WO2018021586A1 - Procédé et appareil destinés à un terminal destinés à la mise à jour d'informations relatives à l'état de canal dans un système de communication sans fil - Google Patents

Procédé et appareil destinés à un terminal destinés à la mise à jour d'informations relatives à l'état de canal dans un système de communication sans fil Download PDF

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Publication number
WO2018021586A1
WO2018021586A1 PCT/KR2016/008138 KR2016008138W WO2018021586A1 WO 2018021586 A1 WO2018021586 A1 WO 2018021586A1 KR 2016008138 W KR2016008138 W KR 2016008138W WO 2018021586 A1 WO2018021586 A1 WO 2018021586A1
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WIPO (PCT)
Prior art keywords
subframe
csi
channel state
state information
updated
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PCT/KR2016/008138
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English (en)
Korean (ko)
Inventor
박창환
황진엽
김성봉
김진우
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엘지전자 주식회사
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Priority to PCT/KR2016/008138 priority Critical patent/WO2018021586A1/fr
Publication of WO2018021586A1 publication Critical patent/WO2018021586A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA

Definitions

  • the present invention relates to a wireless communication system, and more particularly, to a method for a terminal to update channel state information on an unlicensed band in a wireless communication system, and an apparatus supporting the same.
  • WLANs wireless local area networks
  • QoS quality of service
  • LTE-U LTE in Unlicensed spectrum
  • LAA Licensed-Assisted Access using LTE
  • CA carrier aggregation
  • the terminal first accesses the network in the licensed band.
  • the base station may offload the traffic of the licensed band to the unlicensed band by combining the licensed band and the unlicensed band according to the situation.
  • LTE-U can extend the advantages of LTE to unlicensed bands to provide improved mobility, security, and communication quality.
  • LTE-U is more efficient in frequency than existing radio access technologies, resulting in increased throughput. Can be.
  • unlicensed bands are shared with various radio access technologies such as WLANs. Accordingly, each communication node acquires channel usage in the unlicensed band based on competition, which is called carrier sense multiple access with collision avoidance (CSMA / CA). Each communication node needs to perform channel sensing before transmitting a signal to check whether the channel is idle. This is called clear channel assessment (CCA).
  • CCA clear channel assessment
  • the terminal reports the most recently measured channel state information to the base station based on the time point for reporting the channel state information.
  • the base station can transmit the downlink burst only for the subframe period passing through the LBT (Listen Before Talk)
  • the UE reports the time when the channel state information is reported.
  • the terminal cannot determine in which downlink burst channel state information should be measured. Accordingly, there is a need to propose a method for updating channel state information by a terminal in an unlicensed band and an apparatus supporting the same.
  • a method of updating, by a terminal, channel state information in a wireless communication system is provided.
  • the terminal detects a downlink burst in an unlicensed band, determines a first valid subframe among one or more subframes in which the detected downlink burst is transmitted, and the channel state in the determined first valid subframe. It may include updating the information.
  • the first valid subframe may include a CSI-RS configured for measuring channel state information.
  • the first valid subframe is a subframe in which a value of Subframe Configuration for Licensed Assisted Access Field is 0 to 7 among one or more subframes in which the detected downlink burst is transmitted. Can be.
  • the subframe configuration field value for the LAA may be obtained by decoding the DCI IC.
  • the first valid subframe may be a periodic CSI measurement reference subframe
  • the periodic CSI measurement reference subframe may be a subframe in which a reference signal is periodically measured in order to periodically update channel state information.
  • the CSI update process value N is less than or equal to the CSI update threshold value Ny, and the CSI update process value is the number of CSI updates performed by the UE at a time corresponding to the first valid subframe.
  • the CSI update threshold may be the maximum number of CSI updates that the UE can perform simultaneously.
  • the first valid subframe may be an aperiodic CSI measurement reference subframe
  • the aperiodic CSI measurement reference subframe may be a subframe in which a reference signal is measured aperiodically to update channel state information aperiodically.
  • the terminal may further include reporting the updated channel state information to a base station.
  • the reported channel state information may be the most recently updated channel state information (latest updated CSI).
  • the most recently updated channel state information may be channel state information updated within a specific time with respect to the time at which the channel state information is reported.
  • the terminal reports the CQI index 0 indicating an out of range to the base station. It may further include.
  • the terminal may not update channel state information in the downlink burst.
  • the terminal further includes reporting updated channel state information to the base station, wherein the reported channel state information may be channel state information updated from a previous downlink burst of the downlink burst in which the CSI is not updated.
  • the updated channel state information may be updated channel state information in a first valid subframe among subframes in which the previous downlink burst is transmitted.
  • the updated channel state information may be updated channel state information within a specific time based on a time at which the channel state information is reported.
  • a terminal for updating Channel State Information in a wireless communication system includes a memory; Transceiver; And a processor connecting the memory and the transceiver, wherein the processor detects a downlink burst in an unlicensed band and selects a first valid subframe among one or more subframes in which the detected downlink burst is transmitted. Determine, and update the channel state information in the determined first valid subframe.
  • the UE can efficiently measure channel state information in the unlicensed band.
  • 1 illustrates a wireless communication system
  • FIG. 2 shows a structure of a radio frame in 3GPP LTE.
  • FIG 3 shows an example of a resource grid for one downlink slot.
  • 5 shows a structure of an uplink subframe.
  • FIG. 6 shows a conventional single carrier system and a carrier aggregation system.
  • FIG 7 shows an example of an LTE service using an unlicensed band.
  • FIG 9 illustrates a procedure of measuring and reporting a CSI by a terminal according to an embodiment of the present invention.
  • FIG. 10 illustrates a procedure of measuring and reporting a CSI by a terminal according to an embodiment of the present invention.
  • FIG. 11 illustrates a procedure of measuring and reporting a CSI by a terminal according to an embodiment of the present invention.
  • 12A and 12B are flowcharts illustrating a procedure of updating a CSI by a terminal according to an embodiment of the present invention.
  • FIG. 13 is a flowchart illustrating a procedure for a UE to report an updated CSI to a base station according to an embodiment of the present invention.
  • FIG. 14 is a block diagram illustrating a method of updating channel state information by a terminal according to an embodiment of the present invention.
  • 15 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.
  • CDMA code division multiple access
  • FDMA frequency division multiple access
  • TDMA time division multiple access
  • OFDMA orthogonal frequency division multiple access
  • SC-FDMA single carrier frequency division multiple access
  • CDMA may be implemented by 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).
  • GSM global system for mobile communications
  • GPRS general packet radio service
  • EDGE enhanced data rates for GSM evolution
  • 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).
  • IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e.
  • UTRA is part of a universal mobile telecommunications system (UMTS).
  • 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), which employs OFDMA in downlink and SC in uplink -FDMA is adopted.
  • LTE-A evolution of 3GPP LTE.
  • 1 illustrates a wireless communication system
  • the wireless communication system 10 includes at least one base station (BS) 11.
  • Each base station 11 provides a communication service for a particular geographic area (generally called a cell) 15a, 15b, 15c.
  • the cell can in turn be divided into a number of regions (called sectors).
  • the UE 12 may be fixed or mobile and may have a mobile station (MS), a mobile terminal (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, or a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms.
  • the base station 11 generally refers to a fixed station communicating with the terminal 12, and may be called in other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like. have.
