WO2017183779A1 - Method for transmitting srs in wireless communication system, and user equipment therefor - Google Patents

Abstract

A method for transmitting an SRS by a user equipment in a wireless communication system may comprise the steps of: measuring a received signal strength variation value during a predetermined period of time, so as to determine an SRS configuration index; determining, on the basis of predefined SRS configuration information, SRS transmission period-related index information and predetermined transmission beam candidate set index information of the user equipment, which correspond to the determined SRS configuration index; transmitting, to a base station, the SRS transmission period-related index information and the predetermined transmission beam candidate set index information; and transmitting the SRS to the base station on the basis of at least one piece of transmission beam identification (ID) candidate information corresponding to the predetermined transmission beam candidate set index information.

Description

Method for transmitting SRS in wireless communication system and terminal for same

The present invention relates to wireless communication, and more particularly, to a method for transmitting an SRS in a wireless communication system and a terminal for the same.

Since the beam scanning procedure has a lot of processing overhead in itself, it is not possible to shorten the beam scanning in an extreme period. The temporal change of channels above 6 GHz is likely to change faster than existing sub-6 GHz channels due to the additional channel factors mentioned above. Also, in the cellular system, the BS beam configuration may be fixed, but the beam of the UE may be changed according to the location of the serving cell, the change of the surrounding environment, the UE behavior pattern, and the like. That is, the Tx / Rx beam mismatch is likely to occur within the beam scanning interval. Therefore, a beam tracking technique is needed to overcome this.

However, the SRS needs to be transmitted for beam tracking, but the technique of transmitting SRS for beam tracking has not been studied in detail.

An object of the present invention is to provide a method for transmitting an SRS by a terminal in a wireless communication system.

Another object of the present invention is to provide a terminal for transmitting an SRS in a wireless communication 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 order to achieve the above technical problem, a method for transmitting an SRS by a terminal in a wireless communication system includes: determining an SRS configuration index by measuring a change value of a received signal strength for a specific time; Determining index information related to an SRS transmission period corresponding to the determined SRS configuration index and specific transmission beam candidate set index information of the terminal based on predefined SRS configuration information; Transmitting index information related to the SRS transmission period and the specific transmission beam candidate set index information to the base station; And transmitting the SRS to the base station based on at least one transmission beam identifier (ID) candidate information corresponding to the specific transmission beam candidate set index information.

The predefined SRS configuration information may include a physical SRS transmission period value corresponding to the determined SRS configuration index and an SRS subframe offset value corresponding to the determined SRS configuration index.

The specific transmission beam candidate set index information may be determined based on index information related to the SRS transmission period corresponding to the determined SRS configuration index or a physical SRS transmission period value.

The at least one transmit beam identifier (ID) candidate information includes at least one transmit beam identifier candidate corresponding to the determined transmit beam candidate set index information, and is respectively assigned to the at least one transmit beam identifier (ID) candidate. SRS may be transmitted through a symbol.

The method comprises the steps of: receiving an optimal transmission beam identifier (ID) and uplink resource allocation information of the terminal from the base station; And performing uplink transmission by using a transmission beam corresponding to the optimal transmission beam identifier (ID). The method may further include performing beam scanning with the base station, wherein the base station is paired with a transmission beam of the terminal and a transmission beam of the terminal based on beam pair information between the terminal and the base station determined by the beam scanning. Uplink transmission may be performed based on a reception beam of.

In order to achieve the above another technical problem, a terminal for transmitting an SRS in a wireless communication system, the transmitter; And a processor,

The processor determines an SRS configuration index by measuring a change value of a received signal strength for a specific time, and index information related to an SRS transmission period corresponding to the determined SRS configuration index based on predefined SRS configuration information and the terminal's index. Determine specific transmission beam candidate set index information, and wherein the transmitter transmits index information related to the SRS transmission period and the specific transmission beam candidate set index information to the base station, and corresponds to the specific transmission beam candidate set index information. The SRS may be controlled to be transmitted to the base station based on at least one transmission beam identifier (ID) candidate information.

The predefined SRS configuration information may include a physical SRS transmission period value corresponding to the determined SRS configuration index and an SRS subframe offset value corresponding to the determined SRS configuration index.

The processor may determine the determined transmission beam candidate set index information based on index information associated with the SRS transmission period or a physical SRS transmission period value corresponding to the determined SRS configuration index.

The at least one transmit beam identifier (ID) candidate information includes at least one transmit beam identifier candidate corresponding to the determined transmit beam candidate set index information, and wherein the processor is further configured to transmit the SRS to the at least one transmit beam identifier. (ID) can be controlled to transmit through the symbols assigned to each candidate.

The terminal further includes a receiver, wherein the processor controls the receiver to receive an optimal terminal transmit beam identifier (ID) and uplink resource allocation information from the base station, and the processor is configured to allow the transmitter to optimize the terminal. It may be controlled to perform uplink transmission by using a transmission beam corresponding to a transmission beam identifier (ID).

The processor is configured to perform beam scanning with the base station, and wherein the transmitter is configured to transmit and transmit a transmission beam of the terminal and a transmission beam of the terminal based on beam pair information between the terminal and the base station determined by the beam scanning. It may be controlled to perform uplink transmission based on the received beams of the paired base stations.

According to an embodiment of the present invention, the efficient resource allocation of the SRS for the UE transmission beam tracking in the base station reception beam and the UE transmission beam pair and the adaptive beam tracking procedure according to the behavior pattern of each UE are efficiently presented. Communication is possible.

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 is a block diagram showing the configuration of a base station 105 and a terminal 110 in a wireless communication system 100.

FIG. 2A is a diagram illustrating a time when meaningful blockage occurs in Series of blockage event duration in Table 2, and FIG. 2B is a diagram illustrating blockage duration (t _D ) in Table 2. FIG.

3 illustrates a wide beam using four narrow beams.

4 is a diagram illustrating an example of a structure of a synchronization subframe.

