WO2011020235A1 - 在通信网络中用于保持预编码信道相干性的方法及装置 - Google Patents
在通信网络中用于保持预编码信道相干性的方法及装置 Download PDFInfo
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- WO2011020235A1 WO2011020235A1 PCT/CN2009/073310 CN2009073310W WO2011020235A1 WO 2011020235 A1 WO2011020235 A1 WO 2011020235A1 CN 2009073310 W CN2009073310 W CN 2009073310W WO 2011020235 A1 WO2011020235 A1 WO 2011020235A1
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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
- H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
- H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B17/00—Monitoring; Testing
- H04B17/20—Monitoring; Testing of receivers
- H04B17/24—Monitoring; Testing of receivers with feedback of measurements to the transmitter
-
- 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
-
- 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
- H04L25/0202—Channel estimation
- H04L25/0222—Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency
-
- 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
- H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
Definitions
- the present invention relates to wireless communication systems, and more particularly to a method and apparatus for processing a precoding matrix in a base station. Background technique
- the non-codebook based precoding technology is based on the inherent reciprocity of the channel, that is, the symmetry of the uplink and downlink frequencies.
- LTE-A Advanced - Long Term Evolution
- TDD Time Division Duplex
- the precoding matrix is obtained at the transmitting end.
- the transmitting end uses the predicted Channel Status Information (CSI) to calculate the precoding matrix.
- CSI Channel Status Information
- the commonly used precoding matrix calculation methods include Singular Value Decomposition (SVD) and uniform channel decomposition (Uniform Channel Decomposizion). , UCD), QR algorithm.
- Figure 1 shows the structure of a transmitter and receiver in a Multiple Input Multiple Output (MIMO) system based on SVD decomposition.
- the transmitter of the base station 1 has N antennas, and the receiver of the mobile terminal 2 has M antennas as an example.
- the effective channel state information (CSI), that is, the dimension of the spatial channel matrix is MXN, H according to The singular value decomposition technique shown by equation (1) treats # as follows:
- the matrix c/ and are respectively the left singular vector matrix and the right singular vector matrix of the matrix #, which is the threshold!
- the corpse is the hermitian operation, indicating that the complex array is transposed (transposed complex conjugate d That is, the dimension of C/ is N x N, V e C MxM , that is, the dimension is ⁇ x M.
- the rank of the CSI matrix should satisfy ⁇ min(M,N).
- Diagonal matrix /) can be table
- Sequence 4 is not listed, and 4 > 2 >... r .
- the obtained right singular vector matrix is a linear precoding matrix, where each column of ! / is called an eigenvector (Eigenvector ) of ff , which is related to the characteristic mode (Eigenmode ) of the communication channel. . If the rank adaptation is required, the column vector corresponding to the larger singular value is selected from the right singular vector matrix to form a precoding matrix according to the size of the rank.
- the non-codebook precoding method requires the use of dedicated pilots, and the data symbols and pilot symbols are used together for precoding operations, so that the receiving end only needs to obtain the equivalent channel after precoding through channel estimation, thereby facilitating data solution. Tune.
- precoding granularity is the unit for precoding, such as one or more resource blocks (RBs).
- Figure 2 shows the precoding performance corresponding to different precoding granularity under the condition of single layer beamforming (BF). It can be seen from the figure that under the same signal-to-noise ratio, the smaller the pre-coding granularity used, the larger the throughput of the system.
- the pre-coded granularity is taken as 10, that is, the same precoding matrix is used for the 10 RBs. However, the channel response corresponding to the 10 RBs is different. Therefore, when the precoding granularity is larger, all the RBs in the precoding granularity are weighted by a precoding matrix. The less the precoding matrix can accurately match the actual channel state of each RB in the precoding unit. Therefore, from the viewpoint of the precoding matrix matching channel to obtain a larger precoding gain, it is desirable that the precoding granularity has a small value.
- CE Channel Estimation
- MU-MIMO Multi-User Multiple Input Mutiple Output
- CoMP Coordinative Multiple Point
- the channel estimation can only be performed within the precoding granularity, because different precoding matrices have different precoding matrices, and different precoding matrices will destroy multiple precoding units.
- Channel coherency Therefore, from the perspective of the accuracy of precoding, it is desirable that the precoding granularity is as small as possible; and from the perspective of channel estimation, it is desirable that the granularity of the precoding is as large as possible, and therefore, the two different factors are mutual Restricted.
