511. The terminal may transmit a power headroom report, which is a difference between the power set by the base station to the maximum transmission power of the terminal in step 512, to the base station. Meanwhile, steps 511 and 512 are sequentially described for convenience of description, and the corresponding steps may be performed simultaneously or may be performed by changing the order of each step. The terminal compares the uplink power set by the base station in step 513 with the maximum transmission power of the terminal. When the terminal transmits the PUSCH with transmission power less than the maximum transmission power, the terminal may determine and determine the number and position of OFDM symbols of the DMRS through RRC signaling in step 514. When the UE transmits the PUSCH with the maximum transmission power, the UE may receive information on the number of OFDM symbols of the DMRS by using the TPC command field included in the DCI to the UE in step 515 as in Method 5. Then, the UE may determine and determine the number and location of OFDM symbols of the DMRS through L1 signaling in step 516. Finally, in step 517, the UE may transmit the DMRS based on the number and location of the OFDM symbols of the DMRS determined in steps 514 and 516.

The above-described Method 1, Method 2, Method 3, Method 4, and Method 5 may be operated in combination with each other.

According to the first embodiment of the present disclosure, by dynamically setting the number of symbols of the PUSCH DMRS according to the environment, the channel estimation performance may be improved and the data decoding performance may be improved.

In addition, the method of implicitly setting the number of DMRS symbols as in Methods 3 and 4 of the first embodiment can always be applied, but it is more efficient to apply this method only in an environment where the number of OFDM symbols of the DMRS is dynamically changed. In the case of methods 3 and 4, it may be necessary to enable (apply only to the configured DCI) or activate (continuously apply until release after configuration). This is proposed in the second embodiment.

The above methods are only examples related to the DMRS associated with the uplink data channel PUSCH, and the method of dynamically changing the number of OFDM symbols of the DMRS is not limited to the above example, and the downlink data channel PDSCH and the uplink control channel PUCCH , Or the downlink control channel PDSCH.

<Second Example>

As described above, in the case of implicitly indicating the number of DMRS symbols based on the existing parameters of DCI as in Methods 3 and 4 in the first embodiment, since there is an existing MCS index value, this method is not always applied. It may be more efficient to apply only in an environment where the number of OFDM symbols is to be changed. Therefore, it is necessary to apply a method of enabling (applied only to the configured DCI) or activation (continuously applied until release after configuration). More specifically, when the following conditions are satisfied, the number of OFDM symbols of the DMRS is dynamically changed only in the PUSCH set by the DCI, and activation is, when the following conditions are satisfied, the DMRS is dynamically activated in the PUSCHs set by all DCIs received before release. The number of OFDM symbols is changed.

The following methods may be considered as a method of enabling (activation) the change of the number of OFDM symbols of the DMRS.

[Method 1]

The base station can explicitly set whether to enable (or activate) the change in the number of uplink DMRS OFDM symbols to the terminal by using a new parameter 1 bit in DCI.

More specifically, in the case of enable/disable, when a new parameter is set to “0” (disable), the UE does not set the number of DMRS OFDM symbols through L1 signaling, or even if it is set, based on the number of DMRS OFDM symbols received through RRC signaling. As a result, the DMRS transmission position is determined and transmitted in the resource for PUSCH transmission. On the contrary, when the new parameter is set to "1" (enable), the UE uses the DMRS resource for PUSCH transmission based on the number of DMRS OFDM symbols set through L1 signaling instead of the number of DMRS OFDM symbols received through RRC signaling. The transmission location is determined and transmitted.

In the case of activation/release, if the new parameter is set to "0" (release), the UE does not set the number of DMRS OFDM symbols through L1 signaling, or even if the number of DMRS symbols is set through L1 signaling, DMRS OFDM received through RRC signaling. Based on the number of symbols, the DMRS transmission position is determined and transmitted in the resources for PUSCH transmission set by all DCIs received before activation. On the contrary, if the new parameter is set to "1" (activation), the UE will receive all DCIs received before release based on the number of DMRS OFDM symbols set through L1 signaling instead of the number of DMRS OFDM symbols received through RRC signaling. The DMRS transmission position is determined and transmitted in the set resource for PUSCH transmission.

[Method 2]

As described above, the environment in which the number of DMRS OFDM symbols needs to be dynamically changed corresponds to an environment in which a user wants to improve a decoding performance of data by improving a channel estimation performance when the terminal exists at a cell edge or when the reception SNR of the base station is low. The most important factor in the following environment is the transmit power of the terminal. When the terminal exists at the cell edge or the reception SNR of the base station is low, the base station may first be set to use the maximum transmission power of the terminal.