FIG. 5 is a diagram illustrating a beam scanning period and a resource area (for example, 5 × N ms periods).

6 is a diagram illustrating SRS transmission corresponding to a terminal beam ID (terminal transmission beam ID number = 8).

7 is a diagram illustrating measured RSRP change of each downlink terminal.

8 illustrates positions of candidate offsets of a terminal transmission beam.

9 is a diagram illustrating an SRS transmission method according to a terminal transmission beam candidate index.

10 is a diagram illustrating a flowchart for UE-specific periodic SRS transmission proposed in 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. For example, the following detailed description will be described in detail on the assumption that the mobile communication system is a 3GPP LTE, LTE-A system, but is also applied to any other mobile communication system except for the specific matters of 3GPP LTE, LTE-A. Applicable

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 addition, in the following description, it is assumed that a terminal collectively refers to a mobile or fixed user terminal device such as a user equipment (UE), a mobile station (MS), an advanced mobile station (AMS), and the like. In addition, it is assumed that the base station collectively refers to any node of the network side that communicates with the terminal such as a Node B, an eNode B, a Base Station, and an Access Point (AP). Although described herein based on the IEEE 802.16 system, the contents of the present invention can be applied to various other communication systems.

In a mobile communication system, a terminal or a user equipment may receive information from a base station through downlink, and the terminal may also transmit information through uplink. The information transmitted or received by the terminal includes data and various control information, and various physical channels exist according to the type and purpose of the information transmitted or received by the terminal.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) employs OFDMA in downlink and SC-FDMA in uplink as part of Evolved UMTS (E-UMTS) using E-UTRA. LTE-A (Advanced) is an evolution of 3GPP LTE.

In addition, specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

1 is a block diagram showing the configuration of a base station 105 and a terminal 110 in a wireless communication system 100.

Although one base station 105 and one terminal 110 are shown to simplify the wireless communication system 100, the wireless communication system 100 may include one or more base stations and / or one or more terminals. .

Referring to FIG. 1, the base station 105 includes a transmit (Tx) data processor 115, a symbol modulator 120, a transmitter 125, a transmit / receive antenna 130, a processor 180, a memory 185, and a receiver ( 190, a symbol demodulator 195, and a receive data processor 197. The terminal 110 transmits (Tx) the data processor 165, the symbol modulator 170, the transmitter 175, the transmit / receive antenna 135, the processor 155, the memory 160, the receiver 140, and the symbol. It may include a demodulator 155 and a receive data processor 150. Although the transmit and receive antennas 130 and 135 are shown as one in the base station 105 and the terminal 110, respectively, the base station 105 and the terminal 110 are provided with a plurality of transmit and receive antennas. Accordingly, the base station 105 and the terminal 110 according to the present invention support a multiple input multiple output (MIMO) system. In addition, the base station 105 according to the present invention may support both a single user-MIMO (SU-MIMO) and a multi-user-MIMO (MU-MIMO) scheme.

On the downlink, the transmit data processor 115 receives the traffic data, formats the received traffic data, codes it, interleaves and modulates (or symbol maps) the coded traffic data, and modulates the symbols ("data"). Symbols "). The symbol modulator 120 receives and processes these data symbols and pilot symbols to provide a stream of symbols.

The symbol modulator 120 multiplexes the data and pilot symbols and sends it to the transmitter 125. In this case, each transmission symbol may be a data symbol, a pilot symbol, or a signal value of zero. In each symbol period, pilot symbols may be sent continuously. The pilot symbols may be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), or code division multiplexed (CDM) symbols.

Transmitter 125 receives the stream of symbols and converts it into one or more analog signals, and further adjusts (eg, amplifies, filters, and frequency upconverts) the analog signals to provide a wireless channel. Generates a downlink signal suitable for transmission via the transmission antenna 130, the transmission antenna 130 transmits the generated downlink signal to the terminal.

In the configuration of the terminal 110, the receiving antenna 135 receives the downlink signal from the base station and provides the received signal to the receiver 140. Receiver 140 adjusts the received signal (eg, filtering, amplifying, and frequency downconverting), and digitizes the adjusted signal to obtain samples. The symbol demodulator 145 demodulates the received pilot symbols and provides them to the processor 155 for channel estimation.

The symbol demodulator 145 also receives a frequency response estimate for the downlink from the processor 155 and performs data demodulation on the received data symbols to obtain a data symbol estimate (which is an estimate of the transmitted data symbols). Obtain and provide data symbol estimates to a receive (Rx) data processor 150. Receive data processor 150 demodulates (ie, symbol de-maps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data.

The processing by symbol demodulator 145 and receiving data processor 150 is complementary to the processing by symbol modulator 120 and transmitting data processor 115 at base station 105, respectively.

The terminal 110 is on the uplink, and the transmit data processor 165 processes the traffic data to provide data symbols. The symbol modulator 170 may receive and multiplex data symbols, perform modulation, and provide a stream of symbols to the transmitter 175. The transmitter 175 receives and processes a stream of symbols to generate an uplink signal. The transmit antenna 135 transmits the generated uplink signal to the base station 105.

In the base station 105, an uplink signal is received from the terminal 110 through the reception antenna 130, and the receiver 190 processes the received uplink signal to obtain samples. The symbol demodulator 195 then processes these samples to provide received pilot symbols and data symbol estimates for the uplink. The received data processor 197 processes the data symbol estimates to recover the traffic data transmitted from the terminal 110.

Processors 155 and 180 of the terminal 110 and the base station 105 respectively instruct (eg, control, coordinate, manage, etc.) operations at the terminal 110 and the base station 105, respectively. Respective processors 155 and 180 may be connected to memory units 160 and 185 that store program codes and data. The memory 160, 185 is coupled to the processor 180 to store the operating system, applications, and general files.