  • eNB evolved-NodeB
  • BTS base transceiver system
  • access point and the like. have.
  • a terminal typically belongs to one cell, and a cell to which the terminal belongs is called a serving cell.
  • a base station that provides a communication service for a serving cell is called a serving BS. Since the wireless communication system is a cellular system, there are other cells adjacent to the serving cell. Another cell adjacent to the serving cell is called a neighbor cell.
  • a base station that provides communication service for a neighbor cell is called a neighbor BS. The serving cell and the neighbor cell are relatively determined based on the terminal.
  • downlink means communication from the base station 11 to the terminal 12
  • uplink means communication from the terminal 12 to the base station 11.
  • the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12.
  • the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11.
  • the wireless communication system may be any one of a multiple-input multiple-output (MIMO) system, a multiple-input single-output (MIS) system, a single-input single-output (SISO) system, and a single-input multiple-output (SIMO) system.
  • MIMO multiple-input multiple-output
  • MIS multiple-input single-output
  • SISO single-input single-output
  • SIMO single-input multiple-output
  • the MIMO system uses a plurality of transmit antennas and a plurality of receive antennas.
  • the MISO system uses multiple transmit antennas and one receive antenna.
  • the SISO system uses one transmit antenna and one receive antenna.
  • the SIMO system uses one transmit antenna and multiple receive antennas.
  • the transmit antenna means a physical or logical antenna used to transmit one signal or stream
  • the receive antenna means a physical or logical antenna used to receive one signal or stream.
  • FIG. 2 shows a structure of a radio frame in 3GPP LTE.
  • a radio frame consists of 10 subframes, and one subframe consists of two slots. Slots in a radio frame are numbered with slots # 0 through # 19. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). TTI may be referred to as a scheduling unit for data transmission. For example, one radio frame may have a length of 10 ms, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.
  • One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and a plurality of subcarriers in the frequency domain.
  • the OFDM symbol is used to represent one symbol period since 3GPP LTE uses OFDMA in downlink, and may be called a different name according to a multiple access scheme.
  • SC-FDMA when SC-FDMA is used as an uplink multiple access scheme, it may be referred to as an SC-FDMA symbol.
  • a resource block (RB) includes a plurality of consecutive subcarriers in one slot in resource allocation units.
  • the structure of the radio frame is merely an example. Accordingly, the number of subframes included in the radio frame, the number of slots included in the subframe, or the number of OFDM symbols included in the slot may be variously changed.
  • 3GPP LTE defines that one slot includes 7 OFDM symbols in a normal cyclic prefix (CP), and one slot includes 6 OFDM symbols in an extended CP. .
  • CP normal cyclic prefix
  • Wireless communication systems can be largely divided into frequency division duplex (FDD) and time division duplex (TDD).
  • FDD frequency division duplex
  • TDD time division duplex
  • uplink transmission and downlink transmission are performed while occupying different frequency bands.
  • uplink transmission and downlink transmission are performed at different times while occupying the same frequency band.
  • the channel response of the TDD scheme is substantially reciprocal. This means that the downlink channel response and the uplink channel response are almost the same in a given frequency domain. Therefore, in a TDD based wireless communication system, the downlink channel response can be obtained from the uplink channel response.
  • the uplink transmission and the downlink transmission are time-divided in the entire frequency band, and thus the downlink transmission by the base station and the uplink transmission by the terminal cannot be simultaneously performed.
  • uplink transmission and downlink transmission are performed in different subframes.
  • FIG 3 shows an example of a resource grid for one downlink slot.
  • the downlink slot includes a plurality of OFDM symbols in the time domain and NRB resource blocks in the frequency domain.
  • the number NRB of resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the cell.
  • the NRB may be any one of 60 to 110.
  • One resource block includes a plurality of subcarriers in the frequency domain.
  • the structure of the uplink slot may also be the same as that of the downlink slot.
  • Each element on the resource grid is called a resource element.
  • Resource elements on the resource grid may be identified by an index pair (k, l) in the slot.
  • an exemplary resource block includes 7 ⁇ 12 resource elements including 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain, but the number of OFDM symbols and the number of subcarriers in the resource block is equal to this. It is not limited. The number of OFDM symbols and the number of subcarriers can be variously changed according to the length of the CP, frequency spacing, and the like. For example, the number of OFDM symbols is 7 for a normal CP and the number of OFDM symbols is 6 for an extended CP. The number of subcarriers in one OFDM symbol may be selected and used among 128, 256, 512, 1024, 1536 and 2048.
  • the downlink subframe includes two slots in the time domain, and each slot includes seven OFDM symbols in the normal CP.
  • the leading up to 3 OFDM symbols (up to 4 OFDM symbols for 1.4Mhz bandwidth) of the first slot in the subframe are the control regions to which control channels are allocated and the remaining OFDM symbols are the physical downlink shared channel (PDSCH). Becomes the data area to be allocated.
  • PDSCH physical downlink shared channel
  • the PDCCH includes resource allocation and transmission format of downlink-shared channel (DL-SCH), resource allocation information of uplink shared channel (UL-SCH), paging information on PCH, system information on DL-SCH, and random access transmitted on PDSCH. Resource allocation of higher layer control messages such as responses, sets of transmit power control commands for individual UEs in any UE group, activation of voice over internet protocol (VoIP), and the like.
  • a plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs.
  • the PDCCH is transmitted on an aggregation of one or several consecutive control channel elements (CCEs).
  • CCEs control channel elements
  • CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to a state of a radio channel.
  • the CCE corresponds to a plurality of resource element groups.
  • the format of the PDCCH and the number of bits of the PDCCH are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.
  • the base station determines the PDCCH format according to the DCI to be sent to the terminal, and attaches a cyclic redundancy check (CRC) to the control information.
  • CRC cyclic redundancy check
  • RNTI a unique radio network temporary identifier
  • RNTI a unique radio network temporary identifier of the terminal, for example, a cell-RNTI (C-RNTI) may be masked to the CRC.
  • C-RNTI cell-RNTI
  • P-RNTI paging indication identifier, for example, p-RNTI (P-RNTI) may be masked to the CRC.
  • SI-RNTI system information-RNTI
  • RA-RNTI random access-RNTI
  • 5 shows a structure of an uplink subframe.
  • the uplink subframe may be divided into a control region and a data region in the frequency domain.
  • the control region is allocated a physical uplink control channel (PUCCH) for transmitting uplink control information.
  • the data region is allocated a physical uplink shared channel (PUSCH) for transmitting data.
  • the terminal may support simultaneous transmission of the PUSCH and the PUCCH.
  • PUCCH for one UE is allocated to an RB pair in a subframe.
  • Resource blocks belonging to a resource block pair occupy different subcarriers in each of the first slot and the second slot.
  • the frequency occupied by the resource block belonging to the resource block pair allocated to the PUCCH is changed based on a slot boundary. This is called that the RB pair allocated to the PUCCH is frequency-hopped at the slot boundary.
  • the terminal may obtain a frequency diversity gain by transmitting uplink control information through different subcarriers over time.
  • m is a location index indicating a logical frequency domain location of a resource block pair allocated to a PUCCH in a subframe.
  • the uplink control information transmitted on the PUCCH includes a hybrid automatic repeat request (HARQ) acknowledgment (ACK) / non-acknowledgement (NACK), a channel quality indicator (CQI) indicating a downlink channel state, and an uplink radio resource allocation request. (scheduling request).