Even when the terminal uses the maximum transmission power, if the reception SNR of the base station is low, the base station can dynamically change the number of DMRS OFDM symbols to improve channel estimation performance and improve data decoding performance. When the UE uses the maximum transmission power, it means that a positive value is not used in the TPC command field included in the downlink control information DCI. That is, when both the base station and the terminal know that the terminal uses the maximum transmission power in the uplink, the base station does not set a positive TPC command field value to the terminal, so this value is meaningless. Based on this, when both the terminal and the base station know that the terminal uses the maximum transmission power, the number of OFDM symbols of the DMRS through L1 signaling may be enabled (or activated) using a positive value of the TPC command field.

For example, as shown in Table 18 below, the base station can enable (activation) or disable (release) the setting of the number of OFDM symbols of the DMRS implicitly or explicitly set through L1 signaling instead of the OFDM symbols of the DMRS determined through RRC signaling. have.

[Table 18]

The above-described method 1 and method 2 may be operated in combination with each other.

6A is a flowchart illustrating an operation of a base station according to the second embodiment.

First, a description of the base station procedure, the base station may set the number of OFDM symbols of the DMRS through higher layer signaling or L1 signaling in step 601. The base station may dynamically set information for enabling/disable (or activating/release) the OFDM symbol number change configuration of the DMRS in step 602. Meanwhile, steps 601 and 602 are sequentially described for convenience of description, and the corresponding steps may be performed simultaneously or may be performed by changing the order of each step. If the base station dynamically disables (or releases) the change of the number of OFDM symbols of the DMRS in step 602, the base station determines in step 603 that the terminal determines the number and location of the OFDM symbols of the DMRS through RRC signaling and determines that it has transmitted. can do. When the base station dynamically configures (or activates) the change in the number of OFDM symbols of the DMRS in step 602, the base station provides the terminal in step 604 based on a new parameter included in the DCI (Method 1 of Embodiment 1). Alternatively, the number of OFDM symbols of the DMRS is set explicitly by method 2) or implicitly based on the existing parameters of DCI (method 3 or method 4 of the first embodiment). Then, the base station may determine that the terminal has determined and transmitted the number and position of OFDM symbols of the DMRS through L1 signaling in step 605. In step 606, the base station estimates a channel based on the number and position of OFDM symbols of the DMRS determined in steps 603 and 605. Finally, the base station may decode and receive uplink data transmitted on the PUSCH based on the channel estimated in step 607.

6B is a flowchart illustrating an operation of a terminal according to the second embodiment.

The terminal may receive information on setting the number of OFDM symbols of the DMRS in step 611. In step 612, the UE may dynamically receive information for enabling/disable (or activating/release) the setting for changing the number of OFDM symbols of the DMRS. Meanwhile, steps 611 and 612 are sequentially described for convenience of description, and the corresponding steps may be performed at the same time or may be performed by changing the order of each step. In step 613, the UE dynamically determines whether to enable/disable (or activate/release) the change in the number of OFDM symbols of the DMRS. When the UE determines that the change in the number of OFDM symbols of the DMRS is dynamically disabled (or released) in step 613, the UE can determine and determine the number and location of OFDM symbols of the DMRS through RRC signaling in step 614. . If the UE determines that the number of OFDM symbols of the DMRS is dynamically enabled (or activated) in step 613, the UE is based on a new parameter included in the DCI in step 615 (method 1 or method of embodiment 1). 2) It is possible to receive information on the number of OFDM symbols of the DMRS explicitly or implicitly based on the existing parameters of DCI (Method 3 or 4 of Embodiment 1). Then, the UE may determine and determine the number and location of OFDM symbols of the DMRS in step 616. Finally, in step 617, the UE may transmit the DMRS based on the number and position of the OFDM symbols of the DMRS determined in steps 614 and 616.

The above methods are only examples related to the DMRS associated with the uplink data channel PUSCH, and the method of enabling (activation) to change the number of OFDM symbols of the DMRS is not limited to the above example, and the downlink data channel PDSCH, the uplink control channel PUCCH , Or the downlink control channel PDSCH.

