WO2011085540A1 - 空间信道状态反馈方法和装置 - Google Patents

空间信道状态反馈方法和装置 Download PDF

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Publication number
WO2011085540A1
WO2011085540A1 PCT/CN2010/070139 CN2010070139W WO2011085540A1 WO 2011085540 A1 WO2011085540 A1 WO 2011085540A1 CN 2010070139 W CN2010070139 W CN 2010070139W WO 2011085540 A1 WO2011085540 A1 WO 2011085540A1
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spatial channel
codebook
channel
spatial
scheduled
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PCT/CN2010/070139
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English (en)
French (fr)
Inventor
张翼
张元涛
周华
田军
吴建明
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富士通株式会社
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Priority to CN201080060291.3A priority Critical patent/CN102696180B/zh
Priority to PCT/CN2010/070139 priority patent/WO2011085540A1/zh
Priority to EP10842824A priority patent/EP2525506A1/en
Publication of WO2011085540A1 publication Critical patent/WO2011085540A1/zh
Priority to US13/541,322 priority patent/US20120281659A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613Diversity 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
    • H04B7/0615Diversity 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
    • H04B7/0619Diversity 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
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413MIMO systems
    • H04B7/0452Multi-user MIMO systems
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613Diversity 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
    • H04B7/0615Diversity 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
    • H04B7/0619Diversity 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
    • H04B7/0621Feedback content
    • H04B7/0626Channel coefficients, e.g. channel state information [CSI]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613Diversity 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
    • H04B7/0615Diversity 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
    • H04B7/0619Diversity 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
    • H04B7/0621Feedback content
    • H04B7/0632Channel quality parameters, e.g. channel quality indicator [CQI]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613Diversity 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
    • H04B7/0615Diversity 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
    • H04B7/0619Diversity 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
    • H04B7/0636Feedback format
    • H04B7/0639Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection

Definitions

  • the present invention relates generally to transmission techniques in communication systems, and more particularly to a spatial channel state feedback method and apparatus therefor.
  • LTE-A Next Generation Wireless Communication System Advanced Long Term Evolution-Advanced
  • LTE-A requires the downlink to provide a peak rate of lGps and a peak spectral efficiency of 30 bps/Hz, which is the system physical layer transmission scheme.
  • a MIMO (Multiple Input Multiple Output) communication system multiplexes channels in space, improving the spectral efficiency of the system.
  • ITU International Telecommunications Union
  • Multi-user multiple input multiple output (MU-MIMO, Multiple-User MIMO) technology is one of the candidate technologies.
  • MU-MIMO Multiple input multiple output
  • a base station transmits multiple data streams of different users using the same time-frequency resource. It can make full use of multi-user broadcast channel capacity and obtain spatial multi-dimensional user diversity gain to better meet the requirements of LTE-A system.
  • the base station sends multiple data streams occupying the same time-frequency resource to a plurality of different users. Different users' data are aliased during spatial transmission, and each mobile station does not know the spatial channels of other users when processing the aliased data. This requires the MU-MIMO system to suppress interference between multiple users at the base station. .
  • the ZF-BF (Zero-Forcing BeamForming) technology is a technique for suppressing multi-user interference. It uses zero-forcing precoding at the base station to eliminate interference between users.
  • the process of zero-forcing beamforming is as follows. It is assumed that the base station has a root transmit antenna and one receive antenna, and the multi-user MIMO system simultaneously transmits data of one user.
  • the base station can perform beamforming according to the zero-forcing precoding matrix described below:
  • the equivalent spatial channel corresponding to each user is the right singular vector after the singular value decomposition of the real space channel.
  • the equivalent spatial channels on all the schedules can form a similar equivalent channel H, and the subsequent zero-forcing beamforming process and the regularized zero-forcing beamforming process are the same as in the case of a single receive antenna.
  • DM-RS Demodulation Reference Signal
  • VSEL Demodulated Reference Signals
  • DM-RS Demodulation Reference Signal
  • VSEL Demodulated Reference Signals
  • This feature simplifies the implementation of zero-forcing beamforming for advanced precoding techniques.
  • This technology eliminates the mutual interference of different user data streams at the transmitting end, and makes full use of the multi-user broadcast channel capacity.
  • Many improved ZF-BF technologies are also being discussed by standardization organizations, such as the regularized ZF-BF technology and the block diagonal ZF-BF technology.
  • These beamforming schemes require channel state information to be known at the transmitting end.
  • FDD frequency division duplex
  • Figure 1 shows a schematic diagram of the structure of a ZF-BF multi-user MIMO system.
  • the base station 110 determines by the scheduling module 114 the users capable of transmitting data and the transmission resources they use.
  • the data of the user being scheduled is processed by the channel coding module 111, the modulation module 112, and the zero-forcing beamforming module 113, and then mapped to the allocated time-frequency transmission resource, and transmitted from the antenna module 115.
  • the transmitted signal arrives at a plurality of mobile stations 120A, 120B after being transmitted over different channels. Each mobile station performs similar processing.
  • the mobile station 120A will be described as an example.
  • the mobile station 120A receives the transmission signal using the receiving antenna 124A.
  • the channel estimation module 121A acquires channel state information based on the received reference signal.
  • demodulation module 122A Based on the estimated channel state information, demodulation module 122A performs symbol decoding on the received data signal.
  • the channel decoding module 123A performs bit-level decoding on the symbol decoding result, and finally obtains the bit information of the transmitting end.
  • the base station 110 performs scheduling 114.
  • Zero-forcing beamforming 113 requires known channel state information, which is provided by the mobile station feedback modules 130A, 130B, and each mobile station performs independently.
  • the base station 110 notifies the mobile station of some transmission related stations through the broadcast module 140.
  • the feedback content includes spatial channel direction information and corresponding channel quality indicator (CQI, Channel Quality Indicator), and the feedback part representing the channel direction may adopt a channel correlation matrix or a channel direction information (CDI).
  • CDI channel quality indicator
  • the codebook is used for quantization, which has a small amount of feedback, which is a good compromise between system capacity performance and feedback overhead.
  • the LTE-A system supports up to 8 antennas at the transmitting end and 4 antennas at the receiving end. Up to 4 channel direction vectors can be matched, and the amount of information that needs to be fed back is still large. This requires further reduction of feedback redundancy and enhancement of the practicality of ZF-BF multi-user MIMO technology in LTE-A.
  • Patent Document 1 ZIFENG YU, et al., Method and device for quantizing multiuser MIMO system channel based on limiting feedback (CN 20081038205);
  • Patent Document 3 Jayakrishnan C. Mundarath, et al" Multiuser MIMO-SDMA for finite rate feedback systems (US 20080165875 Al);
  • Patent Document 5 Jim Zheng, et al "Method and system for a simplified user group selection scheme with finite-rate channel state information feedback for FDD multiuser MIMO downlink transmission (US 20070064829 Al);
  • Non-Patent Document 1 T. ⁇ , ⁇ . Jandel, A. Goldsmth, "Multiple-antenna downlink channels with limited feedback and user selection," IEEE J. Select. Areas Commun., Vol. 25 , pp. 1478-1491, Sep. 2007;
  • Non-Patent Document 2 3GPP Rl-062483. Philips, "Comparison between MU-MIMO codebook-based channel reporting techniques for LTE downlink," 3GPP TSG RAN WG1 Meeting #46bis;
  • Non-Patent Document 3 3GPP Rl-070223. Freescale Semiconductor Inc., "Scheme for MU-MIMO in DL EUTRA,” 3GPP TSG RAN WG1 Meeting #47bis.
  • the present invention considers the possibility that the user space channel is scheduled in the feedback process.
  • Even the spatial channels with very low scheduling possibilities do not feed back the corresponding CDI and CQI.
  • the possibility of specifically measuring the scheduling of a certain user space channel is represented by the ratio of the eigenvalues of the spatial channels to the maximum eigenvalues.
  • a spatial channel state feedback method including: determining a probability that a spatial channel is scheduled; determining feedback information according to a probability that a spatial channel is scheduled; and transmitting the determined Feedback information; wherein, the spatial channel having a high probability of being scheduled uses more feedback information than the spatial channel having a lower probability of being scheduled.
  • the feedback information may include the number of channel direction vectors and the use of codebook indications, spatial channel direction vector indications, and spatial channel quality indications.
