WO2018212557A1 - Method and device for receiving downlink signal in wireless communication system - Google Patents

Abstract

A method for receiving a downlink signal in a wireless communication system according to an embodiment of the present invention is performed by a terminal, and may comprise the steps of: receiving, from a base station, a dynamic change configuration into a predetermined transmission scheme related to a short transmission time interval (sTTI)-based downlink operation; when the dynamic change configuration is received, detecting a downlink control information format including a field related to the dynamic change; and when a value of the field indicates the predetermined transmission scheme, receiving a signal on a downlink data channel according to the predetermined transmission scheme.

Description

Method for receiving downlink signal in wireless communication system and apparatus therefor

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for receiving a downlink signal supporting a plurality of transmission time intervals, a plurality of processing time or a plurality of numerologies, and the like.

Latency in packet data is one of the important performance metrics, and reducing it and providing faster Internet access to end users is not only in LTE, but also in the design of next-generation mobile systems, the so-called new RAT. One of the important tasks.

The present invention deals with the contents related to the downlink signal reception or transmission scheme in a wireless communication system supporting such a reduction in latency.

The present invention relates to downlink reception of a terminal having a plurality of transmission time intervals, a plurality of processing times or a plurality of numerologies, and the like in a carrier aggregation system.

Technical problems to be achieved in the present invention are not limited to the above technical problems, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

In a method for receiving a downlink signal in a wireless communication system according to an embodiment of the present invention, the method is performed by a terminal and is associated with a short transmission time interval (sTTI) based downlink operation. Receiving from the base station a dynamic change setting to a predetermined transmission scheme; When the dynamic change setting is received, detecting a downlink control information format including a field related to the dynamic change; And if a value of the field indicates the predetermined transmission scheme, receiving a signal on a downlink data channel according to the predetermined transmission scheme.

Additionally or alternatively, the dynamic change setting may be set for each TTI length.

Additionally or alternatively, the dynamic change configuration may be set regardless of the transmission mode associated with the sTTI based downlink operation.

Additionally or alternatively, the predetermined transmission scheme may be transmit diversity.

Additionally or alternatively, the method may include reporting terminal capability to the base station as to whether to support dynamic change to the predetermined transmission scheme.

Additionally or alternatively, the terminal capability report may be defined for each TTI length.

Additionally or alternatively, the downlink control information format schedules downlink data channels in a plurality of TTIs, and hybrid automatic repeat request (HARQ) -ACK (acknowledgment) for downlink data channels in the plurality of TTIs. The response may be transmitted separately at a timing corresponding to each of the downlink data channels in the plurality of TTIs.

Additionally or alternatively, the downlink control information format schedules downlink data channels in a plurality of TTIs, and hybrid automatic repeat request (HARQ) -ACK (acknowledgment) for downlink data channels in the plurality of TTIs. The response can be bundled or aggregated and sent.

Additionally or alternatively, the HARQ-ACK response may be previously determined from a resource determined by a lowest control channel element (CCE) index of the downlink control information format or a resource connected to states of an ACK / NACK resource indicator (ARI) field. It may be transmitted on resources that are separated by the determined offset.

Additionally or alternatively, an aggregation level and / or number of monitoring candidates to be used in the resource block set for monitoring the downlink control information format and the resource block set for monitoring the downlink control information format may be set.

In a terminal for receiving a downlink signal in a wireless communication system according to another embodiment of the present invention, the terminal includes a receiver and a transmitter; And a processor for controlling the receiver and the transmitter, the processor receiving a dynamic change setting from a base station to a predetermined transmission scheme related to a short transmission time interval (sTTI) based downlink operation, When the dynamic change setting is received, a downlink control information format including a field related to the dynamic change is detected, and when a value of the field indicates the predetermined transmission method, downlink data according to the predetermined transmission method. A signal can be received on the channel.

Additionally or alternatively, the dynamic change setting may be set for each TTI length.

Additionally or alternatively, the dynamic change configuration may be set regardless of the transmission mode associated with the sTTI based downlink operation.

Additionally or alternatively, the predetermined transmission scheme may be transmit diversity.

Additionally or alternatively, the processor may report to the base station the terminal capabilities as to whether it supports dynamic change to the predetermined transmission scheme.

Additionally or alternatively, the terminal capability report may be defined for each TTI length.

Additionally or alternatively, the downlink control information format schedules downlink data channels in a plurality of TTIs, and hybrid automatic repeat request (HARQ) -ACK (acknowledgment) for downlink data channels in the plurality of TTIs. The response may be transmitted separately at a timing corresponding to each of the downlink data channels in the plurality of TTIs.

Additionally or alternatively, the downlink control information format schedules downlink data channels in a plurality of TTIs, and hybrid automatic repeat request (HARQ) -ACK (acknowledgment) for downlink data channels in the plurality of TTIs. The response can be bundled or aggregated and sent.

Additionally or alternatively, the HARQ-ACK response may be previously determined from a resource determined by a lowest control channel element (CCE) index of the downlink control information format or a resource connected to states of an ACK / NACK resource indicator (ARI) field. It may be transmitted on resources that are separated by the determined offset.

Additionally or alternatively, an aggregation level and / or number of monitoring candidates to be used in the resource block set for monitoring the downlink control information format and the resource block set for monitoring the downlink control information format may be set.

The problem solving methods are only a part of embodiments of the present invention, and various embodiments reflecting the technical features of the present invention are based on the detailed description of the present invention described below by those skilled in the art. Can be derived and understood.

According to embodiments of the present invention, downlink reception may be efficiently performed.

Effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide an embodiment of the present invention and together with the description, illustrate the technical idea of the present invention.

1 illustrates an example of a radio frame structure used in a wireless communication system.

2 illustrates an example of a downlink / uplink (DL / UL) slot structure in a wireless communication system.

3 illustrates a downlink (DL) subframe structure used in a 3GPP LTE / LTE-A system.

4 illustrates an example of an uplink (UL) subframe structure used in a 3GPP LTE / LTE-A system.

5 shows a decrease in TTI length with a decrease in user plane latency.

6 illustrates an example in which a plurality of short TTIs are set in one subframe.

7 shows a DL subframe structure consisting of short TTIs of several lengths (number of symbols).

8 shows a DL subframe structure consisting of short TTIs of two symbols or three symbols.

9 shows a block diagram of an apparatus for implementing an embodiment (s) of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details.

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

In the present invention, a user equipment (UE) may be fixed or mobile, and various devices which transmit and receive user data and / or various control information by communicating with a base station (BS) belong to this. The UE may be a terminal equipment (MS), a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), or a wireless modem. It may be called a modem, a handheld device, or the like. In addition, in the present invention, a BS generally refers to a fixed station communicating with the UE and / or another BS, and communicates with the UE and another BS to exchange various data and control information. BS includes Advanced Base Station (ABS), Node-B (NB), evolved-NodeB (eNB), Base Transceiver System (BTS), Access Point, Processing Server (PS), Transmission Point (TP) May be called in other terms. In the following description of the present invention, BS is collectively referred to as eNB.

In the present invention, a node refers to a fixed point capable of transmitting / receiving a radio signal by communicating with a user equipment. Various forms of eNBs may be used as nodes regardless of their name. For example, the node may be a BS, an NB, an eNB, a pico-cell eNB (PeNB), a home eNB (HeNB), a relay, a repeater, and the like. Also, the node may not be an eNB. For example, it may be a radio remote head (RRH), a radio remote unit (RRU). RRHs, RRUs, etc. generally have a power level lower than the power level of the eNB. Since RRH or RRU, RRH / RRU) is generally connected to an eNB by a dedicated line such as an optical cable, RRH / RRU and eNB are generally compared to cooperative communication by eNBs connected by a wireless line. By cooperative communication can be performed smoothly. At least one antenna is installed at one node. The antenna may mean a physical antenna or may mean an antenna port, a virtual antenna, or an antenna group. Nodes are also called points. Unlike conventional centralized antenna systems (ie, single node systems) where antennas are centrally located at base stations and controlled by one eNB controller, in a multi-node system A plurality of nodes are typically located farther apart than a predetermined interval. The plurality of nodes may be managed by one or more eNBs or eNB controllers that control the operation of each node or schedule data to be transmitted / received through each node. Each node may be connected to the eNB or eNB controller that manages the node through a cable or dedicated line. In a multi-node system, the same cell identifier (ID) may be used or different cell IDs may be used for signal transmission / reception to / from a plurality of nodes. When a plurality of nodes have the same cell ID, each of the plurality of nodes behaves like some antenna group of one cell. If the nodes have different cell IDs in the multi-node system, such a multi-node system may be regarded as a multi-cell (eg, macro-cell / femto-cell / pico-cell) system. When the multiple cells formed by each of the plurality of nodes are configured to be overlaid according to coverage, the network formed by the multiple cells is particularly called a multi-tier network. The cell ID of the RRH / RRU and the cell ID of the eNB may be the same or may be different. When the RRH / RRU uses eNBs with different cell IDs, both the RRH / RRU and the eNB operate as independent base stations.

