WO2012020862A1 - Terminal, station de base, et procédé correspondant dans un système de communication sans fil - Google Patents

Terminal, station de base, et procédé correspondant dans un système de communication sans fil Download PDF

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Publication number
WO2012020862A1
WO2012020862A1 PCT/KR2010/005315 KR2010005315W WO2012020862A1 WO 2012020862 A1 WO2012020862 A1 WO 2012020862A1 KR 2010005315 W KR2010005315 W KR 2010005315W WO 2012020862 A1 WO2012020862 A1 WO 2012020862A1
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Prior art keywords
channel quality
subband
cqi
quality information
channel
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PCT/KR2010/005315
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English (en)
Inventor
Jianjun Li
Kyoungmin Park
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Pantech Co.,Ltd.
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Priority to PCT/KR2010/005315 priority Critical patent/WO2012020862A1/fr
Publication of WO2012020862A1 publication Critical patent/WO2012020862A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0641—Differential feedback
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0632—Channel quality parameters, e.g. channel quality indicator [CQI]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection

Definitions

  • the present invention relates to precoding and feedback channel information in wireless communication system.
  • CL-MIMO Closed-loop MIMO
  • a method comprising: estimating a downlink channel from a received signal transmitting a first channel quality information on the estimated downlink channel which is an average of all subband CQIs(Channel quality indicators); and transmitting a second channel quality information reflecting the average channel quality of two or more selected subbands by a terminal.
  • a terminal comprising:an channel estimator configured to estimate a downlink channel from a received signal and transmit a first channel quality information on the estimated downlinkchannel which is an average of all subband CQIs(Channel quality indicators) and a second channel quality information reflecting the average channel quality of two or more selected subbands and a post-decoder configured to decode the received signal to recover the set of data symbols.
  • a method for the base station comprising: receiving a first channel quality information on the estimated downlink channel which is an average of all subband CQIs(Channel quality indicators) from the terminal; and receiving a second channel quality information reflecting the average channel quality of two or more selected subbands by a terminal.
  • the base station may receive the third channel quality informations which are the CQIs of the selected subbands from a terminal.
  • a base station comprising: comprising: a scheduler configured to receive a first channel quality information on the estimated downlink channel which is an average of all subband CQIs(Channel quality indicators) from the terminal and a second channel quality information reflecting the average channel quality of two or more selected subbands and sometimes the third channel quality informations which are the CQIs of the selected subbands by the terminal and schedule at least one subband to at least one terminal based on the first and the second channel quality information; and a precoder configured to transmit data symbol via the subband to the terminal.
  • FIG.1 is the functional flowchartof the wireless communication system using closed-loop spatial multiplexing according to one embodiment.
  • FIG. 2 illustrates a diagram of a frequency-time operating resource space 200 as may be employed by an OFDMA communications system.
  • FIG.3 is the block diagram of the wireless communication system using closed-loop spatial multiplexing according to the other embodiment.
  • FIG.4 is the flowchart of a method for feedbacking the channel information for the terminal according to other embodiment.
  • FIG.5 is the flowchart of a method for processing the channel information for the base station according to another embodiment.
  • FIG.1 is the functional flowchart of the wireless communication system using closed-loop spatial multiplexing according to one embodiment.
  • the communication system 100 may be any type of wireless communication system, including but not limited to a MIMO system, SDMA system, CDMA system, OFDMA system, OFDM system, etc.
  • the wireless communication system 100 using closed-loop spatial multiplexing comprises a transmitter 110 and a receiver 120.
  • the transmitter 110 may act as a base station or an eNode(eNB), while the receiver 120 may act as a subscriber station or an user equipment(UE), which can be virtually any type of wireless one-way or two-way communication device such as a cellular telephone, wireless equipped computer system, and wireless personal digital assistant.
  • UE user equipment
  • the receiver/subscriber station 120can also transmits signals which are received by the transmitter/base station 110.
  • the transmitter 110 may transmit a reference singal(RS) such as a channel state information reference signal(CSI-RS) to the receiver 120 at S130.
  • RS reference singal
