WO2012063980A1 - 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
WO2012063980A1
WO2012063980A1 PCT/KR2010/007853 KR2010007853W WO2012063980A1 WO 2012063980 A1 WO2012063980 A1 WO 2012063980A1 KR 2010007853 W KR2010007853 W KR 2010007853W WO 2012063980 A1 WO2012063980 A1 WO 2012063980A1
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Prior art keywords
matrix
mimo
precoder
channel
mod16
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PCT/KR2010/007853
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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/KR2010/007853 priority Critical patent/WO2012063980A1/fr
Publication of WO2012063980A1 publication Critical patent/WO2012063980A1/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
    • H04B7/0413—MIMO systems
    • H04B7/0417—Feedback systems
    • 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
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03343—Arrangements at the transmitter end
    • 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
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03426—Arrangements for removing intersymbol interference characterised by the type of transmission transmission using multiple-input and multiple-output channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/03777—Arrangements for removing intersymbol interference characterised by the signalling
    • H04L2025/03802—Signalling on the reverse channel
    • H04L2025/03808—Transmission of equaliser coefficients
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0001—Arrangements for dividing the transmission path
    • H04L5/0014—Three-dimensional division
    • H04L5/0023—Time-frequency-space
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H04L5/0055—Physical resource allocation for ACK/NACK

Definitions

  • the present invention relates to precoding and feedback channel information in wireless communication system.
  • CL-MIMO Closed-loop MIMO
  • a method of one of at least two of terminals in a wireless communications system that supports multi-user multiple-input multiple-output(MU-MIMO) communications between a base station and the terminals.
  • the method may comprise: transmitting, to the base station, a second channel quality information for the MU-MIMO communications when its own data signal is precoded by using the first precoder matrix and the second procoder matrix, and the data signal of the other terminal precoded by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix.
  • a terminals in a wireless communications system that supports multi-user multiple-input multiple-output(MU-MIMO) communications between a base station and the terminals.
  • the terminal may comprise a post decoder configured to recover a signal from the base station; and a channel estimator configured to estimate a downlink channel from a received signal from the base station, transmit a first channel state information of a first precoder matrix which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix, the Nb is adjacent overlapping beams and the 0 is 4x4 zero matrix and a second channel state information of a second procoder matrix which selects one of adjacent overlapping beams, a first channel quality information of its own channel quality on the estimated downlink channel with the SU-MIMO PMIs of two stage precoding when its own data signal is precoded by using the first precoder matrix and the second procoder matrix and a second channel quality information for the MU-MIMO communications when its own data signal
  • a method for the base station in a wireless communications system that supports multi-user multiple-input multiple-output(MU-MIMO) communications between a base station and the terminals, comprising: receiving a first channel quality information of its own channel quality on the estimated downlink channel from one of the terminals; and receiving a second channel quality information for the MU-MIMO communications when its own data signal is precoded by using a first precoder matrix which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix, the Nb is adjacent overlapping beams and the 0 is 4x4 zero matrix and a second channel state information of a second procoder matrix which selects one of adjacent overlapping beams, and the data signal of the other terminal precoded by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix from one of the terminals.
  • a first precoder matrix which is [X 0;0 X] block diagonal where
  • a base station comprising: a scheduler configured to receive a first channel quality information of its own channel quality on the estimated downlink channel from one of the terminals and a second channel quality information for the MU-MIMO communications when its own data signal is precoded by using a first precoder matrix which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix, the Nb is adjacent overlapping beams and the 0 is 4x4 zero matrix and a second channel state information of a second procoder matrix which selects one of adjacent overlapping beams, and the data signal of the other terminal precoded by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix from one of the terminals; and a precoder configured to transmit data symbol to the terminal.
  • a first precoder matrix which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix, the Nb is adjacent overlapping beams
  • FIG.1 is the functional flowchart of 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 DFT beam based PMI paring table generation algorithm.
  • FIG.5 is the flowchart of a method for feedbacking the channel information for the terminal according to other embodiment.
  • FIG.6 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 120 can 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.
  • the receiver 120 selects the precoding matrix from the codebook which has the best performance in the codebook based on the estimated channel state information (CSI).