  • HARQ hybrid automatic repeat request
  • ACK acknowledgment
  • NACK non-acknowledgement
  • CQI channel quality indicator
  • the PUSCH is mapped to the UL-SCH, which is a transport channel.
  • the uplink data transmitted on the PUSCH may be a transport block which is a data block for the UL-SCH transmitted during the TTI.
  • the transport block may be user information.
  • the uplink data may be multiplexed data.
  • the multiplexed data may be a multiplexed transport block and control information for the UL-SCH.
  • control information multiplexed with data may include a CQI, a precoding matrix indicator (PMI), a HARQ, a rank indicator (RI), and the like.
  • the uplink data may consist of control information only.
  • CA carrier aggregation
  • FIG. 6 shows a conventional single carrier system and a carrier aggregation system.
  • a single carrier system only one carrier is supported to the UE in uplink and downlink.
  • the bandwidth of the carrier may vary, but only one carrier is allocated to the terminal.
  • a plurality of component carriers (DL CC A to C, UL CC A to C) may be allocated to a terminal. For example, three 20 MHz component carriers may be allocated to allocate a 60 MHz bandwidth to the terminal.
  • the carrier aggregation system may be classified into a continuous carrier aggregation system in which each carrier is aggregated and a non-contiguous carrier aggregation system in which each carrier is separated from each other.
  • a carrier aggregation system simply referred to as a carrier aggregation system, it should be understood to include both the case where the component carrier is continuous and the case where it is discontinuous.
  • the target component carrier may use the bandwidth used by the existing system as it is for backward compatibility with the existing system.
  • the 3GPP LTE system supports bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz, and the 3GPP LTE-A system may configure a bandwidth of 20 MHz or more using only the bandwidth of the 3GPP LTE system.
  • broadband can be configured by defining new bandwidth without using the bandwidth of the existing system.
  • the system band of a wireless communication system is divided into a plurality of carrier frequencies.
  • the carrier frequency means a center frequency of a cell.
  • a cell may mean a downlink frequency resource and an uplink frequency resource.
  • the cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource.
  • CA carrier aggregation
  • one cell may always have uplink and downlink frequency resources in pairs.
  • the terminal In order to transmit and receive packet data through a specific cell, the terminal must first complete configuration for a specific cell. In this case, the configuration refers to a state in which reception of system information necessary for data transmission and reception for a corresponding cell is completed.
  • the configuration may include an overall process of receiving common physical layer parameters required for data transmission and reception, or MAC layer parameters, or parameters required for a specific operation in the RRC layer.
  • the set cell receives only the information that the packet data can be transmitted, the cell can be immediately transmitted and received.
  • the cell in the configuration complete state may exist in an activation or deactivation state.
  • activation means that data is transmitted or received or is in a ready state.
  • the UE may monitor or receive a control channel (PDCCH) and a data channel (PDSCH) of an activated cell in order to identify resources (which may be frequency, time, etc.) allocated thereto.
  • PDCCH control channel
  • PDSCH data channel
  • Deactivation means that transmission or reception of traffic data is impossible, and measurement or transmission of minimum information is possible.
  • the terminal may receive system information (SI) required for packet reception from the deactivated cell.
  • SI system information
  • the terminal does not monitor or receive the control channel (PDCCH) and data channel (PDSCH) of the deactivated cell in order to check the resources (may be frequency, time, etc.) allocated to them.
  • PDCH control channel
  • PDSCH data channel
  • the cell may be divided into a primary cell, a secondary cell, and a serving cell.
  • the primary cell refers to a cell operating at a primary frequency, and is a cell in which the terminal performs an initial connection establishment procedure or connection reestablishment with the base station, or is indicated as a primary cell in a handover process. It means a cell.
  • the secondary cell refers to a cell operating at the secondary frequency and is set up once the RRC connection is established and used to provide additional radio resources.
  • the serving cell is configured as a primary cell when the carrier aggregation (CA) is not configured or the terminal cannot provide the CA.
  • CA carrier aggregation
  • the term serving cell is used to indicate a set of primary cells + one of a plurality of secondary cells or a plurality of secondary cells. That is, the primary cell refers to one serving cell that provides security input and NAS mobility information in an RRC connection or re-establishment state.
  • at least one cell may be configured to form a serving cell set together with a primary cell, wherein the at least one cell is called a secondary cell. Therefore, the set of serving cells configured for one terminal may consist of only one primary cell or one primary cell and at least one secondary cell.
  • a primary component carrier refers to a component carrier (CC) corresponding to a primary cell.
  • the PCC is a CC in which the terminal initially makes a connection (connection or RRC connection) with the base station among several CCs.
  • the PCC is a special CC that manages a connection (Connection or RRC Connection) for signaling regarding a plurality of CCs and manages UE context, which is connection information related to a terminal.
  • the PCC is connected to the terminal and always exists in the active state in the RRC connected mode.
  • Secondary component carrier refers to a CC corresponding to the secondary cell. That is, the SCC is a CC allocated to the terminal other than the PCC, and the SCC is an extended carrier for the additional resource allocation other than the PCC and may be divided into an activated or deactivated state.
  • the downlink component carrier corresponding to the primary cell is called a downlink primary component carrier (DL PCC), and the uplink component carrier corresponding to the primary cell is called an uplink major component carrier (UL PCC).
  • DL PCC downlink primary component carrier
  • U PCC uplink major component carrier
  • DL SCC DL secondary CC
  • UL SCC uplink secondary component carrier
  • the primary cell and the secondary cell have the following characteristics.
  • the primary cell is used for transmission of the PUCCH.
  • the primary cell is always activated, while the secondary cell is a carrier that is activated / deactivated according to specific conditions.
  • RLF Radio Link Failure
  • the primary cell may be changed by a security key change or a handover procedure accompanying a RACH (Random Access Channel) procedure.
  • NAS non-access stratum
  • the primary cell always consists of a pair of DL PCC and UL PCC.
  • a different CC may be configured as a primary cell for each UE.
  • procedures such as reconfiguration, adding, and removal of the secondary cell may be performed by the RRC layer.
  • RRC signaling may be used to transmit system information of a dedicated secondary cell.
  • the downlink component carrier may configure one serving cell, or the downlink component carrier and the uplink component carrier may be configured to configure one serving cell.
  • the serving cell is not configured with only one uplink component carrier.
  • the activation / deactivation of the component carrier is equivalent to the concept of activation / deactivation of the serving cell. For example, assuming that serving cell 1 is configured of DL CC1, activation of serving cell 1 means activation of DL CC1. If the serving cell 2 assumes that DL CC2 and UL CC2 are configured to be configured, activation of serving cell 2 means activation of DL CC2 and UL CC2. In this sense, each component carrier may correspond to a cell.
  • the number of component carriers aggregated between the downlink and the uplink may be set differently.
  • the case where the number of downlink CCs and the number of uplink CCs are the same is called symmetric aggregation, and when the number is different, it is called asymmetric aggregation.
  • the size (ie bandwidth) of the CCs may be different. For example, assuming that 5 CCs are used for a 70 MHz band configuration, 5 MHz CC (carrier # 0) + 20 MHz CC (carrier # 1) + 20 MHz CC (carrier # 2) + 20 MHz CC (carrier # 3) It may be configured as + 5MHz CC (carrier # 4).
