KR20220029041A - Method and Apparatus for Transmitting And Receiving Downlink Signal And for Estimating Downlink Channel Using The Same - Google Patents

Abstract

Disclosed are methods and apparatuses for transmitting and receiving a downlink signal and for estimating a downlink channel by using the same. One aspect of the present invention relates to a base station transmitting downlink data, which comprises: a grant transmission unit transmitting first to M^th (M is a natural number no less than 2) downlink grant at a first slot; and a data transmission unit transmitting the downlink data and a demodulation reference signal (DMRS) at a slot indicated by each downlink grant. Accordingly, DMRS interpolation among a plurality of slots is performed to enhance the accuracy of channel estimation and minimize overhead caused by DMRS assignment.

Description

Downlink signal transmission and reception and downlink channel estimation method and apparatus using the same

This embodiment relates to a downlink signal transmission/reception and a downlink channel estimation method and apparatus using the same.

The content described in this section merely provides background information on the present invention and does not constitute the prior art.

In a 5G NR system (5th Generation New Radio system), a base station uses a Physical Downlink Shared Channel (PDSCH) to transmit downlink data to a terminal. The base station transmits a demodulation reference signal (DMRS) for PDSCH demodulation in the same set as a resource block (RB) through which the PDSCH is transmitted. The same precoding is applied to the DMRS and the PDSCH, and an antenna port used for DMRS transmission is the same as the PDSCH. That is, the DMRS and the PDSCH always experience the same channel characteristics, the UE estimates the downlink channel using the DMRS, and decodes the PDSCH based on this.

On the other hand, different precoding may be applied to every slot for transmitting downlink data. In the conventional 5G NR system, there is no method for the base station to separately inform the terminal of the precoding applied value, so inter-slot DMRS interpolation ) is impossible.

Therefore, in the conventional 5G NR system, inter-symbol DMRS interpolation is used instead of inter-slot DMRS interpolation. Referring to FIG. 1 , a method of additionally allocating one or more DMRSs in one slot and performing DMRS interpolation between symbols is used. However, when a plurality of DMRSs are allocated in one slot, there is a problem that downlink throughput (DL THP) decreases because the number of available symbols for the PDSCH is reduced.

Although a dynamic DMRS allocation technique has been developed to solve the above-mentioned problem, there is a problem in that a change in DMRS allocation is accompanied by a change in RRC (Radio Resource Control) configuration, thereby increasing the probability that the RRC connection is disconnected.

According to an embodiment of the present disclosure, by performing DMRS interpolation between a plurality of slots, downlink signal transmission/reception capable of increasing the accuracy of channel estimation and at the same time minimizing overhead due to DMRS allocation and downlink channel estimation using the same The main object is to provide a method and apparatus.

Furthermore, according to an embodiment of the present disclosure, the base station notifies the terminal that the same precoding is applied between a plurality of slots, thereby reducing the time required for the terminal to estimate the precoding, and a downlink signal capable of performing DMRS interpolation between slots A main object is to provide a method and apparatus for transmitting and receiving and estimating a downlink channel using the same.

According to an aspect of this embodiment, in a base station transmitting downlink data, the first to Mth (M is a natural number equal to or greater than 2) downlink grant in a first slot Grant transmission unit for transmitting (grant transmission unit); and a data transmission unit for transmitting downlink data and a demodulation reference signal (DMRS) in a slot indicated by each downlink grant.

According to another aspect of this embodiment, in a terminal performing downlink channel estimation, the first to Mth downlink grants (M is a natural number equal to or greater than 2) in a first slot (M is a natural number equal to or greater than 2) a grant reception unit for receiving a downlink grant; and an estimation unit for estimating a downlink channel using a demodulation reference signal (DMRS) received in a slot indicated by each downlink grant.

As described above, according to the embodiment of the present disclosure, by performing DMRS interpolation between a plurality of slots, it is possible to increase the accuracy of channel estimation and minimize overhead due to DMRS allocation. there is.