  • CSI channel state information
  • 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 or feedbacks are derived from the reference signal.
  • MU-MIMO Multiple User Multiple Input Multiple Output
  • CQI CQI feedback for MU-MIMO.
  • a MU-MIMO CQI in addition to a SU-MIMO CQI is also fed back which is calculated based on the MU-MIMO PMI pairing table.
  • the receiver 120 may estimate and transmit a first channel quality information of its own channel quality on the estimated downlink channel with the SU-MIMO PMIs of two stage precoding when its own data signal is precoded by using the first precoder matrix and the second procoder matrix.
  • the receiver 120 may estimate and transmit a second channel quality information for the MU-MIMO communications when its own data signal is precoded by using the first precoder matrix and the second procoder matrix and the data signal of the other terminal is precoded by using orthogonal precoder matrices with the dual stage precoder.
  • the interference among different layers in MIMO is simply taken into account for this CQI. Then the receiver 120 feedbacks the index of the selected precoding matrix and the CQIs to the transmitter 110.
  • These channel quality information reporting may be scheduled by the transmitter/base station 110.
  • 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 transmitter 110 Based on the PMIs and CQIs feedback from each receiver 120, the transmitter 110 performs MU-MIMO scheduling.
  • the transmitter 110 selects at least two receivers 120 to pair them together with orthogonal PMIs. Then the transmitter 120 transmits the data symbols to at least two receivers which are precoded by the precoding matrix.
  • the transmitter 110 may decided the MCS level for each receiver 120 by the MU-MIMO CQI feedback.
  • each receiver 120 estimates the precoded channel by DM-RS. Then each receiver 120 recovers the original data symbols by post decoder with the precoded channel information.
  • 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 defined a 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 N is 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 is 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 in detail 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 communications system may support multi-user multiple-input multiple-output(MU-MIMO) communications between a transmitter 310 and the receivers 320.
  • 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 stage precoders to optimize the performance.
  • the first precoder may precode a set of symbols from the layer mapper by means of a precoding matrix W 1 .
  • the second precoder may also precode a set of symybols from the first precoder by means of a precoding matrix W 2 .
  • These two precodings may be individually performed by each of two precoding matrices or jointly performed by both of two precoding matrices.
  • the transmitter 310 transmits the 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 scheduler 314 selects the receivers to be transmitted on each RB along with corresponding modulation and coding schemes. Modulation and coding is provided for the different receivers, and a resulting signal is then summed up and transmitted on a downlink channel to a plurality of the receivers, for example, the receiver 320.
  • 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 feedbacks the 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 wideband codebook C1 is not unitary which consist of DFT beams.
  • the subband codebook C2 is vectors for beam selection and co-phasing.
  • the final precoding matrix when harmonized C1 and C2 is DFT beams with extension by different co-phasing.
  • the receiver 320 may report several DFT beams in frequency-selective manner via PMI1.
  • PMI1 reports bundles of DFT beams which would be a neighboring beams.
  • the first precoder matrix which is [X 0;0 X] block diagonal as follows.
  • the X is 4xNb matrix
  • the Nb is adjacent overlapping beams(the subset W1)
  • the 0 is 4x4 zero matrix.
  • beam index is 0,1,2, ...,31.
  • W1 matrices per rank There are sixteen W1 matrices per rank: ⁇ 0,1,2,3 ⁇ , ⁇ 2,3,4,5 ⁇ , ⁇ 4,5,6,7 ⁇ , ..., ⁇ 28,29,30,31 ⁇ , ⁇ 30,31,0,1 ⁇ .
  • the second procoder matrix may select one of adjacent overlapping beams and perform a co-phasing.
  • PMI2 reports which beam belongs to the subset W1 should be used in each subband and how to perform phase adaptation between co-polarized domains.
  • W2 matrices which is four elements by four 4x1 selection vectors.
  • the CQI calculator 322b may calculate many kinds of CQI.
  • the CQI calculator 322b may estimate a first channel quality information of its own channel quality on the estimated downlink channel with the SU-MIMO PMIs of two stage precoding when the receiver 320 precodes its own data signal by using the first precoder matrix W 1 and the second procoder matrix W 2 .