  • CSI-RS channel state information reference signal
  • the receiver/mobile terminal 120 may report channel information such as a recommended number of layers(expressed as a Rank Indication, RI) or a recommended precoding matrix(Precoding Matrix Index, PMI) corresponding to that number of layers, depending on estimates of the downlink channel conditions at S140.
  • channel information such as a recommended number of layers(expressed as a Rank Indication, RI) or a recommended precoding matrix(Precoding Matrix Index, PMI) corresponding to that number of layers, depending on estimates of the downlink channel conditions at S140.
  • the quality of the signal received by the receiver 120 depends on the channel quality from the transmitter 110, the level of interference from other cells, and the noise level.
  • the transmitter 110 may try to match the information data rate for each user to the variations in received signal quality.
  • the receiver 120 may be configured to report Channel Quality Indicators(CQIs) to assist the transmitter 110 in selecting an appropriate Modulation and Coding Scheme(MCS) to use for the downlink transmission at S150.
  • CQI reports are derived from the reference signal.
  • the transmitter 110 may transmit a transmission signal to the receiver 120 at S160.
  • the transmission signal communicated between the transmitter 110 and the receiver 120 may include voice, data, electronic mail, video, and other data, voice, and video signals.
  • the transmitter 110 transmits a signal data stream through one or more antennas and over a channel to the receiver 120.
  • the receiver may combine the received signal from one or more receive antennas to reconstruct the transmitted data.
  • the receiver 120 recovers the original data symbols.
  • FIG. 2 illustrates a diagram of a frequency-time operating resource space 200 as may be employed by an OFDMA communications system.
  • An operating bandwidth of the operating resource space 200 may be divided into L resource blocks(RB 1 -RB L ) wherein each of the N resource blocks may be defined as a set of adjacent subcarriers.
  • L resource blocks RB 1 -RB L
  • each of the N resource blocks may be defined as a set of adjacent subcarriers.
  • a 3GPP LTE system with 5 MHz bandwidth employs 25 RBs wherein each has a 180 kHz bandwidth for a total operating bandwidth of 4.5 MHz, with the remaining 0.5 MHz providing a guard band separating transmissions on two adjacent bands on different cells.
  • a subband of the operating bandwidth corresponds to a collection of one or more RBs.
  • One subband may be defined as the smallest unit for CQI reporting.
  • the RBs may also be concatenated to form larger ones thereby fundamentally reducing the CQI reporting overhead and the control channel overhead in the downlink that signals their allocated RBs to the receivers that have been scheduled.
  • the receiver 120 may compute the CQI for each subband.
  • Some examples of CQI are SINR, recommended or supportable spectral efficiency, recommended or supportable modulation-and-coding-scheme(MCS), received signal strength and mutual information. Since the CQI is typically quantized or discrete, a set of possible CQI values is predefined along with the respective index of each.
  • a resource block is defined as a set of adjacent subcarriers(tones).
  • it may be defineda subband as the smallest entity for CQI report where one subband consists of k contiguous Resource Blocks(RBs).
  • the system bandwidth contains N subbands where Nis approximately or exactly L/k.
  • a 3GPP E-UTRA system with 10 MHz bandwidth has 50 RBs, each having 180 kHz.
  • the receiver 120 may compute the CQI for each of the N subbands. This is defined for each spatial stream or codeword.
  • the CQI is defined in terms of a suggested or recommended data rate or spectral efficiency where the CQI may be a suggested transport block size(TBS) or modulation-and-coding scheme(MCS).
  • TBS transport block size
  • MCS modulation-and-coding scheme
  • a simple method by which the receiver 120 may choose an appropriate CQI value may be based on a set of Block Error Rate(BLER) thresholds.
  • the receiver 120 may report the CQI value corresponding to the MCS that ensures BLER ⁇ 10 -1 based on the measured received signal quality.
  • AMC can exploit the receiver feedback by assuming that the channel fading is sufficiently slow. This requires the channel coherence time to be at least as long as the time between the receiver's measurement of the downlink reference signals and the subframe containing the correspondingly-adapted downlink transmission on the PDSCH. This time may be typically 7-8ms(equivalent to a UE speed of -10Km/h at 1.9GHz).
  • the periodicity and frequency resolution to be used by the receiver/mobile terminal 120 to report the CQI are both controlled by the transmitter/base station 110. In the time domain, both periodic and aperiodic CQI reporting are supported.
  • the PUCCH is used for periodic CQI reporting only.
  • the PUSCH is used for aperiodic reporting of the CQI, whereby the transmitter 110 specifically instructs the receiver 120 to send an individual CQI report embedded into a resource which is scheduled for uplink data transmission.