  • the possibility of determining that the spatial channel is scheduled comprises: acquiring a spatial channel matrix H by channel estimation; performing singular value decomposition on the spatial channel matrix H; arranging in descending order The singular value ⁇ ⁇ ⁇ 2 ⁇ ⁇ .. ⁇ , where L represents the number of mobile station antennas; and the calculation of (1 ⁇ ⁇ £) as the probability of each spatial channel being scheduled.
  • the spatial channel state feedback method further includes receiving a threshold interval used by each codebook from a broadcast channel.
  • determining the feedback information according to the probability that the spatial channel is scheduled includes: determining each spatial channel direction vector according to the value of ⁇ Ki ⁇ ⁇ and the threshold interval used by each codebook received from the broadcast channel. Quantization codebook; and determining the number of channel direction vectors and using the codebook indication based on the quantized codebook used for each of the determined spatial channel direction vectors.
  • a high-precision code is used for a spatial channel direction vector having a large value of 1 ⁇ ⁇
  • the quantized codebook may be a DFT matrix codebook, a random quantized codebook, a Grassamannian codebook, or a norm codebook designed for a single-user system in an LTE system, and the like.
  • determining the feedback information according to the probability that the spatial channel is scheduled further includes: calculating a spatial channel matrix H right singular vector ⁇ ,, ⁇ , ..., ⁇ ;
  • the spatial direction vector ⁇ . (1 ⁇ ⁇ and the determined corresponding quantized codebook, the vector with the smallest angle is selected from the set of quantized codebooks C, and the spatial channel direction that needs to be fed back for each spatial channel in the feedback information
  • the feedback information for the spatial channel corresponding to the lowest scheduling possibility is not transmitted.
  • each spatial channel direction vector uses a quantized codebook; if the value of (1 ⁇ i ⁇ L) is smaller than the threshold interval received from the broadcast channel Not quantizing the information of the spatial channel and not feeding back the spatial channel direction vector indication and the spatial channel quality indication of the spatial channel; and the number of channel direction vectors as feedback information and using the codebook indication to indicate only the spatial channel requiring feedback Quantity.
  • the determined feedback information may be sent through a physical uplink control channel or a periodic/aperiodic physical uplink shared channel.
  • a spatial channel state feedback device comprising: a scheduling possibility determining unit configured to determine a possibility that a spatial channel is scheduled; a feedback information determining unit configured to be used for Determining feedback information according to a probability that the spatial channel is scheduled; and a transmitting unit configured to transmit the determined feedback information; wherein, the spatial channel having a high probability of being scheduled is used with a spatial channel lower than a probability of being scheduled More feedback.
  • the spatial channel state feedback method and apparatus thereof reduce the feedback information of the spatial channel with lower scheduling possibility compared with the conventional spatial channel feedback method and apparatus, thereby further eliminating redundancy. Feedback, a compromise between system capacity performance and feedback overhead is achieved.
  • the present invention also provides a calculation sequence for implementing the above spatial channel state feedback method.
  • the present invention also provides a computer program product in the form of at least a computer readable medium having recorded thereon computer program code for implementing the spatial channel state feedback method described above.
  • FIG. 1 is a schematic diagram showing the structure of a zero-forcing beamforming multi-user MIMO system with reduced feedback overhead
  • FIG. 2 is a schematic diagram showing a schematic diagram of a spatial channel state feedback method in accordance with an embodiment of the present invention
  • FIG. 3 is a block diagram schematically showing the structure of feedback of each mobile station according to an embodiment of the present invention.
  • FIG. 4 is a flow chart showing in detail a method for implementing spatial channel state feedback by each mobile station according to an embodiment of the present invention
  • FIG. 5 schematically shows a schematic diagram of codebook selection
  • Figure 6 shows a block diagram of a spatial channel state feedback device in accordance with one embodiment of the present invention.
  • the spatial channel state feedback method and apparatus first determines the likelihood that a spatial channel is scheduled, then determines feedback information based on the likelihood that the spatial channel is scheduled, and finally transmits the determined feedback information. Among them, there is more feedback information for a spatial channel having a higher probability of being scheduled than a spatial channel having a lower probability of being scheduled.
  • the present invention proposes a method and apparatus for reducing feedback overhead using scheduling information. It is suitable for zero-forcing beamforming multi-user MIMO communication systems.
  • the interval threshold of each user using different quantized codebooks is broadcasted at the base station.
  • the corresponding codebook is selected to quantize the channel direction vector, and the corresponding channel direction vector indication (CDI), channel quality indicator (CQI) and channel direction vector are fed back.
  • CDI channel direction vector indication
  • CQI channel quality indicator
  • NCI codebook indication
  • CDI and CQI reflecting these spatial channel information do not require feedback. This feedback method reduces feedback redundancy based on scheduling requirements and significantly reduces the amount of feedback from the client without affecting system throughput.
  • FIG. 2 is a schematic diagram showing a schematic diagram of a spatial channel state feedback method in accordance with one embodiment of the present invention.
  • the base station 210 notifies the scheduling information or the variation of the scheduling information associated with each mobile station 220A, 220B via the broadcast channel 240.
  • the base station 210 broadcasts a wide interval of the codebook used by the mobile station to quantize the CDI, and it can perform corresponding adjustment according to the scheduled information. For example, when a user's scheduling priority is high, a high-precision codebook is used to quantize the spatial channel by adjusting the threshold area.
  • the mobile station receives broadcast information and uses it during CDI quantization.
  • the signals of the base station 210 are transmitted to the mobile stations 220A, 220B, etc., and their equivalent spatial channels are 231A, 232A, 231B, 232B, and the like, respectively.
  • the equivalent spatial channel 231A has a greater probability of use relative to 232A, then the feedback spatial channel information uses a larger amount of feedback.
  • CDI information quantize with a higher precision codebook.
  • the direction vector of the equivalent spatial channel is represented by the right singular vector of the spatial channel matrix, and the quality of the equivalent spatial channel is characterized by the corresponding direction vector. The value is expressed.
  • the probability that the spatial channel is scheduled is characterized by the ratio of the eigenvalue corresponding to the spatial channel to the maximum eigenvalue.
  • the mobile station determines the codebook used to quantize the CDI information based on the received broadcast threshold.
  • FIG. 3 is a block diagram schematically showing the contents of feedback of each mobile station according to an embodiment of the present invention.
  • the feedback content includes three parts: (1) the number of channel direction vectors and the use codebook indication (NCI) 301; (2M speech direction vector indication (CDI) 302, 304, 306; (3) Channel Quality Indicators (CQI) 303, 305, 307.
  • NCI number of channel direction vectors and the use codebook indication
  • CDI 2M speech direction vector indication
  • CQI Channel Quality Indicators
  • the first part 301 is used to indicate the number of channel direction vectors for feedback and the codebook used for quantization in each direction, which can be indicated by means of bit mapping.
  • the system has a total of spatial channels, and each spatial channel can use M precision codebooks (including a null codebook, which corresponds to the case where no quantitative feedback is needed), and NCI needs l.
  • the g 2 (M" ) bit indicates (the quantized codebook of the channel vector having the largest eigenvalue does not need to be indicated, which corresponds to the most accurate codebook).
  • each mobile station has only one feedback codebook.
  • the NCI only needs to indicate the number of spatial channels for codebook quantization, which only requires i. g 2 ( ) bit indication. Obviously, the amount of feedback from the client can be significantly reduced.
  • CDI 302. 304, 306 respectively quantize the right singular isotropic amount of the channel matrix by using the corresponding codebook, and the specific codebook selection method will be described in detail in FIG.
  • CQI 303. 305, 307 can be obtained according to the traditional zero-forcing MU-MIMO method, which can take the form of feedback-quantized receiver-side signal-to-noise ratio or modulation coding order.
  • CDI 306 and CQI 307 are indicated by dashed lines in Figure 3, indicating that information on these spatial channels is not necessarily required to be fed back.
  • These feedback information can be transmitted over the physical uplink control channel or the periodic ⁇ aperiodic physical uplink shared channel.
  • the mobile station first receives the threshold interval used by each codebook from the broadcast channel in step 401.
  • the downlink channel state station is estimated based on the received reference signal.
  • the quantized codebook for each spatial channel direction vector is determined based on the ratio of the data and the threshold interval obtained in step 401.
