WO2012060631A2 - 보간을 이용한 프리코딩 행렬 지시자 피드백 방법 및 장치 - Google Patents
보간을 이용한 프리코딩 행렬 지시자 피드백 방법 및 장치 Download PDFInfo
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- WO2012060631A2 WO2012060631A2 PCT/KR2011/008296 KR2011008296W WO2012060631A2 WO 2012060631 A2 WO2012060631 A2 WO 2012060631A2 KR 2011008296 W KR2011008296 W KR 2011008296W WO 2012060631 A2 WO2012060631 A2 WO 2012060631A2
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- pmi
- window
- pmis
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Definitions
- the present invention relates to a wireless access system, and more particularly, to a method and apparatus for channel feedback through precoding linear indicator (PMI) interpolation.
- the present invention also relates to a method and apparatus for setting a window for PMI interpolation.
- Wireless access systems are widely deployed to provide various kinds of communication services such as voice and data.
- a wireless access system is a multiple access system capable of supporting communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.).
- multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and single carrier SC-FDMA. frequency division multiple access) systems.
- 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 SC-FDMA. frequency division multiple access
- CSI channel state information
- Another object of the present invention is to provide a feedback method that provides higher channel accuracy in order to remove interference between terminals in a comp environment.
- the present invention relates to a wireless access system and provides various methods for feeding back channel state information in a comp environment.
- a method for feeding back a precoding matrix indicator (PMI) in a CoMP environment includes a step in which a terminal performs PI interpolation using PMIs included in a PMI window and the terminal interpolates.
- the PMI and the step of selecting the optimum PMI by comparing the channel status of the channels are O ( ⁇ may be a terminal comprising the step of feeding back the joejeok PMI to the base station.
- a terminal for feeding back a precoding matrix indicator (PMI) in a CoMP environment includes: a transmission module for transmitting a radio signal, receiving modules for receiving a radio signal, and a feedback for the PMI It may include a processor for.
- the processor performs PMI interpolation using the PMIs included in the PMI window, compares the interpolated PMI with the channel state of the current channel, selects the optimal PMI, and uses the transmitting module to transmit the sinister PMI to the base station. You can feedback.
- PMI interpolation may be performed by calculating an average value of PMIs included in a PMI window.
- Each phase coefficient for PMIs may be considered when calculating the average value of PMIs.
- the average value of the PMIs may be a phase average of each of the PMIs.
- PMIs included in the PMI window may include PMIs in a current subframe and PMIs previously fed to a base station.
- the PMI window may be determined in consideration of the transmission period of the channel state information reference signal (CSI-RS). If this PMI window is sleeping, the new ⁇ window removes all ⁇ s contained in the ⁇ window and starts with the current subframe. Can be reset. Or, when the PMI window is multiple, the new PMI window may be set by reusing some of the PMIs included in the PMI window.
- CSI-RS channel state information reference signal
- the terminal may receive a message (RRC signaling or PDCCH signal) including information on the PMI window from the base station.
- a message RRC signaling or PDCCH signal
- feedback methods according to embodiments of the present invention may provide higher channel accuracy by eliminating interference between terminals in a comp environment.
- high channel accuracy can be provided by avoiding interference caused by the serving cell to the serving shell in the comp environment.
- the PMI I interpolation can improve the channel accuracy by feeding back the PMI that is closest to the current channel.
- FIG. 1 is a view showing the structure of a radio frame that can be used in embodiments of the present invention.
- FIG. 2 is a diagram illustrating a resource grid for one downlink slot that can be used in embodiments of the present invention.
- FIG. 3 is a diagram illustrating a structure of a downlink subframe that can be used in embodiments of the present invention.
- FIG. 4 is a diagram illustrating an example of an uplink subframe structure that can be used in embodiments of the present invention.
- FIG. 5 is a configuration diagram of a wireless communication system having multiple antennas.
- FIG 6 illustrates an example of interpolation used in embodiments of the present invention.
- FIG. 7 is a diagram illustrating one method of determining and feeding back a PMI through interpolation as an embodiment of the present invention.
- FIG. 8 is a diagram illustrating another method of determining and feeding back a PMI through interpolation according to an embodiment of the present invention.
- FIG. 9 illustrates how to determine the interpolation window size used in embodiments of the present invention.
- FIG. 10 is a diagram illustrating another embodiment of the present invention, in which the embodiments of the present invention described with reference to FIGS. 1 to 9 may be performed. [Form for implementation of invention]
- various methods of feeding back CSI under a comp environment are disclosed. Also disclosed are channel feedback methods via precoding matrix indicator (PMI) interpolation, methods of establishing a window for PMI interpolation, and an apparatus supporting the methods.
- PMI precoding matrix indicator
- each component or particular may be considered optional unless otherwise stated.
- Each component or feature may be embodied in a form that is not combined with other components or features.
- some components and / or features may be combined to form an embodiment of the present 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 correspond to corresponding components or features of another embodiment. Can be associated.
- the base station has a meaning as a terminal node of a network which directly communicates with a mobile station. Certain operations described as being performed by the base station in this document may be performed by an upper node of the base station in some cases.
- various operations performed for communication with a mobile station in a network composed of a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station.
- the 'base station' may be substituted by terms such as a fixed station, a Node B, an eNode B (eNB), an advanced base station (ABS), or an access point.
- a terminal may be a user equipment (UE) or a mobile station (MS). It may be replaced with terms such as a mobile station, a subscriber station (SS), a mobile subscriber station (MSS), a mobile terminal, or an advanced mobile station (AMS).
- UE user equipment
- MS mobile station
- SS subscriber station
- MSS mobile subscriber station
- AMS advanced mobile station
- the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service
- the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in uplink, a mobile station may be a transmitting end and a base station may be a receiving end. Similarly, in downlink, a mobile station may be a receiving end and a base station may be a transmitting end.
- Embodiments of the present invention may be supported by standard documents disclosed in at least one of the IEEE 802.XX system, the 3rd Generation Partnership Project (3GPP) system, the 3GPP LTE system, and the 3GPP2 system, which are wireless access systems.
- Embodiments of the invention may be supported by 3GPP TS 36.211, 3GPP TS 36.212, 3GPP TS 36.213 and 3GPP TS 36.321 documents. That is, obvious steps or parts which are not described among the embodiments of the present invention may be described with reference to the above sentences.
- all terms disclosed in this document may be described by the above standard document.