  • the CQI calculator 322b may estimate a second channel quality information for the MU-MIMO communications when the receiver 320 precodes its own data signal by using the first precoder matrix W 1 and the second procoder matrix W 2 and the other terminal precodes its own data signal by using two precoder matrices with the dual stage precoder.
  • the received signal Y can be express as follows.
  • j 1,...,N and are the channel for the paired receivers.
  • n is the noise plus intercell interference at the receiver side.
  • the receiver i can get its date symbols as follows.
  • the received signal at the receiver 1 may be express as follows.
  • the post SU-MIMO and MU-MIMO CQI at the receiver 1 can be expressed as follows.
  • C 1 is the precoding matrix for the receiver 1 and C 2 is the precoding matrix for the receiver 2.
  • the receiver 1 should exactly know the PMI of the receiver 2. However, it is impossible for the receiver 1 to exactly know the PMI or the precoding matrix C 2 of the receiver 2 . So the receiver 1 may only predict the MU-MIMO CQI from the companion PMI set which are orthogonal to the C 1 .
  • the receiver 1 precodes its own data signal by using the first precoder matrix w 1 which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix and the Nb is adjacent overlapping beams and the 0 is 4x4 zero matrix and the second procoder matrix W 2 which selects one of adjacent overlapping beams, it’s better to select two precoder matrices with the dual stage precoder of the other receiver each of which has the orthogonal beams for the first precoding matrix w 1 and the orthogonal co-phasing matrix for the second procoding matrix W 2 .
  • Fig.4 is the flowchart of DFT beam based PMI paring table generation algorithm.
  • the selected beam from the first and the second procoder matrices of SU-MIMO PMIs may be gotten at S462.
  • the terminal may pick one SU-MIMO PMI set with one for W1 from its own codebook C1 and one for W2 from its own codebook C2.
  • the PMI calculator may select the first PMI of C1 and the second PMI of C2.
  • the first precoder matrix W1 is [X 0;0 X] block diagonal wherein the X is 4xNb matrix and the Nb is adjacent overlapping beams and the 0 is 4x4 zero matrix.
  • the second procoder matrix W2 selects one of adjacent overlapping beams.
  • the final precoding vector is gotten by combining W1 and W2 together and the DFT beam V1 is found in the final precoding vector.
  • the adjacent overlapping beams consisting of the first precoder matrix W1 are b4, b5, b6, b7 and the second precoder matrix W2 selects one beam b4 of them.
  • the final DFT beam V1 is b4 in the above example.
  • the pair PMIs for MU-MIMO CQI calculation are ⁇ (i 1 +4)mod16,(i 2 +8)mod16 ⁇ , ⁇ (i 1 +8)mod16, (i 2 +8)mod16 ⁇ and ⁇ (i 1 +12)mod16, (i 2 +8)mod16 ⁇ .
  • C 2 from the three paired PMIs may be used at the above MU-MIMO CQI equation.
  • the CQI calculator 322b may calculate the MU-MIMO CQI based on the pairing table generated by the above algorithm, and feedback the MU-MIMO CQI to the transmitter 310 along with the PMIs and SU-MIMO CQI.
  • the type of MU-MIMO CQI reporting is configured by the transmitter 310 by RRC signaling.
  • the MU-MIMO 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.
  • one of the MU-MIMO channel quality information is possible for either periodic or aperiodic CQI reporting using the PUCCH or the PUSCH.
  • the scheduler 314 may receive the channel information such as the PMIs and the CQIs.
  • the scheduler 314 selects the receivers to be transmitted on each RB along with corresponding modulation and coding schemes. Modulation and coding is provided for the different receivers, and a resulting signal is then summed up and transmitted on a downlink channel to a plurality of the receivers, for example, the receiver 320.
  • the transmitter 310 Based on the PMIs and CQIs feedback from each receiver 320, the transmitter 310 performs MU-MIMO scheduling.
  • the transmitter 310 may select at least two receivers 320 to pair them together with orthogonal PMIs. Then the transmitter 320 transmits the data symbols to at least two receivers which are precoded by the precoding matrix. In this case, when the MIMO operation in the MU-MIMO mode, the transmitter 310 may decide the MCS level for each receiver 320 by the MU-MIMO CQI feedback.