  • the feature vector having the largest singular value is fixed and quantized using a high precision codebook.
  • the quantized codebook can use various forms such as DFT matrix codebook, random quantization codebook, Grassamannian codebook, and normal mode codebook designed for single-user system in LTE system.
  • step 405 the NCI is determined based on the quantized codebook selected for each spatial direction vector.
  • the specific determination method of the NCI please refer to the detailed description of the above with reference to Figures 2 and 3, which are omitted here.
  • step 406 according to each spatial direction vector ⁇ ( ⁇ ⁇ ⁇ ) and the selected quantized codebook, the vector with the smallest angle is selected from the codebook set c and the spatial direction vector V, respectively.
  • ⁇ ⁇ ⁇
  • V the spatial direction vector
  • ie ⁇ which represents the number of codebook sets. The amount of them The indication is the CDI that each spatial channel needs feedback.
  • step 407 according to the singular value ⁇ , . ( ⁇ ⁇ ⁇ ⁇ ?) of each spatial channel, the right singular vector V, . (1 ⁇ ⁇ ) and the quantized codebook C are formed according to the conventional zero-forcing beamforming
  • the CQI calculation method obtains the CQI that each spatial channel needs to feed back.
  • step 408 the NCI acquired in step 405, the spatial channels CDI acquired in step 406, are obtained in step 407 according to the feedback format shown in FIG. Each spatial channel CQI is fed back to the base station through a physical uplink control channel or a periodic/non-periodic physical uplink shared channel.
  • FIG. 5 is a schematic diagram showing the codebook selection of each spatial channel.
  • the mobile station obtains the threshold value ⁇ of the selected quantized codebook through the broadcast channel, . . . ⁇ (7; ⁇ ⁇ 2 ⁇ ... ⁇ .
  • the threshold value divides the value range of the parameter representing the scheduling possibility into a plurality of intervals 501, 502, 503, wherein the interval 501 corresponds to the lowest scheduling possibility, and the corresponding spatial channel information is not fed back; the interval 502 corresponds to a lower scheduling possibility, and the corresponding spatial direction vector is quantized with a lower precision codebook; the interval 503 corresponds to a higher The scheduling possibility, the corresponding spatial direction vector, is quantized with a higher precision codebook.
  • the parameter characterizing the scheduling probability is the ratio of the spatial channel characteristic value to the maximum eigenvalue.
  • the spatial channel state feedback apparatus includes a wide value inter-region receiving unit 610, a scheduling possibility determining unit 620, a feedback information determining unit 630, and a transmitting unit 640.
  • the threshold interval receiving unit 610 is configured to receive the threshold interval used by each codebook from the broadcast channel.
  • the threshold interval receiving unit 610 is an optional configuration. In fact, the mobile station can also determine the threshold interval by itself.
  • the scheduling possibility determining unit 620 is configured to determine a possibility that the spatial channel is scheduled
  • the feedback information determining unit 630 is configured to determine feedback information according to the possibility that the spatial channel is scheduled
  • the transmitting unit 640 is configured to use Sending the determined feedback information.
  • the spatial channel having a high probability of being scheduled uses more feedback information than the spatial channel having a lower probability of being scheduled.
  • the feedback information to be transmitted may include the number of channel direction vectors and the use codebook indication, the spatial channel direction vector indication, the spatial channel quality indication, and the like.
  • the scheduling possibility determining unit 620 acquires the spatial channel matrix H by channel estimation and The spatial channel matrix H is subjected to singular value decomposition, and then the singular values are arranged in descending order and (1 ⁇ ⁇ ) are respectively calculated as the probability that each spatial channel is scheduled, where L represents the number of mobile station antennas.
  • the feedback information determining unit 630 After the scheduling possibility determining unit 620 determines the possibility that the spatial channel is scheduled, the feedback information determining unit 630 according to the value of ( ⁇ ⁇ ⁇ £) and the threshold interval used for each codebook received from the broadcast channel, A quantized codebook for each spatial channel direction vector is determined. Then, the feedback information determining unit 630 determines the number of channel direction vectors and the use codebook indication based on the determined quantized codebook used for each spatial channel direction vector.
  • the feedback information determining unit 630 is directed to a spatial channel having a large value of 1 ⁇ ⁇
  • the direction vector is quantized using a high-precision codebook, and the spatial channel direction vector having a small value of ⁇ (1 ⁇ ⁇ £) is quantized using a low-precision codebook.
  • the quantized codebook used herein may be a DFT matrix codebook, a random quantized codebook, a Grassamannian codebook, a norm codebook designed for a single-user system in an LTE system, and the like.
  • the feedback information determining unit 630 calculates the spatial channel matrix H right singular vector ⁇ ,, ⁇ ., ⁇ According to each spatial direction vector V,. (l ⁇ ⁇ ) and the determined corresponding quantized codebook, the vector with the smallest angle is selected from the set of quantized codebooks C as the spatial direction channel in the feedback information.
  • Feedback channel direction vector indication
  • the feedback information determining unit 630 also obtains feedback information according to the singular value ⁇ , . (l ⁇ i ⁇ L), the right singular vector V,. (1 ⁇ ⁇ L) and the quantized codebook C of each spatial channel.
  • Each spatial channel requires a channel quality indication (CQI) of feedback.
  • each spatial channel direction vector uses a quantized codebook.
  • the information of the spatial channel is not quantized and the spatial channel direction vector indication and the spatial channel quality indication of the spatial channel are not fed back.
  • the number of channel direction vectors as feedback information and the use of the codebook indication only indicate the number of spatial channels that need to be fed back, and the feedback redundancy of the spatial channels can be greatly eliminated.
  • the sending unit 640 feeds back the NCI, CDI, and CQI determined by the feedback information determining unit 630 according to the feedback format shown in FIG. 3 to the base station through a physical uplink control channel or a periodic/non-periodic physical uplink shared channel.
  • a quantization codebook is used in each spatial channel direction vector, and the transmitting unit 640 only needs to transmit the number of spatial channels that need feedback, thereby realizing the feedback redundancy of the spatial channel and improving the system performance.
  • the spatial channel state feedback method and apparatus thereof according to the present invention are also applicable to an improved zero-forcing beamforming multi-user MIMO system, such as a regularized zero-forcing beamforming multi-user MIMO system. Further, the spatial channel state feedback method and apparatus according to the present invention are also applicable to a wireless communication system such as Wimax.
  • the present invention takes into account the possibility of the user space channel being scheduled during the feedback process.
  • the spatial channel is hierarchically quantized by scheduling possibility, and the feedback redundancy of the spatial channel is further eliminated, which achieves a good compromise between system capacity performance and feedback overhead.
  • he is not aware of the spatial channel direction information of other mobile stations.
  • the ratio of the eigenvalues of the spatial channels to the maximum eigenvalues can better reflect the possibility that the spatial channel is scheduled, and it is reasonable for the mobile station to adjust the level of the quantized codebook by this ratio.
  • the method of the present invention is not limited to being performed in accordance with the chronological order described in the specification. Rows can also be executed sequentially, in parallel, or independently in other time periods. Therefore, the order of execution of the methods described in the present specification does not limit the technical scope of the present invention.
  • a spatial channel state feedback method including:
  • Supplementary note 2 The spatial channel state feedback method according to Supplementary Note 1, wherein the feedback information includes a number of channel direction vectors and a use codebook indication, a spatial channel direction vector indication, and a spatial channel quality indication.
  • the spatial channel state feedback method further comprising: receiving a threshold interval used by each codebook from a broadcast channel;
  • determining the feedback information according to the possibility that the spatial channel is scheduled includes: a value of ⁇ i ⁇ L) and a threshold interval used by each codebook received from the broadcast channel, determining a quantized codebook for each spatial channel direction vector; and determining each spatial channel direction according to the determined
  • the quantized codebook used by the vector determines the number of channel direction vectors and uses the codebook indication.
  • the spatial channel direction vector with a small value of ⁇ i ⁇ L) is quantized using a low-precision codebook.
  • Supplementary Note 6 The spatial channel state feedback method according to Supplementary Note 5, wherein the quantized codebook is a DFT matrix codebook, a random quantized codebook, a Grassamannian codebook or a norm codebook.
  • the vector with the smallest angle is selected from the set of quantized codebooks C as the spatial channel in the feedback information.