- I 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. Can be used in various wireless access systems such as 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. Can be used in various wireless access systems such as 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. Can be used in various wireless access systems such as 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. Can be used in various wireless access systems such as CDMA, frequency division multiple access (FDMA), time division multiple access (TDMA
- CDMA can be implemented with UT A (Universal Terrestrial Radio Access) or CDMA2000 high-end radio technologies such as ⁇ TDMA is the Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced (EDGE). Data rates for GSM Ev can be implemented with the same wireless technologies: OFDMA is IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), LTE May be implemented with a wireless technology such as -A or the like.
- UTRA is the Universal Mobile Telecommunications System (U TS)
- 3GPP Long Term Evolution is an Evolved UMTS (E-UMTS) using E-UTRA
- E-UMTS Evolved UMTS
- OFDMA is employed in downlink
- SC-FDMA is employed in uplink.
- LTE-A Advanced
- I will focus on 3GPP LTE / LTE-A, but can also be applied to IEEE 802.16e / m systems and the like.
- FIG. 1 is a view showing the structure of a radio frame that can be used in embodiments of the present invention.
- a radio frame consists of 10 subframes, and one subframe consists of two slots.
- a time taken for transmitting one subframe is referred to as a transmission time interval (TTl).
- Tl transmission time interval
- the length of one subframe is 1ms
- the length of one slot is 0.5ms.
- One slot is a plurality of OFDM (thogonal) in the time domain
- Frequency division multiplexing symbol, and includes a plurality of It includes a resource block (RB).
- the OFDM symbol is for representing one symbol period in a 3GPP LTE system using Orthogonal Frequency Division Multiplexing Access (OFDMA) scheme in downlink. That is, the OFDM symbol may be referred to as an SC-FDMA symbol or a symbol interval according to a multiple access scheme.
- the RB includes a plurality of consecutive subcarriers in one slot in resource allocation units.
- the structure of the radio frame of FIG. 1 is merely an example, and the number of subframes included in the radio frame, the number of slots included in the subframe, and the number of OFDM symbols included in the slot may be variously changed.
- FIG. 2 is a diagram illustrating a resource grid for one downlink slot that can be used in embodiments of the present invention.
- the downlink slot includes a plurality of OFDM symbols in the time domain.
- one downlink slot includes seven OFDM symbols, and one resource block (RB) includes 12 subcarriers in a frequency domain.
- Each element on the resource grid is called a resource element (RE).
- One resource block (RB) includes 12x7 resource elements (RE).
- the number N DL of resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the shell.
- FIG. 3 is a diagram illustrating a structure of a downlink subframe that can be used in embodiments of the present invention.
- the subframe includes two slots in the time domain. Up to three OFDM symbols of the first slot in the subframe are the control region to which control channels are allocated, and the remaining OFDM symbols are the data region to which the Physical Downlink Shared Channel (PDSCH) is allocated.
- PDSCH Physical Downlink Shared Channel
- PCFICH Physical FICH
- the PCFICH signal transmitted in the first OFDM symbol of the subframe carries information about the number of OFDM symbols (that is, the size of the control region) used for transmission of the control channel signal in the subframe.
- PHICH carries an AcknowledgmentVNACK (None-Acknowledgement) signal for an uplink HARQ (Hybrid Automatic Repeat Request).
- the ACK / NACK signal for the uplink data transmitted by the user equipment is transmitted on the PHICH.
- DCI Downlink control information
- DCI includes resource allocation information and other control information for a UE or UE group.
- the DCI may include uplink resource allocation information, downlink resource allocation information, and uplink transmission power control command.
- the PDCCH is a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format and resource allocation information of an uplink shared channel (UL-SCH), a paging channel ( Paging information on PCH: Paging Channel, system information on DL-SCH, resource allocation information for higher layer control messages such as random access response transmitted on PDSCH, transmission power for individual UEs in any UE group. It can carry information about control command set, transmit power control command, Voice of Internet Protocol (VoIP) and activation.
- DL-SCH downlink shared channel
- UL-SCH uplink shared channel
- Paging information on PCH Paging Channel
- system information on DL-SCH system information on DL-SCH
- resource allocation information for higher layer control messages such as random access response transmitted on PDSCH
- transmission power for individual UEs in any UE group can carry information about control command set, transmit power control command, Voice of Internet Protocol (VoIP) and activation.
- VoIP Voice of Internet Protocol
- PDCCH Physical Downlink Control Channel
- PDCCH is one or more
- CCE is in the state of the wireless channel It is a logical allocation resource used to provide a single PDCCH coding.
- CCE has multiple Resource Element Groups (REG) 0
- the number of available bits is determined by the correlation between the number of CCEs and the coding provided in the CCEs.
- the base station determines the PDCCH format according to the DCI to be transmitted to the UE, and invokes CRC on the control information.
- the CRC is masked with a unique Radio Network Temporary Identifier (RNTI), depending on how I use or owner of the PDCCH.
- RNTI Radio Network Temporary Identifier
- the unique identifier of the UE e.g, C-RNTI: Cell-RNTI
- the paging indicator identifier for example, P-RNTI: Paging-RNTI
- the system information identifier and system information RNTI S—RNTI
- a random access RNTI (RA-RNTI) may be masked to the CRC to indicate a random access answer, which is an answer to the reception of the random access preamble of the UE.
- the PDCCH may be transmitted through one or more component carriers and may include resource allocation information for one or more component carriers. Can be.
- the PDCCH is transmitted on one component carrier, but may include resource allocation information for one or more PDSCHs and PUSCHs.
- FIG. 4 is a diagram illustrating an example of an uplink subframe structure that can be used in embodiments of the present invention.
- the uplink subframe includes a plurality of (eg, two) slots.
- the slot may include different numbers of SC-FDMA symbols according to a cyclic prefix (CP) length.
- the uplink subframe is divided into a data region and a control region in the frequency domain.
- the data area includes a PUSCH (Physical Uplink Shared Channel) and is used to transmit a data signal including voice information.
- the control region includes a PUCCH (Physical Uplink Control Channel) and is used to transmit uplink control information (UCI).
- the PUCCH includes RB pairs located at both ends of the data region on the frequency axis and hops to slot boundaries.
- the UE does not simultaneously transmit the PUCCH signal and the PUSCH signal in order to maintain a single carrier characteristic.
- the PUCCH signal and the PUSCH signal may be simultaneously transmitted in the same subframe according to the transmission mode of the UE.
- the PUCCH signal may be piggybacked on the PUSCH signal and transmitted.
- the UE may transmit uplink control information through the PUSCH according to the channel situation.