<Third Example>

In the third embodiment of the present disclosure, a method for the base station to set the number of OFDM symbols of the DMRS as a reference signal in case of retransmission will be described. More specifically, in a low SNR or high-speed environment, the base station has a high probability of not receiving the initial transmission of the terminal, so the base station may request retransmission from the terminal. The UE determines whether to retransmit through toggle of the new data indicator value included in the DCI transmitted by the base station. As an example, if the new data indicator value of the DCI scheduled for initial transmission is 1, the new data indicator value included in the DCI scheduled for retransmission is 1, and if the new data indicator value included in the DCI is 0, the DCI is a new initial transmission. Schedule.

In this case, in the case of retransmission, since the reception SNR of the base station increases with an effect similar to that of repetition transmission, the channel estimation performance becomes important. Therefore, in the case of retransmission, it is necessary to improve the channel estimation performance by setting a large number of OFDM symbols to be used as DMRS. In this way, when the reference signal is adaptively transmitted according to the retransmission environment, the performance of signal transmission can be maximized by improving the channel estimation performance. Accordingly, an embodiment of the present disclosure proposes a method of setting the number of OFDM symbols of a DMRS, which is a reference signal, in case of retransmission.

The following methods may be considered as a method of setting the number and location of OFDM symbols of the DMRS.

[Method 1]

Unlike initial transmission, the number of OFDM symbols of the DMRS for retransmission may be set to be semi-static through higher layer signaling (RRC signaling). As described above, when the number of OFDM symbols of the DMRS of retransmission is different from the number of OFDM symbols of the initial transmission according to the environment, performance can be improved.Therefore, the new data indicator is toggled to change the number of DMRS OFDM symbols of initial transmission and retransmission If not (that is, if the previous transmission and the new data indicator value are the same), the number of OFDM symbols of the DMRS may be determined based on a configuration by higher layer signaling different from the initial transmission. For this, as an example, higher layer signaling for setting the DMRS may include information on the number of OFDM symbols for retransmission, which, for example, indicates information indicating the number of DMRS symbols during retransmission, or a difference between the number of DMRS symbols during initial transmission and retransmission. It may be information indicative of and is not limited to the above example.

[Method 2]

The base station may explicitly set the number of uplink DMRS OFDM symbols for retransmission to the terminal by using a new parameter included in DCI (for example, a maximum of 2 bits). The value of the set bit of the new parameter may be interpreted based on other settings (new data indicator, DMRS symbol pattern, PUSCH mapping type, frequency hopping setting, etc.). More specifically, if the new data indicator is not toggled (i.e., if the previous transmission and the new data indicator value are the same), when the new parameter is set to "00", RRC signaling regardless of the number of symbols of PUSCH or PDSCH allocated to one slot The DMRS is transmitted at the OFDM symbol position (l ₀ ) of the first DMRS set in FIG. The new parameters are "01", "10". When set to "11", the location of the OFDM symbol through which the DMRS is transmitted is changed in association with the PUSCH mapping type determined through RRC signaling, the number of symbols of the PUSCH allocated to one slot determined by L1 signaling, and frequency hopping. I can. This instruction method may be used in combination with the method of the first embodiment or/and the second embodiment described above.

[Method 3]

Since Method 2 uses a maximum of 2 bits, the overhead of DCI increases, and thus a method of reducing the overhead of DCI that increases through a maximum of 1 bit is proposed.

In dynamically changing the number of OFDM symbols of the DMRS in relation to retransmission, the overhead of the reference signal may not be optimized, but one of the preset number of OFDM symbols through RRC signaling may be selected through 1 bit of DCI. Specifically, if the new data indicator is not toggled (i.e., if the previous transmission and the new data indicator value are the same), the value indicated through 1 bit of DCI is among the two values (for example, 1, 3) set by the base station for RRC signaling. It can be determined by the number of DMRS OFDM symbols. The value set for the RRC signaling is only an example, and all combinations of selecting two of the numbers 0 to 3 may be set as RRC signaling. This instruction method may be used in combination with the method of the first embodiment or/and the second embodiment described above.

[Method 4]

In the above methods 2 and 3, in setting the number of OFDM symbols in the DMRS, the total number of bits of the DCI can be increased and overhead can be increased by adding a new parameter of the DCI. A method of setting the number of DMRS symbols for retransmission is proposed.