  • FIG 7 shows an example of an LTE service using an unlicensed band.
  • the wireless device 730 establishes a connection with the first base station 710 and receives a service through a licensed band. For offloading traffic, the wireless device 730 may be provided with a service through an unlicensed band with the second base station 720.
  • the second base station 720 may support other communication protocols such as a wireless local area network (WLAN) in addition to the LTE.
  • the first base station 710 and the second base station 720 may be combined in a carrier aggregation (CA) environment so that a specific cell of the first base station 710 may be a primary cell.
  • CA carrier aggregation
  • the first base station 710 and the second base station 720 may be combined in a dual connectivity environment so that a specific cell of the first base station 710 may be a primary cell.
  • a first base station 710 with a primary cell has wider coverage than a second base station 720.
  • the first base station 710 may be referred to as a macro cell.
  • the second base station 720 may be referred to as a small cell, femto cell or micro cell.
  • the first base station 710 may operate a primary cell and zero or more secondary cells.
  • the second base station 720 may operate one or more secondary cells.
  • the secondary cell may be activated / deactivated by the indication of the primary cell.
  • the above-described example is only an example, and the first base station 710 corresponds to the primary cell, and the second base station 720 corresponds to the secondary cell and may be managed by one base station.
  • the licensed band is a band that guarantees exclusive use for a specific communication protocol or a specific operator.
  • the unlicensed band is a band in which various communication protocols coexist and guarantee shared use.
  • the unlicensed band may include the 2.5 GHz and / or 5 GHz bands used by the WLAN.
  • LBT listen before talk
  • CCA clear channel assessment
  • channel-status information (CSI) will be described.
  • Downlink channel-dependent scheduling which selects downlink transmission configuration and related parameters according to the downlink channel state, is one of downlink main functions.
  • As a main part of helping the scheduling according to the downlink channel there is channel state information provided by the terminal to the base station, and the base station makes a scheduling decision based on this.
  • the channel state information may include at least one of the following.
  • Rank Indication This indicator provides rank information of a channel.
  • the rank information may be information about the number of layers desired to be used in downlink transmission to the corresponding terminal.
  • the rank indicator may have a value of 1 to 8.
  • PMI Precoder Matrix Indicator
  • CQI Channel-Quality Indicator
  • QPSK quadrature phase shift keying
  • 16QAM 16 quadrature amplitude modulation
  • 64QAM 64QAM corresponding to 0 to 15 using 4-bit values.
  • CSI Report channel state information report
  • the UE-EUTRA-Capability IE is used to convey the E-UTRA terminal radio access capability parameter to the network.
  • the UE may report the maximum number of CSI processors that can be updated in a specific subframe to the base station through maxNumberUpdatedCSI-Proc-r13 of the UE-EUTRA-Capability IE.
  • the base station may transmit the CSI measurement related parameter to the terminal through the CQI-ReportConfig IE.
  • the base station may set the CSI reporting related parameters so as not to exceed the maxNumberUpdatedCSI-Proc-r13 reported from the terminal.
  • the base station may receive a periodic CSI report or an aperiodic CSI report from the terminal.
  • different combinations of RI, PMI, and CQI may configure CSI reporting.
  • Aperiodic or trigger-based CSI reporting can be delivered when the base station explicitly requests it.
  • the base station may request aperiodic CSI reporting through a "channel-status request" flag included in the uplink scheduling grant using Downlink Control Information (DCI) format 0.
  • DCI Downlink Control Information
  • Aperiodic CSI reporting can always be delivered on the PUSCH.
  • the periodic CSI report may be set by the base station so that the terminal transmits to the base station at a specific period.
  • the different kinds of information do not all have to be reported in the same period.
  • RI may be reported with a longer period than PMI and CQI. This is because the number of layers suitable for transmission is generally slower than the channel change which affects the selection of the precoder matrix, the modulation scheme and the coding rate.
  • periodic CSI reports can be delivered using PUCCH. If the UE has a valid uplink scheduling grant, the CSI report may be delivered using the PUSCH.
  • a periodic CSI report type with distinct periods and offsets may be provided for PUCCH reporting.
  • aperiodic reporting and periodic reporting provide estimates of channel conditions, but the details of the report and its intended use are different.
  • aperiodic reporting is larger than periodic reporting and contains detailed information. Since the PUSCH in which the aperiodic report is transmitted may carry a larger payload compared to the PUCCH in which the periodic report is transmitted, the aperiodic report may be more detailed than the periodic report. Unlike the periodic report, since the aperiodic report is transmitted only when necessary, the overhead caused by the large size of the aperiodic report is not a big problem.
  • periodic reporting and aperiodic reporting will be described in detail.
  • the aperiodic CSI report is transmitted on the PUSCH at the request of the network.
  • Three aperiodic reporting modes are supported for LTE.
  • Wideband Report reflects the average channel quality over the entire cell bandwidth with one CQI value.
  • One average CQI value is provided for the entire bandwidth, but PMI reporting is frequency selective.
  • Frequency selective reporting is obtained by dividing the total downlink bandwidth of each component carrier into a subvan consisting of a plurality of contiguous resource blocks of the same size. The size of the subband is 4 to 8 resource blocks depending on the cell bandwidth. Therefore, PMI is reported for each subband.
  • CQI and PMI are calculated assuming a channel rank known by RI, otherwise rank 1 is assumed. Broadband reporting is smaller than frequency selective reporting, but does not provide any information about the frequency domain.
  • the UE-Selected Report In the UE-selected report, the UE selects and reports the best M subbands. At this time, the UE reports one wideband CQI reflecting channel quality over the entire downlink carrier bandwidth, an indicator indicating what the selected subbands are, and one CQI indicating the average channel quality of the selected M subbands. Report additionally. Thus, this type provides information on the frequency domain of the channel state.
  • the subband size may be between 2 and 4 resource blocks, and the M value may be a value between 1 and 6.
  • PMI and RI may be reported together according to the transmission mode configured.
  • the subband that the UE should report is set by the network.
  • the UE reports one CQI per subband set together with one wideband CQI report reflecting channel quality over the entire downlink carrier bandwidth.
  • the subband size depends on the downlink carrier bandwidth and may be 4 to 8 resource blocks.
  • PMI and RI may be reported together according to the transmission mode configured.
  • channel state reporting for a plurality of downlink component carriers is similar to that described above except for some modifications and improvements.
  • CA carrier aggregation
  • three different CSI report types may be requested by the 2-bit CSI request field in downlink control signaling. Among the three types, one is used to request CQI reporting for the downlink component carrier associated with the uplink component carrier with which the uplink scheduling grant is associated. The rest is used to indicate two configurable combinations between component carriers for which CSI reporting should be generated.
  • aperiodic reporting may be performed for a primary component carrier, for a secondary component carrier, or both carriers. May be requested for.
  • Periodic reporting is set by the network to be sent with a specific period.
  • the periodic report is transmitted on the PUCCH, except that the UE has scheduling for PUSCH transmission at the same time and does not use simultaneous PUSCH and PUCCH transmission.
  • periodic reporting may be difficult to provide various information in one subframe. Therefore, in some reporting modes, one or several wideband CQIs, wideband CQIs including PMIs and RIs, or subband CQIs selected by the UE at different times are transmitted.