  • the spatial channel quality indication that each spatial channel in the feedback information needs to feed back is obtained.
  • Supplementary note 8 The spatial channel state feedback method according to supplementary note 7, wherein the feedback information for the spatial channel corresponding to the lowest scheduling possibility is not transmitted.
  • Appendix 9 Appendix spatial channel state feedback method of claim 7, wherein each spatial channel volume preclude the use of a direction quantization codebook; if ⁇ ⁇ i ⁇ L) is smaller than the width value from the broadcast channel receiving section Not quantizing the information of the spatial channel and not feeding back the spatial channel direction vector of the spatial channel.
  • the spatial and spatial channel quality indications; and the number of channel direction vectors as feedback information and the use of the codebook indication only indicate the number of spatial channels that require feedback.
  • the spatial channel state feedback method according to any one of supplementary notes 1 to 9, wherein the determined feedback information is transmitted through a physical uplink control channel or a periodic/non-periodic physical uplink shared channel.
  • a spatial channel state feedback device comprising:
  • a scheduling possibility determining unit configured to determine a possibility that the spatial channel is scheduled
  • a feedback information determining unit configured to determine feedback information according to a probability that the spatial channel is scheduled
  • a sending unit configured to send the determined feedback information
  • the spatial channel state feedback device further comprising: a threshold interval receiving unit configured to receive a threshold interval used by each codebook from a broadcast channel;
  • the feedback information determining unit a value of ⁇ i ⁇ L) and a threshold interval used by each codebook received from the broadcast channel, determining a quantized codebook for each spatial channel direction vector; and determining each spatial channel direction according to the determined
  • the quantized codebook used by the vector determines the number of channel direction vectors and uses the codebook indication.
  • Supplementary note 15 The spatial channel state feedback device according to supplementary note 14, wherein the spatial channel direction vector having a large value of 1 ⁇ ⁇ is quantized using a high-precision codebook,
  • the spatial channel direction vector with a small value of ⁇ i ⁇ L) is quantized using a low-precision codebook.
  • Supplementary note 16 The spatial channel state feedback device according to supplementary note 15, wherein the quantized codebook is a DFT matrix codebook, a random quantized codebook, a Grassamannian codebook or a norm codebook.
  • the spatial channel state feedback device according to supplementary note 14, wherein the feedback information determining unit further
  • the vector with the smallest angle is selected from the set of quantized codebooks C as the spatial channel in the feedback information.
  • the channel quality indication that each spatial channel in the feedback information needs to feed back is obtained.
  • Supplementary note 18 The spatial channel state feedback device according to supplementary note 17, wherein the feedback information for the spatial channel corresponding to the lowest scheduling possibility is not transmitted.
  • each spatial channel volume preclude the use of a direction quantization codebook; if ⁇ ⁇ i ⁇ L) is smaller than the width value from the broadcast channel receiving section Not quantizing the information of the spatial channel and not feeding back the spatial channel direction vector of the spatial channel.
  • the spatial and spatial channel quality indications; and the number of channel direction vectors as feedback information and the use of the codebook indication only indicate the number of spatial channels that require feedback.