Furthermore, according to an embodiment of the present disclosure, since the base station notifies the terminal that the same precoding is applied between a plurality of slots, there is an effect that the terminal can shorten the time required for precoding estimation and perform DMRS interpolation between slots. .

1 is an exemplary diagram for explaining a downlink signal transmission structure of a 5G NR system.
2 is an exemplary diagram illustrating a downlink signal transmission structure according to an embodiment of the present disclosure.
3 is a block diagram schematically illustrating a base station according to an embodiment of the present disclosure.
4 is a block diagram schematically illustrating a terminal according to an embodiment of the present disclosure.
5 is a flowchart illustrating an operation of a base station according to an embodiment of the present disclosure.
6 is a flowchart illustrating an operation of a terminal according to an embodiment of the present disclosure.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the component from other components, and the essence, order, or order of the component is not limited by the term. Throughout the specification, when a part 'includes' or 'includes' a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. . In addition, the '... Terms such as 'unit' and 'module' mean a unit that processes at least one function or operation, which may be implemented as hardware or software or a combination of hardware and software.

On the other hand, in the following, based on the 5G NR system (5th Generation New Radio system), downlink signal transmission and reception and downlink channel estimation using a downlink grant (DL grant) including K ₀ parameters are described. , This is for convenience of description, and the present invention is expandable to other systems in addition to the 5G NR system. Accordingly, any person skilled in the art will be able to use the K ₀ parameter of the present disclosure and/or other information serving as a downlink grant in order to apply the present invention to other systems.

1 is an exemplary diagram for explaining a downlink signal transmission structure of a 5G NR system.

In the 5G NR system, downlink data is transmitted to the terminal through a physical downlink shared channel (PDSCH), which is a physical channel for downlink data transmission. In this case, scheduling information (hereinafter, DL grant) for downlink data is determined based on downlink control information (DCI) transmitted through a physical downlink control channel (PDCCH).

The DL grant includes time domain resource assignment information for downlink data. Accordingly, the base station may transmit information about a slot through which downlink data is transmitted to the terminal by using the DL grant.

In the 5G NR system, the base station transmits time domain resource allocation information to the terminal based on the configuration table. Specifically, the base station transmits, to the terminal, a configuration table including various combinations of information on slots in which downlink data is transmitted by using a radio resource control message (RRC message). Thereafter, the base station may transmit information about a slot in which downlink data is transmitted to the terminal by transmitting a specific index value of the configuration table to the terminal using DCI. Table 1 exemplarily shows a configuration table transmitted by the base station to the terminal using an RRC message, and the configuration table transmitted by the base station to the terminal is not limited to this example.

index dmrs-TypeA-Position PDSCH mapping type K ₀ S L One 2 Type A 0 2 12 3 Type A 0 3 11 2 2 Type A 0 2 10 3 Type A 0 3 9 3 2 Type A 0 2 9 3 Type A 0 3 8 4 2 Type A 0 2 7 3 Type A 0 3 6 5 2 Type A 0 2 5 3 Type A 0 3 4 6 2 Type B 0 9 4 3 Type B 0 10 4 7 2 Type B 0 4 4 3 Type B 0 6 4 8 2,3 Type B 0 5 7 9 2,3 Type B 0 5 2 10 2,3 Type B 0 9 2 11 2,3 Type B 0 12 2 12 2,3 Type A 0 One 13 13 2,3 Type A 0 One 6 14 2,3 Type A 0 2 4 15 2,3 Type B 0 4 7 16 2,3 Type B 0 8 4

In Table 1, the PDSCH mapping type is information indicating the location of a symbol in which DMRS is transmitted in a specific slot. Type A is a slot based allocation method, and the position of the DMRS is determined by the dmrs-TypeA-Position value with the boundary of the slot as the starting point. Type B is an allocation method for a mini-slot or a flexible slot, and a DMRS is located at a start symbol of a time domain resource region to which data is allocated.