- the base station dynamically monitors the channel, acquires the real-time state of the channel, selects corresponding precoding granularity according to information such as channel coherence and signal to interference and noise ratio, and then the base station selects the precoding.
- the granularity is sent to the mobile terminal, and is used to notify the terminal base station of the granularity of the precoding, and the mobile terminal performs channel estimation inside the resource block defined by the precoding granularity according to the indication information.
- the indication information needs to notify the terminal in real time, and therefore occupies considerable time-frequency resources. Summary of the invention
- the present invention analyzes channel coherence between multiple precoding units.
- coherence that is, the statistical characteristics of the channel, that is, the frequency domain selection characteristics and time-varying characteristics of the channel.
- CTFP Coherent Time Fringing Procoding
- the present invention proposes a Coherent Time Fringing Procoding (CTFP) method, which makes precoding consider both coherence between channels and system capacity. That is, the base station (eNB) can adjust the phase and/or amplitude of the precoding matrix corresponding to each precoding unit to maintain the coherency of the related information of the entire precoding channel, and the related information of the precoding channel includes, for example, CSI or pre A matrix of eigenvalues of the coded channel.
- CFP Coherent Time Fringing Procoding
- the mobile terminal can perform channel estimation based on reference signals (RSs) of multiple precoding units, thereby avoiding that the mobile terminal in the prior art can only be pre-
- RSs reference signals
- the limitation of channel estimation is performed internally by one or more resource blocks defined by the coded granularity.
- the base station can employ as small a precoding granularity as possible without affecting the mobile terminal for channel estimation.
- a method for transmitting precoded matrix weighted pilots and/or data in a base station of a wireless communication system comprising the steps of: The state information is subjected to matrix decomposition to obtain an initial precoding matrix, wherein the initial precoding matrix is not unique; linearly transforming the initial precoding matrix such that under the weighted condition of the precoding matrix after the linear transformation Correlating information of the first corrected precoding channel to maintain coherency; transmitting, to the mobile terminal, pilot and/or data weighted by the transformed precoding matrix;
- a processing apparatus for transmitting precoded matrix weighted pilots and/or data in a base station of a wireless communication system, wherein the base station acquires channel state information, including: initial pre- a coding matrix obtaining apparatus, configured to perform matrix transformation on the channel state information to obtain an initial precoding matrix, where the initial precoding matrix is not unique; and correcting means, configured to perform linear transformation on the initial precoding matrix And the related information of the corrected precoding channel under the linearly transformed precoding matrix weighting condition is kept coherent; the transmitting device is configured to send, to the mobile terminal, the pilot and the weighted pilot of the transformed precoding matrix / or data.
- the base station does not need to provide the mobile terminal with indication information of the precoding granularity, thereby saving the corresponding signaling overhead;
- the scheme can select the optimal coding granularity between each group of base stations and users without considering the channel characteristics of the coordinated base station or the terminal.
- FIG. 1 is a structural diagram of a transmitter and a receiver in a multiple input multiple output (MIMO) system based on SVD decomposition;
- MIMO multiple input multiple output
- Figure 2 shows the precoding performance corresponding to different precoding granularity under the condition of single layer beamforming (BF);
- Figure 3 shows the absolute value of the amplitude of the channel after the precoding operation through the initial precoding matrix
- FIG. 4 shows the phase of the channel after the precoding operation through the initial precoding matrix
- FIG. 5 shows a method flow diagram according to an embodiment of the present invention
- FIG. 6 shows the phase relative to FIG. Rotating channel curve
- Figure 9 illustrates a method flow diagram in accordance with another embodiment of the present invention
- Figure 10 illustrates a block diagram of a device in accordance with an embodiment of the present invention
- Figure 11 shows a block diagram of a device in accordance with another embodiment of the present invention.
- H, V x D ( 2 )
- 1 is the sequence number of the precoding unit
- A is the eigenvalue matrix, that is, the singular value matrix, which is the Hermitian conjugate transform of ⁇ .
- the weighting matrix ⁇ and ⁇ of SVD are not unique, that is, for example, after the first column of ⁇ can be rotated by 7T ⁇ 2, equation (1) still holds, or the first column of the sum is Rotate After the equation (1) is still true, or if the same column of the sum is rotated by 7T ⁇ 2, the equation (1) still holds.