  • the frequency granularity of the CQI reporting is determined by defining a number of subbands(N), each comprised of k contiguous Resource Blocks(RBs). The value of k depends on the type of CQI report considered.
  • the CQI reporting modes can be many kinds of CQI as explained indetail in the following.
  • CQI value(s) may be reported for two or more codewords.
  • FIG.3 is the block diagram of the wireless communication system using closed-loop spatial multiplexing according to the other embodiment.
  • the wireless communication system 300 using closed-loop spatial multiplexing comprises a transmitter 310 and a receiver 320.
  • the transmitter 310 comprises a precoder 312 and a scheduler 314.
  • the precoder 312 may linearly combine and map a set of N L symbols(one symbol from each layer) to the N A antenna port by after layer mapping by the layer mapper.
  • the precoder 312 may comprise two precoders to optimize the performance.
  • the first precoder may precode a set of symbols from the layer mapper by means of a precoding matrix R of size N L ⁇ N L.
  • the second precoder may also precode a set of symybols from the first precoder by means of a precoding matrix W of size N L ⁇ N A .
  • the transmitter 310 transmitsthe precoded data symbols by different antennas.
  • separate codebooks of the transmitter 310 and the receiver 320 may be stored.
  • separate indices may be generated wherein each index points to a codeword in its corresponding codebook, and each of these indices may be transmitted over a feedback channel to the transmitter 310, so that the transmitter 310 may use these indices to access the corresponding codewords from the corresponding codebooks and determine a transmission profile or precoding information.
  • the scheduler 314 may receive the channel information such as the PMIs and the CQIs.
  • the receiver 320 may comprise a channel estimator 322 and a post-decoder 324.
  • the channel estimator 322 of the receiver 320 estimates the downlink channel condition.
  • the channel estimator 322 feedbacks the PMI as the channel information to the transmitter 320.
  • the channel estimator 322 may perform many kinds of codebook based PMI feedback where the receiver/mobile terminal 320 feedbacksthe precoding matrix indicator(PMI) of the favorite matrix in the codebook to the transmitter/base station 310 to support CL-MIMO(closed MIMO) operation in wireless communication system.
  • the channel estimator 322 feedbacks the CQI as the channel information to the transmitter 310.
  • the channel estimator 322 may perform many kinds of CQI feedback.
  • the channel estimator 322 may comprise a PMI calculator 322a for many kinds of codebook based PMI feedback and a CQI calculator 322b for many kinds of CQI feedback.
  • the PMI calculator 322a may selects the precoding matrix for each level from the corresponding codebooks. Once the precoding matrix for each level is decided, the PMI calculator 322a separately feedback the PMIs of multilevel, for example, both level to the transmitter 310.
  • the CQI calculator 322b may calculate many kinds of CQI such as a first channel quality information on the estimated downlink channel(the wideband CQI), second channel quality information(average M selected subband CQI) and a third channel quality information (subband CQI) for the selected PMI.
  • the type of CQI report may be configured by the transmitter 310 by RRC signaling.
  • the CQI calculator 322b may report one wideband CQI value for the whole system bandwidth.
  • the CQI calculator 322b may feedback the corresponding wideband CQI to the transmitter 310 by PUCCH, which is periodical feedback.
  • the wideband CQI may be by fully 4bits feedback, but not limited thereto.
  • the type of periodic reporting is configured by the transmitter 310 by RRC signaling.
  • the period may be configured to ⁇ 2, 5, 10, 16, 20, 32, 40, 64, 80, 160 ⁇ ms or off.
  • the wideband CQI are basic feedback which have the hightest priority.
  • the CQI calculator 324b may check whether the M selected subband CQI needs to be fedback or not.
  • the CQI calculator 324b may select a set of M selected subbands of size k(where k and M are given for each system bandwidth range) within the whole system bandwidth.
  • the CQI calculator 324b may report not only one wideband CQI value but also one CQI value reflecting the average channel quality of the M selected subbands.
  • the average M selected subband CQI, CQI best-M is the average CQI of the M selected subbands or an average of the selected subband CQIs.
  • a "argmax" stands for the argument of the maximum, that is to say, the set of points of the given argument for which the value of the given expression attains its maximum value. In other words, a argmax stands for the index of CQI which the value is maximum.
  • CQI best-M ⁇ CQI wideband in case the CQI is computed based on, for example, SINR.
  • the average M selected subband CQI may be the average of the selected subband CQIs in itself.
  • the CQI calculator 324b may feedback the differential M selected subband CQI, CQI diff,best-M , which is the differential value between the wideband CQI and the average M selected subband CQI.
  • the differential M selected subband CQI, CQI diff,best-M may greatly reduce the feedback overhead.
