KR20180090429A - Apparatus and method of downlink control channel transmission and reception for NR(New Radio) UEs - Google Patents

Abstract

The present invention proposes a method for transmitting and receiving downlink control information for an arbitrary terminal in a next generation/5G wireless access network under discussion in 3GPP. In particular, proposed is a 2-stage downlink control information (DCI) transmission and reception method for transmitting a part of downlink control information through a downlink data channel (NR-PDSCH) instead of a downlink control channel (NR-PDCCH). The method includes the steps of: setting a modulation order for the transmission and reception of the DCI transmitted through the NR-PDCCH for each terminal or cell/beam by a base station; and transmitting the set modulation order through UE-specific or cell-specific/beam-specific RRC signaling.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for downlink control channel transmission and reception for a next generation wireless terminal,

The present embodiments relate to a method for transmitting and receiving downlink control information for an arbitrary terminal in a next generation / 5G radio access network (hereinafter referred to as "NR [New Radio]") under discussion in 3GPP.

In one aspect, the present embodiments provide a method for transmitting and receiving a downlink control channel for a next-generation wireless terminal, the method comprising: setting a modulation order for DCI transmission and reception for each UE or each cell / And transmitting the set modulation order via UE-specific or cell-specific / beam-specific RRC signaling.

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 this 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, the PDCCH, which is an embodiment of the present invention, may be applied to the PDCCH, and the PDCCH may be applied to the portion described with the EPDCCH.

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, when the SCS is 60 kHz as shown in FIG. 1, since the symbol length is reduced to about 1/4 of that of the SCS 15 kHz, if one slot is composed of 7 OFDM symbols, The length is 0.5ms while the slot length based on 60kHz is reduced to about 0.125ms.

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

<LTE PDCCH transmission / reception method>

In the LTE system, a Physical Downlink Control Channel (PDCCH) is defined to transmit and receive downlink control information for an arbitrary terminal. The control region for the PDCCH transmission is configured through the first one to three OFDM symbols of each subframe. The REs excluding the RE (Resource Element) s allocated for CRS, PCFICH, and PHICH transmission in the corresponding control region A REG (Resource Element Group) is constructed by grouping four REs consecutively on the frequency axis, and a method for obtaining a frequency diversity gain is to group nine non-consecutive interleaved REGs to form a CCE (Control Channel Element.

In LTE system, it is defined to use QPSK as fixed modulation scheme for transmitting PDCCH. In order to perform link adaptation according to the amount of DCI information and radio channel state transmitted for each UE, a number of CCEs, That is, to adjust the aggregation level. That is, the LTE base station is defined to be capable of using one CCE as a PDCCH transmission resource for transmitting a DCI for an arbitrary terminal, or by using 2, 4, and 8 CCEs, A separate search space is defined for each aggregation level and defined to perform blind decoding based on the defined search space.

&Lt; 2-stage DCI transmission method >

According to the DCI transmission method currently under discussion in the NR, in addition to the single-stage DCI transmission method of transmitting all the DCI information through the NR PDCCH, which is a downlink control channel, as in the existing LTE system, It is considered to introduce a 2-stage DCI transmission method in which some information is transmitted through the corresponding NR PDCCH and the remaining DCI information is transmitted through a subsequent NR PDCCH or NR PDSCH. When the 2-stage DCI method is applied, some information is transmitted through the 1 ^st stage DCI through the NR PDCCH when the downlink data channel scheduling control information is transmitted, and the 2 ^nd stage DCI including the remaining information is May be defined to be transmitted on the NR PDCCH or on the NR PDSCH region transmitted through the subsequent OFDM symbol of the NR PDCCH symbol with the 1 ^st stage DCI transmission.

However, in this case, the 2 ^nd stage DCI may be configured to include only allocation information other than information included in the 1 ^st stage DCI, or other cross-slot NR PDSCH allocation information or UL grant information may be additionally included.

The present invention proposes a 2 ^nd stage DCI configuration method for supporting a 2-stage DCI transmission / reception method.

Point 1: Modulation order configuration

In the existing LTE system, QPSK is applied collectively as a modulation order or modulation scheme for transmitting downlink control information (in the present invention, modulation order and modulation scheme will be used in the same sense). That is, QPSK is defined as a modulation scheme for downlink control channel transmission and reception for general LTE terminals such as PDCCH, EPDCCH, MPDCCH, and NPDCCH, and MTC and NB-IoT terminals.

However, in the case of the NR system, a scenario in which the beamforming gain is maximized based on the massive antenna ports in the high frequency band is also considered. Therefore, unlike the conventional LTE, the robust DCI transmission method based on the omni- Control information transmission that maximizes efficiency can be considered.

As a method for that, it is possible to define a modulation order for DCI transmission and reception for each UE to be set by the BS. Specifically, each base station defines a modulation order for DCI transmission / reception transmitted through the NR PDCCH for each UE or cell / beam, and transmits the UE-specific or cell-specific / beam-specific RRC signaling .

In other words, when a single-stage DCI transmission / reception method based on NR PDCCH is established in a DCI transmission / reception method for an arbitrary terminal similar to the existing LTE, DCI transmission / reception method using a DC- Modulation order for transmission / reception, or modulation order for DCI transmission / reception through NR PDCCH through UE-group specific or cell-specific / beam-specific higher layer signaling for each UE group or cell / beam Can be defined.

