KR20180081662A - Apparatus and method of reference signal transmission and reception for NR(New Radio) - Google Patents

Abstract

Provided is a method for transmitting a downlink reference signal for supporting efficient multiplexing between traffic having different QoS requirement such as eMBB, mMTC and URLLC in a next generation/5G wireless access network (NR) which has been discussed in 3GPP. The method comprises the steps of: puncturing eMBB data; shifting a DM-RS transmission symbol; and transmitting through a preceding OFDM symbol or a subsequent OFDM symbol with respect to the symbol.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for transmitting and receiving a reference signal for a next generation radio access network,

The present invention relates to a method for transmitting a downlink reference signal in a next generation / 5G radio access network (hereinafter referred to as "NR [New Radio]").

In one embodiment, a reference signal transmission / reception method for a next-generation radio access network includes performing eMBB data puncturing for URLLC data transmission in an OFDM symbol including a DM-RS among allocated eMBB downlink data channels, Shifting a DM-RS transmission symbol for modulation of data, and transmitting the shifting of the DM-RS transmission symbol through a preceding OFDM symbol or a subsequent OFDM symbol with respect to the punctured symbol.

FIG. 1 shows an example of symbol level alignment among different SCS.
2 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.
3 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Herein, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In this specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, the MTC terminal may refer to a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, the MTC terminal in this specification may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC-related operations. Alternatively, the MTC terminal may support enhanced coverage over the existing LTE coverage or a UE category / type defined in the existing 3GPP Release-12 or lower that supports low power consumption, or a newly defined Release-13 low cost low complexity UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, the base station or the cell in this specification is interpreted as a comprehensive meaning indicating a partial region or function covered by BSC (Base Station Controller) in CDMA, NodeB in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in the present specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

In systems such as LTE and LTE-advanced, a standard is constructed by configuring uplink and downlink based on a single carrier or carrier pair. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmit and receive points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multipoint transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiple transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

NR (New Radio)

3GPP recently approved the study item "Study on New Radio Access Technology" for research on next generation / 5G radio access technology, and based on this, RAN WG1 has frame structure, channel coding and modulation , waveform & multiple access scheme and so on. NR is required not only to improve the data transmission rate as compared with LTE, but also to design various requirements that are required according to granular and specific usage scenarios. In particular, enhancement mobile broadband (eMBB), massive MTC (MMTC) and URLLC (Ultra Reliable and Low Latency Communications) have been proposed as typical usage scenarios of NR. As a method to satisfy the requirements of each usage scenario, structure design is required. Specifically, eMBB, mMTC, and URLLC are considered as typical usage scenarios of NR that are being discussed in 3GPP. Since each usage scenario has different requirements for data rates, latency, coverage, etc., it is necessary to use different numerology (eg subcarrier) to efficiently satisfy the requirements of each usage scenario through frequency bands constituting an NR system there is a need for a method of effectively multiplexing a radio resource unit based on a space, a subframe, a TTI, etc.

One method is to support TDM, FDM, or TDM / FDM based multiplexing on a single NR carrier for numerology with different subcarrier spacing values, and to construct a scheduling unit in the time domain. The discussion on how to support the unit has been discussed. In this regard, NR is a type of time domain structure defined as a subframe. Reference numerology for defining the subframe duration is defined as 14 OFDM symbols of 15 kHz sub-carrier spacing (SCS) based normal CP overhead equivalent to LTE To define a single subframe duration. Thus, subframes in NR have a time duration of 1ms. However, unlike LTE, NR subframes are absolute reference time durations, and slots and mini-slots can be defined as time units that are the basis of actual uplink and downlink data scheduling. In this case, the number of OFDM symbols constituting the slot, y value is defined as y = 7 and 14 for the numerology having the SCS value of up to 60 kHz, and for the numerology having the SCS value larger than 60 kHz, y = Lt; / RTI >

Accordingly, any slot can be composed of 7 or 14 symbols, and all symbols are used for DL transmission according to the transmission direction of the corresponding slot, or all symbols are used for UL transmission, or the DL portion + (gap) + UL portion.