In Table 1, K ₀ is information indicating the location of a slot in which downlink data is transmitted in a time domain resource. Specifically, K ₀ means an offset between a slot in which a DL grant is transmitted and a slot in which downlink data scheduled by the DL grant is transmitted. For example, when a DL grant is transmitted in slot n, a slot in which downlink data is transmitted is slot n+K ₀ . In Table 1, S denotes a start index of a symbol in which data is transmitted within one slot. L denotes the length of a symbol through which data is transmitted in one slot.

1 (a) shows an example in the case of K ₀ =0. The UE receives a DL grant transmitted through a PDCCH in slot n, and receives downlink data transmitted through a PDSCH in slot n based on the DL grant. Similarly, the UE receives the DL grant transmitted through the PDCCH in slot n+1, and receives downlink data transmitted through the PDSCH in the slot n+1 based on the DL grant.

Figure 1 (b) shows an example in the case of K ₀ =1. The UE receives a DL grant transmitted through the PDCCH in slot n, and receives downlink data transmitted through the PDSCH in slot n+1 based on the DL grant.

The conventional 5G NR system uses a method of transmitting a DL grant within the same slot for every slot for transmitting downlink data as shown in FIG. 1(a).

Meanwhile, in the 5G NR system, the DMRS configuration for the PDSCH can be flexibly configured, and is configured in consideration of a SU-MIMO (Single User MIMO) or MU-MIMO (Multi-User MIMO) environment. Hereinafter, main variables for DMRS configuration will be described.

The DMRS configuration is information indicating a resource used for DMRS in a frequency domain and is classified into type 1 or type 2.

DMRS length is information indicating the length of a symbol through which DMRS is transmitted. Single-symbol means transmitting DMRS using one symbol, and double-symbol means transmitting DMRS using two consecutive symbols.

DMRS Additional Positions is information indicating DMRS additional allocation. DMRS Additional Positions are determined by the RRC Parameter, dmrs-AdditionalPosition. pos 0 means allocating one DMRS in one slot, pos 1 means allocating two DMRSs in one slot, and pos 2 means allocating three DMRSs in one slot. By setting DMRS Additional Positions to pos 1 or pos 2, inter-slot DMRS interpolation is possible.

2 is an exemplary diagram illustrating a downlink signal transmission structure according to an embodiment of the present disclosure.

According to an embodiment of the present disclosure, downlink data transmitted in a plurality of slots is scheduled using a plurality of DL grants transmitted in a single slot. For example, referring to FIG. 2, a DL grant transmitted through PDCCH in symbol 0 of slot n schedules downlink data transmitted through PDSCH in slot n, and is transmitted through PDCCH in symbol 1 of slot n. The DL grant schedules downlink data transmitted through the PDSCH in slot n+1.

According to an embodiment of the present disclosure, a plurality of DL grants transmitted in a single slot are allocated to consecutive symbols in a single slot. For example, referring to FIG. 2 , a DL grant is allocated to symbol 0 and symbol 1 of slot n, respectively.

In order for the plurality of DL grants to respectively indicate different slots, each of the plurality of DL grants has different K ₀ values. For example, referring to FIG. 2 , a K ₀ value of a DL grant transmitted in symbol 0 is 0, and a K ₀ value of a DL grant transmitted in symbol 1 is 1. As such, a plurality of DL grants may have K ₀ values that increase in ascending order as a symbol index to which each DL grant belongs increases to indicate a plurality of consecutive slots. not.

According to an embodiment of the present disclosure, the same precoding is applied to a plurality of slots indicated by a plurality of DL grants transmitted in a single slot. For example, referring to FIG. 2 , the same precoding is applied to downlink data and DMRS transmitted through PDSCH in slot n and downlink data and DMRS transmitted through PDSCH in slot n+1.