In the multi-node system of the present invention to be described below, one or more eNB or eNB controllers connected with a plurality of nodes may control the plurality of nodes to simultaneously transmit or receive signals to the UE via some or all of the plurality of nodes. Can be. Although there are differences between multi-node systems depending on the identity of each node, the implementation of each node, etc., these multi-nodes in that multiple nodes together participate in providing communication services to the UE on a given time-frequency resource. The systems are different from single node systems (eg CAS, conventional MIMO system, conventional relay system, conventional repeater system, etc.). Accordingly, embodiments of the present invention regarding a method for performing data cooperative transmission using some or all of a plurality of nodes may be applied to various kinds of multi-node systems. For example, although a node generally refers to an antenna group spaced apart from another node by a predetermined distance or more, embodiments of the present invention described later may be applied even when the node means any antenna group regardless of the interval. For example, in case of an eNB equipped with a cross polarized (X-pol) antenna, the eNB may control the node configured as the H-pol antenna and the node configured as the V-pol antenna, and thus embodiments of the present invention may be applied. .

Nodes that transmit / receive signals through a plurality of Tx / Rx nodes, transmit / receive signals through at least one node selected from a plurality of Tx / Rx nodes, or transmit downlink signals A communication scheme that enables different nodes to receive the uplink signal is called multi-eNB MIMO or CoMP (Coordinated Multi-Point TX / RX). Cooperative transmission schemes among such cooperative communication between nodes can be largely classified into joint processing (JP) and scheduling coordination. The former may be divided into joint transmission (JT) / joint reception (JR) and dynamic point selection (DPS), and the latter may be divided into coordinated scheduling (CS) and coordinated beamforming (CB). DPS is also called dynamic cell selection (DCS). Compared to other cooperative communication techniques, more diverse communication environments may be formed when JP is performed among cooperative communication techniques among nodes. JT in JP refers to a communication scheme in which a plurality of nodes transmit the same stream to the UE, and JR refers to a communication scheme in which a plurality of nodes receive the same stream from the UE. The UE / eNB combines the signals received from the plurality of nodes to recover the stream. In the case of JT / JR, since the same stream is transmitted to / from a plurality of nodes, the reliability of signal transmission may be improved by transmit diversity. DPS in JP refers to a communication technique in which a signal is transmitted / received through one node selected according to a specific rule among a plurality of nodes. In the case of DPS, since a node having a good channel condition between the UE and the node will be selected as a communication node, the reliability of signal transmission can be improved.

Meanwhile, in the present invention, a cell refers to a certain geographic area in which one or more nodes provide a communication service. Therefore, in the present invention, communication with a specific cell may mean communication with an eNB or a node that provides a communication service to the specific cell. In addition, the downlink / uplink signal of a specific cell means a downlink / uplink signal from / to an eNB or a node that provides a communication service to the specific cell. The cell providing uplink / downlink communication service to the UE is particularly called a serving cell. In addition, the channel state / quality of a specific cell means a channel state / quality of a channel or communication link formed between an eNB or a node providing a communication service to the specific cell and a UE. In a 3GPP LTE-A based system, a UE transmits a downlink channel state from a specific node on a channel CSI-RS (Channel State Information Reference Signal) resource to which the antenna port (s) of the specific node is assigned to the specific node. Can be measured using CSI-RS (s). In general, adjacent nodes transmit corresponding CSI-RS resources on CSI-RS resources orthogonal to each other. Orthogonality of CSI-RS resources means that the CSI-RS is allocated by CSI-RS resource configuration, subframe offset, and transmission period that specify symbols and subcarriers carrying the CSI-RS. This means that at least one of a subframe configuration and a CSI-RS sequence for specifying the specified subframes are different from each other.

In the present invention, Physical Downlink Control CHannel (PDCCH) / Physical Control Format Indicator CHannel (PCFICH) / PHICH (Physical Hybrid automatic retransmit request Indicator CHannel) / PDSCH (Physical Downlink Shared CHannel) are respectively DCI (Downlink Control Information) / CFI ( Means a set of time-frequency resources or a set of resource elements that carry downlink format ACK / ACK / NACK (ACKnowlegement / Negative ACK) / downlink data, and also a Physical Uplink Control CHannel (PUCCH) / Physical (PUSCH) Uplink Shared CHannel / PACH (Physical Random Access CHannel) means a set of time-frequency resources or a set of resource elements that carry uplink control information (UCI) / uplink data / random access signals, respectively. PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH RE or the time-frequency resource or resource element (RE) assigned to or belonging to PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH, respectively. The PDCCH / PCFICH / PHICH / PDSCH / PUCCH / PUSCH / PRACH resource is referred to below: The expression that the user equipment transmits the PUCCH / PUSCH / PRACH is hereinafter referred to as uplink control information / uplink on or through PUSCH / PUCCH / PRACH, respectively. It is used in the same sense as transmitting a data / random access signal, and the expression that the eNB transmits PDCCH / PCFICH / PHICH / PDSCH is used for downlink data / control information on or through PDCCH / PCFICH / PHICH / PDSCH, respectively. It is used in the same sense as sending it.

1 illustrates an example of a radio frame structure used in a wireless communication system. In particular, Figure 1 (a) shows a frame structure for frequency division duplex (FDD) used in the 3GPP LTE / LTE-A system, Figure 1 (b) is used in the 3GPP LTE / LTE-A system The frame structure for time division duplex (TDD) is shown.

Referring to FIG. 1, a radio frame used in a 3GPP LTE / LTE-A system has a length of 10 ms (307200 Ts), and is composed of 10 equally sized subframes (SF). Numbers may be assigned to 10 subframes in one radio frame. Here, Ts represents a sampling time and is represented by Ts = 1 / (2048 * 15 kHz). Each subframe has a length of 1 ms and consists of two slots. 20 slots in one radio frame may be sequentially numbered from 0 to 19. Each slot is 0.5ms long. The time for transmitting one subframe is defined as a transmission time interval (TTI). The time resource may be classified by a radio frame number (also called a radio frame index), a subframe number (also called a subframe number), a slot number (or slot index), and the like.

The radio frame may be configured differently according to the duplex mode. For example, in the FDD mode, since downlink transmission and uplink transmission are divided by frequency, a radio frame includes only one of a downlink subframe or an uplink subframe for a specific frequency band. In the TDD mode, since downlink transmission and uplink transmission are separated by time, a radio frame includes both a downlink subframe and an uplink subframe for a specific frequency band.

Table 1 illustrates a DL-UL configuration of subframes in a radio frame in the TDD mode.

DL-UL configuration

Downlink-to-Uplink Switch-point periodicity

Subframe number

0

One

2

3

4

5

6

7

8

9

0

5 ms

D

S

U

U

U

D

S

U

U

U

One

5 ms

D

S

U

U

D

D

S

U

U

D

2

5 ms

D

S

U

D

D

D

S

U

D

D

3

10 ms

D

S

U

U

U

D

D

D

D

D

4

10 ms

D

S

U

U

D

D

D

D

D

D

5

10 ms

D

S

U

D

D

D

D

D

D

D

6

5 ms

D

S

U

U

U

D

S

U

U

D

In Table 1, D represents a downlink subframe, U represents an uplink subframe, and S represents a special subframe. The singular subframe includes three fields of Downlink Pilot TimeSlot (DwPTS), Guard Period (GP), and Uplink Pilot TimeSlot (UpPTS). DwPTS is a time interval reserved for downlink transmission, and UpPTS is a time interval reserved for uplink transmission. Table 2 illustrates the configuration of a singular frame.

Special subframe configuration	Normal cyclic prefix in downlink			Extended cyclic prefix in downlink
	DwPTS	UpPTS		DwPTS	UpPTS
		Normal cyclic prefix in uplink	Extended cyclic prefix in uplink		Normal cyclic prefix in uplink	Extended cyclic prefix in uplink
0	6592T s	2192T s	2560T s	7680T s	2192T s	2560T s
One	19760T s			20480T s
2	21952T s			23040T s
3	24144T s			25600T s
4	26336T s			7680T s	4384T s	5120T s
5	6592T s	4384T s	5120T s	20480T s
6	19760T s			23040T s
7	21952T s			12800 · T s
8	24144T s			-	-	-
9	13168T s			-	-	-

2 illustrates an example of a downlink / uplink (DL / UL) slot structure in a wireless communication system. In particular, FIG. 2 shows a structure of a resource grid of a 3GPP LTE / LTE-A system. There is one resource grid per antenna port.

Referring to FIG. 2, a slot includes a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. An OFDM symbol may mean a symbol period. 2, the signal transmitted in each slot is

*

Subcarriers and

It may be represented by a resource grid composed of OFDM symbols. here,

Represents the number of resource blocks (RBs) in the downlink slot,

Represents the number of RBs in the UL slot.