- PUCCH for one UE is allocated as an RB pair in a subframe, and RBs belonging to the RB pair occupy different subcarriers in each of two slots.
- This RB pair allocated to the PUCCH is said to be frequency hopping at the slot boundary (slot boundary).
- PUCCH may be used to transmit the following control information.
- SR Service Request: Information used for requesting an uplink UL-SCH resource. It is transmitted using OOK (On-Off Keying) method.
- HARQ AC / NAC downlink data packet or PDS on PDSCH
- a response signal to a PDCCH indicating release A response signal to a PDCCH indicating release.
- the HARQ AC / NAC signal indicates whether a downlink data packet or a PDCCH indicating SPS release has been successfully received.
- One bit of ACK / NACK is transmitted in response to a single downlink codeword, and two bits of ACK / NACK are transmitted in response to two downlink codewords.
- ACK / NACK responses for a plurality of downlink subframes are collected and bundled. It is transmitted on one PUCCH through multiplexing.
- CQI Channel Quality Indicator
- CSI Channel State Information
- MIMO Multiple Input Multiple Output
- RI rank indicator
- PMI precoding matrix indicator
- 20 bits are used per subframe.
- CSI may be used as a concept including all CQI, I, and PMI values.
- the amount of uplink control information (UCI) I can transmit in a subframe depends on the number of SC-FDMAs available for transmission of control information.
- SC-FDMA available for transmission of control information means the remaining SC-FDMA symbol except for the SC-FDMA symbol for transmitting the reference signal in the subframe, and in the case of the subframe in which the Sounding Reference Signal (SRS) is set, the subframe I The last SC-FDMA symbol is also excluded.
- the reference signal is used for coherent detection of the PUCCH.
- PUCCH supports seven formats according to the transmitted information.
- Table 1 shows the mapping of PUCCH format and UCI in LTE. Represents a relationship.
- the communication environment considered in the embodiments of the present invention includes a multi-carrier aggregation supporting environment. That is, a multicarrier system or a carrier aggregation system used in the present invention refers to a target broadband when configuring a target broadband to support wideband. One or more with a small bandwidth
- Component Carrier (CC Component) CC Component
- Carrier refers to a system that uses a combination (aggregation).
- multi-carrier means carrier aggregation (or carrier coupling), and carrier aggregation means not only coupling between adjacent carriers but also coupling between non-adjacent carriers.
- carrier combining may be used interchangeably with terms such as carrier aggregation, bandwidth combining, and the like.
- a multicarrier ie, carrier aggregation
- CCs component carriers
- the bandwidth of the combining carrier may be limited to the bandwidth used by the existing system to maintain backward compatibility with the existing IMT system.
- the existing 3GPP LTE system supports ⁇ 1.4, 3, 5, 10, 15, 20 ⁇ MHz bandwidth
- the 3GPP LTE_advanced system ie LTE_A
- LTE_A uses only the bandwidths supported by LTE. It can be used to support bandwidth greater than 20MHz.
- the multicarrier system used in the present invention supports carrier combining (i.e. carrier aggregation, etc.) by defining a new bandwidth regardless of the bandwidth used in the existing system. You may want to.
- LTE-A system uses the concept of a cell (cell) to manage radio resources.
- a cell is defined as a combination of downlink resources and uplink resources, and uplink resources are not required. Accordingly, the cell may be configured with only downlink resources or with downlink resources and uplink resources. If multicarrier (i.e. carrier aggregation) is supported, the linkage between the carrier frequency (or DL CC) of the downlink resource and the carrier frequency (or UL CC) of the uplink resource is determined by the system information. Can be indicated.
- multicarrier i.e. carrier aggregation
- Cells used in the LTE-A system include a primary cell (PCell: Primary Cell) and a secondary cell (SCell: Secondary Cell).
- the P shell may refer to a shell operating on the primary frequency (or primary CC)
- the S cell may refer to a shell operating on the secondary frequency (or secondary CC).
- only one P cell is allocated to a specific terminal, and one or more S cells may be allocated.
- the P shell is used by the terminal to perform an initial connection establishment process or to perform a connection re-establishment process.
- the P shell may refer to a shell indicated in the handover process.
- the SCell may be referred to as Radio Resource Control (RRC). After the connection is made, it is configurable and can be used to provide additional radio resources.
- RRC Radio Resource Control
- the Pcell and Scell can be used as serving shells.
- a UE that is in an RRC ⁇ CONNECTED state but carrier aggregation is not configured or does not support carrier aggregation there is only one serving cell consisting of a PCell.
- one or more serving cells may exist, and the entire serving shell includes a PCell and one or more S shells.
- the E-UTRAN may configure a network including one or more S shells in addition to the Pcell initially configured in the connection establishment process.
- the Pcell and Sshell may operate as respective component carriers. That is, carrier matching may be understood as a combination of one or more S cells.
- the primary component carrier (PCC) may be used in the same sense as the Pcell, and the secondary component carrier (SCC) may be used in the same meaning as the SCell.
- MI O Feedback Multi-Input Multi-Output Feedback
- a MIMO feedback method using more than one input / output antenna may also be supported.
- MI O feedback consists of a Precoding Matrix Index (PMI), a Rank Indicator (RI) and a Channel Quality Information (CQI) index.
- PMI represents the index of the precoding matrix constituting the codebook.
- the RI is determined from the number of assigned transmission layers, and the UE can obtain the RI value from the associated DCI.
- PMI is defined in the 3GPP TS 36.211 standard, the terminal may determine the SINR, and may optimally select the I PMI in consideration of the accumulated SINR.
- the CQI represents the quality of the channel
- the CQI index represents the channel coding and modulation method.
- FIG. 5 is a configuration diagram of a wireless communication system having multiple antennas.
- the number of transmitting antennas is increased to ⁇ ⁇ and the number of receiving antennas is increased, the number of transmitting antennas is increased in proportion to the number of antennas.
- Channel transmission capacity increases. Therefore, the transmission rate can be improved and the frequency effect can be significantly improved.
- the transmission rate is theoretically the maximum with a single antenna. The transmission rate can be increased by multiplying by the rate of increase in rate.
- a MIMO communication system using four transmit antennas and four receive antennas can theoretically achieve four times the transmission rate compared to a single antenna system. Since the theoretical increase in capacity of multi-antenna systems was demonstrated in the mid-90s, various techniques have been actively studied to bring this to practical data transfer. In addition, some technologies are already being reflected in various wireless communication standards such as 3G mobile communication generation next generation WLAN.
