MIMO-OFDM system and pre-coding and feedback method therein
First Claim
1. An antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system, comprising:
- MR receiving antennas;
MR frequency band demodulators, coupled to the receiving antennas for demodulating the signals received by the receiving antennas, wherein each frequency band demodulator obtains tones of N different frequency bands;
a channel estimator &
feedback parameter generator, coupled to the frequency band demodulators and used for estimating the obtained channel state information (CSI) of the N different frequency bands according to the outputs from the frequency band demodulators and producing a feedback parameter according to the CSI;
N detectors, coupled to the frequency band demodulators and the channel estimator &
feedback parameter generator and used for conducting decoding on the outputs from the frequency band demodulators according to the CSI and obtaining N receiving data vectors, wherein a single detector receives the tones with a same frequency band output from all the frequency band demodulators;
a vector-coding matrix generator, used for producing N spatial vector-coding matrixes W(n) according to the feedback parameter, wherein when H(n) is a MIMO channel matrix of the n-th frequency band, the QR decomposition of H(n) is expressed by;
H(n)=R(n)Q*(n), wherein R(n) is a lower triangular matrix with a dimension of MR×
MT, Q(n) is an orthonormal matrix with a dimension of MT×
MT and Q*(n) represents the complex conjugate transpose matrix of Q(n), and when Q(n)=[q1(n) q2(n) . . . qMT(n)], qm(n) represents the m-th column vector in the matrix Q(n), thus;
W(n)=[q1(n)q2(n) . . . qM(n)];
N coders, coupled to the vector-coding matrix generator and used for receiving N transmission data vectors, wherein each transmission data vector has a dimension of M×
1, and according to the vector-coding matrixes, the coders conduct coding on the transmission data vectors and each coder outputs MT tones with a same frequency band but different from the other coders;
MT transmitting antennas; and
MT frequency band modulators, coupled to the coders and the transmitting antennas and used for conducting modulations on the outputs from the coders, then outputting the modulated signals at the transmitting antennas, wherein each frequency band modulator receives the tones of different frequency bands output from all the coders, wherein MR, MT, M, N, m and n are natural numbers and 0<
M≦
MT, 0<
n≦
N.
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Abstract
The present invention provides an antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system and a pre-coding and feedback method used in the same. The present invention uses QR decompositions of the MIMO channel matrixes to parameterize the channel state information (CSI) of every OFDM frequency band. In addition, the present invention feeds back the information related to θ and φ in the Givens rotation matrixes of the partial frequency bands and then uses an interpolation method to generate θ and φ in the Givens rotation matrixes of all the frequency bands, which further is able to represent the CSI of all the frequency bands. In this way, the present invention has advantages of low complexity and low feedback rate requirement.
39 Citations
17 Claims
-
1. An antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system, comprising:
-
MR receiving antennas;
MR frequency band demodulators, coupled to the receiving antennas for demodulating the signals received by the receiving antennas, wherein each frequency band demodulator obtains tones of N different frequency bands;
a channel estimator &
feedback parameter generator, coupled to the frequency band demodulators and used for estimating the obtained channel state information (CSI) of the N different frequency bands according to the outputs from the frequency band demodulators and producing a feedback parameter according to the CSI;
N detectors, coupled to the frequency band demodulators and the channel estimator &
feedback parameter generator and used for conducting decoding on the outputs from the frequency band demodulators according to the CSI and obtaining N receiving data vectors, wherein a single detector receives the tones with a same frequency band output from all the frequency band demodulators;
a vector-coding matrix generator, used for producing N spatial vector-coding matrixes W(n) according to the feedback parameter, wherein when H(n) is a MIMO channel matrix of the n-th frequency band, the QR decomposition of H(n) is expressed by;
H(n)=R(n)Q*(n),wherein R(n) is a lower triangular matrix with a dimension of MR×