- FIG. 3 shows the absolute value of the amplitude of the initial precoding channel after the precoding operation by the initial precoding matrix
- FIG. 4 shows the initial precoding The phase of the initial precoded channel after the precoding operation of the matrix.
- /2' indicates the impulse response of the channel of the antenna TX1 to the antenna RX
- /3 ⁇ 2 2 indicates the impulse response of the channel of the antenna TX1 to the antenna RX2
- ⁇ indicates the impact of the channel of the antenna TX2 to the antenna RX1.
- Response; /3 ⁇ 4 2 represents the impulse response of the channel from antenna TX2 to antenna RX2.
- the matrix obtained by SVD decomposition of the matrix is used as the initial precoding matrix of the channel corresponding to each precoding unit.
- the sequence number of the granularity, ⁇ represents the initial precoding channel.
- the parameters of the channel are estimated using a DFT based channel estimation algorithm. It is easy to see that the absolute value of the amplitude of the initial precoded channel is coherent/smooth, and there are some hopping points or hopping segments in the phase curve. Moreover, a column of the initial precoded channel (e.g., a feature vector) has the same hopping segment.
- the precoding subchannel corresponding to different SVD decomposition modes is used for each subcarrier, that is, the precoding granularity shown in FIG. 3 and FIG. It is 1 subcarrier.
- RB Resource Block
- a possible hop point occurs between the edges of two adjacent resource blocks.
- the precoding unit includes a plurality of resource blocks, a possible trip point occurs between the edges of two adjacent precoding units.
- each resource block includes 12 subcarriers.
- the base station 1 can perform downlink channel estimation according to the received uplink reference signal sent by the mobile terminal 2 to obtain a channel matrix; in the FDD system, the mobile terminal 2 measures the downlink channel, and the measured downlink channel feedback To the base station 1, therefore, the base station 1 acquires the downlink channel matrix.
- the base station 1 performs matrix decomposition according to the downlink channel matrix to obtain an initial precoding matrix.
- the initial precoding matrix V is obtained using SVD decomposition.
- QR decomposition can also be used to obtain an initial precoding matrix Q. Where Q represents an orthogonal matrix and R represents an upper triangular matrix. Note that the solutions to these matrix decompositions are not unique. Therefore, the corresponding precoding matrix obtained is not unique.
- phase rotation matrix is used for maintaining the coherence of the channel precoded with the initial precoding matrix corresponding to the plurality of different precoding units, and therefore, the new precoding matrix is expressed as:
- Equation (3) it is a diagonal matrix for adjusting the phase of the initial precoding channel so that the channel coherence between the plurality of precoded units is restored.
- Figure 5 illustrates a method flow diagram in accordance with an embodiment of the present invention.
- step S50 the base station 1 detects the phase of the initial precoding channel on each subcarrier and acquires the phase of the initial precoding channel on the adjacent subcarrier of each subcarrier.
- the base station 1 wants to examine the phase corresponding to one subcarrier, and hereinafter, the subcarrier is referred to as a target subcarrier.
- step S51 the base station 1 selects the phase of the initial precoding channel on the target subcarrier and the adjacent subcarrier of the target subcarrier, optionally, the previous one of the target subcarrier.
- the difference between the phases of the corrected (initial) precoding channels on the subcarriers is compared with (-2 r , - r A ⁇ , 2 ⁇ ).
- the difference is closest to 0 or ⁇ 2 ⁇ , indicating that the phase of the initial precoding channel on the target subcarrier does not phase jump with respect to the phase of the corrected (initial) precoding channel on the previous subcarrier; If the difference is closest to ⁇ 7 ⁇ , it indicates that the phase of the initial precoding channel on the target subcarrier has hopped relative to the phase of the corrected (initial) precoding channel on the previous subcarrier. For example, if i takes the initial precoding channel corresponding to 1, and the phase of / 21 is relative to the initial precoding channel corresponding to the zero of i,
- the phase of the initial precoding channel on the second subcarrier is compared with the phase of the initial precoding channel on the first subcarrier that has been corrected.
- the precoding unit includes a plurality of subcarriers
- the precoding matrices used by the respective subcarriers in the same precoding unit are the same, we can extract only the subcarriers having the same intrasequence number in the different precoding units.