An environment requiring a large number of DMRS OFDM symbols generally corresponds to an environment in which the UE is moving at high speed or the UE is located at the cell edge and the base station has a low reception SNR as described above. Conversely, an environment in which performance can be guaranteed even when a small number of DMRS OFDM symbols is used corresponds to an environment in which the terminal moves at a low speed or the base station has a high reception SNR because the terminal is located in the cell center. Similar to the above environment, the MCS (modulation and coding scheme) value, which is one of the parameters of DCI, is suitable for the base station to set a high MCS index to the terminal at high reception SNR, and the base station to set a low MCS index to the terminal at low reception SNR It is appropriate to do it. Accordingly, the number of OFDM symbols of the DMRS can be changed according to the MCS index among the parameters of the DCI. Specifically, if the new data indicator is not toggled (i.e., if the previous transmission and the new data indicator value are the same), in an area in which a low MCS is set, a large number of DMRS OFDM symbols are set to improve channel estimation performance, and a high MCS is set. In the region, a large number of DMRS OFDM symbols may be set. This instruction method may be used in combination with the method of the first embodiment or/and the second embodiment described above.

[Method 5]

As in Method 4, we propose a method of implicitly setting the number of DMRS symbols based on the existing parameter values of DCI. As described above, an environment requiring a large number of DMRS OFDM symbols corresponds to an environment in which the UE is moving at high speed or the UE is located at a cell edge and the base station has a low reception SNR. In such an environment, use a lower modulation order (1:pi/2 BPSK, 2:QPSK, 4:16QAM, etc.) than increasing the data rate by using a high modulation order (4:16 QAM, 6:64QAM, 8:256QAM). Thus, it is effective to increase the reliability. As existing MCS tables are divided into modulation orders 1, 2, 4, 6, and 8 as described above, MCS indexes not used in the environment with low reception SNR described above (e.g., modulation orders 4, 6, Since there are many MCS indexes corresponding to 8), it is possible to create a new MCS index table that is associated with the number of OFDM symbols of the DMRS while being composed of only modulation orders 1 and 2.

Considerations for designing a new MCS index table

One. Correspondence between the number of OFDM symbols in the DMRS and the MCS index

2. Composed of only low modulation order

As an additional method, since the target coding rate and spectral efficiency are different for each MCS index, not only a low modulation order and many DMRS OFDM symbols are set at a low MCS index, but a new MCS table that is formed by mixing modulation order and DMRS OFDM symbols .

Considerations for designing a new MCS index table

One. Correspondence between the number of OFDM symbols in the DMRS and the MCS index

2. Composed of only low modulation order

3. Correspondence of modulation orders according to various target coding rates or spectral efficiency and the number of OFDM symbols of DMRS

In addition, the existing MCS index table may be interpreted differently to lower the modulation order. More specifically, if the terminal receives a setting to interpret the MCS index table differently through RRC signaling or DCI signaling, the modulation order of the existing MCS index table can be lowered according to an equation or condition and analyzed. The number of OFDM symbols of the DMRS can be matched to the modulation order.

Therefore, if the new data indicator is not toggled (i.e., if the previous transmission and the new data indicator value are the same), a new MCS index table is referred, and conversely, if the new data indicator is toggled (that is, if the new data indicator value is different from the previous transmission) You can refer to the existing MCS index table. This instruction method may be used in combination with the method of the first embodiment or/and the second embodiment described above. That is, the new MCS index table may be Table 15 or 16.

[Method 6]

As described above, the environment in which the number of DMRS OFDM symbols for retransmission needs to be dynamically changed corresponds to an environment in which a user wants to improve the decoding performance of data by improving the channel estimation performance when the terminal exists at the cell edge or the reception SNR of the base station is low. . The most important factor in the following environment is the transmit power of the terminal. In the initial transmission when the terminal exists at the cell edge or the reception SNR of the base station is low, the base station may first be set to use the maximum transmission power of the terminal.

Even when the terminal uses the maximum transmission power, if the reception SNR of the base station is low, the base station can dynamically change the number of DMRS OFDM symbols to improve channel estimation performance and improve data decoding performance. When the data is not decoded in the initial transmission, the fact that the terminal uses the maximum transmission power means that a positive value is not used in the TPC command field included in the downlink control information DCI for retransmission. That is, when both the base station and the terminal know that the terminal uses the maximum transmission power in the uplink, the base station does not set a positive TPC command field value to the terminal, so this value is meaningless. Based on this, if both the UE and the base station know that the UE uses the maximum transmission power and the new data indicator is not toggled (that is, if the new data indicator value is the same as the previous transmission), the OFDM of the DMRS is performed using the positive value of the TPC command field. You can implicitly inform the number of symbols.

The above-described Method 1, Method 2, Method 3, Method 4, Method 5, and Method 6 may be operated in combination with each other.