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Description

空间信道状态反馈方法和装置
技术领域
[01] 本发明一般地涉及通信系统中的传输技术, 更具体地说, 本发明 涉及一种空间信道状态反馈方法及其装置。
背景技术
[02] 3GPP的下一代无线通信系统高级长期演进方案(LTE-A, Long Term Evolution-Advanced )要求下行链路提供 lGps的峰值速率以及 30bps/Hz的峰值频谱效率,这为系统物理层传输方案带来挑战。多输 入多输出 ( MIMO, Multiple Input Multiple Output )通信系统在空 间上复用信道,提高了系统的频谱效率。但是,仅使用单用户 MIMO 技术不能在任何测试场景下都满足国际电信联盟(ITU ) 的要求, 这 就要求物理层釆用更先进的技术。多用户多输入多输出( MU-MIMO, Multiple-User MIMO )技术正是其中的候选技术之一。在 MU-MIMO 系统中, 基站使用相同的时频资源传输不同用户的多个数据流。 它能 够充分利用多用户广播信道容量, 获取空间多维用户分集增益, 更好 地满足 LTE-A系统的要求。
[03] 下行 MU-MIMO系统中基站将占用相同时频资源的多个数据流 发给多个不同用户。 不同用户的数据在空间传输的过程中发生混叠, 而各移动台在对混叠数据进行处理时未知其它用户的空间信道,这需 要 MU-MIMO系统在基站端来抑制多用户之间的干扰。 迫零波束成 型 ( ZF-BF, Zero-Forcing BeamForming )技术就是这一类抑制多用 户干扰的技术, 它在基站端釆用迫零预编码来消除用户间的干扰。
[04] 迫零波束成型的过程如下所述。 假设基站具有 根发射天线, 1 根接收天线, 多用户 MIMO 系统同时传送 个用户的数据。 基站和 每个移动台的空间信道为 Η = [Hu H1 2 .. H1 M , 那么基站和所有移动台 构成的空间信道为 Η = Η2… f。 基站可以按照下述迫零预编码矩 阵进行波束成型:
G = uH( iH ( 1 ) [05] 考虑到天线的实际发射功率问题, 接收端还需要进行功率规一 化, 保证发射天线的功率平衡。 如果功率规一化矩阵表示为 P, 它为 对角矩阵, 其中每个对角元素为 = ), 其中 |G』2
Figure imgf000004_0001
表第 列的元素的模值的平方和。
[06] 所有用户接收到的信号 γ = , y2 ,… f可表示为:
Y - HGPS + N ( 2 )
[07] 其中 S为所有用户传输的数据, N为接收的噪声信号。 将式(1 ) 代入式(2 )可得:
Y - PS + N ( 3 ) 由于 P为对角矩阵, 因此用户间的干扰被消除。
[08] 当 H不满秩时, P会引起信道间能量分配不平衡的问题。 当系统 工作在低信噪比时, 它会严重影响系统性能。 针对这一问题提出了规 则化迫零波速成型方案,
Figure imgf000004_0002
它通过引入少量的用户间干扰来最大化接收端的信干噪比, 由此提高 了系统性能。
[09] 对于多根接收天线的多用户 MIMO系统, 如果每个用户釆用奇 异值分解接收机,每个用户对应的等效空间信道就是实际空间信道 奇异值分解后的右奇异向量。所有调度上的等效空间信道可组成类似 的等效信道 H, 后续的迫零波束成型过程和规则化迫零波束成型过程 与单接收天线的情况相同。
[10] 另外, 在 LTE-A 系统中, 提供解调参考信号 (DM-RS , Demodulated Reference Signals ), 它能够保证接收端在未知预编码矩 阵(向量)时实现译码。 这一特性简化了高级预编码技术迫零波束成 型的实现。 这一技术在发射端消除不同用户数据流的相互干扰, 较充 分利用多用户广播信道容量。 许多改进型 ZF-BF技术也在被标准化 组织讨论, 比如规则化 ZF-BF技术、 块对角 ZF-BF技术。 这些波束 成型方案都要求在发射端已知信道状态信息。 在频分双工 (FDD , Frequency Division Duplex ) 系统中, 信道状态信息可以通过接收端 反馈传输。
[11] 图 1示出了 ZF-BF多用户 MIMO系统结构的示意图。 基站 110 通过调度模块 114确定能够传输数据的用户和它们使用的传送资源。 被调度上的用户的数据经过信道编码模块 111、 调制模块 112、 迫零 波束成型模块 113处理后映射到分配的时频传送资源上,从天线模块 115发射出去。
[12] 发射信号经过不同的信道传输后到达多个移动台 120A、 120B。 各移动台进行类似的处理, 下面以移动台 120A为例进行说明。
[13] 移动台 120A使用接收天线 124A接收发射信号。 信道估计模块 121A根据接收到的参考信号获取信道状态信息。 根据估计的信道状 态信息, 解调模块 122A对接收的数据信号进行符号译码。 信道译码 模块 123A再对符号译码结果进行比特级译码, 最终获取发射端的比 特信息。
[14] 基站 110进行调度 114、 迫零波束成型 113处理时需要已知信道 状态信息, 它由移动台反馈模块 130A、 130B来提供, 各移动台相互 独立的进行。基站 110通过广播模块 140通知移动台一些传输相关信 台
[15] 反馈内容包括空间信道方向信息和对应的信道质量指示 (CQI, Channel Quality Indicator ), 表征信道方向的反馈部分可釆用信道相 关矩阵或信道方向向量 ( CDI, Channel Direction Information )的形 式。 反馈 CDI 时釆用码本进行量化, 具有较小的反馈量, 较好实现 了系统容量性能和反馈开销的良好折中。
[16] 但是, LTE-A系统最大支持发射端 8根天线, 接收端 4根天线。 最多可对应 4个信道方向向量, 需要反馈的信息量仍然很大。 这需要 进一步减少反馈冗余, 增强 ZF-BF多用户 MIMO技术在 LTE-A中 的实用性。
[17] 应该注意,上面对常规技术的说明只是为了方便对本发明的技术 方案进行清楚、完整的说明,并方便本领域技术人员的理解而阐述的。 不能仅仅因为这些方案在本发明的背景技术部分进行了阐述而认为 上述技术方案为本领域技术人员所公知。
[18] 以下列出了本发明的参考文献, 通过引用将它们并入于此, 如同 在本说明书中作了详尽描述。
[19] 1、 [专利文献 1】: ZIFENG YU, et al., Method and device for quantizing multiuser MIMO system channel based on limiting feedback (CN 20081038205);
[20] 2、 [专利文献 2】: Zhang Wei, et al., Multiuser scheduling for A2);
[21] 3、 [专利文献 3】: Jayakrishnan C. Mundarath,et al" Multiuser MIMO-SDMA for finite rate feedback systems (US 20080165875 Al);
[22] 4、 [专矛 J文献 4]: Myeon-kyun CHO, et al" Apparatus and method for scheduling multiuser/ single user in multiple input multiple output (MIMO) system (US 20080025336 Al);
[23] 5、 [专利文献 5】: Jim Zheng, et al" Method and system for a simplified user group selection scheme with finite-rate channel state information feedback for FDD multiuser MIMO downlink transmission (US 20070064829 Al);
[24] 6、 [非专利文献 1】: T. Υοο, Ν. Jandel, A. Goldsmth, "Multiple-antenna downlink channels with limited feedback and user selection,"IEEE J. Select. Areas Commun., Vol. 25, pp. 1478-1491, Sep. 2007;
[25] 7、 [非专利文献 2】: 3GPP Rl-062483. Philips, "Comparison between MU-MIMO codebook-based channel reporting techniques for LTE downlink," 3GPP TSG RAN WG1 Meeting #46bis;
[26] 8、 [非专利文献 3】: 3GPP Rl-070223. Freescale Semiconductor Inc., "Scheme for MU-MIMO in DL EUTRA," 3GPP TSG RAN WG1 Meeting #47bis。