The processors 155 and 180 may also be referred to as controllers, microcontrollers, microprocessors, microcomputers, or the like. The processors 155 and 180 may be implemented by hardware or firmware, software, or a combination thereof. When implementing embodiments of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the processors 155 and 180.

Meanwhile, when implementing embodiments of 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 to perform the present invention. The firmware or software configured to be may be provided in the processors 155 and 180 or stored in the memory 160 and 185 to be driven by the processors 155 and 180.

The layers of the air interface protocol between the terminal and the base station between the wireless communication system (network) are based on the lower three layers of the open system interconnection (OSI) model, which is well known in the communication system. ), And the third layer L3. The physical layer belongs to the first layer and provides an information transmission service through a physical channel. A Radio Resource Control (RRC) layer belongs to the third layer and provides control radio resources between the UE and the network. The terminal and the base station may exchange RRC messages through the wireless communication network and the RRC layer.

In the present specification, the processor 155 of the terminal and the processor 180 of the base station process the signals and data, except for the function of receiving or transmitting the signal and the storage function of the terminal 110 and the base station 105, respectively. For convenience of description, the following description does not specifically refer to the processors 155 and 180. Although not specifically mentioned by the processors 155 and 180, it may be said that a series of operations such as a function of receiving or transmitting a signal and a data processing other than a storage function are performed.

For Tx beam tracking of the terminal, the terminal needs to transmit the SRS according to each candidate terminal transmission beam (Tx beam). Since SRS transmission according to many beam directions (transmission beam set of UE in all directions) generates a large amount of resource loss, according to the present invention, SRS transmission is flexibly transmitted according to UE change pattern, thereby adaptive UE transmission. We propose a method for performing beam tracking.

First, contents related to SRS transmission in 3GPP LTE / LTE-A system are described in Table 1 below.

A UE shall transmit Sounding Reference Symbol (SRS) on per serving cell SRS resources based on two trigger types:-trigger type 0: higher layer signaling-trigger type 1: DCI formats 0/4 / 1A for FDD and TDD and DCI formats 2B / 2C / 2D for TDD. In case both trigger type 0 and trigger type 1 SRS transmissions would occur in the same subframe in the same serving cell, the UE shall only transmit the trigger type 1 SRS transmission.A UE may be configured with SRS parameters for trigger type 0 and trigger type 1 on each serving cell. The following SRS parameters are serving cell specific and semi-statically configurable by higher layers for trigger type 0 and for trigger type 1.-Transmission comb , as defined in subclause 5.5.3.2 of [3] for trigger type 0 and each configuration of trigger type 1-Starting physical resource block assignment n RRC , as defined in subclause 5.5.3.2 of [3] for trigger type 0 and each configuration of trigger type 1-duration: single or indefinite (until disabled), as defined in [11] for trigger type 0-srs-ConfigIndex I SRS for SRS periodicity T SRS and SRS subframe offset T offset , as defined in Table 8.2-1 and Table 8.2-2 for trigger type 0 and SRS periodicity T SRS, 1 , and SRS subframe offset T SRS, 1 , as defined in Table 8.2-4 and Table 8.2-5 trigger type 1-SRS bandwidth B SRS , as defined in subclause 5.5.3.2 of [3] for trigger type 0 and each configuration of trigger type 1-Frequency hopping bandwidth, b hop , as defined in subclause 5.5.3.2 of [3] for trigger type 0-Cyclic shift , as defined in subclause 5.5.3.1 of [3] for trigger type 0 and each configuration of trigger type 1-Number of antenna ports N p for trigger type 0 and each configuration of trigger type 1For trigger type 1 and DCI format 4 three sets of SRS parameters, srs-ConfigApDCI-Format4, are configured by higher layer signaling. The 2-bit SRS request field [4] in DCI format 4 indicates the SRS parameter set given in Table 8.1-1. For trigger type 1 and DCI format 0, a single set of SRS parameters, srs-ConfigApDCI-Format0, is configured by higher layer signaling. For trigger type 1 and DCI formats 1A / 2B / 2C / 2D, a single common set of SRS parameters, srs-ConfigApDCI-Format1a2b2c, is configured by higher layer signaling. The SRS request field is 1 bit [4] for DCI formats 0 / 1A / 2B / 2C / 2D, with a type 1 SRS triggered if the value of the SRS request field is set to '1'. A 1-bit SRS request field shall be included in DCI formats 0 / 1A for frame structure type 1 and 0 / 1A / 2B / 2C / 2D for frame structure type 2 if the UE is configured with SRS parameters for DCI formats 0 / 1A / 2B / 2C / 2D by higher-layer signalling.

Table 2 below shows a SRS Request Value for trigger type 1 in DCI format 4 in 3GPP LTE / LTE-A system.

Value of SRS request field	Description
'00'	No type 1 SRS trigger
'01'	The 1 st SRS parameter set configured by higher layers
'10'	The 2 nd SRS parameter set configured by higher layers
'11'	The 3 rd SRS parameter set configured by higher layers

Table 3 below is a table for further explaining the additional information related to the SRS transmission in the 3GPP LTE / LTE-A system.