In addition, the method of implicitly setting the number of DMRS symbols as in Methods 4 and 5 of the third embodiment can always be applied, but it is more efficient to apply this method only in an environment where the number of OFDM symbols of the DMRS is dynamically changed. In the case of methods 4 and 5, it may be necessary to enable (apply only to the configured DCI) or activate (continuously apply until release after configuration). To this, the method proposed in the second embodiment described above may be applied.

The above methods are only examples related to the DMRS associated with retransmission of the uplink data channel PUSCH, and the method of dynamically changing the number of OFDM symbols of the DMRS is not limited to the above example, and may be applied to retransmission of the downlink data channel PDSCH.

7 is a block diagram of a terminal 700 according to an embodiment.

Referring to FIG. 7, the terminal 700 may include a transceiver 710, a processor 720, and a memory 730. According to a method of setting the DMRS, which is a reference signal, in the 5G communication system according to the above-described embodiment, the transmission/reception unit 710, the processor 720, and the memory 730 of the terminal 700 may operate. However, the components of the terminal 700 according to an embodiment are not limited to the above-described example. According to another embodiment, the terminal 700 may include more or fewer components than the above-described components. In addition, in a specific case, the transceiver 710, the processor 720, and the memory 730 may be implemented in the form of a single chip.

The transmission/reception unit 710 may be configured as a transmission unit and a reception unit according to another embodiment. The transceiver 710 may transmit and receive signals to and from the base station. The signal may include control information and data. To this end, the transceiver 710 may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transceiver 710 may receive a signal through a wireless channel, output it to the processor 720, and transmit a signal output from the processor 720 through a wireless channel.

The processor 720 may control a series of processes in which the terminal 700 can operate according to the above-described embodiment of the present disclosure. For example, the processor 720 is a method of setting the DMRS, which is a reference signal, according to an embodiment of the present disclosure, that is, a method of setting the number and location of OFDM symbols of the DMRS, a method of enabling (activation) changing the number of OFDM symbols of the DMRS, etc. Can be controlled differently.

The memory 730 may store control information or data, such as information on the number of OFDM symbols of the DMRS included in a signal acquired from the terminal 700, and data required for control of the processor 720 and when controlled by the processor 720. It may have an area for storing generated data and the like.

8 is a block diagram of a base station 800 according to an embodiment. Referring to FIG. 8, the base station 800 may include a transceiver 810, a processor 820, and a memory 830. According to a method of setting the DMRS, which is a reference signal, in the 5G communication system according to the above-described embodiment, the transceiver 810, the processor 820, and the memory 830 of the base station 800 may operate. However, components of the base station 800 according to an embodiment are not limited to the above-described example. According to another embodiment, the base station 800 may include more or fewer components than the above-described components. In addition, in certain cases, the transmission/reception unit 810, the processor 820, and the memory 830 may be implemented in the form of a single chip. It can also be configured. The transceiving unit 810 may transmit and receive signals with the terminal. The signal may include control information and data. To this end, the transceiver 810 may include an RF transmitter that up-converts and amplifies a frequency of a transmitted signal, and an RF receiver that amplifies a received signal with low noise and down-converts a frequency. In addition, the transmission/reception unit 810 may receive a signal through a wireless channel, output it to the processor 820, and transmit a signal output from the processor 820 through a wireless channel.

The processor 820 may control a series of processes so that the base station 800 may operate according to the above-described embodiment of the present disclosure. For example, the processor 820 provides a method of setting the DMRS, which is a reference signal, according to an embodiment, that is, a method of determining the number and location of OFDM symbols of the DMRS, a method of determining enable (activation) of changing the number of OFDM symbols of the DMRS, etc. It can be controlled differently.

The memory 830 may store control information, such as information on the number of OFDM symbols of the DMRS determined by the base station 800, data or control information received from the terminal, and data required for control of the processor 820 and the processor It may have an area for storing data, etc. generated during control in 820.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are only provided specific examples to easily explain the technical content of the present invention and to aid understanding of the present invention, and are not intended to limit the scope of the present invention. That is, it is apparent to those of ordinary skill in the art that other modifications based on the technical idea of the present invention can be implemented. In addition, each of the above embodiments may be combined and operated as necessary.

Claims (1)

In the control signal processing method in a wireless communication system,
Receiving a first control signal transmitted from a base station;
Processing the received first control signal; And
And transmitting a second control signal generated based on the processing to the base station.

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