Also, a mini-slot composed of a smaller number of symbols than a corresponding slot is defined in an arbitrary numerology (or SCS), and a short-time time-domain scheduling interval is set for uplink / downlink data transmission or reception, A long-time time-domain scheduling interval for uplink / downlink data transmission and reception can be configured. Especially, in case of sending / receiving latency critical data such as URLLC, it is difficult to satisfy the latency requirement when scheduling is performed in 0.5 ms or 1 ms slot unit defined in a numerology based frame structure having a small SCS value such as 15 kHz Therefore, it is possible to define a mini-slot composed of a smaller number of OFDM symbols than the corresponding slot and to schedule the latency critical data such as the URLLC based on the defined mini-slot.

Alternatively, as described above, by supporting the numerology having different SCS values in one NR Carrier by multiplexing the TDM and / or FDM scheme, it is possible to reduce the number of slots based on the slot (or mini-slot) length defined for each numerology Scheduling of data according to latency requirement is also considered. For example, as shown in FIG. 1, when the SCS is 60 kHz, the symbol length is reduced to about 1/4 of that of the SCS 15 kHz. Therefore, when one slot is composed of 7 OFDM symbols, While the slot length based on 60 kHz is reduced to about 0.125 ms.

In this way, the NR is discussing how to satisfy the requirements of URLLC and eMBB by defining different SCSs or different TTI lengths.

As described above, in order to support the URLLC service in NR, it is necessary to support a short scheduling unit (or TTI, Transmission Time Interval) that can satisfy the latency boundary in the time domain. On the other hand, in the case of eMBB or mMTC, it is effective to apply the time-domain resource allocation unit, which is slightly longer than the URLLC usage scenario, in terms of control overhead and coverage in defining the scheduling unit in the time domain. In order to satisfy these various NR usage scenarios, numerology of subcarrier spacing (eg, larger subcarrier spacing such as 60kHz, 120kHa, etc.) and subcarrier spacing suitable for eMBB and mMTC (for example, 15kHz for eMBB or 3.75kHz for mMTC) in a mixed numerology structure supporting one numerical value via an NR carrier, or a subframe or slot or mini-slot in an NR carrier operating in any one numerology It is necessary to simultaneously support time-domain scheduling units having different lengths. As a method, semi-static time / frequency resource (or region) in which resource allocation is performed based on the optimal scheduling unit for each usage scenario is semi-static, and according to the usage scenario of each terminal, You can define resource allocation using time / frequency resources.

However, if the semi-static method is used to distinguish the regions according to the usage scenario, the efficiency in terms of the NR system may be somewhat reduced. For example, it may not be desirable to dedicate a time / frequency resource that supports a short time-domain scheduling unit in order to satisfy a sparse URLLC service in any NR cell where URLLC traffic spurs.

As a method to solve this problem, a scheduling method for satisfying a corresponding URLLC latency requirement using dynamic scheduling resources of eMBB or mMTC is required every time the corresponding URLLC traffic is generated.

To this end, NR is discussing a dynamic puncturing based eMBB / URLLC multiplexing method which punctures some OFDM symbols allocated to arbitrary eMBB or mMTC data channels and uses them for urgent URLLC data transmission / reception.

Specifically, when dynamic puncturing based multiplexing between eMBB and URLLC is applied, a method for notifying resources of a punctured resource for a URLLC data transmission to a corresponding eMBB terminal, includes a pre-notification method for indicating the corresponding information before puncturing, a post-notification method that indicates whether puncturing is performed after going transmission is considered.

For the description of the present invention, the eMBB terminal and the URLLC terminal generally apply the concept discussed in the 3GPP, but a detailed distinction is made as to whether the monitoring of the dynamic puncturing notification information is performed and the length of the time slot scheduling unit Lt; / RTI >

Specifically, when dynamic puncturing is applied, a UE requiring monitoring of notification information (or channel) for dynamic puncturing corresponds to the eMBB UE, and a UE that does not need monitoring for the UE may correspond to a URLLC UE. Also, the division between the eMBB terminal and the URLLC terminal can be determined by a subcarrier spacing (SCS) value set for the corresponding terminal and a time slot scheduling unit (e.g., slot, aggregate slot, mini-slot, etc.) For example, a UE having a long time-slot scheduling unit of a slot unit or an aggregate-slot unit below a certain SCS value is an eMBB terminal, has transmission numerology higher than a specific SCS value, or has a mini-slot A terminal having a short time slot scheduling unit of a unit may be a URLLC terminal. (Eg XMS) value of a time interval scheduling unit (or interval) for distinguishing between eMBB and URLLC, and a UE having a time interval scheduling unit larger than the threshold defines a time interval scheduling unit smaller than the threshold of the eMBB UE May be a URLLC terminal.