Accordingly, when the UE detects a plurality of DL grants in a single slot, it can be recognized that the same precoding is applied to a plurality of slots indicated by the plurality of DL grants. Referring to FIG. 2 , the UE estimates a precoding value by decoding the DMRS received in slot n, and may utilize the estimated precoding value when decoding the DMRS received in slot n+1.

The UE can improve the accuracy of channel estimation by performing DMRS interpolation between slots indicated by a plurality of DL grants. Referring to FIG. 2 , the UE may perform interpolation between the DMRS allocated to symbol 2 of slot n and the DMRS allocated to symbol 2 of slot n+1. The UE may perform inter-slot DMRS interpolation using linear interpolation, etc., but is not limited to this example, and anyone skilled in the art may add or change another technique for DMRS interpolation.

As described above, according to an embodiment of the present disclosure, the base station notifies the terminal that the same precoding is applied between the plurality of slots using a plurality of DL grants transmitted in a single slot, thereby enabling inter-slot DMRS interpolation.

Meanwhile, the overhead due to the DL grant and DMRS allocation can be expressed as Equation (1).

은 슬롯 내 심볼 수,

는 PDCCH 전송 심볼 수,

는 DMRS 전송 심볼 수이다. here,

is the number of symbols in the slot,

is the number of PDCCH transmission symbols,

is the number of DMRS transmission symbols.

Referring to FIG. 2 , the overhead in slot n is 21.4%, and the overhead in slot n+1 is 7.1%. Meanwhile, referring to FIG. 1 , the overhead for performing inter-symbol interpolation is 21.4% in every slot. As described above, according to an embodiment of the present disclosure, it is possible to increase the PDSCH transmission rate by minimizing the overhead due to the DL grant and DMRS allocation.

3 is a block diagram schematically illustrating a base station according to an embodiment of the present disclosure.

Referring to FIG. 3 , the base station 300 according to an embodiment of the present disclosure includes all or part of a grant transmission unit 310 and a data transmission unit 320 . Not all blocks shown in FIG. 3 are essential components, and in another embodiment, some blocks included in the base station 300 may be added, changed, or deleted. That is, in the case of FIG. 3 , the base station 300 according to the present embodiment exemplarily shows components for transmitting a downlink signal, and the base station 300 has more than those shown for implementing other functions. It should be appreciated that it may have more or fewer components or different component configurations.

The grant transmitter 310 transmits a DL grant for scheduling downlink data. Specifically, the grant transmitter 310 transmits a plurality of DL grants in a single slot. For example, the grant transmitter 310 transmits M DL grants in slot n. In this case, the DL grant may be transmitted to the UE through the PDCCH.

According to an embodiment of the present disclosure, the grant transmitter 310 allocates a plurality of DL grants to consecutive symbols in a single slot. For example, the grant transmitter 310 allocates M DL grants to M consecutive symbols of slot n on a one-to-one basis. That is, one DL grant is allocated to one symbol.

The grant transmitter 310 transmits a plurality of DL grants each indicating different slots. To this end, each of the plurality of DL grants has different K ₀ values.

According to an embodiment of the present disclosure, a plurality of DL grants indicate a plurality of consecutive slots. For example, M DL grants indicate consecutive M slots. A plurality of DL grants may have K ₀ values that increase in an ascending order as a symbol index to which each DL grant belongs increases to indicate a plurality of consecutive slots.

The data transmitter 320 transmits downlink data and a demodulation reference signal to the terminal. Specifically, the data transmitter 320 transmits downlink data and a demodulation reference signal in a slot indicated by the DL grant. For example, the data transmitter 320 transmits downlink data and demodulation reference signals in M slots indicated by M DL grants. In this case, the downlink data may be transmitted to the terminal through the PDSCH.