- the corresponding precoding channels are compared. For example, in step S50, the base station 1 detects the phase of the initial precoding channel on the first subcarrier in each precoding unit.
- step S51 the phase of the precoding channel of each subcarrier in the i-th precoding unit is adjusted accordingly.
- the signal from the transmitter to the receiver usually contains various signal components such as reflection, diffraction and diffraction. Different signal components arrive at the receiver with different strength, time and direction, and the difference in different environments. Very big. Due to different multipath components The arrival time causes the time domain of the received signal to broaden. The basic feature of multipath propagation is that the transmitted signals arriving at the receiver have different attenuation factors and delays. The extension of the received signal in the time domain is called delay spread, which directly reflects the frequency domain selectivity of the channel (signal Different spectrums carry different powers, and delay spread is defined as the largest delay among multiple paths. Therefore, we further observe the precoding channel with phase rotation, that is, correct the time domain characteristics of the precoding channel.
- each resource block with phase rotation is precoded to approximate a more realistic scenario.
- the precoded channel with phase rotation is converted to the time domain (120 point IFFT with respect to 10 resource block resource allocations) to observe statistical properties, as shown in Figures 7 and 8.
- the precoded corrected precoding channel has statistical characteristics that are very similar to the unprecoded raw channel. Therefore, the user equipment can perform channel estimation on the allocated resources to determine parameters of the precoding channel.
- phase rotation can also be considered for phase rotation if desired. That is, one or more symbols (slots, ie, Time Slot, TS or Subframe) in the precoding granularity and one or more symbols in the adjacent precoding granularity (slots) are considered. Coherence between or sub-frames.
- the channel state information is obtained.
- the base station 1 can perform downlink channel estimation according to the received uplink reference signal sent by the mobile terminal 2 to obtain a channel matrix; in the FDD system, the mobile terminal 2 measures the downlink channel, and the measured downlink signal The channel is fed back to the base station 1, and therefore, the base station 1 acquires the downlink channel matrix.
- the base station 1 performs matrix decomposition according to the downlink channel matrix to obtain an initial precoding matrix.
- the initial precoding matrix V is obtained using SVD decomposition.
- QR decomposition can also be used to obtain an initial precoding matrix Q. Where Q represents an orthogonal matrix and R represents an upper triangular matrix. Note that the solutions to these matrix decompositions are not unique. Therefore, the corresponding precoding matrix obtained is not unique.
- the matrix can also be used to smooth the amplitude of the initial precoded channel, if desired.
- an FFT-based smoothing scheme will be specifically described with reference to FIG.
- the phase smoothing can be performed in an overall initial precoding channel consisting of an initial precoding channel corresponding to a plurality of precoding granularities, and we denote the overall initial precoding channel matrix by flick ⁇ ec .
- step S90 the base station 1 performs an inverse inverse Fourier Transform (IFFT) operation on the channel to obtain a channel impact corresponding to the time domain corresponding to h;
- IFFT inverse inverse Fourier Transform
- step S91 the base station 1 truncates h, retains only a certain length (for example, the length of the cyclic prefix Cyclic Prefix, CP ), and zeros the cut point to obtain /
- the base station 1 can only fill the points in / ⁇ before the time point corresponding to the maximum multipath delay desired, according to the maximum multipath delay desired, and fill all the remaining other points with zeros. That is, it is equivalent to shortening the maximum multipath delay in the time domain.
- step S92 the base station 1 performs a Fourier Transform (FFT) on / ⁇ to restore the smoothed channel.
- FFT Fourier Transform
- step S93 according to the acquired Get the correction matrix
- ⁇ / denotes scalar quantity division (element-wise division), which means that each element in the matrix is extracted, and the value of each element in multiple precoding units is divided by scalar.
- the amplitude smoothing operation can also consider time domain coherence if needed. That is, the coherence between one or more symbols (slots or subframes) in the precoded granularity and one or more symbols (slots or subframes) in the adjacent precoded granularity is examined. To maintain temporal coherence between different precoded granularities, the operations performed are fully similar to those that maintain frequency domain coherence. Of course, the operation of correcting to maintain temporal coherence may be performed after the operation of correcting to maintain frequency domain coherence, or may be performed separately.
- Option 3 Combination of phase rotation and amplitude smoothing
- the first precoding matrix can be corrected by combining Scheme 1 with Scheme 2.