- the research trends related to multi-antennas to date include the study of information theory axis related to the calculation of multi-antenna communication capacity in various channel environments and multiple access environments, the study of wireless channel measurement and model derivation of multi-antenna systems, and the improvement of transmission reliability. Research has been actively conducted from various viewpoints, such as research on space-time signal processing technology for improving transmission.
- the communication method in a multi-antenna system is described in more detail using mathematical modeling.
- the system includes ⁇ r transmit and receive antennas Assume that exists.
- the transmission signal when there are ⁇ / transmit antennas, the maximum information that can be transmitted is ⁇ ⁇ .
- the transmission information may be expressed as follows.
- Each transmission information 15 25 , ⁇ ⁇ may have a different transmission power. If each transmission power is ,, '' , '' ,., The following information may be expressed as the transmission information whose transmission power is adjusted.
- s may be expressed as follows using the diagonal matrix ⁇ of the transmission power.
- the weighting matrix W is applied to the information vector s of which the transmission power is adjusted to transmit the actual basis i. That is, consider the case where the ⁇ gaeeu i transmission signal, " ⁇ 2 ' ⁇ Nr configuration weighting if haengreol W serves to appropriately distributed to the respective antennas according to the transmission channel condition to transmit information, ⁇ 2, ''' , ⁇ Can be expressed as
- 3 ⁇ 4 means a weight between the / 3 ⁇ 4 th transmission antenna and the y th information.
- W is also called a precoding hangar.
- the received signal may be expressed as a received signal of each antenna;, 2 , '" ,) ⁇ as a vector.
- the channel When modeling a channel in a multi-antenna wireless communication system, the channel is transmitted and received It can be classified according to the antenna index.
- the channel over the receive antenna / from the transmit antenna J! Will be marked with ⁇ . Note that the index display order in ⁇ is that the receiving antenna index is first and the transmitting antenna index is later.
- FIG. 5 (b) shows a channel from ⁇ / ⁇ transmit antennas to a receive antenna.
- the channels may be bundled and displayed in the form of a vector and a matrix.
- a channel arriving from the total ⁇ ⁇ transmit antennas to the receive antenna / can be represented as follows.
- the actual channel has white noise (AWGN; Additive White) Gaussian Noise is added.
- AWGN Additive White
- the white noise «1, « 2 , '" , ⁇ added to each of the R reception antennas can be expressed as follows.
- the received signal is expressed as follows through the above-described equation modeling.
- the number of rows and columns of the channel matrix H representing the channel state is determined by the number of transmit and receive antennas.
- the number of rows in the channel matrix H is equal to the number of receive antennas, and the number of columns is equal to the number ⁇ of transmit antennas. That is, the channel matrix ⁇ is a matrix N R xN T.
- the rank of a matrix is defined as the number of places in the number of rows or columns that are independent of each other. Therefore, the rank of a row barrel cannot be larger than the number of rows or columns.
- the rank ra (H) of the channel matrix H is limited as follows. [Equation 11]
- rank can be defined as the number of eigenvalues that are non-zero [ Eigen value decomposition].
- another definition of rank can be defined as the number of nonzero singular values when singular value decomposition. Therefore, the physical meaning of rank in a channel matrix is the maximum number of different information that can be sent in a given channel.
- 'rank' for MIMO transmission refers to the number of paths that can transmit signals independently at a specific time point and at a specific frequency resource, and 'number of layers' It indicates the number of signal streams transmitted through each path.
- the transmitting end since the transmitting end transmits the number of layers corresponding to the number of ranks used for signal transmission, unless otherwise specified, the rank has the same meaning as the number of layers. 4. Feedback method under CoMP general and comp environment
- CoMP Coordinatd Multi-Point
- Comp is also called co-MIMO, collaborated MIMO, and network MIMO.
- Comp is a technique designed to improve the terminal operation of the cell boundary and to improve the average throughput of each sector.
- inter-cell interference reduces terminal performance of a cell boundary and reduces average sector storage in a multicell environment using frequency reuse factor 1.
- simple techniques e.g., FFR (Fractional Frequency Reuse) in UE specific power control
- LTE-A system can be applied to The use of FFR is more effective in reducing ICI or reusing ICI as a desired signal instead of reducing the use of frequency resources per cell.
- the comp schemes may be classified into joint processing (JP) and coordinated scheduling / beamforming (CS / CB) schemes.
- JP joint processing
- CS / CB coordinated scheduling / beamforming
- the PDSCH signal is transmitted simultaneously in multiple points (premise or part of a comp cooperation set).
- the data for a single endpoint is It is transmitted simultaneously from multiple transmission points to eliminate new signal quality and / or active interference to other terminals.
- PDSCH signals are transmitted from one transmission point (comp cooperative set) at a time.
- comp reception means reception of coordinated transmission signals at multiple points, and geographically separated transmission points and comp schemes are classified into joint reception (JR) and coordinated scheduling / beamforming (CS / RS). Can be.
- JR joint reception
- CS / RS coordinated scheduling / beamforming
- the PUSCH signal transmitted is received at multiple reception points
- the CS / CB scheme the PUSCH signal is received at only one reception point, but user scheduling / beamforming is performed in shells adjusted according to the comp cooperation set. Is determined by
- Transceiver is multiplexing gain of MIMO antenna in closed loop MIMO
- beamforming is performed based on channel information (for example, CSI).
- the base station may command to feedback the downlink CSI by allocating a PUCCH or a PUSCH to the UE to obtain the downlink CSI.
- CSI may be classified into three types of information: a rank indicator (RI), a precoding matrix indicator ( ⁇ ⁇ . Precoding Matrix Indicator), and channel quality information (CQI).
- RI rank indicator
- ⁇ precoding matrix indicator
- CQI channel quality information
- RI represents rank information of the corresponding channel, and means the number of streams received by the UE through the same frequency time resource.
- the RI value is dominantly determined by the long term fading of the channel and is fed back from the UE to the base station in a period longer than the PMI and CQI values.
- PMI is a value reflecting the spatial characteristics of the channel and represents the precoding index of the base station preferred by the UE based on a metric such as SINR.
- CQI is a value representing the strength of the channel, and means the reception SINR that can be obtained when the base station uses PMI.
- MU-MIMO multi-user MIM
- BCPMI Best Companion PMI
- UE-A UE-A
- BCPMI Best Companion PMI
- the base station may MU-MIMO schedule another UE that prefers Best Companion Precoding Matrix (BCPM) precoding indicated by UE-A O I "BCPMI based on the BCPMI information.