Or the modulation order for the NR-PDCCH is defined similarly to the conventional LTE so as to have an arbitrary fixed modulation order and (eg QPSK), for a UE 2-stage DCI transmission and reception method of the applied, for the 2 ^nd stage DCI transceiver it is possible to define that the base station only sets the modulation order implicitly or explicitly. 2, the modulation order ^nd stage DCI A method for setting through explicit signalling, according as the base station configuring the 1 ^st DCI, by defining an information area for setting the modulation order corresponding 2 ^nd stage DCI, it the 2 ^nd through stage DCI can be defined to dynamically set the modulation order. Alternatively, it is possible to define the modulation order for the corresponding 2 ^nd stage DCI to be semi-static by UE-specific higher layer signaling or UE-group specific / cell-specific / beam-specific higher layer signaling for each UE have. The second as a method for implicit set the modulation order ^nd stage DCI, applicable to two-stage DCI to be sent to the NR PDSCH modulation order comprising the assignment via the transmission and reception through the 1 ^st stage DCI, the 2 ^nd stage DCI of the modulation order can be defined to be implicitly determined as a function of the modulation order of the NR PDSCH (e.g., the same modulation order as the modulation order of the corresponding NR PDSCH).

Point 2. 2 ^nd  stage Of DCI  How to set the aggregation level or amount of resource allocation

In the case of DCI transmission through the NR PDCCH as the downlink control channel, NR-REG based on 1 OFDM x 1 PRB is defined, and NR-CCEs that are transmission units of the NR PDCCH are defined by grouping arbitrary M NR-REGs Respectively. In the case of a UE receiving a DCI through an NR-PDCCH, a UE-specific search space composed of NR PDCCH candidates having different aggregation levels for link adaptation is configured similar to LTE, It is possible to receive the DCI for the UE by performing blind decoding on the UE. However, when the 2-stage DCI transmission / reception method is applied, it is necessary to define a resource allocation method in the NR-PDSCH for 2 ^nd stage DCI. In particular, it is necessary to define the resource allocation method for the 2 ^nd stage DCI transceiver transmitted within the NR-PDSCH area or NR PDCCH region in order not to cause an additional blind decoding complexity of the UE for the 2 ^nd stage DCI received . In the present invention, a method of explicitly or implicitly setting the amount of radio resources allocated for 2 ^nd stage DCI transmission / reception is proposed.

Specifically, an implicit signaling method for allocating the amount of radio resources in an NR PDSCH region or an NR PDCCH region for a 2 ^nd stage DCI transmission / reception of a NR terminal in which a 2-stage DCI transmission / reception method is applied, includes 1 ^st stage DCI and 2 ^nd stage A function that parameterizes the payload size ratio of the DCI and the aggregation level at which the corresponding 1 ^st stage DCI is transmitted, or a aggregation level at which the corresponding 1 ^st stage DCI is transmitted as a parameter, is used as a radio resource for transmission and reception of the corresponding 2 ^nd stage DCI (Eg, number of NR CCEs or aggregation level or number of symbols or number of sub-carriers, etc. used for 2 ^nd stage DCI transmissions in the NR PDCCH or NR PDSCH region).

In this case, the ratio between the 1 ^st stage DCI and the 2 ^nd stage DCI is defined as an information region defined to be transmitted through the 1 ^st stage DCI among the scheduling information for NR PDSCH allocation, and information defined to be transmitted through the 2 ^nd stage DCI Can be determined by the payload size of the area. Or NR PDSCH allocation information based on the UL PDSCH allocation that is scheduled through the 1 ^st stage DCI through the 2 ^nd stage DCI as well as additional UL grand or cross-slot based NR PDSCH allocation information, ^{The information such as the} presence of additional scheduling DCIs transmitted through the ^nd stage DCI, additional scheduling DCI types (eg, UL grant or cross-slot PDSCH assignment DCI), and the number of additional scheduling DCIs are signaled through the corresponding 1 ^st stage DCI ^And the payload size of the 2 ^nd stage DCI can be determined based on this.

2-stage DCI as the explicit signaling method for transmitting and receiving method is applied to allocate the amount of radio resources in the 2 ^nd stage DCI NR PDSCH region within or NR PDCCH regions for transmission and reception of NR terminal, the first through ^st DCI 2 ^nd stage DCI The mobile station can signal the radio resource allocation related information. In one embodiment, as described above, the number of additional scheduling DCIs, such as UL grant or cross-slot PDSCH assignment DCI included in the 2 ^nd stage DCI, is signaled, or 2 ^nd stage DCI We can define a quantized 2 ^nd stage DCI payload size table to indicate the payload size and signaling the corresponding table index. Or the number of PRBs or number of OFDM symbols or number of CCEs allocated for 2 ^nd stage DCI, or the aggregation level through the corresponding 1 ^st stage DCI and signaling to the corresponding UE.

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 above-described downlink control channel transmission / reception for the next generation wireless terminal according to the present invention.

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.

In addition, the controller 1120 controls the overall operation of the UE according to the above-described downlink control channel transmission / reception for the next generation wireless terminal 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 for transmitting and receiving a downlink control channel for a next generation wireless terminal,
Setting a modulation order for DCI transmission / reception through the NR PDCCH for each UE or each cell / beam; And
And transmitting the set modulation order via UE-specific or cell-specific / beam-specific RRC signaling.

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