Wow

Depends on the DL transmission bandwidth and the UL transmission bandwidth, respectively.

Denotes the number of OFDM symbols in the downlink slot,

Denotes the number of OFDM symbols in the UL slot.

Denotes the number of subcarriers constituting one RB.

The OFDM symbol may be called an OFDM symbol, a Single Carrier Frequency Division Multiplexing (SC-FDM) symbol, or the like according to a multiple access scheme. The number of OFDM symbols included in one slot may vary depending on the channel bandwidth and the length of the cyclic prefix (CP). For example, in case of a normal CP, one slot includes 7 OFDM symbols, whereas in case of an extended CP, one slot includes 6 OFDM symbols. Although FIG. 2 illustrates a subframe in which one slot includes 7 OFDM symbols for convenience of description, embodiments of the present invention can be applied to subframes having other numbers of OFDM symbols in the same manner. 2, each OFDM symbol, in the frequency domain,

*

Subcarriers are included. The types of subcarriers may be divided into data subcarriers for data transmission, reference signal subcarriers for transmission of reference signals, null subcarriers for guard band, and direct current (DC) components. . The null subcarrier for the DC component is a subcarrier left unused and is mapped to a carrier frequency f0 during an OFDM signal generation process or a frequency upconversion process. The carrier frequency is also called the center frequency.

1 RB in the time domain

It is defined as (eg, seven) consecutive OFDM symbols, and is defined by c (for example 12) consecutive subcarriers in the frequency domain. For reference, a resource composed of one OFDM symbol and one subcarrier is called a resource element (RE) or tone. Therefore, one RB is

*

It consists of three resource elements. Each resource element in the resource grid may be uniquely defined by an index pair (k, 1) in one slot. k is from 0 in the frequency domain

*

Index given up to -1, where l is from 0 in the time domain

Index given up to -1.

In one subframe

Two RBs, one in each of two slots of the subframe, occupying the same consecutive subcarriers, are called a physical resource block (PRB) pair. Two RBs constituting a PRB pair have the same PRB number (or also referred to as a PRB index). VRB is a kind of logical resource allocation unit introduced for resource allocation. VRB has the same size as PRB. According to the mapping method of the VRB to the PRB, the VRB is divided into a localized type VRB and a distributed type VRB. Localized type VRBs are mapped directly to PRBs, so that a VRB number (also called a VRB index) corresponds directly to a PRB number. That is, n _PRB = n _VRB . Localized type VRBs start at 0

Numbered in -1 order,

=

to be. Therefore, according to the localization mapping scheme, VRBs having the same VRB number are mapped to PRBs having the same PRB number in the first slot and the second slot. On the other hand, the distributed type VRB is mapped to the PRB through interleaving. Therefore, a distributed type VRB having the same VRB number may be mapped to different numbers of PRBs in the first slot and the second slot. Two PRBs, one located in two slots of a subframe and having the same VRB number, are called VRB pairs.

3 illustrates a downlink (DL) subframe structure used in a 3GPP LTE / LTE-A system.

Referring to FIG. 3, a DL subframe is divided into a control region and a data region in the time domain. Referring to FIG. 3, up to three (or four) OFDM symbols located in the first slot of a subframe correspond to a control region to which a control channel is allocated. Hereinafter, a resource region available for PDCCH transmission in a DL subframe is called a PDCCH region. The remaining OFDM symbols other than the OFDM symbol (s) used as the control region correspond to a data region to which a Physical Downlink Shared CHannel (PDSCH) is allocated. Hereinafter, a resource region available for PDSCH transmission in a DL subframe is called a PDSCH region. Examples of DL control channels used in 3GPP LTE include a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), a physical hybrid ARQ indicator channel (PHICH), and the like. The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols used for transmission of a control channel within the subframe. The PHICH carries a Hybrid Automatic Repeat Request (HARQ) ACK / NACK (acknowledgment / negative-acknowledgment) signal in response to the UL transmission.

Control information transmitted through the PDCCH is referred to as downlink control information (DCI). DCI includes resource allocation information and other control information for the UE or UE group. For example, the DCI includes a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format and resource allocation information of an uplink shared channel (UL-SCH), and a paging channel. channel, PCH) paging information, system information on the DL-SCH, resource allocation information of an upper layer control message such as a random access response transmitted on the PDSCH, transmission power control command for individual UEs in the UE group ( It includes a Transmit Control Command Set, a Transmit Power Control command, activation indication information of Voice over IP (VoIP), a Downlink Assignment Index (DAI), and the like. The transmission format and resource allocation information of a downlink shared channel (DL-SCH) may also be called DL scheduling information or a DL grant, and may be referred to as an uplink shared channel (UL-SCH). The transmission format and resource allocation information is also called UL scheduling information or UL grant. The DCI carried by one PDCCH has a different size and use depending on the DCI format, and its size may vary depending on a coding rate. In the current 3GPP LTE system, various formats such as formats 0 and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3, and 3A are defined for uplink. Hopping flag, RB allocation, modulation coding scheme (MCS), redundancy version (RV), new data indicator (NDI), transmit power control (TPC), and cyclic shift DMRS Control information such as shift demodulation reference signal (UL), UL index, CQI request, DL assignment index, HARQ process number, transmitted precoding matrix indicator (TPMI), and precoding matrix indicator (PMI) information The selected combination is transmitted to the UE as downlink control information.

In general, the DCI format that can be transmitted to the UE depends on the transmission mode (TM) configured in the UE. In other words, not all DCI formats may be used for a UE configured in a specific transmission mode, but only certain DCI format (s) corresponding to the specific transmission mode may be used.

The PDCCH is transmitted on an aggregation of one or a plurality of consecutive control channel elements (CCEs). CCE is a logical allocation unit used to provide a PDCCH with a coding rate based on radio channel conditions. The CCE corresponds to a plurality of resource element groups (REGs). For example, one CCE corresponds to nine REGs and one REG corresponds to four REs. In the 3GPP LTE system, a CCE set in which a PDCCH can be located is defined for each UE. The set of CCEs in which a UE can discover its PDCCH is referred to as a PDCCH search space, simply a search space (SS). An individual resource to which a PDCCH can be transmitted in a search space is called a PDCCH candidate. The collection of PDCCH candidates that the UE will monitor is defined as a search space. In the 3GPP LTE / LTE-A system, a search space for each DCI format may have a different size, and a dedicated search space and a common search space are defined. The dedicated search space is a UE-specific search space and is configured for each individual UE. The common search space is configured for a plurality of UEs. An aggregation level defining the search space is as follows.

Search Space S K (L)			Number of PDCCH candidates M (L)
Type	Aggregation Level L	Size [in CCEs]
UE-specific		One	6	6
	2	12	6
	4	8	2
	8	16	2
Common	4	16	4
	8	16	2

One PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs depending on the CCE aggregation level. The eNB sends the actual PDCCH (DCI) on any PDCCH candidate in the search space, and the UE monitors the search space to find the PDCCH (DCI). Here, monitoring means attempting decoding of each PDCCH in a corresponding search space according to all monitored DCI formats. The UE may detect its own PDCCH by monitoring the plurality of PDCCHs. Basically, since the UE does not know where its PDCCH is transmitted, every Pframe attempts to decode the PDCCH until every PDCCH of the corresponding DCI format has detected a PDCCH having its own identifier. It is called blind detection (blind decoding).

The eNB may transmit data for the UE or the UE group through the data area. Data transmitted through the data area is also called user data. For transmission of user data, a physical downlink shared channel (PDSCH) may be allocated to the data area. Paging channel (PCH) and downlink-shared channel (DL-SCH) are transmitted through PDSCH. The UE may read data transmitted through the PDSCH by decoding control information transmitted through the PDCCH. Information indicating to which UE or UE group data of the PDSCH is transmitted, how the UE or UE group should receive and decode PDSCH data, and the like are included in the PDCCH and transmitted. For example, a specific PDCCH is masked with a cyclic redundancy check (CRC) with a Radio Network Temporary Identity (RNTI) of "A", a radio resource (eg, a frequency location) of "B" and a transmission of "C". It is assumed that information about data transmitted using format information (eg, transport block size, modulation scheme, coding information, etc.) is transmitted through a specific DL subframe. The UE monitors the PDCCH using its own RNTI information, and the UE having the RNTI "A" detects the PDCCH, and the PDSCH indicated by "B" and "C" through the received PDCCH information. Receive

For demodulation of a signal received by the UE from the eNB, a reference signal (RS) to be compared with the data signal is required. The reference signal refers to a signal of a predetermined special waveform that the eNB and the UE know each other, which the eNB transmits to the UE or the eNB, and is also called a pilot. Reference signals are divided into a cell-specific RS shared by all UEs in a cell and a demodulation RS (DM RS) dedicated to a specific UE. The DM RS transmitted by the eNB for demodulation of downlink data for a specific UE may be specifically referred to as a UE-specific RS. In the downlink, the DM RS and the CRS may be transmitted together, but only one of the two may be transmitted. However, when only the DM RS is transmitted without the CRS in the downlink, the DM RS transmitted by applying the same precoder as the data may be used only for demodulation purposes, and thus RS for channel measurement should be separately provided. For example, in 3GPP LTE (-A), in order to enable the UE to measure channel state information, an additional measurement RS, CSI-RS, is transmitted to the UE. The CSI-RS is transmitted every predetermined transmission period consisting of a plurality of subframes, unlike the CRS transmitted every subframe, based on the fact that the channel state is relatively not changed over time.