The serving cell specific SRS transmission bandwidths C SRS are configured by higher layers. The allowable values are given in subclause 5.5.3.2 of [3]. The serving cell specific SRS transmission sub-frames are configured by higher layers. The allowable values are given in subclause 5.5.3.3 of [3]. For a TDD serving cell, SRS transmissions can occur in UpPTS and uplink subframes of the UL / DL configuration indicated by the higher layer parameter subframeAssignment for the serving cell.When closed-loop UE transmit antenna selection is enabled for a given serving cell for a UE that supports transmit antenna selection, the index a (n SRS ), of the UE antenna that transmits the SRS at time n SRS is given bya (n SRS ) = n SRS mod 2, for both partial and full sounding bandwidth, and when frequency hopping is disabled (ie, ), when frequency hopping is enabled (ie where values B SRS , b hop , N b , and n SRS are given in subclause 5.5.3.2 of [3], and (where regardless of the N b value), except when a single SRS transmission is configured for the UE. If a UE is configured with more than one serving cell, the UE is not expected to transmit SRS on different antenna ports simultaneously.A UE may be configured to transmit SRS on Np antenna ports of a serving cell where Np may be configured by higher layer signalling. For PUSCH transmission mode 1 and for PUSCH transmission mode 2 with two antenna ports configured for PUSCH and with 4 antenna ports configured for PUSCH. A UE configured for SRS transmission on multiple antenna ports of a serving cell shall transmit SRS for all the configured transmit antenna ports within one SC-FDMA symbol of the same subframe of the serving cell. The SRS transmission bandwidth and starting physical resource block assignment are the same for all the configured antenna ports of a given serving cell.A UE not configured with multiple TAGs shall not transmit SRS in a symbol whenever SRS and PUSCH transmissions happen to overlap in the same symbol.For TDD serving cell, when one SC-FDMA symbol exists in UpPTS of the given serving cell, it can be used for SRS transmission. When two SC-FDMA symbols exist in UpPTS of the given serving cell, both can be used for SRS transmission and for trigger type 0 SRS both can be assigned to the same UE.If a UE is not configured with multiple TAGs, or if a UE is configured with multiple TAGs and SRS and PUCCH format 2 / 2a / 2b happen to coincide in the same subframe in the same serving cell, -The UE shall not transmit type 0 triggered SRS whenever type 0 triggered SRS and PUCCH format 2 / 2a / 2b transmissions happen to coincide in the same subframe; The UE shall not transmit type 1 triggered SRS whenever type 1 triggered SRS and PUCCH format 2a / 2b or format 2 with HARQ-ACK transmissions happen to coincide in the same subframe; -The UE shall not transmit PUCCH format 2 without HARQ-ACK whenever type 1 triggered SRS and PUCCH format 2 without HARQ-ACK transmissions happen to coincide in the same subframe.If a UE is not configured with multiple TAGs, or if a UE is configured with multiple TAGs and SRS and PUCCH happen to coincide in the same subframe in the same serving cell, -The UE shall not transmit SRS whenever SRS transmission and PUCCH transmission carrying HARQ-ACK and / or positive SR happen to coincide in the same subframe if the parameter ackNackSRS-Simultaneous Transmission is FALSE; -For FDD-TDD and primary cell frame structure 1, the UE shall not transmit SRS in a symbol whenever SRS transmission and PUCCH transmission carrying HARQ-ACK and / or positive SR using shortened format as defined in subclauses 5.4.1 and 5.4.2A of [3] happen to overlap in the same symbol if the parameter ackNackSRS-SimultaneousTransmission is TRUE. -Unless otherwise prohibited, the UE shall transmit SRS whenever SRS transmission and PUCCH transmission carrying HARQ-ACK and / or positive SR using shortened format as defined in subclauses 5.4.1 and 5.4.2A of [3] happen to coincide in the same subframe if the parameter ackNackSRS-SimultaneousTransmission is TRUE.A UE not configured with multiple TAGs shall not transmit SRS whenever SRS transmission on any serving cells and PUCCH transmission carrying HARQ-ACK and / or positive SR using normal PUCCH format as defined in subclauses 5.4.1 and 5.4.2A of [3] happen to coincide in the same subframe.In UpPTS, whenever SRS transmission instance overlaps with the PRACH region for preamble format 4 or exceeds the range of uplink system bandwidth configured in the serving cell, the UE shall not transmit SRS.The parameter ackNackSRS-Simultaneous Transmission provided by higher layers determines if a UE is configured to support the transmission of HARQ-ACK on PUCCH and SRS in one subframe. If it is configured to support the transmission of HARQ-ACK on PUCCH and SRS in one subframe, then in the cell specific SRS subframes of the primary cell UE shall transmit HARQ-ACK and SR using the shortened PUCCH format as defined in subclauses 5.4. 1 and 5.4.2A of [3], where the HARQ-ACK or the SR symbol corresponding to the SRS location is punctured. This shortened PUCCH format shall be used in a cell specific SRS subframe of the primary cell even if the UE does not transmit SRS in that subframe. The cell specific SRS subframes are defined in subclause 5.5.3.3 of [3]. Otherwise, the UE shall use the normal PUCCH format 1 / 1a / 1b as defined in subclause 5.4.1 of [3] or normal PUCCH format 3 as defined in subclause 5.4.2A of [3] for the transmission of HARQ-ACK and SR.Trigger type 0 SRS configuration of a UE in a serving cell for SRS periodicity, T SRS , and SRS subframe offset, T offset , is defined in Table 8.2-1 and Table 8.2-2, for FDD and TDD serving cell, respectively . The periodicity T SRS of the SRS transmission is serving cell specific and is selected from the set {2, 5, 10, 20, 40, 80, 160, 320} ms or subframes. For the SRS periodicity T SRS of 2 ms in TDD serving cell, two SRS resources are configured in a half frame containing UL subframe (s) of the given serving cell. Type 0 triggered SRS transmission instances in a given serving cell for TDD serving cell with T SRS > 2 and for FDD serving cell are the subframes satisfying , where for FDD k SRS = {0, 1 ,,,, 0} is the subframe index within the frame, for TDD serving cell k SRS is defined in Table 8.2-3. The SRS transmission instances for TDD serving cell with T SRS = 2 are the subframes satisfying k SRS -T offset . For TDD serving cell, and a UE configured for type 0 triggered SRS transmission in serving cell c, and the UE configured with the parameter EIMTA-MainConfigServCell-r12 for serving cell c, if the UE does not detect an UL / DL configuration indication for radio frame m (as described in section 13.1), the UE shall not transmit trigger type 0 SRS in a subframe of radio frame m that is indicated by the parameter eimta-HarqReferenceConfig-r12 as a downlink subframe unless the UE transmits PUSCH in the same subframe.Trigger type 1 SRS configuration of a UE in a serving cell for SRS periodicity, T SRS, 1 , and SRS subframe offset, T offset, 1 , is defined in Table 8.2-4 and Table 8.2-5, for FDD and TDD serving cell, respectively. The periodicity T SRS, 1 of the SRS transmission is serving cell specific and is selected from the set {2, 5, 10} ms or subframes. For the SRS periodicity T SRS, 1 of 2 ms in TDD serving cell, two SRS resources are configured in a half frame containing UL subframe (s) of the given serving cell. A UE configured for type 1 triggered SRS transmission in serving cell c and not configured with a carrier indicator field shall transmit SRS on serving cell c upon detection of a positive SRS request in PDCCH / EPDCCH scheduling PUSCH / PDSCH on serving cell cA UE configured for type 1 triggered SRS transmission in serving cell c and configured with a carrier indicator field shall transmit SRS on serving cell c upon detection of a positive SRS request in PDCCH / EPDCCH scheduling PUSCH / PDSCH with the value of carrier indicator field corresponding to serving cell c . A UE configured for type 1 triggered SRS transmission on serving cell c upon detection of a positive SRS request in subframe n of serving cell c shall commence SRS transmission in the first subframe satisfying and for TDD serving cell c with T SRS, 1 > 2 and for FDD serving cell c, for TDD serving cell c with T SRS, 1 = 2where for FDD serving cell c is the subframe index within the frame n f , for TDD serving cell ck SRS is defined in Table 8.2-3.A UE configured for type 1 triggered SRS transmission is not expected to receive type 1 SRS triggering events associated with different values of trigger type 1 SRS transmission parameters, as configured by higher layer signaling, for the same subframe and the same serving cell.For TDD serving cell c, and a UE configured with EIMTA-MainConfigServCell-r12 for a serving cell c, the UE shall not transmit SRS in a subframe of a radio frame that is indicated by the corresponding eIMTA-UL / DL-configuration as a downlink subframe.A UE shall not transmit SRS whenever SRS and a PUSCH transmission corresponding to a Random Access Response Grant or a retransmission of the same transport block as part of the contention based random access procedure coincide in the same subframe.