发明内容
[27] 鉴于此, 本发明在反馈过程中考虑用户空间信道被调度的可能 性。 对较高调度可能性的空间信道使用较多的反馈比特, 比如釆用较 高精度的码本量化 CDI,而对较低调度可能性的空间信道釆用较少的 反馈比特, 比如釆用较低精度的码本量化 CDI。 甚至, 对很低调度可 能性的空间信道不反馈对应的 CDI和 CQI。 具体衡量某一用户空间 信道被调度的可能性是通过各空间信道的特征值与最大特征值的比 值来表征。
[28] 具体地说, 根据本发明的一个方面, 提供一种空间信道状态反馈 方法, 包括: 确定空间信道被调度的可能性; 根据空间信道被调度的 可能性确定反馈信息; 以及发送所确定的反馈信息; 其中, 对被调度 的可能性高的空间信道使用比被调度的可能性低的空间信道多的反 馈信息。
[29] 反馈信息可以包括信道方向向量的数量和使用码本指示、空间信 道方向向量指示和空间信道质量指示。
[30] 根据本发明的一个实施例,所述确定空间信道被调度的可能性包 括: 通过信道估计获取空间信道矩阵 H; 对空间信道矩阵 H进行奇 异值分解; 按照从大到小的顺序排列奇异值 σι≥σ2≥· ..≥ , 其中 L表 示移动台天线数量;以及分别计算 (1≤ ≤£)作为每一个空间信道被调 度的可能性。
[31] 另夕卜, 根据本发明一个实施例的空间信道状态反馈方法, 还包括 从广播信道接收各码本使用的阔值区间。 在这种情况下, 根据空间信 道被调度的可能性确定反馈信息包括:根据^ Ki≤ ≤ 的值和从广播信 道接收的各码本使用的阔值区间,确定每一个空间信道方向向量釆用 的量化码本; 以及根据所确定的每一个空间信道方向向量所釆用的量 化码本确定信道方向向量的数量和使用码本指示。
[32] 优选地,对于 (1≤ ≤ 的值大的空间信道方向向量使用高精度码
本进行量化,对于 ^(1≤ ≤ 的值小的空间信道方向向量使用低精度码 本进行量化。 [33] 量化码本可以为 DFT矩阵码本、随机量化码本、 Grassamannian 码本或 LTE系统中针对单用户系统设计的常模码本等等。
[34] 此外, 根据本发明的一个实施例, 根据空间信道被调度的可能性 确定反馈信息还包括: 计算空间信道矩阵 H右奇异向量 {ν,,ν ,... ,^} ; 根据各空间方向向量 Λζ. (1≤ ≤ 和确定的相应量化码本,从量化码本集 合 C中选择与空间方向向量 V,具有最小夹角的向量 作为反馈信息 中各空间信道需要反馈的空间信道方向向量指示; 以及根据各空间信 道的奇异值 σ, (1≤ ≤ )、右奇异向量 V, (1≤ ≤ )和量化码本 C获取反馈信 息中各空间信道需要反馈的空间信道质量指示。
[35] 优选地,对于相应于最低调度可能性的空间信道的反馈信息不进 行发送。
[36] 根据本发明的一个优选实施例的空间信道状态反馈方法,各空间 信道方向向量均釆用一个量化码本;如果 (1 < i < L)的值小于从广播信 道接收的阔值区间, 不对该空间信道的信息进行量化并且不反馈该空 间信道的空间信道方向向量指示和空间信道质量指示; 以及作为反馈 信息的信道方向向量的数量和使用码本指示仅指示需要反馈的空间 信道的数量。
[37] 所确定的反馈信息可以通过物理上行控制信道或者周期 /非周期 物理上行共享信道来发送。
[38] 根据本发明的另一方面,提供一种空间信道状态反馈装置,包括: 调度可能性确定单元, 配置为用于确定空间信道被调度的可能性; 反 馈信息确定单元,配置为用于根据空间信道被调度的可能性确定反馈 信息; 以及发送单元, 配置为用于发送所确定的反馈信息; 其中, 对 被调度的可能性高的空间信道使用比被调度的可能性低的空间信道 多的反馈信息。
[39] 可以看出, 根据本发明的空间信道状态反馈方法及其装置, 相对 传统的对空间信道反馈方法和装置,减少了较低调度可能性的空间信 道的反馈信息, 进一步消除了冗余反馈, 实现了系统容量性能和反馈 开销较好折中。 [40] 另夕卜,本发明还提供用于实现上述空间信道状态反馈方法的计算 序。
[41] 此外, 本发明也提供至少计算机可读介质形式的计算机程序产 品,其上记录有用于实现上述空间信道状态反馈方法的计算机程序代 码。
附图说明
[42] 参照以下的附图可以更好地理解本发明的很多方面。附图中的部 件不是成比例绘制的, 而只是为了示出本发明的原理。 为了便于示出 和描述本发明的一些部分, 附图中对应部分可能被放大, 即, 使其相 对于在依据本发明实际制造的示例性装置中的其它部件变得更大。在 本发明的一个附图或一种实施方式中描述的元素和特征可以与一个 或更多个其它附图或实施方式中示出的元素和特征相结合。 此外, 在 附图中, 类似的标号表示几个附图中对应的部件, 并可用于指示多于 一种实施方式中使用的对应部件。 附图中:
[43] 图 1 示意性地示出了减少反馈开销的迫零波束成型多用户 MIMO系统的结构才匡图;
[44] 图 2 示意性示出根据本发明的一个实施例的空间信道状态反馈 方法的原理图;
[45] 图 3 示意性地示出了根据本发明的一个实施例的各移动台的反 馈内容的结构图;
[46] 图 4详细示出了根据本发明的一个实施例的各移动台实现空间 信道状态反馈方法的流程图;
[47] 图 5示意性地示出了码本选择的原理图; 以及
[48] 图 6 示出根据本发明的一个实施例的空间信道状态反馈装置的 方框图。
具体实施方式
[49] 下面参照附图来说明本发明的实施例。在本发明的一个附图或一 种实施方式中描述的元素和特征可以与一个或更多个其它附图或实 施方式中示出的元素和特征相结合。 应当注意, 为了清楚的目的, 附 图和说明中省略了与本发明无关的、本领域普通技术人员已知的部件 和处理的表示和描述。
[50] 根据本发明的空间信道状态反馈方法和装置首先确定空间信道 被调度的可能性, 然后根据空间信道被调度的可能性确定反馈信息, 最后发送所确定的反馈信息。 其中, 对被调度的可能性高的空间信道 使用比被调度的可能性低的空间信道多的反馈信息。
[51] 也就是说,本发明提出了一种利用调度信息减少反馈开销的方法 和装置。 它适用于迫零波束成型多用户 MIMO通信系统。 在基站端 广播各用户使用不同量化码本的区间阔值。在用户端根据信道特征值 的比值所处的区间, 选择相应的码本对信道方向向量进行量化, 并反 馈相应的信道方向向量指示(CDI )、信道质量指示(CQI )和信道方 向向量的数目和使用码本指示 (NCI )。 特别的, 当某些信道方向向 量的特征值远小于最大特征值时,它对应的空间信道不太可能被基站 调度适用。 因此, 反映这些空间信道信息的 CDI、 CQI不需要反馈。 这种反馈方法根据调度需求减少反馈冗余,在不影响系统吞吐量的前 提下显著减少了用户端的反馈量。
[52] 下面将首先参照图 2至图 5描述才艮据本发明的实施例的空间信道 状态反馈方法的基本工作原理。
[53] 图 2 示意性示出根据本发明的一个实施例的空间信道状态反馈 方法的原理图。基站 210通过广播信道 240通知各移动台 220A、 220B 相关的调度信息或者调度信息的变化形式。本实施例中基站 210广播 移动台量化 CDI使用的码本的阔值区间, 它可以根据调度的信息做 相应的调整。 比如, 当某个用户调度的优先级高时, 通过调整阔值区 间使量化空间信道时釆用较高精度的码本。 移动台接收广播信息, 在 CDI量化时使用。
[54] 基站 210的信号传输到各移动台 220A、 220B等, 它们的等效空 间信道分别为 231A、 232A以及 231B、 232B等。 对移动台 220A, 如 果等效空间信道 231A相对 232A有较大的使用概率, 则反馈的空间 信道信息釆用较大的反馈量。 对于 CDI信息, 釆用较高精度的码本 进行量化。 在本实施例中, 等效空间信道的方向向量釆用空间信道矩 阵的右奇异向量表示,等效空间信道的质量釆用对应方向向量的特征 值来表示。 对某一用户, 空间信道被调度的可能性用该空间信道对应 的特征值与最大特征值的比值来表征。移动台根据接收到的广播阔值 确定量化 CDI信息时使用的码本。
[55] 图 3 示意性地示出了根据本发明的一个实施例的各移动台的反 馈内容的结构图。 如图 3所示, 反馈内容包括三部分: (1 )信道方向 向量的数目和使用码本指示( NCI )301; ( 2 M言道方向向量指示( CDI ) 302、 304、 306; ( 3 )信道质量指示 (CQI ) 303、 305、 307。
[56] 第一部分 301 用来指示反馈的信道方向向量数目和每个方向量 化时使用的码本, 它可以釆用比特映射的方法来指示。 例如, 对于某 一个用户, 系统共有 个空间信道, 每个空间信道都可釆用 M个精 度的码本(包括一个空码本, 它对应不需要量化反馈的情况)进行量 化, NCI需要 l。g2 (M" )比特指示(具有最大特征值的信道向量的量化 码本不需要指示, 它对应最高精度的码本)。
[57] 才艮据本发明的一个优选实施例特别关心一种简单实用的情况, 即 各移动台仅有一个反馈码本。 此时, NCI只需要指示进行码本量化的 空间信道的数量, 它仅需要 i。g2 ( )比特指示。 显然, 能够显著减少用 户端的反馈量。
[58] CDI 302. 304、 306分别釆用相应的码本对信道矩阵的右奇异向 量进行量化, 具体码本选择的方法将在图 5部分详细说明。