4 illustrates an example of an uplink (UL) subframe structure used in a 3GPP LTE / LTE-A system.

Referring to FIG. 4, the UL subframe may be divided into a control region and a data region in the frequency domain. One or several physical uplink control channels (PUCCHs) may be allocated to the control region to carry uplink control information (UCI). One or several physical uplink shared channels (PUSCHs) may be allocated to a data region of a UL subframe to carry user data.

In the UL subframe, subcarriers having a long distance based on a direct current (DC) subcarrier are used as a control region. In other words, subcarriers located at both ends of the UL transmission bandwidth are allocated for transmission of uplink control information. The DC subcarrier is a component that is not used for signal transmission and is mapped to a carrier frequency f0 during frequency upconversion. The PUCCH for one UE is allocated to an RB pair belonging to resources operating at one carrier frequency in one subframe, and the RBs belonging to the RB pair occupy different subcarriers in two slots. The PUCCH allocated in this way is expressed as that the RB pair allocated to the PUCCH is frequency hopped at the slot boundary. However, if frequency hopping is not applied, RB pairs occupy the same subcarrier.

PUCCH may be used to transmit the following control information.

SR (Scheduling Request): Information used for requesting an uplink UL-SCH resource. It is transmitted using OOK (On-Off Keying) method.

HARQ-ACK: A response to a PDCCH and / or a response to a downlink data packet (eg, codeword) on a PDSCH. This indicates whether the PDCCH or PDSCH is successfully received. One bit of HARQ-ACK is transmitted in response to a single downlink codeword, and two bits of HARQ-ACK are transmitted in response to two downlink codewords. HARQ-ACK response includes a positive ACK (simple, ACK), negative ACK (hereinafter, NACK), DTX (Discontinuous Transmission) or NACK / DTX. Here, the term HARQ-ACK is mixed with HARQ ACK / NACK, ACK / NACK.

Channel State Information (CSI): Feedback information for the downlink channel. Multiple Input Multiple Output (MIMO) -related feedback information includes a rank indicator (RI) and a precoding matrix indicator (PMI).

The amount of uplink control information (UCI) that a UE can transmit in a subframe depends on the number of SC-FDMA available for control information transmission. SC-FDMA available for UCI means the remaining SC-FDMA symbol except for the SC-FDMA symbol for transmitting the reference signal in the subframe, and in the case of a subframe including a Sounding Reference Signal (SRS), the last SC of the subframe The -FDMA symbol is also excluded. The reference signal is used for coherent detection of the PUCCH. PUCCH supports various formats according to the transmitted information.

Table 4 shows mapping relationship between PUCCH format and UCI in LTE / LTE-A system.

PUCCH format	Modulation scheme	Number of bits per subframe	Usage	Etc.
One	N / A	N / A (exist or absent)	SR (Scheduling Request)
1a	BPSK	One	ACK / NACK orSR + ACK / NACK	One codeword
1b
QPSK	2	ACK / NACK orSR + ACK / NACK		Two codeword
2	QPSK	20	CQI / PMI / RI	Joint coding ACK / NACK (extended CP)
2a	QPSK + BPSK	21	CQI / PMI / RI + ACK / NACK	Normal CP only
2b	QPSK + QPSK	22	CQI / PMI / RI + ACK / NACK	Normal CP only
3	QPSK	48	ACK / NACK orSR + ACK / NACK orCQI / PMI / RI + ACK / NACK

Referring to Table 4, the PUCCH format 1 series is mainly used to transmit ACK / NACK information, and the PUCCH format 2 series is mainly used to carry channel state information (CSI) such as CQI / PMI / RI. In particular, the PUCCH format 3 series is mainly used to transmit ACK / NACK information.

Reference Signal (RS)

When transmitting a packet in a wireless communication system, since the transmitted packet is transmitted through a wireless channel, signal distortion may occur during the transmission process. In order to correctly receive the distorted signal at the receiving end, the distortion must be corrected in the received signal using the channel information. In order to find out the channel information, a method of transmitting the signal known to both the transmitting side and the receiving side and finding the channel information with the distortion degree when the signal is received through the channel is mainly used. The signal is called a pilot signal or a reference signal.

When transmitting and receiving data using multiple antennas, it is necessary to know the channel condition between each transmitting antenna and the receiving antenna to receive the correct signal. Therefore, a separate reference signal should exist for each transmit antenna and more specifically for each antenna port (antenna port).

The reference signal may be divided into an uplink reference signal and a downlink reference signal. In the current LTE system, as an uplink reference signal,

i) Demodulation-Reference Signal (DM-RS) for Channel Estimation for Coherent Demodulation of Information Transmitted over PUSCH and PUCCH

ii) There is a sounding reference signal (SRS) for the base station to measure uplink channel quality at different frequencies.

Meanwhile, in the downlink reference signal,

i) Cell-specific reference signal (CRS) shared by all terminals in the cell

ii) UE-specific reference signal for specific UE only

iii) when PDSCH is transmitted, it is transmitted for coherent demodulation (DeModulation-Reference Signal, DM-RS)

iv) Channel State Information Reference Signal (CSI-RS) for transmitting Channel State Information (CSI) when downlink DMRS is transmitted;

v) MBSFN Reference Signal, which is transmitted for coherent demodulation of the signal transmitted in Multimedia Broadcast Single Frequency Network (MBSFN) mode.

vi) There is a Positioning Reference Signal used to estimate the geographical location information of the terminal.

Reference signals can be classified into two types according to their purpose. There is a reference signal for obtaining channel information and a reference signal used for data demodulation. In the former, since the UE can acquire downlink channel information, it should be transmitted over a wide band and must receive the reference signal even if the UE does not receive downlink data in a specific subframe. It is also used in situations such as handover. The latter is a reference signal transmitted together with a corresponding resource when the base station transmits a downlink, and the terminal can demodulate data by performing channel measurement by receiving the reference signal. This reference signal should be transmitted in the area where data is transmitted.

Carrier Aggregation (CA)

The CA is a frequency block or (logical sense) cell in which a terminal is composed of uplink resources (or component carriers) and / or downlink resources (or component carriers) so that the wireless communication system uses a wider frequency band. This means using multiple large logical frequency bands.

In the LTE system, one downlink component carrier and one uplink component carrier are used, whereas in the LTE-A system, several component carriers may be used. In this case, a method of scheduling a data channel by the control channel may be classified into a conventional link or self carrier scheduling method and a cross carrier scheduling (CCS) method.

More specifically, in the link / self-carrier scheduling, as in the existing LTE system using a single component carrier, a control channel transmitted through a specific component carrier only schedules a data channel through the specific component carrier.

On the other hand, the cross scheduling is a data channel in which a control channel transmitted through a primary CC using a carrier indicator field (CIF) is transmitted through the primary CC or through another CC. Scheduling

Enhanced PDCCH (EPDCCH) General

Due to the introduction of a multi-node system, various communication techniques can be applied to improve channel quality.However, in order to apply the aforementioned MIMO and inter-cell cooperative communication techniques to a multi-node environment, introduction of a new control channel is required. As a result, the control channel introduced in the LTE-A system is an Enhanced-PDCCH (EPDCCH), and the EPDCCH is allocated to a data region other than a control region within one transmission time interval (TTI) or one subframe. In conclusion, the EPDCCH can transmit control information for the node for each UE, thereby solving the problem that the existing PDCCH region may be insufficient.