Table 4 below shows a subframe offset configuration (T _offset) and UE-specific SRS periodicity (T _SRS ) for trigger type 0 in FDD.

SRS Configuration Index I SRS	SRS Periodicity (ms)	SRS Subframe Offset
0-1	2	I SRS
2-6	5	I SRS -2
7-16	10	I SRS -7
17-36	20	I SRS -17
37-76	40	I SRS -37
77-156	80	I SRS -77
157-316	160	I SRS -157
317-636	320	I SRS -317
637-1023	reserved	reserved

Table 5 below shows subframe offset configuration (T _offset) and UE-specific SRS periodicity (T _SRS ) for trigger type 0 in TDD.

SRS Configuration Index I SRS	SRS Periodicity (ms)	SRS Subframe Offset
0-1	2	I SRS
2-6	5	I SRS -2
7-16	10	I SRS -7
17-36	20	I SRS -17
37-76	40	I SRS -37
77-156	80	I SRS -77
157-316	160	I SRS -157
317-636	320	I SRS -317
637-1023	reserved	reserved

SRS Configuration Index I SRS	SRS Periodicity (ms)	SRS Subframe Offset
0	2	0, 1
One	2	0, 2
2	2	1, 2
3	2	0, 3
4	2	1, 3
5	2	0, 4
6	2	1, 4
7	2	2, 3
8	2	2, 4
9	2	3, 4
10-14	5	I SRS -10
15-24	10	I SRS -15
25-44	20	I SRS -25
45-84	40	I SRS -45
85-164	80	I SRS -85
165-324	160	I SRS -165
325-644	320	I SRS -325
645-1023	reserved	reserved

Table 7 shows k _SRS for TDD.

	subframe index n
	0	One		2	3	4	5	6		7	8	9
		1st symbol of UpPTS	2nd symbol of UpPTS					1st symbol of UpPTS	2nd symbol of UpPTS
k SRS in case UpPTS length of 2 symbols		0	One	2	3	4		5	6	7	8	9
k SRS in case UpPTS length of 1 symbol		One		2	3	4		6		7	8	9

Table 8 below shows a subframe offset configuration (T _{offset, 1} ) and UE-specific SRS periodicity (T _{SRS, 1} ) for trigger type 1 in FDD.

SRS Configuration Index I SRS	SRS Periodicity (ms)	SRS Subframe Offset
0-1	2	I SRS
2-6	5	I SRS -2
7-16	10	I SRS -7
17-31	reserved	reserved

Table 9 below shows a subframe offset configuration (T _{offset, 1} ) and UE-specific SRS periodicity (T _{SRS, 1} ) for trigger type 1 in TDD.

SRS Configuration Index I SRS	SRS Periodicity (ms)	SRS Subframe Offset
0	reserved	reserved
One	2	0, 2
2	2	1, 2
3	2	0, 3
4	2	1, 3
5	2	0, 4
6	2	1, 4
7	2	2, 3
8	2	2, 4
9	2	3, 4
10-14	5	I SRS -10
15-24	10	I SRS -15
25-31	reserved	reserved

The following Table 10 shows additional channel change characteristics (blockage effect) compared to less than 6Ghz channel of more than 6Ghz channel.