  • RI is generally reported more frequently than PMI and CQI reporting because the number of suitable layers changes relatively slowly, whereas the channel state affecting the precoding matrix, modulation scheme, and coding rate selection changes relatively quickly. It may not be.
  • One CQI value reflects average channel quality over the entire cell bandwidth. If PMI reporting is set, one PMI over the entire bandwidth is reported.
  • -UE selection report Although the name itself is the same as aperiodic reporting, the principle of periodic reporting that the UE selects and reports is different.
  • the total bandwidth of the component carrier is divided into 1 to 4 bandwidth parts according to the cell bandwidth.
  • the terminal selects the best subband therein.
  • the subband size is 4 to 8 resource blocks. Since the size of the payload supported in the PUCCH is limited, reporting is made for a plurality of bandwidth parts. In reporting in one subframe, the best subband in that bandwidth portion and the CQI for that subband are reported along with the wideband CQI and PMI for that bandwidth portion. If the RI report is configured, the RI is reported in a separate subframe.
  • the basic principle of setting the reporting period of periodic reporting is that CQI reporting for different CCs is not transmitted simultaneously on the PUCCH. Therefore, channel state information reports for different CCs are transmitted in different subframes.
  • the channel state information in the downlink may be identified using a reference signal transmitted by the base station to the terminal.
  • RS reference signal
  • data / signals in a wireless communication system are transmitted over wireless channels
  • data / signals may be distorted over the air during transmission.
  • the distorted signal is preferably corrected using the channel information.
  • the transmitting end and / or the receiving end may use a reference signal RS that is known to both sides to detect channel information.
  • the reference signal may be called a pilot signal.
  • a channel state between the transmitting antenna and the receiving antenna is detected in order to receive the data accurately at the receiving end.
  • each transmitting antenna of the transmitting end preferably has a separate reference signal.
  • the downlink reference signal refers to a common reference signal (CRS: Common RS) shared by all terminals in a cell, a UE-specific RS (UE-specific RS) only for a specific terminal, and a multimedia broadcast and multicast single frequency network (MBSFN). Signal, positioning reference signal (PRS) and channel state information (CSI) reference signal (CSI RS).
  • CRS Common RS
  • PRS positioning reference signal
  • CSI channel state information
  • the transmitter may provide the receiver with information for demodulation and channel measurement using the reference signals.
  • the receiving end measures the channel state using the CRS, and according to the measured channel state, channel quality such as a channel quality indicator (CQI), a precoding matrix index (PMI), and / or a rank indicator (RI) May be fed back to the transmitter (eg, the base station).
  • CQI channel quality indicator
  • PMI precoding matrix index
  • RI rank indicator
  • the CRS may be referred to as a cell-specific RS.
  • the CRS is transmitted in every downlink subframe in a cell supporting PDSCH transmission.
  • the CRS may refer to section 6.10.1 of 3GPP TS 36.211 V10.1.0 (2011-03).
  • the reference signal associated with the feedback of the channel state information may be defined as CSI-RS.
  • the CSI RS may be relatively sparse in the frequency domain or the time domain and may be punctured in the data region of the general subframe or the MBSFN subframe. If necessary through the estimation of the CSI, CQI, PMI and RI may be reported from the terminal.
  • the UE-specific reference signal may be transmitted to the terminals through the resource elements when data demodulation on the PDSCH is needed.
  • the terminal may receive the presence of a terminal specific reference signal through higher layer signaling.
  • the UE specific reference signal is valid only when a corresponding PDSCH signal is mapped.
  • the MBSFN reference signal may be transmitted in a subframe allocated for MBSFN transmission.
  • the PRS may be used for position estimation of the terminal.
  • the CSI RS is used for channel estimation for the PDSCH of the LTE-A terminal.
  • Reference signal is generally transmitted in sequence.
  • the reference signal sequence may use a PSK-based computer generated sequence.
  • PSK include binary phase shift keying (BPSK) and quadrature phase shift keying (QPSK).
  • the reference signal sequence may use a constant amplitude zero auto-correlation (CAZAC) sequence.
  • CAZAC sequences are ZC-based sequences, ZC sequences with cyclic extensions, ZC sequences with truncation, etc. There is this.
  • the reference signal sequence may use a pseudo-random (PN) sequence.
  • PN sequences include m-sequences, computer generated sequences, Gold sequences, and Kasami sequences.
  • the reference signal sequence may use a cyclically shifted sequence.
  • the DCI format includes fields to be described next, and each field may be mapped to information bits a0 to aA-1. Each field may be mapped in the order described in each DCI format, and each field may include padding bits having a value of '0'.
  • the first field may be mapped to the lowest order information bit a0 and other consecutive fields may be mapped to the higher order information bits.
  • the most significant bit (MSB) in each field may be mapped to the lowest order information bit of the field. For example, the most significant bit of the first field may be mapped to a0.
  • a set of fields included in each existing DCI format is called an information field.
  • DCI format 0 is used for PUSCH scheduling.
  • DCI format 1 is used for one PDSCH codeword scheduling.
  • DCI format 1A is used for a simple scheduling or random access procedure of one PDSCH codeword.
  • DCI format 1B is used for simple scheduling of one PDSCH codeword including precoding information.
  • DCI format 1C is used for very compact scheduling of one PDSCH codeword.
  • DCI format 1C may include an indicator indicating a gap value, a resource block designation, a transport block size index, and the like.
  • DCI format 1D contains precoding and power offset information and is used for simple scheduling for one PDSCH codeword.
  • DCI format 2 is used for PDSCH designation for Peruvian MIMO operation.
  • DCI format 2A is used for PDSCH designation for open loop MIMO operation.
  • DCI format 3 is used to send TPC commands for PUCCH and PUSCH with 2-bit power adjustment.
  • DCI format 3A is used to send TPC commands for PUCCH and PUSCH with one bit of power adjustment.
  • DCI formats 2B, 2C, 2D, 4, and the like there are DCI formats 2B, 2C, 2D, 4, and the like.
  • DCI formats 0 and 4 are used for uplink
  • the remaining DCI formats are used for downlink. Accordingly, the remaining DCI formats may be referred to as a DL DCI format.
  • the horizontal axis is the time axis
  • the vertical axis is the frequency axis
  • one rectangle is one subframe.
  • the base station may configure and operate an aperiodic CSI report and a periodic CSI report with respect to an unlicensed carrier and a licensed carrier by referring to maxNumberUpdatedCSI-Proc-r13 of the terminal. Therefore, the base station may update the CSI process not exceeding the maximum Ny in a specific subframe. For example, the base station may allocate up to Ny aperiodic CSI reports, and the periodic CSI report may be configured and operated so as not to overlap with other CSI reporting intervals.
  • the base station may trigger an aperiodic CSI report in the nth subframe (S801).
  • the UE may perform CSI measurement based on CRS or CSI-RS in the reference subframe (S802).
  • the reference subframe may be a reference subframe on a licensed band in which the UE measures CSI.
  • the reference subframe may coincide on the time axis with the subframe that triggers aperiodic CSI reporting.
  • the UE may update the CSI through the CSI measurement.
  • the terminal may report the updated CSI to the base station in the n + 4th subframe (S803).
  • the updated CSI report may be an aperiodic CSI report.
  • the base station may trigger an aperiodic CSI report in an n ′ th frame (S811).
  • the UE may perform CSI measurement based on the CRS or CSI-RS in the reference subframe (S812).