[59] CQI 303. 305、 307可按照传统迫零 MU-MIMO的方法来获取, 它可以釆用反馈量化后的接收端信干噪比或调制编码阶数的形式。
CQI的具体算法请参见上面列出的参考文献 7和 8中所给出的计算方 法, 在此略去其详细描述。
[60] 特别需要指出的是,在图 3中 CDI 306、 CQI 307釆用虚线表示, 说明实际上不一定需要反馈这些空间信道的信息。
[61] 这些反馈信息可以通过物理上行控制信道或周期 \非周期的物理 上行共享信道来传输。
[62] 下面将结合图 4详细描述根据本发明的一个实施例的各移动台 实现空间信道状态反馈方法的流程图。
[63] 如图 4所示,移动台首先在步骤 401从广播信道接收到各码本使 用的阔值区间。 [64] 接着, 在步骤 402根据接收到的参考信号估计下行信道状态信 台
[65] 在步骤 403中, 对空间信道矩阵 Η进行奇异值分解, 按照从大到 小的顺序排列奇异值 σι≥σ2≥· ..≥^和右奇异向量 {V,,^,... ,^} , 其中 L = Mr , Mr≤Mt , ^和 代表接收、 发射天线的数目, 移动台天线数 目 ^小于基站天线数目 。 分别计算 ^(1≤ ≤£), 作为选择量化码本 的尺度。
[66] 然后,在步骤 404中,才艮据 的比值和在步骤 401中获取的阔值 区间, 确定每个空间信道方向向量釆用的量化码本。 根据本发明的一 个具体实施例, 具有最大奇异值 的特征向量固定釆用高精度码本量 化。量化码本可以釆用 DFT矩阵码本、随机量化码本、 Grassamannian 码本、 LTE系统中针对单用户系统设计的常模码本等多种形式。
[67] 接下来, 在步骤 405中, 根据各空间方向向量选择的量化码本确 定 NCI。 NCI的具体确定方法请参见上面结合附图 2和 3的详细描述, 在此略去。
[68] 然后,在步骤 406中,才艮据各空间方向向量 Λζ (ΐ≤ ≤ )和选择的量 化码本, 分别从码本集合 c中选择与空间方向向量 V,具有最小夹角的 向量 , 即^ , 其中 代表码本集合的数量。 它们的量
Figure imgf000012_0001
化指示即为各空间信道需要反馈的 CDI。
[69] 接着, 在步骤 407中, 根据各空间信道的奇异值 σ,. (ΐ≤ ≤^? )、 右奇 异向量 V,. (1≤ ≤ )和量化码本 C按照传统迫零波束成型 CQI计算方法 (请参见上面列出的参考文献 7和 8中所给出的计算方法)获取各空 间信道需要反馈的 CQI。
[70] 最后, 在步骤 408中, 按照图 3所示的反馈格式将在步骤 405中 获取的 NCI、在步骤 406中获取的各空间信道 CDI、在步骤 407中获 取的各空间信道 CQI, 通过物理上行控制信道或者周期 /非周期物理 上行共享信道等反馈给基站。
[71] 图 5示意性地给出了各空间信道的码本选择示意图。移动台通过 广播信道获取选择量化码本的阔值 η , . .. Λ (7;≤ Γ2≤…≤ 。 阔值将表征 调度可能性的参量的值域分为多个区间 501、 502、 503,其中区间 501 对应最低调度可能性, 相应的空间信道信息不进行反馈; 区间 502对 应较低的调度可能性, 相应的空间方向向量釆用精度较低的码本量 化; 区间 503对应较高的调度可能性, 相应的空间方向向量釆用精度 较高的码本量化。
[72] 特别地, 如果系统仅使用一个阔值时, 当表征调度的参量不小于 阔值, 说明该空间向量需要使用码本量化, 否则说明该空间信道信息 不需要反馈。 在该具体实例中, 表征调度可能性的参量为该空间信道 特征值与最大特征值比值。
[73] 以上结合附图 2至 5描述了根据本发明的具体实施例的空间信道 状态反馈方法,下面将结合附图 6描述根据本发明的一个实施例的空 间信道状态反馈装置。
[74] 如图 6所示,才艮据该实施例的空间信道状态反馈装置包括阔值区 间接收单元 610、 调度可能性确定单元 620、 反馈信息确定单元 630、 以及发送单元 640。
[75] 阔值区间接收单元 610 配置为用于从广播信道接收各码本使用 的阔值区间。 这里, 阔值区间接收单元 610为可选配置。 实际上, 移 动台也完全可以自行确定该阔值区间。
[76] 调度可能性确定单元 620 配置为用于确定空间信道被调度的可 能性,反馈信息确定单元 630配置为用于根据空间信道被调度的可能 性确定反馈信息,发送单元 640则配置为用于发送所确定的反馈信息。 在根据本发明的一个具体示例中 ,对被调度的可能性高的空间信道使 用比被调度的可能性低的空间信道多的反馈信息。
[77] 这里,要发送的反馈信息可以包括信道方向向量的数量和使用码 本指示、 空间信道方向向量指示和空间信道质量指示等等。
[78] 根据本发明的一个优选实施例,在确定空间信道被调度的可能性 时, 调度可能性确定单元 620通过信道估计获取空间信道矩阵 H并 对空间信道矩阵 H进行奇异值分解, 然后按照从大到小的顺序排列 奇异值 并分别计算 (1≤ ≤ )作为每一个空间信道被调度 的可能性, 其中 L表示移动台天线数量。
[79] 在调度可能性确定单元 620确定了空间信道被调度的可能性之 后,反馈信息确定单元 630根据 (ι≤ ≤£)的值和从广播信道接收的各 码本使用的阔值区间, 确定每一个空间信道方向向量釆用的量化码 本。 然后, 反馈信息确定单元 630根据所确定的每一个空间信道方向 向量所釆用的量化码本确定信道方向向量的数量和使用码本指示。
[80] 优选地,反馈信息确定单元 630针对 (1≤≤ 的值大的空间信道
方向向量使用高精度码本进行量化,并且针对^ (1≤ ≤£)的值小的空间 信道方向向量使用低精度码本进行量化。
[81] 在此使用的量化码本可以为 DFT 矩阵码本、 随机量化码本、 Grassamannian码本、 LTE系统中针对单用户系统设计的常模码本等 多种形式。
[82] 如上所述,在确定了反馈信息中的信道方向向量的数量和使用码 本指示( NCI )之后, 反馈信息确定单元 630计算空间信道矩阵 H右 奇异向量 {ν,,ν^.,ν 根据各空间方向向量 V,. (l≤ ≤ )和确定的相应量 化码本, 从量化码本集合 C中选择与空间方向向量 V,具有最小夹角的 向量 作为反馈信息中各空间信道需要反馈的信道方向向量指示
( CDI )。
[83] 另外, 反馈信息确定单元 630 还根据各空间信道的奇异值 σ,. (l≤i≤L)、右奇异向量 V,. (1 < < L)和量化码本 C获取反馈信息中各空间 信道需要反馈的信道质量指示 (CQI )。
[84] 特别地,对于相应于最低调度可能性的空间信道的反馈信息不进 行发送。 [85] 根据本发明的一个优选具体示例,各空间信道方向向量均釆用一 个量化码本。此时,如果 (1≤ ≤£)的值小于从广播信道接收的阔值区 间,则不对该空间信道的信息进行量化并且不反馈该空间信道的空间 信道方向向量指示和空间信道质量指示。 在这种情况下, 作为反馈信 息的信道方向向量的数量和使用码本指示仅指示需要反馈的空间信 道的数量, 能够大大消除空间信道的反馈冗余。
[86] 最后,发送单元 640按照图 3所示的反馈格式将反馈信息确定单 元 630所确定的 NCI、 CDI、 以及 CQI, 通过物理上行控制信道或者 周期 /非周期物理上行共享信道等反馈给基站。 当然, 在各空间信道 方向向量均釆用一个量化码本,发送单元 640仅需发送需要反馈的空 间信道的数量, 实现了空间信道的反馈冗余, 提高了系统性能。
[87] 需要指出的是,根据本发明的空间信道状态反馈方法及其装置也 适用于改进的迫零波束成型多用户 MIMO系统, 例如规则化迫零波 束成型多用户 MIMO系统。 另外, 根据本发明的空间信道状态反馈 方法及其装置也适用于 Wimax等无线通信系统。
[88] 如上所详细描述的,本发明在反馈过程中考虑用户空间信道被调 度的可能性。 利用调度可能性对空间信道进行分层次量化, 进一步消 除了空间信道的反馈冗余, 实现了系统容量性能和反馈开销较好折 中。而且,对于某一移动台,他未知其它移动台的空间信道方向信息。 各空间信道的特征值与最大特征值的比值能够较好反映这一空间信 道被调度的可能性,在移动台通过这个比值调整码本量化的等级的方 法比较合理。
[89] 这里还应该指出的是, 在上面对本发明具体实施例的描述中, 针 对一种实施方式描述和 /或示出的特征可以以相同或类似的方式在一 个或更多个其它实施方式中使用, 与其它实施方式中的特征相组合, 或替代其它实施方式中的特征。
[90] 应该强调, 术语 "包括 /包含" 在本文使用时指特征、 要素、 步 骤或组件的存在, 但并不排除一个或更多个其它特征、 要素、 步骤或 组件的存在或附加。
[91] 此外, 本发明的方法不限于按照说明书中描述的时间顺序来执 行, 也可以按照其他的时间顺序地、 并行地或独立地执行。 因此, 本 说明书中描述的方法的执行顺序不对本发明的技术范围构成限制。
[92] 尽管上面已经通过对本发明的具体实施例的描述对本发明进行 了披露, 但是, 应该理解, 本领域的技术人员可在所附权利要求的精 神和范围内设计对本发明的各种修改、 改进或者等同物。 这些修改、 改进或者等同物也应当被认为包括在本发明的保护范围内。
附记
附记 1. 一种空间信道状态反馈方法, 包括:
确定空间信道被调度的可能性;