Ref.	Test description	Tx height	Rx height	Test frequency	Blockage rate relative parameter
[2]	One blocker moving (1m / s) Horn (22.4dBi, 12˚) Patch (4.3dBi / 2.2dBi, 58˚)	2.2 / 1.2m	1.2 m	60 GHz	Series of Blockage event duration (threshold 5dB) 780 ~ 1839ms (Horn) 640 ~ 1539ms (Patch)
	4 blockers moving				Series of Blockage event duration (threshold 5 dB) 688 ms (Horn, average) 278 ms (Patch, average)
[5]	1 ~ 15 blockers movingThe horns (22.4 dBi, 12˚ in azimuth, about 10˚ in elevation) The patches (about 3 dBi, 60˚ both in elevation and azimuth.The vertical polarization)	1.58 / 2.77 m	1.55m	60 GHz	Series of Blockage event duration
					(Threshold 10dB) 300ms (1 ~ 5 persons) 350ms (6 ~ 10 persons) 450ms (11 ~ 15 persons)	(Threshold 20dB) 100ms (1 ~ 5 persons) 150ms (6 ~ 10 persons) 300ms (11 ~ 15 persons)
[6]	-	-	-	60 GHz	93 ms (Mean Drop Rate)
[7]	One blocker moving (Walking speed) 20dBi, 10˚	1.1m	0.75m	67 GHz	t D = 230ms (average, Threshold 20dB)
[8]	One blocker moving (Walking speed) 20dBi, 10˚	1.1m	0.75m	67 GHz	t D = 370 ms to 820 mst decay = 230 ms (mean), 92 ms (sd) (Threshold 20 dB) t rising = 220 ms (mean), 100 ms (sd) (Threshold 20 dB)

FIG. 2 is a diagram for describing a blocakage duration in relation to Table 10. FIG. FIG. 2A illustrates a time when a series of blockage event duration in Table 10 generates meaningful blockage (i.e., blockage causing attenuation below a specific power threshold), and FIG. 2B illustrates blockage duration (Table 2) in FIG. t _D ). The Series of Blockage event represents the time when a meaningful blockage occurs, and t _D represents the time when the blockage occurs and the blockage ends again and returns to the normal state.

Table 11 is a table for showing the pattern relationship between t _decay , t _rising and the terminal.

	Walking (0.6m / s) [7]	Sprinting (10m / s) [9]	Swift Hand swing (43m / s)
t decay , t rising (ms)	150ms (measure)	9 ms (calculation)	2.093 ms (calculation)

The blockage change in Table 11 is basically about 100 ms (walking obstacle speed (4 km / h)), but this may vary from 2 to several hundred ms, depending on the pattern of the terminal and the surrounding environment.

Need for Beam Tracking

3 and the wide beam can be defined when the multi-beams are properly positioned.

3 illustrates a wide beam using four narrow beams.

Referring to FIG. 3, four sub-arrays are used to define a wide beam. In the present invention, it is assumed that a transmitter transmits a synchronization signal using the wide beam. That is, it is assumed that all sub-arrays transmit identical Primary Synchronization Signals (PSS) / Secondary Synchronization Signals (SSS) / Physical Broadcast CHannel (PBCH).

On the other hand, when a plurality of beams are defined to cover a large area, the beam gain becomes small. To offset this, additional power gain can be provided through repeated transmissions on the time axis. The synchronization subframe structure based on such repeated transmission may be represented as shown in FIG. 4.

4 is a diagram illustrating an example of a structure of a synchronization subframe.

4 shows a synchronization subframe structure and defines PSS / SSS / PBCH. In this case, in FIG. 5, a block having the same hatching shape refers to an orthogonal frequency division multiplexing (OFDM) symbol group to which the same RF beam group (defined using four subarray beams) is applied. That is, four OFDM symbols use the same multi-RF beam. The beam scanning section may be configured as shown in FIG. 4 in a general form in New RAT with reference to the structure of FIG. 4.

FIG. 5 is a diagram illustrating a beam scanning period and a resource area (for example, 5 × N ms periods).

Basically, because the beam scanning procedure itself has a lot of processing overhead, it is not possible to shorten the beam scanning in extreme periods. In addition, the temporal change of the channel above 6GHz is likely to change faster than the existing channel below 6GHz due to the aforementioned additional channel elements. Also, in the cellular system, the BS beam configuration may be fixed, but the beam of the UE may be changed according to the location of the serving cell, the change of the surrounding environment, the UE behavior pattern, and the like. That is, the Tx / Rx beam mismatch is likely to occur within the beam scanning interval. Therefore, a beam tracking technique is needed to overcome this.

In the case of downlink, the received signal strength (Rx beam) of the terminal is applied to each BRS by using the BRS illustrated in FIG. 4 (hereinafter, referred to as RSRP (Reference Signal Received Power)). It can be done by measuring. If the reciprocity of the Tx / Rx beam pair for downlink (ie, base station transmit beam / terminal receive beam pair and terminal transmit beam / base station receive beam) is established, The obtained transmit / receive beam pair can be applied to uplink. However, if not, the uplink case may use SRS. If the most reliable uplink beam tracking is desired, the SRS corresponding to the entire transmission beam ID of each UE should be transmitted. This means that a physical uplink shared channel (PUSCH) transmission interval becomes smaller according to SRS transmission, and impairs uplink throughput performance.

6 is a diagram illustrating SRS transmission corresponding to a terminal beam ID (terminal transmission beam ID number = 8).

As shown in FIG. 6, as the terminal beam ID increases, the SRS transmission area may increase. Hereinafter, various embodiments according to the present invention will be described.

For Tx beam tracking of the terminal, the terminal needs to transmit an SRS according to each candidate terminal transmission beam. Since SRS transmission according to many beam directions (terminal transmission beam set in all directions) generates a lot of resource loss, the present invention flexibly transmits SRS transmission according to a terminal change pattern in order to perform adaptive terminal transmission beam tracking. I would like to suggest a method.

Embodiment 1: UE-specific SRS period setting for transmission beam tracking of UE and UE-specific SRS transmission method corresponding thereto

As a sub-embodiment of Embodiment 1, a method for setting a UE-specific SRS transmission period and an SRS transmission subframe for adaptive Tx beam tracking is proposed.

Embodiment 1-1: UE-Specific SRS Transmission Period and SRS Transmission Subframe Configuration

7 is a diagram illustrating measured RSRP change of each downlink terminal.