  • the transmitter 310 transmits the data symbols of the terminals which are precoded by the precoding matrix.
  • each receiver 320 estimates the precoded channel by DM-RS. Then each receiver 320 may recover the original data symbols by a post decoder with the precoded channel information.
  • the receiver 320 recovers the original data symbols by post-decoder 314 with the previous feedback precoding matrices combination.
  • the post-decoder 314
  • 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.
  • the scheduler 314 is configured to determine one of SU-MIMO mode or MU-MIMO mode and select at least one of the receiver based on the PMIs and CQIs report from each receiver. In detail, the scheduler 314 is configured to determine MU-MIMO mode if the SU-MIMO CQIs and the MU-MIMO CQIs are the larger enough to perform the MU-MIMO mode. Otherwise the scheduler 314 is configured to determine SU-MIMO mode.
  • the precoder 312 precodes the data signal of one receiver by using the first precoder matrix which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix and the Nb is adjacent overlapping beams and the 0 is 4x4 zero matrix and the second procoder matrix which selects one of adjacent overlapping beams.
  • the precoder 312 precodes the data signal of the co-scheduled other terminal by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix based on the pairing table of table 1.
  • FIG.5 is the flowchart of a method for feedbacking the channel information for 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 wideband codebook C1 is not unitary which consist of DFT beams.
  • the subband codebook C2 is vectors for beam selection and co-phasing.
  • the final precoding matrix when harmonized C1 and C2 is DFT beams with extension by different co-phasing.
  • the first precoder matrix W1 is [X 0;0 X] block diagonal wherein the X is 4xNb matrix, the Nb is adjacent overlapping beams(the subset W1) and the 0 is 4x4 zero matrix.
  • W1 matrices per rank There are sixteen W1 matrices per rank: ⁇ 0,1,2,3 ⁇ , ⁇ 2,3,4,5 ⁇ , ⁇ 4,5,6,7 ⁇ , ..., ⁇ 28,29,30,31 ⁇ , ⁇ 30,31,0,1 ⁇ .
  • the second procoder matrix may select one of adjacent overlapping beams and perform a co-phasing.
  • the second PMI2 reports which beam belongs to the subset W1 should be used in each subband and how to perform phase adaptation between co-polarized domains.
  • W2 matrices which is four elements by four 4x1 selection vectors.
  • the adjacent overlapping beams consisting of the first precoder matrix W1 are b4, b5, b6, b7 and the second precoder matrix W2 selects one beam b4 of them.
  • the final DFT beam V1 is b4 in the above example.
  • the terminal is configured to precode a set of symbols from the layer mapper by means of the result of these two precoding matrices with the dual stage precoder.
  • the terminal may transmit a first channel quality information on the estimated downlink channel which is a SU-MIMO CQI(Channel quality indicator) at S425.
  • a SU-MIMO CQI(Channel quality indicator) is a channel quality when the downlink signal is precoded by the downlink precoding matrix.
  • the terminal may transmit a second channel quality information for the MU-MIMO communications when the terminal precodes its own data signal by using the first precoder matrix which is [X 0;0 X] block diagonal and the second procoder matrix which selects one of adjacent overlapping beams, and the other terminal precodes its own data signal by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix at S460.
  • the first precoder matrix which is [X 0;0 X] block diagonal and the second procoder matrix which selects one of adjacent overlapping beams
  • the other terminal precodes its own data signal by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix at S460.
  • the receiver In order to calculate the MU-MIMO CQI, the receiver should exactly know the PMI of another receiver. So the receiver may only predict the MU-MIMO CQI from the companion PMI set which are orthogonal to the C 1 .
  • the DFT beams involved in the paring PMI sets may be orthogonal to each other and the W2 co-phasing PMIs may be also orthogonal to each other.
  • the pair PMIs for MU-MIMO CQI calculation are ⁇ (i 1 +4)mod16, (i 2 +8)mod16 ⁇ , ⁇ (i 1 +8)mod16, (i 2 +8)mod16 ⁇ and ⁇ (i 1 +12)mod16, (i 2 +8)mod16 ⁇ .