- BCPM Best Companion Precoding Matrix
- the BCPMI feedback method can be classified into two types, an explicit feedback method and an implicit feedback method, depending on the presence or absence of a feedback payload.
- the explicit feedback scheme is a feedback scheme with a feedback payload.
- the feedback method is a method in which the terminal determines the BCPMI in the codebook of the precoding matrix and then feeds back to the base station through the control channel.
- the terminal may select an interference signal precoding hangar in which the estimated SINR becomes a band in the codebook and feed it back to the base station as a BCPMI value.
- An advantage of the explicit feedback scheme is that the UE can select a BCPMI that is more effective for interference cancellation and transmit it to the base station. This is because the UE assumes the interference beams one by one for all codewords in the codebook, and then determines BCPMI as the most effective value for interference cancellation by comparing metrics such as SINR.
- the explicit feedback method as the codeword size increases, the candidate of BCPMI increases, which requires a larger feedback payload size.
- An implicit feedback method is a feedback method without a feedback payload.
- the implicit feedback method is not a method in which the UE searches for a codeword having less interference in the codeword and selects it as a BCPMI. Instead, a corresponding BCPMI is statically determined when an optimal PMI is determined.
- the BCPM is preferably composed of vectors orthogonal to the determined optimal PMI. Because, optimal PMI is used to maximize received SINR Since the interfering signal is selected to avoid the direction of the PMI, since the channel gain of the channel H is set in such a way as to condense, the interference gain is effective.
- the channel H between the terminal and the base station is analyzed as a plurality of independent channels through singular value decomposition (SVD), the advantages of the BCPMI determination method become clearer. For example, the 4x4 channel H can be resolved through SVD as shown in Equation 12 below.
- Equation 12 the linear U, V are unitary matrices, where, ⁇ and are respectively 4x1 left singular vectors, 4x1 right singular vectors, and singular values of channel H. ), Sorted in descending order by> + ,.
- the terminal transmits a transmission beamforming vector ⁇ and a reception beamforming actor 11, respectively.
- ⁇ 2 results in sinister performance in terms of SNR.
- the reception beam is set to u, and the transmission beam of the interference signal is set in the direction perpendicular to the PM, so that the UE can completely remove the interference signal without losing the optimal signal.
- the optimal PM is slightly different from ⁇ ⁇ due to quantization error, the transmission beam of the interference signal set in the direction perpendicular to the PM is no longer equal to the vertical beam, so that the terminal does not interfere with the optimal signal without loss.
- small quantization errors can help control interfering signals.
- the LTE codebook shown in Table 2 may be used.
- BCPMI may be statically determined as shown in Table 3 as a vector index orthogonal to ⁇ .
- Table 2 shows a case of 4 antenna port transmission, and the precoding matrix W may be selected as a subset of Table 2 or Table 2.
- I is a 4x4 unit row barrel, and each vector 1 may refer to Table 2.
- the reception rank of the terminal fed back ⁇ is 1, optimal
- Three vectors orthogonal to the PMI may be represented by three BCPMIs as shown in Table 3.
- PMI 3
- the BCPMI is determined to be (0, 1, 2).
- PMI O BCPMI indicates the index of the 4x1 vector codeword in the codebook.
- the advantage of the implicit feedback method is that there is no additional feedback overhead since the sinful PMI and BCPMI sets are mapped 1: 1.
- the BCPM dependent thereon may also have a sinusoidal interference cancellation beam direction and error.
- each BCPM may differ from the ideal interference beam.
- WCPMI Wood Companion PMI
- WCPMI is the opposite of BCPMI.
- WCPMI means an index for BCPM that gives the largest interference to the terminal when PMI is used as a precoding matrix of the interference signal.
- the base station receiving the WCPMI may mitigate the interference by determining a precoding row of the cooperative terminal with a beam having a small correlation with the WCPMI.
- the neighbor cell base station that has received the WCPMI may mitigate the interference by determining a precoding matrix of the UE with a beam having a small correlation with the WCPMI.
- the neighbor cell base station receiving the WCPMI may determine a precoding matrix of the comp terminal with a beam having a high correlation with the WCPMI.
- the effective channel is a channel obtained by applying a reception beamforming hangar to the measured channel, and is represented as U * H when the reception beamforming rowar of the UE is U and the measured channel is H.
- the terminal determines a reception beam capable of obtaining high received signal power from a channel with a serving cell.
- the receive beam is directed to the left dominant singular vector of the channel from the serving cell
- the comp UE or cooperative terminal quantizes U * H to a serving shell and U * H C to an adjacent cell and transmits data, and the serving cell receives the U * H out correlation. Set the beam with high relation.
- the neighboring shell may reduce the interference by determining a precoding matrix of the UE with a beam having a small correlation with U * H C.
- the neighbor cell may determine the precoding matrix of the comp terminal with a beam having a high correlation with U * H C.
- the terminal performs interpolation of the PMIs that have already fed back the PMI existing within the window size promised with the base station.
- PMI interpolation methods that feed back the PMI with the closest result compared to the channel will be described in detail.
- FIG 6 illustrates an example of interpolation used in embodiments of the present invention.
- FIG. 6 illustrates a case in which four precoding matrices (PM) are interpolated with respect to the current channel when the window size is four.
- PM precoding matrices
- FIG. 6 for convenience, a vector represented by a current channel in a three-dimensional space and represented by an F PMI (that is, a codeword) is geometrically represented.
- the base station and the terminal may share a window size interpolation method for PMI interpolation. Therefore, when the base station receives the interpolated PMI from the terminal, it can estimate the channel by performing the PMI interpolation in the same manner as the terminal.
- the window size specifies the number of PMIs that feed back currently and the number of PMIs that have fed back in the past. That is, when the window size is promised to N between the base station and the terminal, previously fed back N-1 PMIs and PMIs to be fed back are used for PMI interpolation. Several variables can be considered to determine the window size.
- the terminal For example, mobility of the terminal, Doppler frequency and / or channel change may be taken into account when determining the window size.
- the channel changes rapidly the correlation between the previous PMI and the current channel is small, so it is difficult to increase the accuracy of the feed back channel even if the interpolation window size is increased. desirable.
- the window size is determined by the base station to be semi-static and transmitted to the UE through higher layer (eg, RRC) signaling, or dynamically determined to be determined by the UE through a control channel such as a PDCCH. I can let you know.
- the base station may transmit not only the window size but also the interpolation method to be performed by the terminal to the terminal (S710).
- step S710 the case where the terminal receives the window size and the interpolation method from the base station is described. However, unlike step S710, the terminal is on the channel. Depending on the situation, the interpolation window size and / or interpolation method for PMI interpolation can be determined and transmitted to the base station.