When a dynamic puncturing based multiplexing method is used, which uses a part of OFDM symbols of a resource for downlink data transmission for an eMBB terminal for URLLC transmission, it is necessary to define a processing method for DM-RS resources of the eMBB.

Specifically, when the slot-based scheduling is applied as a downlink data channel resource allocation unit for an arbitrary eMBB UE, in some of the 7 or 14 OFDM symbols constituting the corresponding slot, DM-RS transmission resources can be defined. However, when eMBB data puncturing for URLLC data transmission is performed through the corresponding symbol, it is necessary to define a processing method for the corresponding DM-RS resource.

As a first method for solving this problem, when eMBB data puncturing for URLLC data transmission is performed in an OFDM symbol including a DM-RS among already allocated eMBB downlink data channels, a corresponding DM-RS transmission symbol for modulating the corresponding eMBB data Can be defined as shifting. In this case, the corresponding DM-RS symbol shifting may be defined to be transmitted through a preceding OFDM symbol or a subsequent OFDM symbol with respect to a symbol punctured for URLLC data in a corresponding slot allocated for the corresponding eMBB data . When DM-RS shifting is performed, it is defined to indicate whether the corresponding DM-RS symbol is shifted through dynamic puncturing notification information for the corresponding eMBB UE, or when dynamic puncturing notification is implicitly performed in the DM-RS symbol, Based shifting or advance-based shifting can be defined. In addition, the corresponding shifting may vary according to the number of punctured OFDM symbols for URLLC, and the BS may indicate the shifting OFDM symbol gap to the eMBB UE.

As another method, DM-RS transmission for the corresponding eMBB data can be defined to be maintained even if puncturing is applied to the corresponding eMBB data. In this case, it is possible to indicate whether on-going eMBB data transmission is indicated in the corresponding resource through the resource allocation information for the corresponding URLLC terminal, thereby indicating whether to use the e-MBB DM-RS resource when transmitting / receiving URLLC data . That is, when the OFDM symbol allocated for the URLLC data transmission is an OFDM symbol including a DM-RS transmission resource in a slot structure serving as an eMBB data channel transmission unit, when data for a URLLC terminal is transmitted, the corresponding eMBB DM- It can be defined to indicate whether the resource is used or not.

2 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

2, a base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

The controller 1010 controls the overall operation of the base station according to the downlink reference signal transmission method for supporting efficient multiplexing between the traffic having different QoS requirements in the next generation / 5G radio access network according to the present invention described above.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

3 is a diagram illustrating a configuration of a user terminal according to another embodiment of the present invention.

3, a user terminal 1100 according to another embodiment of the present invention includes a receiving unit 1110, a control unit 1120, and a transmitting unit 1130.

The receiving unit 1110 receives downlink control information, data, and messages from the base station through the corresponding channel.

Also, the controller 1120 controls the overall operation of the UE according to the downlink reference signal reception method for supporting efficient multiplexing between the traffic having different QoS requirements in the next generation / 5G radio access network according to the present invention .

The transmitter 1130 transmits uplink control information, data, and a message to the base station through the corresponding channel.

The standard content or standard documents referred to in the above-mentioned embodiments constitute a part of this specification, for the sake of simplicity of description of the specification. Therefore, it is to be understood that the content of the above standard content and portions of the standard documents are added to or contained in the scope of the present invention.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (1)

A method of transmitting and receiving a reference signal for a next-generation radio access network,
Performing eMBB data puncturing for URLLC data transmission in an OFDM symbol including a DM-RS among the allocated eMBB downlink data channels;
Shifting a DM-RS transmission symbol for modulation of the eMBB data; And
And transmitting the shifting of the DM-RS transmission symbol through a preceding OFDM symbol or a subsequent OFDM symbol with respect to a punctured symbol.

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