  • Some of SU MIMO rank-1 PMIs W1/W2 and interfering rank-1 PMIs assumed for CQI calculation W1/W2(three paired PMIs) is referred to the table 1.
  • C 2 from the three paired PMIs may be used at the above MU-MIMO CQI equation.
  • the terminal may calculate the MU-MIMO CQI based on the pairing table generated by the above algorithm, and feedback the MU-MIMO CQI to the base station.
  • the second channel quality information MU-MIMO CQI may be possible for either periodic or aperiodic CQI reporting using the PUCCH or the PUSCH.
  • FIG.6 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 receive the PMIs of multilevel, for example, both level from the base station.
  • the first PMI1 is the index of the first precoder matrix W1 which is [X 0;0 X] block diagonal wherein the X is 4xNb matrix, the Nb is adjacent overlapping beams(the subset W1) and the 0 is 4x4 zero matrix.
  • W1 matrices per rank There are sixteen W1 matrices per rank: ⁇ 0,1,2,3 ⁇ , ⁇ 2,3,4,5 ⁇ , ⁇ 4,5,6,7 ⁇ , ..., ⁇ 28,29,30,31 ⁇ , ⁇ 30,31,0,1 ⁇ .
  • the first PMI1 is the index of the second procoder matrix which may select one of adjacent overlapping beams and perform a co-phasing.
  • W2 matrices which is four elements by four 4x1 selection vectors.
  • the base station may receive a first channel quality information on the estimated downlink channel which is a SU-MIMO CQI(Channel quality indicator) at S525
  • the base station may receive a second channel quality information for the MU-MIMO communications at S560.
  • the base station is configured to determine one of SU-MIMO mode or MU-MIMO mode and select at least one of the receiver based on the PMIs and CQIs report from each receiver at S570.
  • the base station is configured to determine MU-MIMO mode if the SU-MIMO CQIs and the MU-MIMO CQIs are the larger enough to perform the MU-MIMO mode. Otherwise the base station is configured to determine SU-MIMO mode.
  • the base station precodes the data signal of one the terminal by using the first precoder matrix and the second procoder matrix which selects one of adjacent overlapping beams.
  • the base station precodes the data signal o the co-scheduled other terminal by using two precoder matrices with the dual stage precoder each of which has the orthogonal beams and the orthogonal co-phasing matrix based on the pairing table of table 1.
  • the base station transmits the data symbols to at least two receivers which are precoded by the precoding matrix.
  • the base station may decide the MCS level for each terminal by the MU-MIMO CQI feedback.
  • 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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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
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  • Mathematical Physics (AREA)
  • Power Engineering (AREA)
  • Radio Transmission System (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/KR2010/007853 2010-11-08 2010-11-08 Terminal, station de base, et procédé correspondant dans un système de communication sans fil WO2012063980A1 (fr)

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014126992A2 (fr) 2013-02-12 2014-08-21 Texas Instruments Incorporated Amélioration de livre de codes 4tx dans une technologie d'évolution à long terme (lte)
EP2992705A4 (fr) * 2013-02-12 2017-01-25 Texas Instruments Incorporated Amélioration de livre de codes 4tx dans une technologie d'évolution à long terme (lte)
US9780850B2 (en) 2013-02-12 2017-10-03 Texas Instruments Incorporated 4Tx codebook enhancement in LTE
US10361760B2 (en) 2013-02-12 2019-07-23 Texas Instruments Incorporated 4Tx codebook enhancement in LTE
US10742280B2 (en) 2013-02-12 2020-08-11 Texas Instruments Incorporated 4Tx codebook enhancement in LTE
US11095346B2 (en) 2013-02-12 2021-08-17 Texas Instruments Incorporated 4TX codebook enhancement in LTE
US11563470B2 (en) 2013-02-12 2023-01-24 Texas Instruments Incorporated 4TX codebook enhancement in LTE
US12126411B2 (en) 2013-02-12 2024-10-22 Texas Instruments Incorporated 4Tx codebook enhancement in LTE

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