In future systems, it is possible to consider the situation where various transmission time intervals (TTIs) can be set for all or specific physical channels to meet the requirements of various applications. More specifically, according to a scenario, a physical channel such as PDCCH / PDSCH / PUSCH / PUCCH may set a TTI smaller than 1 msec in order to reduce latency in communication between an eNB and a UE (hereinafter, Each represented by sPDCCH / sPDSCH / sPUSCH / sPUCCH. In addition, a plurality of physical channels may exist within a single subframe (eg, 1 msec) for a single UE or a plurality of UEs, and each may have a different TTI. In the following embodiment, an LTE system will be taken as an example for convenience of description. In this case, the TTI may be 1 msec as a general subframe size in the LTE system (hereinafter, referred to as a general TTI), and a short TTI may refer to a smaller value, and may be a single / plural OFDM or SC-FDMA symbol unit. For convenience of explanation, a short TTI (that is, a case in which the TTI length is smaller than one subframe) is assumed, but the main feature of the present invention is extended and applied even when the TTI is longer than one subframe or 1 ms or more. This is possible. In particular, even when a short TTI is introduced in a form of increasing subcarrier spacing in the next system, the main features of the present invention may be extended. For convenience, the present invention will be described based on LTE, but the contents can be applied to a technology in which other waveform / frame structures such as new radio access technology (RAT) are used. In general, the present invention assumes sTTI (<1 msec), longTTI (= 1 msec), and longerTTI (> 1 msec). The following embodiments have been described with respect to a plurality of UL channels having different TTI lengths / numerology / processing time, but a plurality of ULs to which different service requirements, latency, and scheduling units are applied. Obviously, it can be extended to / DL channel.

In order to satisfy the above-described latency reduction, that is, low latency, it is necessary to design a shortened TTI (sTTI) of 0.5 msec or less by reducing TTI, which is the minimum unit of data transmission. For example, as shown in FIG. 5, the user plane (U-plane) latency until the eNB starts transmitting data (PDCCH and PDSCH) until the UE completes transmission of A / N (ACK / NACK). In order to reduce to 1 msec, sTTI may be configured in units of about 3 OFDM symbols.

In a downlink environment, a PDCCH (ie, sPDCCH) for transmitting / scheduling data in such an sTTI and a PDSCH (ie, sPDSCH) for transmitting in an sTTI may be transmitted. For example, as shown in FIG. A plurality of sTTIs may be configured using different OFDM symbols in a subframe of. In particular, the OFDM symbols constituting the sTTI may be configured to exclude the OFDM symbols through which legacy control channels are transmitted. In the sTTI, sPDCCH and sPDSCH may be transmitted in a time division multiplexing (TDM) form using different OFDM symbol regions, and in a frequency division multiplexing (FDM) form using different PRB regions / frequency resources. May be sent.

Like the downlink mentioned above, the uplink environment is capable of data transmission / scheduling in the sTTI, and refers to a channel corresponding to the existing TTI-based PUCCH and PUSCH as sPUCCH and sPUSCH.

In the present specification, the invention is described with reference to an LTE / LTE-A system. In the existing LTE / LTE-A, a 1 ms subframe consists of 14 OFDM symbols when having a normal CP, and when configuring a TTI of a unit shorter than 1 ms, a plurality of TTIs may be configured in one subframe. In the method of configuring a plurality of TTIs, two symbols, three symbols, four symbols, and seven symbols may be configured as one TTI, as shown in FIG. 7. Although not shown, a case in which one symbol has a TTI may be considered. If one symbol becomes one TTI unit, 12 TTIs are generated under the assumption that the legacy PDCCH is transmitted in two OFDM symbols. Similarly, as shown in FIG. 7A, when two symbols are in one TTI unit, six TTIs and four TTIs in FIG. 7 when three symbols are in one TTI unit as shown in FIG. 7B. As shown in (c), three TTIs can be generated by using four symbols as one TTI unit. In this case, of course, the first two OFDM symbols assume that the legacy PDCCH is transmitted.

As shown in (d) of FIG. 7, when seven symbols are configured as one TTI, one TTI in seven symbol units including the legacy PDCCH and the following seven symbols may be configured as one TTI. In this case, in case of a UE supporting sTTI, if one TTI is composed of 7 symbols, the TTI (first slot) located in the front end of one subframe is popped for the two OFDM symbols in front of the legacy PDCCH. Assume that it is punched or rate-matched, and then that its data and / or control information is transmitted in five symbols. In contrast, for the TTI (second slot) located at the rear end of one subframe, it is assumed that the terminal can transmit data and / or control information in all seven symbols without puncturing or rate-matching resource regions. .

In addition, in the present invention, an sTTI composed of two OFDM symbols (hereinafter, referred to as "OS") and an sTTI composed of three OSs are considered to include an sTTI structure that is mixed and present in one subframe as shown in FIG. An sTTI composed of such a 2-OS or 3-OS sTTI may be simply defined as a 2-symbol sTTI (ie, 2-OS sTTI). Also, two-symbol sTTIs or three-symbol sTTIs may be referred to simply as two-symbol TTIs or three-symbol TTIs, all of which are intended to be clear that the TTIs are shorter than the 1 ms TTI, the legacy TTI presupposed by the present invention. That is, the specification indicates that "TTI" does not mean that it is not an sTTI, and the present invention, regardless of its name, relates to a communication scheme in a system configured with a TTI having a shorter length than a legacy TTI.

In addition, in this specification, numerology refers to a parameter such as determining a length of a TTI to be applied to a wireless communication system, a subcarrier spacing, or a predetermined TTI length or a subcarrier spacing, or a communication structure or system based thereon. And the like.

In the <3,2,2,2,2,3> sTTI pattern illustrated in (a) of FIG. 8, the sPDCCH may be transmitted according to the number of symbols of the PDCCH. In the <2,3,2,2,2,3> sTTI pattern of FIG. 8 (b), transmission of the sPDCCH may be difficult because of the legacy PDCCH region.

New radio technology (NR)

In the above description, the structure, operation, or function of the 3GPP LTE (-A) system has been described, but in NR, the structure, operation, or function of the 3GPP LTE (-A) may be slightly modified or implemented in other ways. have. Some of them are briefly explained.

In NR, various numerologies are supported. For example, subcarrier spacing supports not only 15KHz but also 2 ⁿ times (n = 1, 2, 3, 4) thereof.

In addition, in the case of the normal CP, the number of OFDM symbols per slot (hereinafter simply referred to as "symbol") is fixed to 14, but the number of slots in one subframe is 2 ^k (k = 0, 1, 2, 3, 4, 5) is supported, but the radio frame is composed of 10 subframes is the same as the existing LTE system. In the case of an extended CP, the number of symbols per slot is fixed to 12, and one subframe consists of 4 slots. In addition, as in the existing LTE system, one resource block is defined as 12 consecutive subcarriers in the frequency domain.

In addition, the usage of each symbol in one slot (eg, downlink, uplink, or flexible) is defined according to a slot format, and both a downlink symbol and an uplink symbol may be configured in one slot. The case is referred to as a self-contained subframe (or slot) structure.

Multi- TTI  Scheduling (Multi- TTI  scheduling)

One way to achieve latency reduction is to consider a shorter TTI transmission. For example, a PDSCH and a PUSCH having a length of 2/3 symbol sTTI are defined, and a method of transmitting / receiving DL and UL data is considered. In consideration of such a scheme, since a control channel for scheduling must also be transmitted for every TTI, a control overhead can be increased. As one solution to this problem, multi-TTI scheduling in which one control channel schedules a plurality of TTIs may be considered. When multi-TTI scheduling is considered, we propose the following.

Multi- TTI  When scheduling HARQ - ACK  resource

A rule may be defined such that HARQ-ACK resources for the PDSCH scheduled by the multi-TTI scheduling DCI are determined as follows.

Alt 1: HARQ-ACK resources for a specific TTI among a plurality of scheduled TTIs are indicated by the multi-TTI scheduling DCI, and HARQ-ACK resources for the remaining scheduled TTIs may be implicitly determined. In one example, the HARQ-ACK resource for the first TTI of the plurality of scheduled TTIs is determined by the lowest CCE index of the multi-TTI scheduling DCI or according to a particular resource associated with a particular state of an A / N resource indicator (ARI). The HARQ-ACK resource for the remaining scheduled TTI may be determined as a resource to which an offset relative to the determined resource is applied.

Here, the offset (or a set of offsets to be applied to each of the plurality of TTIs) may be 0, or may be a value previously promised by the index of the scheduled TTI and / or the information of the number of scheduled TTIs. Alternatively, an offset (or a set of offsets to be applied to each of the plurality of TTIs) may be indicated / set by the DCI or higher layer signal. As a more detailed example, when the PUCCH resource index of the first scheduled TTI is m, a rule may be defined such that the PUCCH resource indexes of the second and third scheduled TTIs are determined to be m + 1 and m + 2, respectively.

Alt 2: HARQ-ACK resource information for a plurality of TTIs is preset for each state of the ARI, and the PUCCH resource of the TTI (s) scheduled by the specific state of the ARI indicated in the multi-TTI scheduling DCI is Can be determined. As an example, each state of the ARI sets the PUCCH resources corresponding to the maximum number that can be scheduled by multi-TTI scheduling, and when scheduling fewer TTIs in the multi-TTI scheduling DCI, the state of the indicated ARI A rule may be defined such that as many PUCCH resources as corresponding to the number of TTIs scheduled from the beginning among the PUCCH resources corresponding to the PDU are used.