- the phase-rotated matrix can be subjected to amplitude smoothing after the phase rotation operation. To further improve the coherence of the precoding matrix.
- Case A is completely transparent to the terminal, and no changes are required on the mobile terminal 2. Since the corrected precoding channel under the corrected precoding matrix weighting satisfies the coherence, the mobile terminal 2 can perform joint channel estimation across different precoding granularities under the three schemes.
- the matrix ( ⁇ ) can be used to smooth the eigenvalue matrix of the precoding channel ⁇ , instead of im, that is, make D, G, a diagonal fading of flat fading.
- the initial precoding matrix ⁇ > may be linearly transformed, for example, the inverse matrix of the left multiplied U, and then, according to the scheme 1 or the scheme 2 or the scheme 3 in the case ⁇ , the subsequent operations are performed. Note that when using the second option for amplitude correction, formula (4)
- G H — . /(UD) needs to be corrected.
- FIG. 10 shows the root A block diagram of a device in accordance with an embodiment of the present invention.
- the processing device 10 of FIG. 10 is located in a base station 1, and the processing device 10 includes an initial precoding matrix acquiring device 100, a correcting device 101, and a transmitting device 102.
- the correction device 101 further includes a first correction matrix acquisition device 1010, a rotation device 1011, a second correction matrix acquisition device 1012, an amplitude adjustment device 1013, and an eigenvalue matrix acquisition device 1014.
- each resource block includes 12 subcarriers.
- the initial precoding matrix acquisition means 100 acquires channel state information.
- the initial precoding matrix obtaining apparatus 100 may perform downlink channel estimation according to the received uplink reference signal sent by the mobile terminal 2 to acquire a channel matrix; in the FDD system, the mobile terminal 2 measures the downlink channel, and measures The obtained downlink channel is fed back to the initial precoding matrix acquiring apparatus 100, and therefore, the base station 1 acquires the downlink channel matrix.
- the initial precoding matrix obtaining apparatus 100 performs matrix decomposition according to the downlink channel matrix to obtain an initial precoding matrix.
- the initial precoding matrix V is obtained using SVD decomposition.
- QR decomposition can also be used to obtain an initial precoding matrix Q. Where Q represents an orthogonal matrix and R represents an upper triangular matrix. Note that the solutions to these matrix decompositions are not unique. Therefore, the corresponding precoding matrix obtained is also not unique.
- a correction matrix is used for maintaining the coherence of the channel precoded with the initial precoding matrix corresponding to the plurality of different precoding units, and therefore, the new precoding matrix is expressed as:
- the first correction matrix acquisition means 1010 in the correction device 101 detects each sub-child The phase of the initial precoded channel on the carrier and the phase of the initial precoded channel on the adjacent subcarriers of each subcarrier.
- the base station 1 wishes to examine the phase corresponding to one subcarrier, and hereinafter, the subcarrier is referred to as a target subcarrier.
- the phase of the initial precoding channel on the target subcarrier and the adjacent subcarrier of the target subcarrier, optionally, the corrected (initial) precoding channel on the previous subcarrier of the target subcarrier The difference between the 4 head positions is ( -2 ⁇ , - ⁇ , 0, ⁇ , 2 ⁇ ) into #1 ⁇ . If the difference is closest to 0 or ⁇ 2 ⁇ , it indicates the initial on the target subcarrier.
- the phase of the precoded channel does not phase jump with respect to the phase of the corrected (initial) precoding channel on the previous subcarrier; conversely, if the difference is closest to ⁇ ; ⁇ , indicating the initial on the target subcarrier
- the phase of the precoded channel is hopped relative to the phase of the corrected (initial) precoding channel on the previous subcarrier.
- i takes the initial precoding channel corresponding to 1 and the phase of / 7 21 relative to i
- the difference between the phase of / z 21 is closest to ⁇
- the phase of /3 ⁇ 4 2 and / 3 ⁇ 4 2 is taken from i in the initial precoding channel corresponding to i. 0 corresponding to the initial precoding channel, / 3 ⁇ 4 phase 2 and / 3 ⁇ 4 2 of 2 closest to the difference, then
- the phase of the initial precoding channel on the second subcarrier is compared with the phase of the initial precoding channel on the first subcarrier that has been corrected.