  • the reference subframe may be a reference subframe on a licensed band in which the UE measures CSI.
  • the reference subframe may not coincide on the time axis with the subframe that triggers aperiodic CSI reporting. That is, the subframe in which the aperiodic CSI report is triggered is the n'-th subframe, while the subframe in which the CSI measurement is performed may be the q-th subframe.
  • the terminal should perform CSI update every time for the reference subframe to which the CSI measurement related parameter is allocated through the CQI-ReportConfig IE, and if the aperiodic CSI report is triggered, the terminal should report the CSI measurement result.
  • the terminal may report the updated CSI to the base station in n ′ + 4th subframe (S813).
  • the updated CSI report may be an aperiodic CSI report.
  • subframe periods for which the base station wants to receive CSI reports are m1 th subframe, m2 th subframe, and m3 th subframe.
  • the subframe periods for which the base station wants to receive the CSI report are the m'1-th subframe, the m'2-th subframe, and the m'3-th subframe.
  • the UE updates the CSI only in the last subframe in which the b1th burst is transmitted, the last subframe in which the b2th burst is transmitted, and the last subframe in which the bMth burst is transmitted (S821).
  • the updated CSI is preferably reported to the base station in the m1 th subframe, the m2 th subframe, and the m3 th subframe, respectively (S822).
  • S822 the updated CSI only in the last subframe in which the b1th burst is transmitted.
  • the UE may perform CSI only in the last subframe in which the b1 + 2 th burst is transmitted, the last subframe in which the b2 + 2 th burst is transmitted, and the last subframe in which the bM + 3 th burst is transmitted. (S831), and report the updated CSI as the m ′ 1st subframe, the m ′ 2nd subframe, and the m ′ 3rd subframe, respectively (S833).
  • the updated CSI report may be a periodic CSI report.
  • the updated CSI report may be an aperiodic CSI report.
  • the base station since the base station can transmit the downlink burst only for the subframe period passing through the LBT, the base station is the position of the subframe valid before the m1 th frame, m2 subframe and m3 subframe Can not be expected. Similarly, the UE cannot predict the position of a valid subframe before the m1 th subframe, the m2 th subframe and the m3 th subframe. For example, the UE performing the CSI reporting in the m'1th subframe is whether the b1 + 1th burst is the most recent downlink burst before performing the CSI reporting in the m'1th subframe, or the b1 + 2th burst.
  • the UE when the UE performs CSI reporting in the m'1th subframe, if the b1 + 1th burst is the last burst before the CSI report, the UE measures CSI in the last subframe in which the b1 + 1th burst is transmitted. Should be done. If the b1 + 2th burst is the last burst before the CSI report, the UE must perform CSI measurement in the last subframe in which the b1 + 2th burst is transmitted, not the last subframe in which the b1 + 1th burst is transmitted.
  • the UE since the UE does not know whether the last burst before the CSI report is the b1 + 1th burst or the b1 + 2th burst, the UE cannot determine in which burst to perform CSI measurement. Therefore, it is necessary to propose a method for the UE to measure the CSI in the unlicensed band. In addition, a method for the UE to report the measured CSI in the unlicensed band needs to be proposed.
  • a valid subframe needs to be defined. If a specific subframe is not part of the burst transmission in the LAA, the specific subframe may not be a valid subframe. In case of the UE set to TM9 or TM10, if the subframe is not configured with CSI-RS configuration for CSI measurement, the corresponding subframe may not be a valid subframe.
  • FIG. 9 illustrates a procedure of measuring and reporting a CSI by a terminal according to an embodiment of the present invention.
  • the horizontal axis is the time axis
  • the vertical axis is the frequency axis
  • one rectangle is one subframe.
  • Subframe periods that the base station wants to receive the CSI report are the m1 th subframe, the m2 th subframe and the m3 th subframe.
  • the subframe periods for which the base station wants to receive the CSI report are the m'1-th subframe, the m'2-th subframe, and the m'3-th subframe.
  • the terminal reports the measured CSI just before (ie, most recently) performing the CSI report to the base station.
  • the base station may transmit the downlink burst only for the subframe period passing through the LBT.
  • the base station and the terminal anticipate positions of valid subframes before the m1 th subframe, the m2 th subframe, the m3 th subframe, the m'1 th subframe, the m'2 th subframe, and the m'3 th subframe. Can not. Therefore, a method of performing CSI measurement on the last valid subframe in which a downlink burst is transmitted and storing the measured CSI in a memory may be proposed. Thereafter, if there is no new valid subframe until the CSI reporting, the UE may update the CSI based on the CSI measurement result stored in the memory and report the same.
  • the terminal may update CSI with respect to the last subframe in which the downlink burst is transmitted (S910).
  • the last subframe may be a valid subframe.
  • the valid subframe may be a subframe other than a partial subframe.
  • the terminal may store the updated CSI in a memory.
  • the UE may perform CSI in the last subframe in which the b1th burst is transmitted, the last subframe in which the b1 + 1th burst is transmitted, and the last subframe in which the b1 + 2th burst is transmitted. Can be updated.
  • the UE may perform CSI in the last subframe in which the b2th burst is transmitted, the last subframe in which the b2 + 1th burst is transmitted, and the last subframe in which the b2 + 2th burst is transmitted. Can be updated.
  • the terminal may transmit the last subframe in which the bMth burst is transmitted, the last subframe in which the bM + 1th burst is transmitted, the last subframe in which the bM + 2nd burst is transmitted, and bM.
  • the CSI may be updated in the last subframe in which the +3 th burst is transmitted.
  • the last subframe is a partial subframe and thus is not a valid subframe. Accordingly, the UE may update the CSI in the previous subframe of the last subframe in which the bM + 1 th burst is transmitted.
  • the terminal may report the updated CSI to the base station (S920).
  • the updated CSI may be the most recently updated CSI based on a reporting time point.
  • the terminal may report the updated CSI in the last subframe in which the b1 th burst is transmitted to the base station in the m1 th subframe.
  • the UE may report the updated CSI in the last subframe in which the b1 + 2 th burst is transmitted to the base station in the m′1 th subframe.
  • the updated CSI in the last subframe in which the b1 + 1th burst is transmitted may not be reported to the base station because it is not the most recently updated CSI based on the CSI reporting time point.
  • the terminal may report the updated CSI in the last subframe in which the b2th burst is transmitted to the base station in the m2th subframe.
  • the UE may report the updated CSI in the last subframe in which the b2 + 2th burst is transmitted to the base station in the m′2th subframe.
  • the updated CSI in the last subframe in which the b2 + 1th burst is transmitted may not be reported to the base station because it is not the most recently updated CSI based on the CSI reporting time point.
  • the UE may report the updated CSI in the last subframe in which the bM th burst is transmitted to the base station in the m3 th subframe.
  • the UE may report the updated CSI in the last subframe in which the bM + 3 th burst is transmitted to the base station in the m'3 th subframe.
  • the updated CSI in the previous subframe of the last subframe in which the bM + 1th burst is transmitted, and the updated CSI in the last subframe in which the bM + 2th burst is transmitted are most recently updated from the CSI reporting time point. Since it is not CSI, it may not be reported to the base station.
  • the terminal can more accurately measure channel state information of the unlicensed band.
  • the number of component carriers (carrier aggregation) of the carrier aggregation is increased, it may be necessary to increase the additional terminal memory size for this purpose.