  • Possible differential CQI values may be ⁇ +1,+2,+3, ⁇ +4 ⁇ .
  • the type of aperiodic reporting is configured by the transmitter 310 by RRC signaling.
  • Aperiodic CQI reporting on the PUSCH is scheduled by the transmitter 310 by setting a CQI request bit in an uplink resource grant sent on the PDCCH.
  • the CQI calculator 324b may also report the positions of the M selected subbands using a combinationatorial index r defined, but not limited therein.
  • N is the total number of subbands and M is the index of each of the selected subbands.
  • the average M selected subband CQI is enough for CL-MIMO operation for the better performance.
  • it may feedback a third channel quality information reflecting a subband CQI for each of one subband which has extreme higher CQI than the average M selected subband CQI.
  • the third channel quality information may be reflecta subband CQI for at least one subband which has extreme lower CQI than the average M selected subband CQI. Therefore the third channel quality information may be reflect either the subband which has extreme higher CQI than the average M selected subband CQIs or the subband which has extreme lower CQI than the average M selected subband CQIs or combination thereof.
  • the CQI calculator 314b may feedback the differential subband CQI, CQI diff,subband ,which is the differential value between the average M selected subband CQIs and the subband CQI.
  • the subband CQI reports are encoded differentially with respect to the average of the M selected subbands using 2-bits defined by Subband differential CQI offset which is difference between “subband CQI index” and “Index for average of M selected subbands”.
  • Possible differential subband CQI offsets may be ⁇ -1, 0, +1, ⁇ +2 ⁇ .
  • subband CQI may be the subband CQI for at least one of the selected subbands in itself.
  • the CQI calculator 314b may also report the positions of either the subband which has extreme higher CQI than the average M selected subband CQIs or the subband which has extreme lower CQI than the average M selected subband CQIs or combination thereof using a combinationatorial index r as defined above.
  • the CQI calculator 314b may also feedback the subband CQI by PUSCH which is aperiodical feedback.
  • the subband CQI is by 2-bits differential feedback.
  • the type of aperiodic reporting is configured by the transmitter 310 by RRC signaling.
  • Aperiodic CQI reporting on the PUSCH is scheduled by the transmitter 310 by setting a CQI request bit in an uplink resource grant sent on the PDCCH.
  • the receiver 320 may transmit the CQI reports using the PUCCH(Physical Uplink Control Channel).
  • one of the first, the second and the third channel quality information is possible for either periodicor aperiodic CQI reporting using the PUCCH or the PUSCH.
  • the receiver 320 recovers the original data symbols by post-decoder 314with the previous feedback precoding matrices combination.
  • the post-decoder 314 processes the received signal and decodes the precoded symbols.
  • the transmitter 310 may know the CQI of subbands in high accuracy to do the scheduling.
  • the scheduler 314 may allocate at least one subband or RB in high accuracy to the receiver.
  • the transmitter 310 may transmit the data symbols to this receiver 320 with the MCS level by CQI feedback and precoded the data symbols based on the receiver's PMI feedback.
  • the scheduler 314 is configured to schedule at least one subband or RB to at least one terminal based on the channel information such as the PMIs and the CQIs.
  • the precoder 312 is configured to transmit data symbol via the subband to the terminal.
  • FIG.4 is the flowchart of a method for feedbacking the channel informationfor the terminal according to other embodiment.
  • the terminal may estimate a downlink channel from a received signal at S410.
  • the terminal may transmit a downlink precoding matrix indicators(PMIs) of the favorite matrix in the codebook based on the estimated downlink channel as the channel information to the base station at S420.
  • the terminal separately feedback the PMIs of multilevel, for example, both level to the base station.
  • the terminal may transmit a first channel quality information on the estimated downlink channel which is an average of all subband CQIs(Channel quality indicators) at S425.
  • a channel quality of the subband CQI is a channel quality when the downlink signal is precoded by the downlink precoding matrix.
  • the wideband CQI, CQI wideband may be got by the Equation 1.
  • the type of periodic reporting is configured by the base station by RRC signaling.
  • the period may be configured to ⁇ 2, 5, 10, 16, 20, 32, 40, 64, 80, 160 ⁇ ms or off.
  • the PMIs feedback and the wideband CQI are basic feedback which have the hightest priority.
  • the terminal may check whether the M selected subband CQI needs to be fed back or not at S430.
  • the terminal may transmit a second channel quality information reflecting the average channel quality of the M selected subbands by the terminal. For example, the terminal may feedback the differential M selected subband CQIbetween the wideband CQI and the average M selected subband CQI at S450. In usual case, the average M selected subband CQI is enough for CL-MIMO operation for best-M feedback.