According to an embodiment of the present disclosure, the data transmitter 320 applies the same precoding to a plurality of slots indicated by a plurality of DL grants transmitted in a single slot. For example, the data transmitter 320 applies the same precoding to the M slots indicated by the M DL grants. Specifically, the data transmitter 320 applies the same precoding to downlink data and DMRS transmitted in M slots.

4 is a block diagram schematically illustrating a terminal according to an embodiment of the present disclosure.

Referring to FIG. 4 , the terminal 400 according to an embodiment of the present disclosure includes all or part of a grant reception unit 410 and an estimation unit 420 . Not all blocks shown in FIG. 4 are essential components, and in another embodiment, some blocks included in the terminal 400 may be added, changed, or deleted. That is, the case of FIG. 4 exemplarily shows components for estimating a downlink channel by the terminal 400 according to the present embodiment, and the terminal 400 has more than those shown for implementing other functions. It should be appreciated that it may have more or fewer components or different component configurations.

The grant receiving unit 410 receives a DL grant for scheduling downlink data. Specifically, the grant receiving unit 410 receives a plurality of DL grants in a single slot. For example, the grant receiving unit 410 receives M DL grants in slot n. The grant receiving unit 410 is instructed by a slot in which downlink data is to be transmitted from the K ₀ parameter included in the DL grant.

The estimator 420 receives the DMRS in the slot indicated by the DL grant, and estimates the downlink channel using the received DMRS.

The estimator 420 according to an embodiment of the present disclosure performs DMRS interpolation between a plurality of slots. For example, the estimator 420 may interpolate the inter-slot downlink channel estimation using DMRS received in two or more consecutive slots.

It is assumed that the estimator 420 according to an embodiment of the present disclosure applies the same precoding to a plurality of slots indicated by a plurality of DL grants received by the grant receiver 410 in a single slot. The estimator 420 estimates a precoding value by decoding a DMRS received in a chronologically earlier slot among a plurality of slots, and may utilize the estimated precoding value when decoding a DMRS received in another slot. .

5 is a flowchart illustrating an operation of a base station according to an embodiment of the present disclosure.

The base station performs scheduling for time domain resource allocation of downlink data (S500). Downlink data is allocated to a plurality of slots, and the base station generates a DL grant including information on a slot in which downlink data is to be transmitted. Here, one DL grant includes information on one slot, and the base station generates a plurality of DL grants to notify the terminal of information on the plurality of slots.

The base station transmits a plurality of DL grants in a single slot (S510). Here, each DL grant includes a K ₀ parameter that is information indicating the location of a slot in which downlink data is transmitted. K ₀ is It means an offset between a single slot in which a DL grant is transmitted and a slot indicated by the corresponding DL grant.

The base station transmits downlink data and DMRS in the slot indicated by each DL grant (S520). In this case, the same precoding is applied to a slot indicated by a DL grant transmitted in a single slot.

6 is a flowchart illustrating an operation of a terminal according to an embodiment of the present disclosure.

The terminal receives a plurality of DL grants in a single slot (S600). The UE determines a slot in which downlink data is scheduled by using K ₀ included in the DL grant. For example, when a DL grant is received in slot n, it is determined that downlink data is scheduled in slot n+K ₀ . In this case, the UE determines a plurality of slots in which downlink data is scheduled by using a plurality of DL grants.

The UE receives the DMRS in the slot indicated by each DL grant (S610).

The UE performs downlink channel estimation using the received DMRS (S620). In this case, the UE assumes that the same precoding is applied between slots indicated by a plurality of DL grants received in a single slot. Accordingly, the terminal may estimate the precoding value by decoding the DMRS received in the chronologically earlier slot among the plurality of slots, and may utilize the estimated precoding value when decoding the DMRS received in another slot. Furthermore, the UE may perform DMRS interpolation between slots indicated by a plurality of DL grants received in a single slot.