  • the horizontal axis is the time axis
  • the vertical axis is the frequency axis
  • one rectangle is one subframe.
  • the base station can transmit the downlink burst only for the subframe period passing through the LBT. Accordingly, the base station and the terminal anticipate positions of valid subframes before the m1 th subframe, the m2 th subframe, the m3 th subframe, the m'1 th subframe, the m'2 th subframe, and the m'3 th subframe. Can not. Therefore, a method in which the UE updates CSI in advance by performing CSI measurement on all valid subframes among the subframes in which the downlink burst is transmitted may be proposed.
  • the UE may update CSI for all subframes in which a downlink burst is transmitted (S1010). Every subframe in which the downlink burst is transmitted may be a valid subframe. In other words, the UE may not update the CSI for an invalid subframe (eg, a partial subframe) among the subframes in which the downlink burst is transmitted. Furthermore, when the reference subframe for CSI measurement in the unlicensed band overlaps with the reference subframe for CSI measurement in the licensed band, the UE may not update the CSI in the reference subframe for the CSI measurement in the unlicensed band.
  • the UE may update CSI in all subframes in which downlink bursts are transmitted. However, the UE may not update the CSI in the partial subframe. In addition, the UE may not update the CSI in a subframe in which a downlink burst overlapping with the reference subframe for CSI measurement in the licensed band is transmitted.
  • the terminal may report the updated CSI to the base station (S1020).
  • the updated CSI may be the most recently updated CSI based on a reporting time point.
  • the channel state information of the unlicensed band may be measured more accurately without increasing the memory size of the terminal.
  • the computational complexity of the UE can be increased.
  • FIG. 11 illustrates a procedure of measuring and reporting a CSI by a terminal according to an embodiment of the present invention.
  • the horizontal axis is the time axis
  • the vertical axis is the frequency axis
  • one rectangle is one subframe.
  • the base station can transmit the downlink burst only for the subframe period passing through the LBT. Accordingly, the base station and the terminal anticipate positions of valid subframes before the m1 th subframe, the m2 th subframe, the m3 th subframe, the m'1 th subframe, the m'2 th subframe, and the m'3 th subframe. Can not. Therefore, the UE may perform a CSI measurement in the first valid subframe among the subframes in which the downlink burst is transmitted, and a method of reporting the measured CSI by the UE may be proposed.
  • the UE may update the CSI in the first subframe of the subframe in which the downlink burst is transmitted (S1110).
  • the first subframe may be the first valid subframe.
  • the UE may not update the CSI in the first invalid subframe (eg, partial subframe) in which the downlink burst is transmitted.
  • the UE may not update the CSI in the reference subframe for the CSI measurement in the unlicensed band.
  • the terminal may report the updated CSI to the base station (S1120).
  • the updated CSI may be the most recently updated CSI based on a reporting time point.
  • the most recently updated CSI may be an updated CSI within a predetermined time based on a reporting time point. If the most recently updated CSI is not an updated CSI within a predetermined time based on a reporting time point, the terminal may not report the updated CSI to the base station, and the terminal may report the CQI index 0 to the base station. .
  • the UE may report the CSI updated in the first valid subframe among the subframes in which the b1 th burst is transmitted to the base station in the m1 th subframe. Since the first subframe among the subframes in which the b1th burst is transmitted is not a valid subframe, the first valid subframe in the subframe in which the b1th burst is transmitted is the second subframe in the subframe in which the b1th burst is transmitted. It may be a frame.
  • the UE may report the CSI updated in the first subframe among the subframes in which the b1 + 1th burst is transmitted to the base station in the m′1th subframe.
  • the CSI updated in the first subframe among the subframes in which the b1 + 1th burst is transmitted is channel state information for which a predetermined time has elapsed based on the CSI reporting time point (m′1 th subframe)
  • the UE indicates the b1.
  • the CSI updated in the first subframe among the subframes in which the +1 th burst is transmitted may not be reported to the base station.
  • the UE determines CQI index 0. Report to the base station.
  • the CQI index 0 may indicate an out of range.
  • the UE since the first valid subframe among the subframes in which the b1 + 2th bursts are transmitted overlaps with the reference subframe for CSI measurement in the license band, the UE is the first of the subframes in which the b1 + 2th bursts are transmitted.
  • the CSI may not be updated in the first valid subframe.
  • 12A and 12B are flowcharts illustrating a procedure of updating a CSI by a terminal according to an embodiment of the present invention.
  • the terminal may evaluate a channel (S1210).
  • the terminal may perform channel estimation for a licensed band.
  • the terminal may perform channel estimation for the unlicensed band.
  • the terminal may detect a downlink burst (S1220).
  • the downlink burst can be detected in the unlicensed band.
  • the UE may determine whether the subframe in which the downlink burst is transmitted is a valid subframe (S1230).
  • the valid subframe may be a subframe capable of CSI measurement and CSI update.
  • the valid subframe may include a CSI reference resource.
  • the valid subframe may exist before the subframe in which the measured channel state information is reported. For example, it may be 'number of valid subframes ⁇ number of subframes in which channel state information is reported-n CQI, ref '.
  • the n CQI, ref may be four.
  • N CQI, ref may be 5 when a plurality of CSI processes are configured.
  • Whether the subframe is a valid subframe may be determined based on a value of Subframe Configuration for Licensed Assisted Access Field for the LLA obtained by decoding the DCI IC. If the subframe configuration field value for the LLA is any one of 0 to 7, the subframe of the downlink burst may be determined to be a valid subframe. Conversely, if the subframe configuration field value for the LLA is not one of 0 to 7, the subframe of the downlink burst may be determined as an invalid subframe.
  • the subframe configuration field value for the LLA may be defined as shown in Table 1.
  • Table 1 Value of "Set subframe for LLA" field in current subframe Setting of occupied OFDM symbol (current subframe, next subframe) 0000 (-, 14) 0001 (-, 12) 0010 (-, 11) 0011 (-, 10) 0100 (-, 9) 0101 (-, 6) 0110 (-, 3) 0111 (14, *) 1000 (12,-) 1001 (11,-) 1010 (10,-) 1011 (9,-) 1100 (6,-) 1101 (3,-) 1110 reserved 1111 reserved
  • the UE may assume that the first Y symbols are occupied in the next subframe, and the remaining symbols are not occupied.
  • the UE may assume that the first X symbols are occupied in the current subframe and the remaining symbols are not occupied.
  • the UE may assume that the first X symbols are occupied in the current subframe and at least the first OFDM symbol is not occupied in the next subframe.
  • the UE may not perform CSI update. That is, the UE may postpone the CSI update until a valid subframe is detected in the downlink burst.
  • the periodic CSI reference subframe may be a subframe in which a reference signal is periodically measured in order to periodically update channel state information. If the valid subframe is determined to be a periodic CSI measurement reference subframe, the UE may determine whether the periodic CSI is updated in the subframe in which the detected downlink burst is transmitted (S1250). If the periodic CSI is already updated in the subframe in which the detected downlink burst is transmitted, the UE may maintain the updated periodic CSI and may not perform the CSI update. For example, if the periodic CSI update is performed in the first valid subframe in which the detected downlink burst is transmitted, the CSI update may not be performed in the remaining subframes of the detected downlink burst.
  • the UE may perform CSI update (S1280).