Multi- TTI  When scheduling PDCCH  Blind decoding; BD )

A rule may be defined such that a PDCCH RB set for monitoring the multi-TTI scheduling DCI may be separately set. Alternatively, a rule may be defined such that an aggregation level (AL) for monitoring multi-TTI scheduling DCI and / or a number of BD candidates (or a reduction factor of BD candidates) is independently set for each PDCCH RB set. In particular, this may be distinct from that for monitoring single-TTI scheduling DCI. Alternatively, whether multi-TTI scheduling is enabled among parameters in the PDCCH RB set may be configured through an upper layer signal.

Utilize Unused Resources

In order to alleviate control overhead, resources other than those used as control channels can be allowed to be used for data channel transmission as much as possible, thereby maximizing use of unused resources. To this end, various schemes are being considered, and when multi-TTI scheduling is applied, it may be desirable to configure resources that are not used to the maximum.

In particular, among TTIs scheduled through the multi-TTI scheduling DCI, the data may be rate matched with respect to the RB or RBG indicated by a specific (or all) PDCCH RB set in the TTI without the corresponding DCI. Rules can be defined so that Such a setting may be commonly applied to a plurality of TTIs in which multi-TTI scheduling has been performed through one setting, and different settings may be given for each TTI constituting the plurality of TTIs. This may be useful if multi-TTI scheduling has been performed and scheduling pre-emption is not allowed for the plurality of scheduled TTIs.

Multi- TTI Not scheduled  Not On TTI  About Signaling

The multi-TTI scheduling may indicate whether the TTI is scheduled for some or all of the TTIs of a plurality of TTIs in a specific interval by the DCI, and a rule may be defined such that the UE does not monitor DCI for TTIs that are not scheduled. Can be. Alternatively, when a TTI scheduled by the multi-TTI scheduling DCI is indicated through an upper layer signal, a rule may be defined such that the UE does not monitor DCI in a TTI that does not include the multi-TTI scheduling DCI among the plurality of scheduled TTIs. Can be.

Multi- TTI  Either CSI reporting or SRS  Sent TTI  Settings

When multi-TTI scheduling is applied based on the proposed method or another method, TTI timing corresponding to a CSI request and an SRS request in the multi-TTI scheduling DCI (eg, transmission of a PUSCH including aperiodic CSI feedback) Time point), and, in particular, the TTI time point may be set to a first or last TTI in which a DMRS exists or a TTI indicated in advance or indicated by DCI among a plurality of scheduled TTIs. This may allow CSI reporting only when DMRS exists in the corresponding TTI for reliable transmission of the triggered CSI.

Alternatively, on the contrary, it may be set to a first or last TTI in which no DMRS exists or a TTI previously designated or indicated by DCI among the plurality of scheduled TTIs. This may be to include CSI reporting in TTI without DMRS to mitigate this, since rate matching due to CSI may increase the coding rate of PUSCH transmission.

Alternatively, a rule may be defined to include the CSI report repeatedly in the TTI of some (or all) of the plurality of scheduled TTIs. This can further improve the reliability of the CSI.

SRS  send TTI

When multi-TTI scheduling is applied based on the proposed method or another method, it is necessary to set a TTI time point (eg, a transmission time point of an aperiodic SRS signal) corresponding to an SRS request in the multi-TTI scheduling DCI. It may be necessary, and the SRS may be transmitted in the last TTI belonging to the SRS subframe among the plurality of scheduled TTIs. Or, if the SRS transmission TTI is defined separately (eg, SRS sTTI) and there is an SRS transmission TTI among the plurality of scheduled TTIs, the SRS may be transmitted in the corresponding TTI.

HARQ - ACK  send TTI

In case of multi-sTTI scheduling, the HARQ-ACK may be raised at the HARQ-ACK timing corresponding to each sPDSCH, and the aggregated and / or bundled HARQ-ACK for the multi-sTTI sPDSCH may be transmitted. Alternatively, the network can configure one of two ways. In the former case, the PUCCH / UCI overhead is increased compared to the fast HARQ-ACK response, and in the latter case, the latency may be delayed. In addition, when one TB is mapped to multi-sTTI scheduling, HARQ-ACK may be assumed to set timing based on the last sTTI, and may be assumed to be transmitted in a corresponding PUCCH / UCI resource at that timing. . In addition, the HARQ-ACK scheme may be associated with retransmission. Even when the multi-sTTI scheduling is received, only a part of the single-sTTI scheduling may be retransmitted, and the multi-sTTI scheduling may be used for retransmission, but the TBs transmitted may be a subset of the TBs transmitted during the initial transmission. That is, it may be assumed that retransmission is performed only for TB corresponding to NACK or DTX. If retransmission is scheduled with a single sTTI, or if a single sTTI and a multi-sTTI DCI can coexist, it can be assumed that the DCI size is adjusted using padding, etc., indicating whether a single sTTI or multi sTTI is used. May be added to the corresponding DCI. Alternatively, the DCI size may be configured for each PRB set to separately transmit the multi sTTI and the single sTTI.

cross- carrier  Scheduling

If the (different) processing time can be set independently for each cell, a rule between the base station and the terminal for deriving the processing time may be necessary in cross-carrier scheduling. As an example, if the processing time indicated by the processing time setting of the scheduling cell and the scheduled cell is different, the terminal may follow DL processing-to-DL data and / or DL data-to-DL HARQ and / or according to either processing time. Or you may be wondering whether you need to determine processing times, such as UL approved-to-UL data. Accordingly, a rule may be defined such that cross-carrier scheduling is allowed only when the processing time indicated by the processing time setting of the scheduling cell and the cell to be scheduled is set equal.

Cross-carrier scheduling in the current LTE standard (TS 36.331) is defined as follows.

CrossCarrierSchedulingConfig

The IE CrossCarrierSchedulingConfig is used to specify the configuration when the cross carrier scheduling is used in a cell.

CrossCarrierSchedulingConfig  information elements

ASN1START

CrossCarrierSchedulingConfig-r10 :: = SEQUENCE {

schedulingCellInfo-r10 CHOICE {

own-r10 SEQUENCE {-No cross carrier scheduling

cif-Presence-r10 BOOLEAN

},

other-r10 SEQUENCE {-Cross carrier scheduling

schedulingCellId-r10 ServCellIndex-r10,

pdsch-Start-r10 INTEGER (1..4)

}

}

}

ASN1STOP

CrossCarrierSchedulingConfig  field descriptions

cif-Presence The field is used to indicate whether carrier indicator field is present (value TRUE) or not (value FALSE) in PDCCH / EPDCCH DCI formats, see TS 36.212 [22, 5.3.3.1].

pdsch -Start The starting OFDM symbol of PDSCH for the concerned SCell, see TS 36.213 [23. 7.1.6.4]. Values 1, 2, 3 are applicable when dl-Bandwidth for the concerned SCell is greater than 10 resource blocks, values 2, 3, 4 are applicable when dl-Bandwidth for the concerned SCell is less than or equal to 10 resource blocks, see TS 36.211 [21, Table 6, 7-1].

schedulingCellId Indicates which cell signals the downlink allocations and uplink grants, if applicable, for the concerned SCell. In case the UE is configured with DC, the scheduling cell is part of the same cell group (ie MCG or SCG) as the scheduled cell.

The cross-carrier scheduling related configuration (eg, scheduling cell information, PDSCH start symbol information, etc.) may be configured or applied to the UE regardless of the processing time related configuration. In this case, a relationship between a scheduling cell having a different processing time setting and a cell to be scheduled may occur, and an operation of the terminal needs to be defined. In one example, the UE may in this case use the longer processing time of its DL allocation-to-DL data and / or DL data-to-DL HARQ and / or UL grant-to secure a conservative processing time margin. It can be applied to processing time such as to-UL data.

Alternatively, the cross-carrier scheduling related configuration may be interpreted differently by the processing time related configuration of the cell to be scheduled. For example, even if cross-carrier scheduling is set for a particular scheduled cell, when the processing time setting with the cell scheduling the cell becomes different (eg, the processing time of the scheduled cell is n + 3, The processing time is n + 4), cross-carrier scheduling is not applied to the corresponding scheduled cell, and only self-carrier scheduling can be applied. Accordingly, a rule may be defined such that the UE monitors a DL allocation / UL grant DCI for a corresponding scheduled cell in a search space configured in the corresponding scheduled cell.

Alternatively, when a short processing time is set for a specific cell, a separate cross-carrier scheduling related setting may be set together. Characteristically, even if cross-carrier scheduling of a particular cell was originally enabled, it can be disabled with the setting of short processing time. Alternatively, a scheduling cell and / or a PDSCH start symbol configured together by a PDSCH start symbol and a short processing time setting may be indicated differently by the cross-carrier scheduling related configuration of a specific cell.