- the base station transmits a reference signal (RS) to the terminal by performing downlink channel measurement (S720).
- RS reference signal
- the UE may obtain a window size for PMI interpolation from the RRC signaling or the PDCCH signal received in step S710.
- the terminal can measure the current channel state based on the received in step S720, in each subframe
- the terminal is included in the window according to the window size.
- PMI interpolation may be performed on the PMIs (S730).
- PMI interpolation can be implemented in a number of ways. Equation 13 below shows an example of PMI interpolation.
- Equation 13 the function f () represents an interpolation function, and the window size is assumed to be N.
- Function nor () is a function that normalizes the norm of a matrix
- PMI u (i) refers to the i th PMI for the current m th subframe.
- PMI M- ⁇ , —, PU refers to PMI, which was fed back just before, and ⁇ , which was fed back N-1 times.
- PM) and PM respectively mean a precoding hangar corresponding to the i th PMI to be fed back and a precoding hangar fed back n times.
- ⁇ means a weighting factor that is rapidly applied to each ⁇ . However, in the case of simplifying normalization, it can be calculated by fixing all « lac to 1.
- the terminal may compare the result of the PMI interpolation with the current channel to determine the final sinuous PMI to feed back to the base station (S740).
- Equation 14 may be used in operation S740 to determine an optimal PMI. All.
- the dist () function is a value representing a correlation between two factors.
- An example of a value representing the correlation between two factors is Euclidean distance.
- the first factor H means a channel between the terminal and the base station.
- the second argument may be the f () function, which is an interpolation term of Equation 13.
- H which is the first factor, can be used directly, or H's dominant singular vector can be used by H function such as singular value decomposition (SVD).
- j denotes a final PMI which is a calculated result.
- the terminal may feed back the determined final PMI (j) to the base station through the PUCCH signal or the PUSCH signal (S750).
- step S750 when the terminal feeds back the final PMI to the base station, the terminal
- the base station may inform the base station about the PMI interpolation method performed in step S730. If the base station informs the interpolation method in step S710, the terminal does not need to inform the base station again the interpolation method. However, the terminal is different from the interpolation method When the interpolation method is used or the base station does not inform the interpolation method in step S710, the UE may inform the base station together with the interpolation method performed by the UE during PMI feedback.
- the base station receiving the PUCCH signal or the PUSCH signal including the final PMI value may check the final PMI value transmitted by the terminal.
- the base station since the base station knows how to interpolate the size of the interpolation window in which the terminal performs interpolation, the base station may estimate the channel by performing interpolation in the same manner as the terminal after receiving the sinusoidal PMI (S760).
- the UE may use another PMI interpolation method. For example, the terminal first separates the current correct channel into one form of linear combination of codewords, and then window size in proportion to the weighting of each codeword (e.g., phase coefficient). The codeword may be determined and reported to the base station within.
- the terminal first separates the current correct channel into one form of linear combination of codewords, and then window size in proportion to the weighting of each codeword (e.g., phase coefficient).
- the codeword may be determined and reported to the base station within.
- the terminal selects codewords (ie, PMI) vl, v2 and vlO from Cl / (d + c2 + c3): c2 / (cl + c2 +): c3 / (cl + c2 + c3) can be fed back to the base station. That is, the terminal may report to the base station by varying the number of transmission times for each PMI. All.
- the PMI interpolation and feedback method described with reference to FIG. 7 focuses on downlink channel estimation of a base station and a terminal
- the PMI interpolation and feedback method may be used as a channel feedback method through a codeword between any one or more terminals.
- the window for PMI interpolation may be called initially. That is, when the window is initialized, the terminal may ignore all previous PMIs and assume the current PMI as the initial PMI and calculate it.
- FIG. 8 is a diagram illustrating another method of determining and feeding back a PMI through interpolation according to an embodiment of the present invention.
- the UE may perform PMI interpolation using Channel State Information / Indication-Reference Signal (CSI-RS).
- CSI—RS is a newly designed RS in LTE-A system and is used for downlink channel measurement.
- a terminal determines a window size and / or an interpolation method for PMI interpolation, and determines the determined window size and / or interpolation method in a PUCCH signal or a PUSCH.
- the signal may be transmitted to the base station eNB (S810).
- step S810 it is assumed that the UE determines the window size and / or interpolation method.
- the BS determines the window size and / or interpolation method and transmits it to the UE through RRC signaling or PDCCH signal. Can be.
- the base station periodically transmits the CSI-RS to the terminal for downlink channel establishment (S820).
- the terminal may perform PMI calculation and interpolation using the window size and / or interpolation method determined in step S810 (S830).
- the terminal may determine the final optimal PMI based on the interpolated PMI in step S830 (S840).
- the interpolation method performed by the UE in step S830 may use the interpolation method of step S730 of FIG. 7, and the method of determining the seconds (the seed PMI) in step S840 may refer to step S740.
- the terminal may feed back the determined final PMI and neighbor cell channel information to the base station using the PUCCH signal or the PUSCH signal (S850). Since the BS knows the size of the window and the interpolation method through the PUCCH signal received in step S810, the base station can accurately estimate the channel by performing the same interpolation with the terminal using the received sinusoid PMI (S860).
- the PMI interpolation method described above with reference to FIGS. 6 to 8 may be used to accurately transmit precoding matrix information of a sinusoidal signal received by the UE from the serving cell.
- the PMI interpolation method can be used to accurately transmit the information of the precoding matrix for the interference signal of the cooperative terminal received from the serving cell in consideration of MU-MIMO.
- the precoding matrix information for the interference signal may be the above-described BCPMI, WCPMI and / or effective channel feedback.
- PMI interpolation can be used to accurately convey channel information about the intake shell for the Comp (CoMP).
- channel information to neighbor cells may be BCPMI, WCPMI and / or effective channel feedback.
- the UE may transmit the BCPMI, WCPMI, and / or the effective channel feedback value together with the neighbor cell channel information as well as the sinusoidal PMI value to the base station.
- FIG. 9 is a diagram illustrating a method of determining a PMI window size used in embodiments of the present invention and a method of performing PMI interpolation using a PMI window.
- CSI-RS is used for downlink channel establishment.
- the number of antennas supported in the LTE-A system is increased to eight (e.g. 8Tx)
- transmitting RS over the entire band every subframe may cause excessive RS overhead as in the existing LTE. Therefore, CSI-RS transmission is performed in a relatively long period of several tens of msec in LTE— ⁇ system.