- the transmitting device 102 transmits the precoding matrix weighted data or pilot corrected by the first correcting means to the mobile terminal 2.
- the precoding unit includes a plurality of subcarriers
- the precoding matrices used by the respective subcarriers in the same precoding unit are the same, only subcarriers having the same intrasequence number in different precoding units can be fetched.
- Corresponding precoding channels are compared.
- the first correction means acquisition means 1010 detects the phase of the initial precoding channel on the first subcarrier in each precoding unit.
- the phase rotation means 1011 adjusts the phase of the precoding channel of each of the i-th precoding units accordingly.
- the signal from the transmitter to the receiver usually contains various signal components such as reflection, diffraction and diffraction. Different signal components arrive at the receiver with different strength, time and direction, and the difference in different environments. Very big. Due to the different arrival times of different multipath components, the time domain of the received signal is broadened. The basic feature of multipath propagation is that the transmitted signals arriving at the receiver have different attenuation factors and delays. The extension of the received signal in the time domain is called delay spread, which directly reflects the frequency domain selectivity of the channel (signal Different spectrums carry different powers, and delay spread is defined as the largest delay among multiple paths. Therefore, we further observe the precoding channel with phase rotation, that is, correct the time domain characteristics of the precoding channel.
- each resource block with phase rotation is precoded to approximate a more realistic scenario.
- the precoded channel with phase rotation is converted to the time domain (120 point IFFT with respect to 10 resource block resource allocations) to observe statistical properties, as shown in Figures 7 and 8.
- the precoded corrected precoding channel has statistical characteristics that are very similar to the unprecoded raw channel. Therefore, the user equipment can perform channel estimation on the allocated resources to determine parameters of the precoding channel.
- phase rotation can also take into account time domain coherence if needed. That is, one or more symbols (slots, ie, Time Slot, TS or Subframe) in the precoding granularity are examined with one or more symbols (slots) of adjacent precoding granularity. Coherence between or sub-frames.
- the base station 1 can perform downlink channel estimation according to the received uplink reference signal sent by the mobile terminal 2 to obtain a channel matrix; in the FDD system, the mobile terminal 2 measures the downlink channel, and the measured downlink channel feedback To the base station 1, therefore, the base station 1 acquires the downlink channel matrix.
- the base station 1 performs matrix decomposition according to the downlink channel matrix to obtain an initial precoding matrix.
- the initial precoding matrix V is obtained using SVD decomposition.
- QR decomposition can also be used to obtain an initial precoding matrix Q. Where Q represents an orthogonal matrix and R represents an upper triangular matrix. Note that the solutions to these matrix decompositions are not unique. Therefore, the corresponding precoding matrix obtained is not unique.
- the matrix can also be used to smooth the amplitude of the initial precoded channel, if desired.
- an FFT-based smoothing scheme will be specifically described with reference to FIG.
- the phase smoothing can be performed in an overall initial precoding channel consisting of an initial precoding channel corresponding to a plurality of precoding granularities, and we denote the overall initial precoding channel matrix by flick ⁇ ec .
- an inverse Fourier transform (IFFT) operation on the channel H int precode is performed by the inverse Fourier transform device (not shown) in the second correction matrix acquiring unit 1012, and the channel impact corresponding to the time domain is obtained.
- IFFT inverse Fourier transform
- the truncation device (not shown) in the second correction matrix acquisition device 1012 truncates / ⁇ , retaining only a certain length (for example, the length of the cyclic prefix Cyclic Prefix, CP ), and filling in the cut points Zero, h clip -
- the truncation device can only obtain the maximum multipath delay that is expected, and only retain the point in / ⁇ before the point in time corresponding to the maximum multipath delay that is desired, and the remaining others Fill in all the points. That is, it is equivalent to shortening the maximum multipath delay in the time domain.
- the shorter the maximum multipath delay in the time domain the smoother the amplitude of the channel in the frequency domain.
- the Fourier transform device (not shown) in the second correction matrix acquisition device 1012 performs a Fourier Transform (FFT) to restore the smoothed smooth smoothing
- FFT Fourier Transform
- the second correction matrix obtaining means 1012 is based on the acquired Get the correction matrix
- ⁇ / denotes scalar quantity division (element-wise division), which means that each element in the matrix is extracted, and the value of each element in multiple precoding units is divided by scalar.