If the cross-carrier scheduling is configured by the serving cell Y for the data channel to be transmitted in the serving cell X, and the sTTI is configured for the serving cell X, the terminal may transmit a subframe duration to be transmitted in the serving cell X. The PDCCH / EPDCCH of the serving cell Y will be monitored for the data channel having N, and the PDCCH / SPDCCH of the serving cell X will be monitored for the data channel having the slot / subslot duration.

As such, monitoring the control channel in the plurality of serving cells for data channels having different durations to be transmitted in one cell may be undesirable as it may affect the processing time of the terminal. Therefore, the operation of the terminal receiving the above configuration is proposed as follows.

Option 1: In order to reduce the impact on the processing time of the terminal, a rule may be defined such that only self-carrier scheduling is supported regardless of the duration of the data channel. In other words, the UE monitors the control channels scheduling the data channels to be transmitted in the serving cell X only in the serving cell X. This may be interpreted as the terminal ignores the cross-carrier scheduling configuration. In particular, for a data channel to be transmitted in the serving cell X, the UE may monitor in the serving cell X only the PDCCH and / or the SPDCCH except for the EPDCCH.

Option 2: A rule may be defined to report the terminal capability as to whether the terminal is supportable for monitoring the control channel in the plurality of serving cells for data channels having different durations to be transmitted in one cell. That is, the UE reports on whether the PDCCH / EPDCCH scheduling subframe-PDSCH / PUSCH is supported by cell Y and the PDCCH / SPDCCH scheduling slot / subslot-PDSCH / PUSCH is simultaneously supported in cell X. can do. If the UE reports that the operation can be supported, the subframe-PDSCH / PUSCH is scheduled by cross-carrier scheduling and the slot / subslot-PDSCH / PUSCH is scheduled by self-carrier scheduling and the UE is scheduled in the corresponding cell. Rules can be defined to monitor each control channel. If the operation is reported as unsupportable, a rule may be defined such that all data channels having a different duration, such as option 1, are operated by self-carrier scheduling and accordingly, the terminal monitors the control channels in the corresponding cell. .

The monitoring operation is applied to an operation itself for monitoring a plurality of control channels for data channels having different durations even if time intervals for which actual monitoring is performed for the plurality of control channels for data channels having different durations do not overlap. It may be.

Option 3: For data channels with different duration to be transmitted in one cell, where the duration includes the TTI length, the terminal expects cross-carrier scheduling to be established for the data channel with either duration I never do that. In other words, a rule may be defined such that the UE sets only self-carrier scheduling for data channels of all durations / TTI lengths / neomerologies / BLER targets (or supported) set in a specific cell. Here, a particular cell may comprise a cell with a different duration / TTI length / neomerology / BLER target set or promised. This setting can be applied regardless of the simultaneous reception capability for a plurality of data channels having different durations.

Option 4: Alternatively, for data channels having different durations, where the duration includes a TTI length, to be transmitted in one cell, the terminal may select a data channel of a particular duration (eg, subframe- For PDSCH, rules may be defined such that self-carrier scheduling is set up, or cross-carrier scheduling is set up that is scheduled from a cell for which EPDCCH is not set. That is, the UE monitors a control channel in a corresponding cell for a data channel of a specific duration (eg, a subframe-PDSCH) of a specific cell or when a control channel other than EPDCCH (eg, PDCCH) is cross-carrier scheduled in another cell. Rules can be defined to monitor only Here, a particular cell may comprise a cell with a different duration / TTI length / neomerology / BLER target set or promised. This setting can be applied regardless of the simultaneous reception capability for multiple data channels with different duration / TTI length / neomerology / BLER target.

The monitoring operation may be performed by performing multiple monitoring on data channels having different durations even if the time intervals in which actual monitoring is performed for the plurality of control channels for data channels having different durations / TTI lengths / numerology / BLER targets do not overlap. The monitoring channel may be applied to the operation itself.

send Diversity  dynamic Fallback (Dynamic fallback to transmit diversity)

In the case of the sTTI operation, the UE is configured to reduce latency according to the capability of the UE reported to the network in the RRC-connected mode. In order to prevent the blind decoding of the UE for the (S) PDCCH from being excessively increased, the sTTI operation does not separately define a DCI format for a fallback transmission scheme. If the base station wants to fall back to a transmission scheme such as transmission diversity due to a change in channel conditions, the DCI format monitored by the terminal according to a TM defined as a transmission mode (TM) -dependent DCI A rule may be defined to instruct the terminal by using (reusing) a specific field. Through this, the terminal may dynamically fall back to the transmit diversity transmission method in the transmission method by the configured TM to expect a higher reception rate for the DL data channel. In the case of sTTI operation, if dynamic fallback is not supported, the base station should always perform scheduling using legacy / default TTI (e.g., 1ms TTI) when it wishes to fall back to a transmission scheme such as transmit diversity. It can cause high DL latency.

A rule may be defined to report to the network terminal capability signaling as to whether the terminal can support dynamic fallback to a particular transmission scheme (eg, transmit diversity) for sTTI operation. In particular, the UE capability signaling may be independently defined for each TTI length (or a TTI group consisting of a plurality of TTI lengths), which may indicate whether the UE supports dynamic fallback operation using a transmit diversity transmission scheme for each TTI length. This may be different. In addition, the configuration of the base station or network that operates the dynamic fallback to a specific transmission scheme (eg, transmit diversity) may be independently set through the higher layer signal independently for each TTI length (or a TTI length group composed of a plurality of TTI lengths). Can be.

And / or, the terminal capability signaling may include information on the number of antenna ports that can be supported. For example, it may be reported to support only 2-port transmit diversity, or may be reported to support both 2-port and 4-port transmit diversity. In addition, the configuration of the base station or network that operates the dynamic fallback to a specific transmission scheme (eg, transmit diversity) may be set through a higher layer signal including information on the number of antenna ports.

The UE capability signaling may be independently defined for each transmission mode (or a TM group composed of a plurality of TMs) in which the UE is configured for sTTI operation. This may be different depending on whether or not the dynamic fallback support for each TM configured to the terminal, the base station may determine whether to set the dynamic fallback to sTTI based on the terminal capability signaling. In addition, the interpretation of the DCI field for dynamic fallback will also be different based on the terminal capability signaling (and / or the configuration of the base station or network to enable / disable dynamic fallback). Alternatively, regardless of the TM set for the sTTI operation, common terminal capability signaling may be defined, which may be interpreted as always supporting the fallback operation in the transmit diversity transmission scheme if the terminal supports the sTTI operation. The base station can also transmit transmission diversity transmission regardless of the set TM can avoid unnecessary latency. In addition, the configuration of the base station or the network that operates the dynamic fallback to a specific transmission scheme (e.g., transmit diversity) is performed through the upper layer signal independently of the TM configured for the sTTI or for each TM (group) configured for the sTTI. Can be set.

It is obvious that examples of the proposed schemes described may also be regarded as a kind of proposed schemes as they may be included as one of the implementation methods of the present invention. In addition, the proposed schemes may be implemented independently, but may be implemented in a combination (or merge) of some proposed schemes. Information on whether the proposed methods are applied (or information on the rules of the proposed methods) may be defined so that the base station notifies the terminal through a predefined signal (eg, a physical layer signal or a higher layer signal).

9 is a block diagram showing the components of the transmitter 10 and the receiver 20 for carrying out the embodiments of the present invention. The transmitter 10 and the receiver 20 are associated with transmitters / receivers 13 and 23 capable of transmitting or receiving radio signals carrying information and / or data, signals, messages, etc. Memory 12, 22 for storing a variety of information, the transmitter / receiver 13, 23 and the memory 12, 22 and the like is operatively connected to control the components to control the components described above And a processor 11, 21, respectively, configured to control the memory 12, 22 and / or the transmitter / receiver 13, 23 to perform at least one of the embodiments of the present invention.

The memories 12 and 22 may store a program for processing and controlling the processors 11 and 21, and may temporarily store input / output information. The memories 12 and 22 may be utilized as buffers. The processors 11 and 21 typically control the overall operation of the various modules in the transmitter or receiver. In particular, the processors 11 and 21 may perform various control functions for carrying out the present invention. The processors 11 and 21 may also be called controllers, microcontrollers, microprocessors, microcomputers, or the like. The processors 11 and 21 may be implemented by hardware or firmware, software, or a combination thereof. When implementing the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays) may be provided in the processors 11 and 21. Meanwhile, when implementing the present invention using firmware or software, the firmware or software may be configured to include a module, a procedure, or a function for performing the functions or operations of the present invention, and configured to perform the present invention. The firmware or software may be provided in the processors 11 and 21 or stored in the memory 12 and 22 to be driven by the processors 11 and 21.