  • the terminal may select a set of the M selected subbands of size k(where k contiguous Resource Blocks(RBs) and M are given for each system bandwidth range) within the whole system bandwidth, then calculate the average M selected subband CQI, CQI best-M, by means of the equation 2, and then the differential M selected subband CQI, CQI diff,best-M ,by means of the equation 3.
  • the differential M selected subband CQI is encoded differentially using 2-bits relative to its respective wideband CQI by PUSCH(Physical Uplink Shared Channel) which is aperiodical feedback.
  • PUSCH Physical Uplink Shared Channel
  • the average M selected subband CQI may be the average of the selected subband CQIs in itself.
  • the terminal may also report the positions of the M selected subbands using a combinationatorial index r as defined at equation 4.
  • the terminal may feedback a third channel quality information reflecting a subband CQI for either the subband which has extreme higher CQI than the average M selected subband CQI or the subband which has extreme lower CQI than the average M selected subband CQI or combination thereof.
  • the terminal may check whether the subband CQI needs to be fedback or not at S450.
  • the terminal may transmit a third channel quality information reflecting either the subband which has extreme higher CQI than the average M selected subband CQI or the subband which has extreme lower CQI than the average M selected subband CQI or combination thereof.
  • subband CQI may be the subband CQI for at least one of the selected subbands in itself.
  • the terminal may also report the positions of either the subband which has extreme higher CQI than the average M selected subband CQI or the subband which has extreme lower CQI than the average M selected subband CQI or combination thereof using a combinationatorial index r as defined above.
  • the differential subband CQI is encoded differentially using 2bits relative to its respective wideband CQI by PUSCH which is aperiodical feedback.
  • Aperiodic CQI reporting on the PUSCH is scheduled by the transmitter 310 by setting a CQI request bit in an uplink resource grant sent on the PDCCH.
  • the base station may know the CQI of subbands in high accuracy to do the scheduling.
  • the base station may allocate at least one subband in high accuracy to the terminal.
  • the base station may transmit the data symbols of this terminal with the MCS level by CQI feedback and precoded the data symbols based on the terminal's PMI feedback.
  • the receiver 320 may transmit the CQI reports using the PUCCH(Physical Uplink Control Channel).
  • One of the first, the second and the third channel quality information is possible for either periodicor aperiodic CQI reporting using the PUCCH or the PUSCH.
  • FIG.5 is the flowchart of a method for processing the channel information for the base station according to another embodiment.
  • the base station may receive a downlink precoding matrix indicators(PMIs) of the favorite matrix in the codebook based on the estimated downlink channel as the channel information to the base station at S520.
  • the base station may separately receivethe PMIs of multilevel, for example, both level from the base station.
  • the base station may receive a first channel quality information on the estimated downlinkchannel which is an average of all subband CQIs(Channel quality indicators) at S525.
  • a channel quality of the subband CQI is a channel quality when the downlink signal is precoded by the downlink precoding matrix.
  • the wideband CQI, CQI wideband may be got by the Equation 1.
  • the type of periodic reporting is configured by the transmitter 310 by RRC signaling.
  • the period may be configured to ⁇ 2, 5, 10, 16, 20, 32, 40, 64, 80, 160 ⁇ ms or off, but not limited to them, may be configured to any required value.
  • the base station may receive a second channel quality information reflecting the average channel quality of the M selected subbands by the terminal.
  • the base station may receive the differential M selected subband CQI between the wideband CQI and the average M selected subband CQI at S550.
  • the differential M selected subband CQI is encoded differentially using 2-bits relative to its respective wideband CQI by PUSCH which is aperiodical feedback.
  • the base station may know the average M selected subband CQI by means of the received differential M selected subband CQI minus the received wideband CQI at S525.
  • the base station may also receive an information on the positions of the M selected subbands.
  • the base station may know the positions of the M selected subbands using a combinationatorial index r as defined at equation 4.
  • the base station may receive a third channel quality information reflecting either the subband which has extreme higher CQI than the average M selected subband CQI or the subband which has extreme lower CQI than the average M selected subband CQI or combination thereof.
  • the base station may receive the differential subband CQI, CQI diff,subband , between the average M selected subband CQI and the subband CQI for better performance as defined at equation 4 at S560.