  • the CSI update may be a periodic channel state information update.
  • the CSI update may be performed in the first valid subframe of the subframe in which the detected downlink burst is transmitted.
  • the UE may compare the CSI update process value N and the CSI update threshold value Ny (S1260). That is, when the valid subframe is determined to be an aperiodic CSI measurement reference subframe, the UE may compare the CSI update process value N and the CSI update threshold value Ny.
  • the aperiodic CSI reference subframe may be a subframe in which a reference signal is measured aperiodically to update channel state information aperiodically.
  • the CSI update process value may mean the number of CSI updates performed by the UE at a time corresponding to the valid subframe
  • the CSI update threshold value may mean the maximum number of CSI updates that the UE can perform simultaneously.
  • the CSI update threshold may mean the maximum number of aperiodic CSI updates that the UE can perform simultaneously.
  • the terminal may not perform the CSI update.
  • the UE may determine whether the aperiodic CSI is updated in the subframe in which the detected downlink burst is transmitted (S1270). If the aperiodic CSI is already updated in the subframe in which the detected downlink burst is transmitted, the UE may maintain the updated aperiodic CSI and may not perform the CSI update. For example, if the aperiodic CSI update is performed in the first valid subframe in which the detected downlink burst is transmitted, the CSI update may not be performed in the remaining subframes of the detected downlink burst.
  • the UE may perform CSI update (S1280).
  • the CSI update may be an aperiodic channel state information update.
  • the CSI update may be performed in the first valid subframe of the subframe in which the detected downlink burst is transmitted.
  • the memory size of the UE may be additionally increased even if the number of component carriers is increased in carrier aggregation. There is no need, and the computational complexity for updating the CSI of the UE is not greatly increased.
  • FIG. 13 is a flowchart illustrating a procedure for a UE to report an updated CSI to a base station according to an embodiment of the present invention.
  • the UE may perform CSI update (S1310).
  • the CSI update may be a periodic CSI update.
  • the CSI update may be an aperiodic CSI update.
  • the CSI update may be performed in an unlicensed band.
  • the UE may compare the number of subframes and the N validCSI value between the CSI updated subframe and the CSI reported subframe (S1320).
  • the N validCSI may be a parameter for preventing the CSI that is not updated for more than a predetermined time because it does not pass the LBT or does not satisfy the CSI update condition, is reported to the base station.
  • the N validCSI may be predefined. When the N validCSI is predefined, the N validCSI may be set differently according to a channel access priority class. When the N validCSI is predefined, the N validCSI may be defined as a function of a parameter having no ambiguity between the base station and the terminal.
  • the N validCSI may be configurable by an RRC message. That is, the N validCSI may be variably set by an RRC message.
  • the UE may report the updated CSI to the base station (S1330). If the periodic CSI report and the aperiodic CSI report overlap, the aperiodic CSI report may be prioritized over the periodic CSI report.
  • the UE may report CQI index 0 to the base station (S1340).
  • the CQI index 0 may indicate an out of range.
  • FIG. 14 is a block diagram illustrating a method of updating channel state information by a terminal according to an embodiment of the present invention.
  • the terminal can detect a downlink burst in an unlicensed band (S1410).
  • the terminal may determine a first valid subframe among one or more subframes in which the detected downlink burst is transmitted (S1420).
  • the first valid subframe may include a CSI-RS configured for measuring channel state information.
  • the first valid subframe is a subframe in which a value of Subframe Configuration for Licensed Assisted Access Field is 0 to 7 among one or more subframes in which the detected downlink burst is transmitted. Can be.
  • the subframe configuration field value for the LAA may be obtained by decoding the DCI IC.
  • the first valid subframe may be a periodic CSI measurement reference subframe, and the periodic CSI measurement reference subframe may be a subframe in which a reference signal is periodically measured in order to periodically update channel state information.
  • the first valid subframe may be an aperiodic CSI measurement reference subframe
  • the aperiodic CSI measurement reference subframe may be a subframe in which a reference signal is measured aperiodically to update channel state information aperiodically.
  • the terminal may update the channel state information in the determined first valid subframe (S1430).
  • the CSI update process value N is less than or equal to the CSI update threshold value Ny, and the CSI update process value is the number of CSI updates performed by the UE at a time corresponding to the first valid subframe.
  • the CSI update threshold may be the maximum number of CSI updates that the UE can perform simultaneously.
  • the comparison of the CSI update process value and the CSI threshold may be considered only for aperiodic CSI update.
  • the terminal may report the updated channel state information to a base station.
  • the reported channel state information may be the most recently updated channel state information (latest updated CSI).
  • the most recently updated channel state information may be channel state information updated within a specific time with respect to the time at which the channel state information is reported.
  • the terminal may report a CQI index 0 indicating an out of range to the base station. Can be.
  • the terminal may not update channel state information in the downlink burst.
  • the terminal reports updated channel state information to the base station, but the reported channel state information may be channel state information updated from a previous downlink burst of the downlink burst in which the CSI is not updated.
  • the updated channel state information may be updated channel state information in a first valid subframe among subframes in which the previous downlink burst is transmitted.
  • the updated channel state information may be updated channel state information within a specific time based on a time at which the channel state information is reported.
  • 15 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.
  • the base station 1500 includes a processor 1501, a memory 1502, and a transceiver 1503.
  • the memory 1502 is connected to the processor 1501 and stores various information for driving the processor 1501.
  • the transceiver 1503 is connected to the processor 1501 to transmit and / or receive a radio signal.
  • Processor 1501 implements the proposed functions, processes, and / or methods. In the above-described embodiment, the operation of the base station may be implemented by the processor 1501.
  • the terminal 1510 includes a processor 1511, a memory 1512, and a transceiver 1513.
  • the memory 1512 is connected to the processor 1511 and stores various information for driving the processor 1511.
  • the transceiver 1513 is coupled to the processor 1511 to transmit and / or receive wireless signals.
  • Processor 1511 implements the proposed functions, processes, and / or methods. In the above-described embodiment, the operation of the terminal may be implemented by the processor 1511.
  • the processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices.
  • the memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device.
  • the transceiver may include baseband circuitry for processing wireless signals.
  • the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function.
  • the module may be stored in memory and executed by a processor.
  • the memory may be internal or external to the processor and may be coupled to the processor by various well known means.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention concerne un procédé destiné à un terminal destiné à la mise à jour d'informations relatives à l'état de canal dans un système de communication sans fil. Le terminal peut détecter une rafale en liaison descendante dans une bande sans licence, déterminer une première sous-trame valide parmi une ou plusieurs sous-trames dans lesquelles la rafale en liaison descendante détectée est transmise et mettre à jour les informations relatives à l'état de canal dans la première sous-trame valide déterminée.
PCT/KR2016/008138 2016-07-26 2016-07-26 Procédé et appareil destinés à un terminal destinés à la mise à jour d'informations relatives à l'état de canal dans un système de communication sans fil WO2018021586A1 (fr)

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PCT/KR2016/008138 WO2018021586A1 (fr) 2016-07-26 2016-07-26 Procédé et appareil destinés à un terminal destinés à la mise à jour d'informations relatives à l'état de canal dans un système de communication sans fil

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CN112655266B (zh) * 2018-09-10 2023-09-01 高通股份有限公司 低延时传输的干扰检测、信令和缓解技术

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