UE-specific SRS transmission cycle

Let's define 7 shows the RSRP change of the i-th terminal with a significant RSRP change, and the figure shown to the right of FIG. 7 shows the RSRP change of the j-th terminal with no large RSRP change. Specific period of i-th UE in a specific base station beam

After measuring the RSRP pattern during each parameter (see Fig. 7)

,

,

The variable period of SRS transmission can be determined as shown in Equation 1 below.

here,

May be configured in the terminal by an upper layer as an additional parameter. Specific time period

The base station may collectively set the terminal to higher layer signaling or the terminal may be set for each terminal.

Table 12 is a table illustrating the SRS configuration and SRS period.

As an example, when T _SRS is defined as shown in Table 12 (T _SRS represents a physical SRS transmission period),

,

Is 5dB and 10ms, respectively, the terminal-specific SRS configuration Index (I _SRS ) can be set by the following equation (2) to indicate the T _SRS . That is, the terminal specific SRS configuration Index (I _SRS ) is

And

Based on the value, it may be determined as in Equation 2 below.

RSRP variation width in Equation 2 (

Increasing) increases the I _SRS value, resulting in a shorter SRS transmission period, and a longer RSRP measurement length increases the I _SRS value, resulting in a long SRS period. Since I _SRS is 2 in Equation 2, the T _SRS exemplifies setting the SRS transmission period to 1 ms with reference to Table 12.

Subframe Setting for SRS Transmission

As illustrated in Table 12, it may be a subframe configuration for SRS transmission. If a plurality of terminals are configured to transmit SRSs to different I _SRSs in a subframe for a specific SRS transmission, a terminal having the largest I _SRS may be defined to transmit _SRSs in the corresponding subframe. That is, I _SRS in a subframe overlapped for SRS transmission is as follows (

). Here, U indicates a set of UEs in which SRS transmission is configured in the subframe (when SRS transmission is performed in corresponding subframes of total U UEs). As an example, a subframe configuration for SRS transmission may be expressed as Equation 3 by modifying the SRS transmission subframe configuration of 3GPP TS 36.213.

Here, N _subframe is the number of subframes included in one frame of the system (for example, N _subframe = 10 in LTE / LTE-A system). n _f is a system frame number.

Or K _SRS = {0,1, ...., 9}. T _offset indicates an SRS subframe offset value, and T _SRS indicates a physical transmission period of the SRS.

Conventionally, the SRS transmission subframe has been determined using the T _SRS value, but in Equation 3, the SRS transmission subframe is determined by the M _SRS index value.

Embodiment 1-2: UE-Specific SRS Transmission Method for Adaptive Transmission Beam Tracking

A method of setting UE-specific SRS transmission will be described.

First, as step 1, each terminal can determine the SRS configuration index I _SRS by measuring the RSRP change according to the above-described embodiment 1-1, and the SRS transmission period corresponding to the determined I _SRS

(T _SRS for the UE of index i) may be set.

Next, as step 2, each terminal may transmit the index M _SRS corresponding to the uplink SRS transmission period and the terminal transmission beam tracking candidate set index to the base station through PUSCH or PUCCH (Physical Uplink Control CHannel).

The terminal transmit beam tracking candidate set index value may be configured as an offset value of the transmit beam ID of the terminal or the receive beam ID of the terminal obtained through beam scanning. The absolute offset ID position may be set in the upper layer. If the SRS transmission period is short, the position of the optimal terminal transmission beam that changes according to the channel change is likely to be near the previous optimal beam position. Therefore, the candidate set of the following Table 13 is set to a set of neighboring beams of the current terminal transmission beam.

Table 13 shows a terminal transmission beam candidate subset corresponding to the terminal transmission beam ID candidate offset index. Table 13 may be shared by the base station and the terminal by a method such as higher layer signaling.

8 illustrates positions of candidate offsets of a terminal transmission beam.

After beam scanning, in a state where the base station transmit beam / terminal receive beam pair is aligned, an ID corresponding to the transmit beam ID of the terminal (

Let 0 be zero. In this case, the terminal transmission beam ID offset set may set the terminal transmission beam tracking candidate set index as shown in Table 13 based on the position of the candidate offset of the terminal transmission beam of FIG. 8. Table 13 above shows only an example based on a 3-bit feedback and is extensible.

The terminal transmission beam ID candidate offset index or the terminal transmission beam candidate index I _{beam_offset} may be generally expressed as a function of T _SRS or M _SRS , and special candidate terminal beams (for example, vertical beam tracking or horizontal beam tracking, etc.). ) May also include a configuration for the determination of V / H polarization).

As an example,

When T _SRS = 1 ms, α = 1 (set by the upper layer), and β = 1 (set to 1 if the change in the vertical pole RSRP is severe), I _{beam_offset} is 2. According to Table 13, the terminal transmission beam candidate set is a set of vertical beams.

In step 3, each terminal may transmit the number of SRSs corresponding to the value of I _{beam_offset} . For example, when a specific terminal selects the terminal transmission beam ID candidate offset index as 1 in Table 13, the terminal transmission beam candidate subset corresponding to the terminal transmission beam ID candidate offset index 1 has a terminal transmission beam ID of 0, 1, Since it is configured as 2, the specific terminal can transmit three SRS corresponding to the corresponding terminal transmit beam IDs. At this time, the physical beam direction of the terminal is in I _{beam_offset}

Move in order of beam direction. The base station may be set so that the SRS resource position of each terminal does not overlap.

As an example, if I _{beam_offset} is 2, according to Table 13, the SRS may transmit as shown in FIG. 9.

9 is a diagram illustrating an SRS transmission method according to a terminal transmission beam candidate index.

As shown in FIG. 9, the base station may set a corresponding SRS transmission resource for each terminal transmission beam ID. For example, SRS 0 for the terminal transmission beam ID 0, SRS 3 for the terminal transmission beam ID 3, and SRS 4 for the terminal transmission beam ID 4 may be configured as an SRS transmission resource. Here, SRS 0, SRS 3 and SRS 4 may be transmitted in different symbols, respectively.