  • the base station may know the subband CQI by means of the differential subband CQI plus the average M selected subband CQI at S560.
  • the differential subband CQI may be encoded differentially using, but not limited, 2-bits relative to its respective wideband CQI by PUSCH which is aperiodical feedback.
  • Aperiodic CQI reporting on the PUSCH is scheduled by the transmitter 310 by setting a CQI request bit in an uplink resource grant sent on the PDCCH.
  • the base station may also receive an information on the positions of the subband which has extreme higher or lower CQI than the average M selected subband CQI.
  • the base station may know the positions of the subband using a combinationatorial index r as defined at equation 4.
  • the base station may know the CQI of subbands in high accuracy to do the scheduling.
  • the base station may schedule at least one subband in high accuracy to the terminal.
  • the base station may transmit the data symbols of this terminal with the MCS level by CQI feedback and precoded the data symbols based on the terminal's PMI feedback.
  • the following table shows comparison of the number of indices between the multilevel differential CQI feedback and the single differential CQI feedback CQI.
  • the single differential CQI is the differential value between the wideband CQI and the subband CQI for each of the M selected subbabds.
  • both the wideband CQI and the subband CQI are fed back from the terminal by PDCCH and PUSCH respectively.
  • the wideband CQI is by fully 4-bits feed back while subband CQI is by 2-bits differential feedback.
  • the differential value of subband CQI can be plus and minus. So 2-bits differential is too coarse for subband CQI.
  • the above embodiments propose the multilevel differential CQI feedback which includes the three types of CQIs such as the wideband CQI, the average M selected subband CQIand the subband CQI.
  • the wideband CQI may be by fully 4bits feedback, while the average M selected subband CQI and the subband CQI may be by 2bits differential feedback.
  • the accuracy of the final subband CQI feedback is greatly improved according to the multilevel differential CQI feedback.
  • the multilevel differential CQI feedback improves the accuracy of the final subband CQI feedback using the three types of CQIs such as the wideband CQI and the subband CQI as well as the average M selected subband CQI.
  • the methods and systems as shown and described herein may be implemented in software stored on a computer-readable medium and executed as a computer program on a general purpose or special purpose computer to perform certain tasks.
  • the elements used to perform various signal processing steps at the transmitter(e.g., coding and modulating the data, precoding the modulated signals, preconditioning the precoded signals, and so on) and/or at the receiver(e.g., recovering the transmitted signals, demodulating and decoding the recovered signals, and so on) may be implemented within one or more application specific integrated circuits(ASICs), digital signal processors(DSPs), digital signal processing devices (DSPDs), programmable logic devices(PLDs), field programmable gate arrays(FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof.
  • ASICs application specific integrated circuits
  • DSPs digital signal processors
  • DSPDs digital signal processing devices
  • PLDs programmable logic devices
  • a software implementation may be used, whereby some or all of the signal processing steps at each of the transmitter and receiver may be implemented with modules(e.g., procedures, functions, and so on) that perform the functions described herein. It will be appreciated that the separation of functionality into modules is for illustrative purposes, and alternative embodiments may merge the functionality of multiple software modules into a single module or may impose an alternate decomposition of functionality of modules.
  • the software code may be executed by a processor or controller, with the code and any underlying or processed data being stored in any machine-readable or computer-readable storage medium, such as an on-board or external memory unit.

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

Abstract

La présente invention se rapporte au précodage et au renvoi par rétroaction d'informations de voie dans un système de communication sans fil.
PCT/KR2010/005315 2010-08-12 2010-08-12 Terminal, station de base, et procédé correspondant dans un système de communication sans fil WO2012020862A1 (fr)

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US20200059282A1 (en) * 2017-05-05 2020-02-20 Qualcomm Incorporated Procedures for differential channel state information (csi) reporting

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US20090168718A1 (en) * 2008-01-02 2009-07-02 Interdigital Patent Holdings, Inc. Configuration for cqi reporting in lte

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20200059282A1 (en) * 2017-05-05 2020-02-20 Qualcomm Incorporated Procedures for differential channel state information (csi) reporting
EP3619848A4 (fr) * 2017-05-05 2020-12-23 QUALCOMM Incorporated Procédures de rapport d'informations d'état de canal (csi) différentielles

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