The processor 11 of the transmission apparatus 10 is predetermined from the processor 11 or a scheduler connected to the processor 11 and has a predetermined encoding and modulation on a signal and / or data to be transmitted to the outside. After performing the transmission to the transmitter / receiver (13). For example, the processor 11 converts the data sequence to be transmitted into K layers through demultiplexing, channel encoding, scrambling, and modulation. The coded data string is also called a codeword and is equivalent to a transport block, which is a data block provided by the MAC layer. One transport block (TB) is encoded into one codeword, and each codeword is transmitted to a receiving device in the form of one or more layers. The transmitter / receiver 13 may include an oscillator for frequency upconversion. The transmitter / receiver 13 may include Nt transmit antennas, where Nt is a positive integer greater than or equal to one.

The signal processing of the receiver 20 is the reverse of the signal processing of the transmitter 10. Under the control of the processor 21, the transmitter / receiver 23 of the receiver 20 receives a radio signal transmitted by the transmitter 10. The transmitter / receiver 23 may include Nr receive antennas, and the transmitter / receiver 23 frequency down-converts each of the signals received through the receive antennas to restore baseband signals. do. Transmitter / receiver 23 may include an oscillator for frequency downconversion. The processor 21 may decode and demodulate a radio signal received through a reception antenna to restore data originally transmitted by the transmission apparatus 10.

The transmitter / receiver 13, 23 is equipped with one or more antennas. The antenna transmits a signal processed by the transmitter / receiver 13, 23 to the outside or receives a radio signal from the outside under the control of the processors 11 and 21, thereby transmitting / receiving the transmitter / receiver. It performs the function of forwarding to (13, 23). Antennas are also called antenna ports. Each antenna may correspond to one physical antenna or may be configured by a combination of more than one physical antenna elements. The signal transmitted from each antenna can no longer be decomposed by the receiver 20. A reference signal (RS) transmitted in correspondence with the corresponding antenna defines the antenna as viewed from the perspective of the receiver 20, and whether the channel is a single radio channel from one physical antenna or includes the antenna. Regardless of whether it is a composite channel from a plurality of physical antenna elements, the receiver 20 enables channel estimation for the antenna. That is, the antenna is defined such that a channel carrying a symbol on the antenna can be derived from the channel through which another symbol on the same antenna is delivered. In the case of a transmitter / receiver that supports a multi-input multi-output (MIMO) function for transmitting and receiving data using a plurality of antennas, two or more antennas may be connected.

In the embodiments of the present invention, the terminal or the UE operates as the transmitter 10 in the uplink and the receiver 20 in the downlink. In the embodiments of the present invention, the base station or eNB operates as the receiving device 20 in the uplink, and operates as the transmitting device 10 in the downlink.

The transmitter and / or the receiver may perform at least one or a combination of two or more of the embodiments of the present invention described above.

As one of the combinations of these proposals, in a terminal receiving a downlink signal in a wireless communication system, the terminal includes a receiver and a transmitter, and a processor controlling the receiver and the transmitter, the processor comprising a short transmission time interval ( Receive a dynamic change setting to a predetermined transmission scheme related to a short transmission time interval (sTTI) based downlink operation from a base station, and when the dynamic change setting is received, a downlink control information format including a field related to the dynamic change And if the value of the field indicates the predetermined transmission scheme, a signal may be received on a downlink data channel according to the predetermined transmission scheme.

The dynamic change setting may be set for each TTI length. In addition, the dynamic change setting may be set regardless of the transmission mode associated with the sTTI based downlink operation.

The predetermined transmission scheme may be transmit diversity.

In addition, the processor may report the terminal capability as to whether the base station supports dynamic change to the predetermined transmission scheme. In this case, the terminal capability report may be defined for each TTI length.

In addition, the downlink control information format schedules downlink data channels in a plurality of TTIs, and a hybrid automatic repeat request (HARQ) -acknowledgment (ACK) response for downlink data channels in the plurality of TTIs is determined in the plurality of TTIs. It may be transmitted separately at the timing corresponding to each of the downlink data channels in the TTI of.

In addition, the downlink control information format schedules downlink data channels in a plurality of TTIs, and a hybrid automatic repeat request (HARQ) -acknowledgment (ACK) response for downlink data channels in the plurality of TTIs is bundled or Can be aggregated and transmitted.

In addition, the HARQ-ACK response is separated by a predetermined offset from a resource determined by a lowest control channel element (CCE) index of the downlink control information format or a resource connected to states of an ACK / NACK resource indicator (ARI) field. Can be sent from a resource.

In addition, a resource block set for monitoring the downlink control information format and an aggregation level and / or the number of monitoring candidates to be used in the resource block set for monitoring the downlink control information format may be set.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable those skilled in the art to implement and practice the invention. While the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will understand that various modifications and changes can be made to the present invention as set forth in the claims below. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The present invention can be used in a wireless communication device such as a terminal, a relay, a base station, and the like.

Claims (20)

1. In the method for receiving a downlink signal in a wireless communication system, the method is performed by a terminal,

   Receiving from the base station a dynamic change setting to a predetermined transmission scheme associated with a short transmission time interval (sTTI) based downlink operation;

   When the dynamic change setting is received, detecting a downlink control information format including a field related to the dynamic change; And

   If a value of the field indicates the predetermined transmission scheme, receiving a signal on a downlink data channel according to the predetermined transmission scheme.
2. The method of claim 1, wherein the dynamic change setting is set for each TTI length.
3. The method of claim 1, wherein the dynamic change setting is set regardless of a transmission mode associated with the sTTI based downlink operation.
4. The method of claim 1, wherein the predetermined transmission scheme is transmit diversity.
5. 2. The method of claim 1, further comprising reporting terminal capability to the base station as to whether to support dynamic change to the predetermined transmission scheme.
6. The method of claim 5, wherein the terminal capability report is defined for each TTI length.
7. The method of claim 1, wherein the downlink control information format schedules downlink data channels in a plurality of TTIs.

   A hybrid automatic repeat request (HARQ) -ACK (acknowledgment) response for downlink data channels in the plurality of TTIs is transmitted separately at a timing corresponding to each of the downlink data channels in the plurality of TTIs. , Way.
8. The method of claim 1, wherein the downlink control information format schedules downlink data channels in a plurality of TTIs.

   And a hybrid automatic repeat request (HARQ) -acknowledgment (ACK) response for downlink data channels in the plurality of TTIs is bundled or aggregated and transmitted.
9. 8. The HARQ-ACK response according to claim 7, wherein the HARQ-ACK response is previously determined from a resource determined by a lowest control channel element (CCE) index of the downlink control information format or a resource connected to states of an ACK / NACK resource indicator (ARI) field. And is transmitted on resources separated by a determined offset.
10. 8. The method of claim 7, wherein an aggregation level and / or number of monitoring candidates to be used in the resource block set for monitoring the downlink control information format and the resource block set for monitoring the downlink control information format are set. , Way.
11. In a terminal for receiving a downlink signal in a wireless communication system, the terminal is:

    Receiver and transmitter; And

    A processor controlling the receiver and the transmitter;

    The processor receives from the base station a dynamic change setting to a predetermined transmission scheme related to a short transmission time interval (sTTI) based downlink operation, and when the dynamic change setting is received, Detect a downlink control information format including a field, and

    And if the value of the field indicates the predetermined transmission scheme, receiving a signal on a downlink data channel according to the predetermined transmission scheme.
12. The terminal of claim 11, wherein the dynamic change setting is set for each TTI length.
13. 12. The terminal of claim 11, wherein the dynamic change setting is set regardless of a transmission mode associated with the sTTI based downlink operation.
14. 12. The terminal of claim 11, wherein the predetermined transmission scheme is transmit diversity.
15. 12. The terminal of claim 11, wherein the processor reports the terminal capability as to whether the base station supports dynamic change to the predetermined transmission scheme.
16. The terminal of claim 15, wherein the terminal capability report is defined for each TTI length.
17. 12. The method of claim 11, wherein the downlink control information format schedules downlink data channels in a plurality of TTIs.

    A hybrid automatic repeat request (HARQ) -ACK (acknowledgment) response for downlink data channels in the plurality of TTIs is transmitted separately at a timing corresponding to each of the downlink data channels in the plurality of TTIs. , Terminal.
18. 12. The method of claim 11, wherein the downlink control information format schedules downlink data channels in a plurality of TTIs.

    And a hybrid automatic repeat request (HARQ) -acknowledgment (ACK) response for downlink data channels in the plurality of TTIs is bundled or aggregated and transmitted.
19. 18. The method of claim 17, wherein the HARQ-ACK response is previously determined from a resource determined by a lowest control channel element (CCE) index of the downlink control information format or a resource connected to states of an ACK / NACK resource indicator (ARI) field. The terminal, characterized in that transmitted in the resources separated by the offset.
20. 18. The method of claim 17, wherein an aggregation level and / or a number of monitoring candidates to be used in the resource block set for monitoring the downlink control information format and the resource block set for monitoring the downlink control information format are set. , Terminal.

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