根据空间信道被调度的可能性确定反馈信息; 以及
发送所确定的反馈信息;
其中,对被调度的可能性高的空间信道使用比被调度的可能性低 的空间信道多的反馈信息。
附记 2. 根据附记 1所述的空间信道状态反馈方法, 其中反馈信 息包括信道方向向量的数量和使用码本指示、空间信道方向向量指示 和空间信道质量指示。
附记 3. 根据附记 2所述的空间信道状态反馈方法, 其中所述确 定空间信道被调度的可能性包括:
通过信道估计获取空间信道矩阵 H;
对空间信道矩阵 H进行奇异值分解;
按照从大到小的顺序排列奇异值 σι≥σ2≥· ..≥^, 其中 L表示移动 台天线数量; 以及 分别计算^ Κι≤ ≤ζ 作为每一个空间信道被调度的可能性。 附记 4. 才艮据附记 3所述的空间信道状态反馈方法, 还包括: 从广播信道接收各码本使用的阔值区间; 并且
其中, 根据空间信道被调度的可能性确定反馈信息包括: ^ ^{\<i<L)的值和从广播信道接收的各码本使用的阔值区间, 确定每一个空间信道方向向量釆用的量化码本; 以及 根据所确定的每一个空间信道方向向量所釆用的量化码本确定 信道方向向量的数量和使用码本指示。
附记 5. 才艮据附记 4 所述的空间信道状态反馈方法, 其中对于 (1≤ ≤ 的值大的空间信道方向向量使用高精度码本进行量化,对于
^{\<i<L)的值小的空间信道方向向量使用低精度码本进行量化。 附记 6. 才艮据附记 5所述的空间信道状态反馈方法, 其中量化码 本为 DFT矩阵码本、 随机量化码本、 Grassamannian码本或常模码 本。
附记 7. 根据附记 4所述的空间信道状态反馈方法, 其中根据空 间信道被调度的可能性确定反馈信息还包括:
计算空间信道矩阵 H右奇异向量 {χ,ν^.,ν^;
根据各空间方向向量 V,. (l< < L)和确定的相应量化码本,从量化码 本集合 C中选择与空间方向向量 V,具有最小夹角的向量 作为反馈 信息中各空间信道需要反馈的空间信道方向向量指示; 以及
根据各空间信道的奇异值 σ,. (1≤ ≤ )、右奇异向量 V,. (1< < L)和量化 码本 C获取反馈信息中各空间信道需要反馈的空间信道质量指示。
附记 8. 根据附记 7所述的空间信道状态反馈方法, 其中对于相 应于最低调度可能性的空间信道的反馈信息不进行发送。
附记 9. 根据附记 7所述的空间信道状态反馈方法, 其中 各空间信道方向向量均釆用一个量化码本; 如果^^ <i≤L)的值小于从广播信道接收的阔值区间,不对该空间 信道的信息进行量化并且不反馈该空间信道的空间信道方向向量指 示和空间信道质量指示; 以及 作为反馈信息的信道方向向量的数量和使用码本指示仅指示需 要反馈的空间信道的数量。
附记 10.才艮据附记 1至 9任一所述的空间信道状态反馈方法,其 中通过物理上行控制信道或者周期 /非周期物理上行共享信道发送所 确定的反馈信息。
附记 11. 一种空间信道状态反馈装置, 包括:
调度可能性确定单元, 配置为用于确定空间信道被调度的可能 性;
反馈信息确定单元,配置为用于根据空间信道被调度的可能性确 定反馈信息; 以及
发送单元, 配置为用于发送所确定的反馈信息;
其中,对被调度的可能性高的空间信道使用比被调度的可能性低 的空间信道多的反馈信息。
附记 12. 根据附记 11所述的空间信道状态反馈装置, 其中反馈 信息包括信道方向向量的数量和使用码本指示、空间信道方向向量指 示和空间信道质量指示。
附记 13. 才艮据附记 12所述的空间信道状态反馈装置, 其中所述 调度可能性确定单元
通过信道估计获取空间信道矩阵 H;
对空间信道矩阵 H进行奇异值分解;
按照从大到小的顺序排列奇异值 σι≥σ2≥·..≥^, 其中 L表示移动 台天线数量; 以及 分别计算^ Ki≤ ≤ 作为每一个空间信道被调度的可能性。 附记 14. 才艮据附记 13所述的空间信道状态反馈装置, 还包括: 阔值区间接收单元,配置为用于从广播信道接收各码本使用的阔 值区间; 并且
其中所述反馈信息确定单元 ^ ^{\<i<L)的值和从广播信道接收的各码本使用的阔值区间, 确定每一个空间信道方向向量釆用的量化码本; 以及 根据所确定的每一个空间信道方向向量所釆用的量化码本确定 信道方向向量的数量和使用码本指示。
附记 15. 根据附记 14所述的空间信道状态反馈装置, 其中对于 (1≤ ≤ 的值大的空间信道方向向量使用高精度码本进行量化,对于
^{\<i<L)的值小的空间信道方向向量使用低精度码本进行量化。 附记 16. 根据附记 15所述的空间信道状态反馈装置, 其中量化 码本为 DFT矩阵码本、 随机量化码本、 Grassamannian码本或常模 码本。
附记 17. 根据附记 14所述的空间信道状态反馈装置, 其中所述 反馈信息确定单元还
计算空间信道矩阵 H右奇异向量 {χ,ν^.,ν^;
根据各空间方向向量 V,. (l< < L)和确定的相应量化码本,从量化码 本集合 C中选择与空间方向向量 V,具有最小夹角的向量 作为反馈 信息中各空间信道需要反馈的信道方向向量指示; 以及
根据各空间信道的奇异值 σ,. (1≤ ≤ )、右奇异向量 V,. (1< < L)和量化 码本 C获取反馈信息中各空间信道需要反馈的信道质量指示。
附记 18. 根据附记 17所述的空间信道状态反馈装置, 其中对于 相应于最低调度可能性的空间信道的反馈信息不进行发送。
附记 19. 根据附记 17所述的空间信道状态反馈装置, 其中 各空间信道方向向量均釆用一个量化码本; 如果^^ <i≤L)的值小于从广播信道接收的阔值区间,不对该空间 信道的信息进行量化并且不反馈该空间信道的空间信道方向向量指 示和空间信道质量指示; 以及 作为反馈信息的信道方向向量的数量和使用码本指示仅指示需 要反馈的空间信道的数量。
附记 20. 才艮据附记 11至 19任一所述的空间信道状态反馈装置, 其中所述发送单元通过物理上行控制信道或者周期 /非周期物理上行 共享信道发送所确定的反馈信息。

Claims

权 利 要 求 书
1. 一种空间信道状态反馈方法, 包括:
确定空间信道被调度的可能性;
根据空间信道被调度的可能性确定反馈信息; 以及
发送所确定的反馈信息;
其中,对被调度的可能性高的空间信道使用比被调度的可能性低 的空间信道多的反馈信息。
2. 根据权利要求 1所述的空间信道状态反馈方法, 其中反馈信 息包括信道方向向量的数量和使用码本指示、空间信道方向向量指示 和空间信道质量指示。
3. 根据权利要求 2所述的空间信道状态反馈方法, 其中所述确 定空间信道被调度的可能性包括:
通过信道估计获取空间信道矩阵 H;
对空间信道矩阵 H进行奇异值分解;
按照从大到小的顺序排列奇异值 σι≥σ2≥·..≥^, 其中 L表示移动 台天线数量; 以及 分别计算^ Ki≤ ≤ 作为每一个空间信道被调度的可能性。
4. 根据权利要求 3所述的空间信道状态反馈方法, 还包括: 从广播信道接收各码本使用的阔值区间; 并且
其中, 根据空间信道被调度的可能性确定反馈信息包括: ^ ^{i≤i≤L)的值和从广播信道接收的各码本使用的阔值区间, 确定每一个空间信道方向向量釆用的量化码本; 以及 根据所确定的每一个空间信道方向向量所釆用的量化码本确定 信道方向向量的数量和使用码本指示。
5. 根据权利要求 4 所述的空间信道状态反馈方法, 其中对于 ^ (1≤ ≤ 的值大的空间信道方向向量使用高精度码本进行量化,对于
^{\ < i < L)的值小的空间信道方向向量使用低精度码本进行量化。
6. 根据权利要求 4所述的空间信道状态反馈方法, 其中 各空间信道方向向量均釆用一个量化码本; 如果^^ < i≤L)的值小于从广播信道接收的阔值区间,不对该空间 信道的信息进行量化并且不反馈该空间信道的空间信道方向向量指 示和空间信道质量指示; 以及 作为反馈信息的信道方向向量的数量和使用码本指示仅指示需 要反馈的空间信道的数量。
7. 一种空间信道状态反馈装置, 包括:
调度可能性确定单元, 配置为用于确定空间信道被调度的可能 性;
反馈信息确定单元,配置为用于根据空间信道被调度的可能性确 定反馈信息; 以及
发送单元, 配置为用于发送所确定的反馈信息;
其中,对被调度的可能性高的空间信道使用比被调度的可能性低 的空间信道多的反馈信息。
8. 根据权利要求 7所述的空间信道状态反馈装置, 其中反馈信 息包括信道方向向量的数量和使用码本指示、空间信道方向向量指示 和空间信道质量指示。
9. 根据权利要求 8所述的空间信道状态反馈装置, 其中所述调 度可能性确定单元
通过信道估计获取空间信道矩阵 Η;
对空间信道矩阵 Η进行奇异值分解; 按照从大到小的顺序排列奇异值 σι≥σ2≥· ..≥^, 其中 L表示移动 台天线数量; 以及 分别计算^ (l≤ ≤ )作为每一个空间信道被调度的可能性。
10. 根据权利要求 9所述的空间信道状态反馈装置, 还包括: 阔值区间接收单元,配置为用于从广播信道接收各码本使用的阔 值区间; 并且
其中所述反馈信息确定单元 ^ ^{i≤i≤L)的值和从广播信道接收的各码本使用的阔值区间, 确定每一个空间信道方向向量釆用的量化码本; 以及 根据所确定的每一个空间信道方向向量所釆用的量化码本确定 信道方向向量的数量和使用码本指示。
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