- the PMI window size for PMI measurement can be fed back through the uplink during the CSI-RS transmission period.
- FIG. 9 (a) shows a case in which the number of PMIs is 5 because the size of the window corresponds to the CSI-RS transmission period.
- CSI-RS transmission includes 10 subframes (ie, 10 msec) once, and the UE may transmit five PMIs over the uplink for 10 msec.
- the window size is set to S, which is the number of PMI reports.
- the UE determines the PMI for the two
- the mobile station 5, 7, 9, and 11 th uplink to feed back the PMI computed based on the first CSI-RS in a subframe to a base station is the second CSI-RS (2 nd in the eleventh downlink subframe CSI-RS) and generates and feeds back PMI information about the newly measured channel based on the second CSI-RS. That is, the terminal feeds back the PMI determined based on the second CSI-RS to the base station after the 13 th uplink subframe.
- the UE calculates a PMI when the window is re-learned in uplink subframes 3, 5, 7, 9, and 11, and the second CSI from uplink subframe 13 Based on -RS I can set up a new window to calculate the PMI.
- the newly set interpolation window is used for subframes 13, 15, 17, 19, and 21. It consists of PMI.
- the window size is preferably determined as a multiple of the number of PMIs fed back during the CSI-RS period (e.g. 10 msec). That is, in FIG. 9, it is preferable to determine 5, 10, or 15, which is a multiple of 5, the number of PMIs fed back during the transmission period of the CSI-RS.
- the problem is how to set a new interpolation window when the size of the interpolation window is different. For example, if the size of the window is 10, the terminal calculates the PMI in the same window until receiving the third CSI-RS (3 rd CSI-RS), and after receiving the third CSI-RS A new interpolation window must be set up to calculate the PMI.
- new interpolation windows can be set in the following two ways. i) The window reset method removes all PMIs of the previous window and reports the PMI of the newly started window. ii) The sliding window method removes some PMIs of the previous window and restarts the remaining PMIs of the previous window. It is a way to consider them together in Windows. i) Window reset method
- the UE calculates the PMI in the same window until it receives when the window size is 10, and the third CSI-RS (3 rd CSI- RS). However, after receiving the third CSI-RS, a new interpolation window is set to calculate the PMI.
- the new window unattends (removes) all PMIs calculated before the third CSI-RS is received, and the fifth CSI-RSs after the PMI calculated using the third CSI-RS (5 th CSI-RS). It can be set up to I PMI until receiving).
- the window resetting method completely initializes the window when the interpolation window is full, and assumes that the PMI generated based on the newly received CSI-RS is the first interpolated PMI without using any previously calculated PMI. That's the way. ii) Sliding window type
- the UE calculates the PMI in the same window until it receives a third CSI-RS (3 rd CSI- RS) if the size of the window 10. However, after receiving the third CSI-RS, a new interpolation window is set to calculate the PMI. At this time, the new window removes the PMI calculated before receiving the second CSI-RS, and the second After the PMI unit Ej calculated using the CSI-RS, it may be set to I PMI until the L) th CSI-RS (4 th CSI-RS) is received.
- the sliding window method initializes a part of the previous window, and sets the PMI remaining in the previous window and the PMI for the newly received third CSI-RS period as the new window.
- the terminal may perform PMI interpolation using a portion of the previous window and a PMI to be accumulated during the newly received CSI-RS period.
- the window is initialized and interpolated when the size of the window is full (reset method).
- the and windows are all closed, you can consider two I emptying the previous window, interpolation using the PMI remaining in the previous window and the newly calculated PMI (sliding method).
- the generated PMI When the generated PMI is set to a window size of more than twice the number of PMIs fed back during the CSI-RS transmission period, it may be more effective when the channel is changed slowly and the channels determined by a plurality of adjacent CSI-RSs are similar.
- the terminal may perform interpolation after setting a new window by resetting or sliding the window.
- the terminal may finally feed back the two I, which has performed interpolation assuming a window resetting method and a sliding method, and a PMI having a small error compared to a recently determined channel, to the base station.
- the UE determines the interpolation window size
- the UE transmits 1 bit of control information (eg, window setting indicator) to the PUCCH signal or PUSCH signal including the optimal PMI in order to inform the base station of how to set the window size.
- feedback to the base station may be provided. For example, when one bit of control information is set to '', the window resetting method may be indicated, and if it is set to ⁇ , the suliding method may be indicated. (4) How to determine interpolation window size 2
- the above-described embodiments of the present invention are methods in which a terminal transmits PMI over several subframes on a time axis and interpolates the PMIs to increase the accuracy of channel feedback.
- the interpolated window size is set in units of time.
- the UE may transmit some or all of the PMIs interpolated in the interpolation window in one subframe.
- the interpolated window may be determined as the number of I PMIs transmitted in one subframe.
- the terminal may interpolate by supplying a phase coefficient to the PMI when the PMI within the interpolation window is interpolated. In this case, the terminal may feed back to the base station together with the PMI interpolated with the phase coefficients.
- the terminal may feed back the channel state to the base station more accurately by performing interpolation with 3 * ⁇ 1 + ⁇ * 2 * ⁇ 2. If there are ⁇ ⁇ s that do not overlap in the interpolation window, the terminal transmits each phase coefficient value for N-1 to the base station. You can do interpolation in the same way by feedin. Additionally, the base station and the terminal may perform interpolation by obtaining a phase average of each PMI, instead of simply obtaining an average of the PMI sum. For example, if three PMI1 and two PMI2 exist in the interpolation window as shown in FIG.
- Equation 15 ph ⁇ avg (PMI ⁇ , PM1 ⁇ , PM1 ⁇ , PM12, ⁇ 2)-
- the interpolation result value maintains the ICM (Constant Modulus) characteristic (that is, the characteristic that the size of each element is set equally) in PMI.
- the terminal selects the PMI by comparing the interpolation result (correlation or Euclidean distance, etc.) of normalization using the nor () function of Equation 13 10 is another embodiment of the present invention, the bones described in Figures 1 to 9
- the terminal may operate as a transmitter in uplink and operate as a receiver in downlink.
- the base station may operate as a receiver in the uplink, and may operate as a transmitter in the downlink.
- the terminal and the base station may include transmission modules (Tx module: 1040, 1050) and reception modules (Rx module: 1050, 1070), respectively, to control transmission and reception of information, data, and / or messages.
- Tx module: 1040, 1050 transmission modules
- Rx module: 1050, 1070 reception modules
- Antennas 1000 and 1010 for transmitting and receiving information, data, and / or messages.