Although it is described that each process is sequentially executed in FIGS. 5 and 6 , this is merely illustrative of the technical idea of an embodiment of the present invention. In other words, one of ordinary skill in the art to which an embodiment of the present invention pertains may change the order described in FIGS. Since the above process can be variously modified and modified by executing the above process in parallel, FIGS. 5 and 6 are not limited to a time series sequence.

Various implementations of the systems and techniques described herein may be implemented in digital electronic circuitry, integrated circuitry, field programmable gate array (FPGA), application specific integrated circuit (ASIC), computer hardware, firmware, software, and/or combination can be realized. These various implementations may include being implemented in one or more computer programs executable on a programmable system. The programmable system includes at least one programmable processor (which may be a special purpose processor) coupled to receive data and instructions from, and transmit data and instructions to, a storage system, at least one input device, and at least one output device. or may be a general-purpose processor). Computer programs (also known as programs, software, software applications or code) contain instructions for a programmable processor and are stored on a "computer-readable recording medium".

The computer-readable recording medium includes all types of recording devices in which data readable by a computer system is stored. These computer-readable recording media are non-volatile or non-transitory, such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, and storage device. medium, and may further include a transitory medium such as a data transmission medium. In addition, the computer-readable 　 recording medium is distributed in a computer system connected to a network, and computer-readable code may be stored and executed in a distributed manner.

Various implementations of the systems and techniques described herein may be implemented by a programmable computer. Here, the computer includes a programmable processor, a data storage system (including volatile memory, non-volatile memory, or other types of storage systems or combinations thereof) and at least one communication interface. For example, a programmable computer may be one of a server, a network appliance, a set-top box, an embedded device, a computer expansion module, a personal computer, a laptop, a Personal Data Assistant (PDA), a cloud computing system, or a mobile device.

The above description is merely illustrative of the technical idea of this embodiment, and various modifications and variations will be possible without departing from the essential characteristics of the present embodiment by those skilled in the art to which this embodiment belongs. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present embodiment.

300: base station 310: grant transmission unit
320: data transmission unit 400: terminal
410: grant receiver 420: estimator

Claims (10)

In the base station (base station) for transmitting downlink data (downlink data),
a grant transmission unit for transmitting first to Mth downlink grants (M is a natural number greater than or equal to 2) in a first slot; and
A data transmission unit that transmits downlink data and a demodulation reference signal (DMRS) in a slot indicated by each downlink grant
A base station comprising a. The method of claim 1,
The data transmission unit,
The base station, characterized in that the same precoding (precoding) is applied to the M slots indicated by the first to Mth downlink grants. The method of claim 1,
Each of the first to Mth downlink grants,
and a parameter indicating an offset between the first slot and a slot indicated by each downlink grant. The method of claim 1,
The first to Mth downlink grants are,
The base station, characterized in that allocated to M consecutive symbols (symbol) in the first slot. The method of claim 1,
The slots indicated by the first to Mth downlink grants are,
A base station, characterized in that there are M consecutive slots in the time domain. The method of claim 1,
The downlink grant is transmitted through a physical downlink control channel (PDCCH),
The downlink data is a base station, characterized in that transmitted through a physical downlink shared channel (Physical Downlink Shared Channel: PDSCH). In a terminal performing downlink channel estimation,
a grant reception unit for receiving first to Mth downlink grants (M is a natural number greater than or equal to 2) in a first slot; and
An estimation unit for estimating a downlink channel using a demodulation reference signal (DMRS) received in a slot indicated by each downlink grant
A terminal comprising a. 8. The method of claim 7,
The estimator is
Interpolation of downlink channel estimation between slots using demodulation reference signals received in two or more consecutive slots in the time domain among the slots indicated by the first to Mth downlink grants terminal characterized. 8. The method of claim 7,
The estimator is
In estimating the downlink channel, it is assumed that the same precoding is applied between M slots indicated by the first to Mth downlink grants. 8. The method of claim 7,
The first to Mth downlink grants are,
and a parameter indicating an offset between the first slot and a slot indicated by each downlink grant.

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