In step 4, the base station measures an SRS corresponding to each T _SRS and offsets an optimal transmit beam ID of each terminal.

(optimum transmission beam ID offset of the i-th terminal) can be predicted and the optimal uplink resource allocation position is identified by measuring the SRS of the entire band of the terminal.

And uplink resource allocation location to the UE through a control channel (for example, Physical Downlink Control CHannel (PDCCH)) or a data channel (for example, PDSCH (Physical Downlink Shared CHannel)).

In step 6, the transmission physical beam ID of the terminal is

It is changed to the beam ID corresponding to.

The UE-specific SRS transmission method for adaptive transmission beam tracking described above can be briefly summarized with reference to FIG. 10.

10 is a diagram illustrating a flowchart for UE-specific periodic SRS transmission proposed in the present invention.

Referring to FIG. 10, the terminal and the base station may determine the base station transmit beam / terminal receive beam pair through beam scanning. The terminal may measure the RSRP and determine the SRS transmission period based on the measured RSRP change value. The terminal may transmit the M _SRS and the selected terminal transmit beam candidate set index to the base station through the PUCCH or the PUSCH. The terminal may transmit an SRS corresponding to the selected terminal transmission beam candidate set index I _{beam_offset} to the base station.

Then, the base station is the best terminal transmit beam ID

And uplink resource allocation information for SRS transmission may be informed to the UE through PDCCH or PDSCH. UE is optimal terminal transmit beam ID

Uplink transmission may be started based on the terminal transmission beam and the base station reception beam pair corresponding to each other.

As described above, the present invention provides efficient uplink communication by presenting an efficient resource allocation of SRS for tracking UE transmit beam in base station receive beam and UE transmit beam pair and adaptive beam tracking according to the behavior pattern of each UE. It becomes possible.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form an embodiment by combining claims that do not have an explicit citation relationship in the claims or as new claims by post-application correction.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

A method for transmitting an SRS in a wireless communication system and a terminal for the same can be industrially used in various wireless communication systems such as 3GPP LTE / LTE-A system and 5G communication system.

Claims (12)

1. In a method for transmitting a sounding reference symbol (SRS) by the terminal in a wireless communication system,

   Determining an SRS configuration index by measuring a change value of a received signal strength for a specific time;

   Determining index information related to an SRS transmission period corresponding to the determined SRS configuration index and specific transmission beam candidate set index information of the terminal based on predefined SRS configuration information;

   Transmitting index information related to the SRS transmission period and the specific transmission beam candidate set index information to the base station; And

   And transmitting the SRS to the base station based on at least one transmission beam identifier (ID) candidate information corresponding to the specific transmission beam candidate set index information.
2. The method of claim 1,

   The predefined SRS configuration information includes a physical SRS transmission period value corresponding to the determined SRS configuration index and an SRS subframe offset value corresponding to the determined SRS configuration index.
3. The method of claim 1,

   And the specific transmission beam candidate set index information is determined based on index information associated with the SRS transmission period corresponding to the determined SRS configuration index or a physical SRS transmission period value.
4. The method of claim 1,

   The at least one transmit beam identifier (ID) candidate information includes at least one transmit beam identifier candidate corresponding to the determined transmit beam candidate set index information,

   SRS transmission method for transmitting the SRS through the symbols respectively assigned to the at least one transmission beam identifier (ID) candidate.
5. The method of claim 1,

   Receiving an optimal transmission beam identifier (ID) and uplink resource allocation information of the terminal from the base station; And

   And performing uplink transmission using a transmission beam corresponding to the optimal transmission beam identifier (ID).
6. The method of claim 5,

   Performing beam scanning with the base station;

   SRS transmission method for performing uplink transmission based on the transmission beam of the terminal and the reception beam of the base station paired with the transmission beam of the terminal based on the beam pair information between the terminal and the base station determined by the beam scanning .
7. In a terminal for transmitting a Sounding Reference Symbol (SRS) in a wireless communication system,

   transmitter; And

   Include processors,

   The processor determines an SRS configuration index by measuring a change value of a received signal strength for a specific time, and index information related to an SRS transmission period corresponding to the determined SRS configuration index based on predefined SRS configuration information and the terminal's index. Determine specific transmit beam candidate set index information,

   The transmitter transmits the index information related to the SRS transmission period and the specific transmission beam candidate set index information to the base station, and includes at least one transmission beam identifier (ID) candidate information corresponding to the specific transmission beam candidate set index information. And control to transmit the SRS to the base station based on the terminal.
8. The method of claim 7, wherein

   The predefined SRS configuration information includes a physical SRS transmission period value corresponding to the determined SRS configuration index and an SRS subframe offset value corresponding to the determined SRS configuration index.
9. The method of claim 7, wherein

   And the processor determines the specific transmission beam candidate set index information based on index information related to the SRS transmission period or a physical SRS transmission period value corresponding to the determined SRS configuration index.
10. The method of claim 7, wherein

    The at least one transmit beam identifier (ID) candidate information includes at least one transmit beam identifier candidate corresponding to the determined transmit beam candidate set index information,

    Wherein the processor controls the transmitter to transmit SRS through symbols assigned to the at least one transmit beam identifier (ID) candidate, respectively.
11. The method of claim 7, wherein

    Further includes a receiver,

    The processor controls the receiver to receive the optimal transmission beam identifier (ID) and uplink resource allocation information of the terminal from the base station,

    The processor controls the transmitter to perform uplink transmission using a transmission beam corresponding to the optimal transmission beam identifier (ID).
12. The method of claim 11,

    The processor is configured to perform beam scanning with the base station,

    The processor,

    Control the transmitter to perform uplink transmission based on the transmission beam of the terminal and the reception beam of the base station paired with the transmission beam of the terminal based on beam pair information between the terminal and the base station determined by the beam scanning Terminal.

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