- the amplitude smoothing means 1013 performs an amplitude smoothing operation on the initial precoded channel based on the precoding matrix corrected by the second correction matrix G acquired by the second correcting means.
- the transmitting device 101 weights the data and the pilot with the corrected precoding matrix corrected by the second correction matrix, and transmits it to the mobile terminal 2.
- the amplitude smoothing operation can also consider time domain coherence if needed. That is, the coherence between one or more symbols (slots or subframes) in the precoded granularity and one or more symbols (slots or subframes) in the adjacent precoded granularity is examined. To maintain temporal coherence between different precoded granularities, the operations performed are completely similar to those of maintaining frequency domain coherence. Of course, the operation of correcting to maintain temporal coherence may be performed after the operation of correcting to maintain frequency domain coherence, or may be performed separately.
- Option III Combination of phase rotation and amplitude smoothing
- Scheme I can be combined with Scheme II to correct the initial precoding matrix.
- the phase-rotated matrix can be subjected to amplitude smoothing after the phase rotation operation. To further improve the coherence of the precoding matrix.
- the mobile terminal 2 can perform joint channel estimation across different precoding granularities.
- the matrix ( ⁇ ) can be used to smooth the eigenvalue matrix of the precoding channel ⁇ , instead of im, that is, make D, G, a diagonal fading of flat fading.
- the mobile terminal 2 can perform joint channel estimation across different precoding granularities. While the invention has been illustrated and described with reference to the particular embodiments
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Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US13/390,586 US8948297B2 (en) | 2009-08-17 | 2009-08-17 | Method of maintaining coherency of a precoding channel in a communication network and associated apparatus |
CN200980158998.5A CN102415005B (zh) | 2009-08-17 | 2009-08-17 | 在通信网络中用于保持预编码信道相干性的方法及装置 |
KR1020127006759A KR101449443B1 (ko) | 2009-08-17 | 2009-08-17 | 통신 네트워크에서 프리코딩 채널 코히어런시 유지 방법 및 장치 |
RU2012110200/07A RU2494541C1 (ru) | 2009-08-17 | 2009-08-17 | Способ и ассоциированное устройство для сохранения когерентности канала предварительного кодирования в сети связи |
BR112012003477A BR112012003477A2 (pt) | 2009-08-17 | 2009-08-17 | "método para manter coerência de um canal de pré-codificação em uma rede de comunicação e aparelho associado." |
PCT/CN2009/073310 WO2011020235A1 (zh) | 2009-08-17 | 2009-08-17 | 在通信网络中用于保持预编码信道相干性的方法及装置 |
EP09848376.1A EP2469729B1 (en) | 2009-08-17 | 2009-08-17 | Method and apparatus for keeping the precoding channel coherency in a communication network |
JP2012525012A JP5624138B2 (ja) | 2009-08-17 | 2009-08-17 | 通信ネットワーク内でプリコーディングチャネルのコヒーレンシーを維持する方法および関連装置 |
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CN109842576B (zh) * | 2017-10-01 | 2020-10-09 | 维沃移动通信有限公司 | 利用控制资源集的预编码粒度进行信道估计的方法和设备 |
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CN115118317A (zh) * | 2022-05-27 | 2022-09-27 | 成都中科微信息技术研究院有限公司 | 一种适用于毫米波的迭代预编码多流方法、介质及装置 |
CN115118317B (zh) * | 2022-05-27 | 2023-10-03 | 成都中科微信息技术研究院有限公司 | 一种适用于毫米波的迭代预编码多流方法、介质及装置 |
Also Published As
Publication number | Publication date |
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KR20120055696A (ko) | 2012-05-31 |
US8948297B2 (en) | 2015-02-03 |
CN102415005A (zh) | 2012-04-11 |
EP2469729A1 (en) | 2012-06-27 |
EP2469729B1 (en) | 2017-08-16 |
JP2013502756A (ja) | 2013-01-24 |
US20120140851A1 (en) | 2012-06-07 |
KR101449443B1 (ko) | 2014-10-13 |
RU2494541C1 (ru) | 2013-09-27 |
BR112012003477A2 (pt) | 2017-05-23 |
JP5624138B2 (ja) | 2014-11-12 |
RU2012110200A (ru) | 2013-09-27 |
EP2469729A4 (en) | 2013-01-30 |
CN102415005B (zh) | 2015-04-08 |
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