- the terminal and the base station may each include a processor 1020 and 1030 for performing the above-described embodiments of the present invention and a memory 1080 and 1090 for temporarily or continuously storing the processing of the processor. Can be.
- the terminal and the base station of FIG. 10 may further include one or more of an LTE module and a low power RF / Intermediate Frequency (IF) module for supporting the LTE system and the LTE-A system.
- IF Intermediate Frequency
- the transmission module and the reception module included in the mobile station and the base station include a packet modulation and demodulation function, a high speed packet null coding function, and an orthogonal frequency division for data transmission.
- Multiple Access Orthogonal Frequency Division Multiple Access (FDMA)) Packet scheduling, time division duplex (TDD) packet scheduling, and / or channel multiplexing.
- FDMA Orthogonal Frequency Division Multiple Access
- FIG. 10 is a means by which the methods described in FIGS. 1 to 9 can be implemented. Embodiments of the present invention can be performed using the components and functions of the above-described mobile terminal and base station apparatus.
- the processor of the terminal may perform PMI interpolation at the size of the interpolation window to determine an optimal PMI and feed it back to the base station.
- the interpolation window size for the PMI interpolation may be determined by the base station and informed to the terminal, or may be determined by determining the channel situation in the processor of the terminal.
- the processor of the terminal may interpolate the PMIs using the interpolation methods described with reference to FIGS. 6 to 9.
- the mobile terminal is a personal digital assistant (PDA), a cell phone, a personal communication service (PCS) phone, a GSM (Global System for Mobile) phone, a WCDMA (Wideband CDMA) phone, MBS (Mobile Broadband System) Phone, Hand-Held PC, Notebook PC, Smart A phone or a Multi Mode Multi Band (MM-MB) terminal may be used.
- PDA personal digital assistant
- PCS personal communication service
- GSM Global System for Mobile
- WCDMA Wideband CDMA
- MBS Mobile Broadband System
- Hand-Held PC Hand-Held PC
- notebook PC Smart A phone or a Multi Mode Multi Band (MM-MB) terminal may be used.
- MM-MB Multi Mode Multi Band
- a smart phone is a terminal that combines the advantages of a mobile communication terminal or a personal portable terminal, and means a terminal integrating data communication functions such as schedule management, fax transmission and internet access, which are functions of a personal portable terminal, in a mobile communication terminal. can do.
- a multimode multiband terminal is a multi-mode chip embedded in a portable Internet system and other mobile communication systems (for example, code division multiple access (CDMA) 2000 system, WCDMA (Wideband CDMA) system, etc.) A terminal that can all work.
- CDMA code division multiple access
- WCDMA Wideband CDMA
- Embodiments of the invention may be implemented through various means.
- embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.
- the method according to embodiments of the present invention may include one or more I ASICs (application specific integrated circuits), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic (PLDs). devices), FPGAs (field programmable gate ' arrays), processors, controllers, microcomputers It can be implemented by a controller, a microprocessor, or the like.
- I ASICs application specific integrated circuits
- DSPs digital signal processors
- DSPDs digital signal processing devices
- PLDs programmable logic
- FPGAs field programmable gate ' arrays
- processors controllers
- microcomputers It can be implemented by a controller, a microprocessor, or the like.
- the method according to the embodiments of the present invention may be implemented in the form of a module, procedure, or function that performs the functions or operations described above.
- software code may be stored in the memory units 1080 and 1090 and driven by the processors 1020 and 1030.
- the memory unit may be located inside or outside the processor, and may transmit and receive the processor off data by various known means.
- Embodiments of the present invention can be applied to various wireless access systems.
- variety Examples of wireless access systems include 3rd Generation Partnership Project (3GPP) LTE systems, 3GPP LTE-A systems, 3GPP2 and / or IEEE 802.xx (Institute of Electrical and Electronic Engineers 802) systems.
- Embodiments of the present invention can be applied not only to the various radio access systems, but also to all technical fields to which the various radio access systems are applied.
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Abstract
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KR1020137003183A KR101891114B1 (ko) | 2010-11-02 | 2011-11-02 | 보간을 이용한 프리코딩 행렬 지시자 피드백 방법 및 장치 |
US13/882,526 US9332528B2 (en) | 2010-11-02 | 2011-11-02 | Method and device for feeding back precoding matrix indicator using interpolation |
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US40951110P | 2010-11-02 | 2010-11-02 | |
US61/409,511 | 2010-11-02 | ||
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US201061427119P | 2010-12-24 | 2010-12-24 | |
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US61/427,479 | 2010-12-28 |
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CN103825677B (zh) * | 2014-02-28 | 2017-03-29 | 北京航空航天大学 | 一种骨干网容量受限时的多基站协作传输方法 |
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US9713126B2 (en) * | 2011-01-10 | 2017-07-18 | Nokia Solutions And Networks Oy | Dynamic transmission set indication |
US8797966B2 (en) | 2011-09-23 | 2014-08-05 | Ofinno Technologies, Llc | Channel state information transmission |
US8848673B2 (en) | 2011-12-19 | 2014-09-30 | Ofinno Technologies, Llc | Beam information exchange between base stations |
US9204317B2 (en) | 2012-05-11 | 2015-12-01 | Telefonaktiebolaget L M Ericsson (Publ) | Methods and arrangements for CSI reporting |
SG11201505013UA (en) * | 2012-12-27 | 2015-08-28 | Huawei Tech Co Ltd | Method for feeding back channel state information, user equipment, and base station |
CN103945555B (zh) * | 2013-01-21 | 2018-03-20 | 电信科学技术研究院 | 多点协作传输下的资源调度方法和设备 |
EP2913952A1 (en) * | 2014-02-28 | 2015-09-02 | Lantiq Israel Ltd. | Apparatus and methods for a dynamic transmission window |
US11303403B2 (en) * | 2014-08-05 | 2022-04-12 | Nokia Technologies Oy | Signaling arrangement for wireless system |
CN109302222B (zh) * | 2016-05-13 | 2019-11-19 | 华为技术有限公司 | 一种信道信息发送方法、数据发送方法和设备 |
CN108111197A (zh) * | 2016-11-25 | 2018-06-01 | 索尼公司 | 电子设备和通信方法 |
US12068989B2 (en) * | 2020-04-08 | 2024-08-20 | Apple Inc. | Signaling approaches for new radio in the unlicensed spectrum |
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US20130242921A1 (en) | 2013-09-19 |
KR101891114B1 (ko) | 2018-08-23 |
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