MT, Q(n) is an orthonormal matrix with a dimension of MT×
MT and Q*(n) represents the complex conjugate transpose matrix of Q(n), and when Q(n)=[q1(n) q2(n) . . . qMT(n)], qm(n) represents the m-th column vector in the matrix Q(n), thus;
W(n)=[q1(n)q2(n) . . . qM(n)];
N coders, coupled to the vector-coding matrix generator and used for receiving N transmission data vectors, wherein each transmission data vector has a dimension of M×
1, and according to the vector-coding matrixes, the coders conduct coding on the transmission data vectors and each coder outputs MT tones with a same frequency band but different from the other coders;
MT transmitting antennas; and
MT frequency band modulators, coupled to the coders and the transmitting antennas and used for conducting modulations on the outputs from the coders, then outputting the modulated signals at the transmitting antennas, wherein each frequency band modulator receives the tones of different frequency bands output from all the coders, wherein MR, MT, M, N, m and n are natural numbers and 0<
M≦
MT, 0<
n≦
N. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A feedback method used in the antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system, wherein the system comprises MR receiving antennas and MT transmitting antennas;
- the feedback method comprising;
demodulating the signals received by the MR receiving antennas, wherein the signals received by each MR receiving antenna can be demodulated to obtain tones of N different frequency bands;
according to the tones of all the different frequency bands, estimating the obtained channel state information (CSI) of the N different frequency bands;
dividing all the tones into N sets, wherein each set sequentially comprises MR tones w with a same frequency band but obtained by different receiving antennas, and according to the CSI the tones of each set are detected and decoded to obtain N receiving data vectors; and
according to the CSI, producing and feeding back feedback parameter, wherein when H(n) is the MIMO channel matrix of the n-th frequency band, the QR decomposition of H(n) is expressed by;
H(n)=R(n)Q*(n),wherein R(n) represents a lower triangular matrix with a dimension of MR×
MT, Q(n) represents an orthonormal matrix with a dimension of MT×
MT and Q*(n) represents the complex conjugate transpose matrix of Q(n);
when Q(n)=[q1(n) q2(n) . . . qMT(n)], qm(n) represents the m-th column vector in the matrix Q(n), and let the spatial vector-coding matrix W(n)=[q1(n) q2(n) . . . qM(n)],thus, a process that the tone of every same frequency band is detected and decoded to obtain all the receiving data vectors corresponds to the coding by using the spatial vector-coding matrixes W(n), wherein MR, MT, M, N, m and n are natural numbers and 0<
M≦
MT, 0<
n≦
N. - View Dependent Claims (9, 10, 11, 12)
- the feedback method comprising;
-
13. A pre-coding method used in the antenna-array-based multiple-input multiple-output orthogonal-frequency-division-multiplexing (MIMO-OFDM) system, wherein the system comprises MR receiving antennas and MT transmitting antennas;
- the pre-coding method comprising;
receiving a feedback parameter;
according to the feedback parameter, producing N spatial vector-coding matrixes, wherein let H(n) be the MIMO channel matrix of the n-th frequency band and the QR decomposition of H(n) is expressed by;
H(n)=R(n)Q*(n),wherein R(n) represents a lower triangular matrix with a dimension of MR×
MT, Q(n) represents an orthonormal matrix with a dimension of MT×
MT and Q*(n) represents the complex conjugate transpose matrix of Q(n);
let Q(n)=[q1(n) q2(n) . . . qMT(n)], wherein qm(n) represents the m-th column vector in the matrix Q(n), thus;
W(n)=[q1(n)q2(n) . . . qM(n)];
receiving N transmission data vectors, wherein each transmission data vector has a dimension of M×
1, according to the vector-coding matrixes, the transmission data vectors are coded and after coding each transmission data vector, MT tones with a same frequency band are obtained, wherein the tones obtained from different transmission data vector have different frequency bands from each other; and
dividing all the tones into MT sets, wherein each set comprises N tones with different frequency bands obtained from the different transmission data vectors, and after conducting modulations on the tones of every set, the modulated signals are output by the transmitting antennas, wherein, MR, MT, M, N, m and n are natural numbers and 0<
M≦
MT, 0<
n≦
N. - View Dependent Claims (14, 15, 16, 17)
- the pre-coding method comprising;
Specification