Generalized decision feedback equalizer precoder with receiver beamforming for matrix calculations in multi-user multiple-input multiple-output wireless transmission systems
First Claim
1. A method for processing user symbols with a generalized decision feedback equalizer (GDFE) based precoder in a base station of a multi-user multiple-input multiple-output (MU-MIMO) wireless system having K user terminals (UTs) which communicate with the base station via an uplink (UL) channel and a corresponding downlink (DL) channel, the method comprising:
- a processor obtaining an effective downlink (DL) channel matrix H for the DL channel after receiver processing at the user terminals;
computing an uplink (UL) covariance matrix D by assuming there are as many user terminals as a number of rows in the effective DL channel matrix H, the UL covariance matrix D being a diagonal matrix;
computing a filter matrix C based on the UL covariance matrix D;
computing a feedforward filter matrix F based on the filter matrix C;
computing an interference pre-cancellation matrix G, based on the feedforward filter matrix F and the filter matrix C, used in a transmitter at an interference pre-cancellation stage of the GDFE precoder; and
processing by the processor user symbols by a decision feedback equalizing stage of the GDFE precoder to produce filtered vector symbols;
wherein the effective downlink (DL) channel matrix is H=
H=[Ĥ
1H,Ĥ
1H, . . . , Ĥ
KH],where Ĥ
k is an effective DL channel sub-matrix for the kth UT
Ĥ
k=SkVkH,where Sk and Vk are matrices obtained from a singular value decomposition (SVD) of and estimated DL channel matrix Hk for the kth UT
Hk=UkSkVkH.
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Abstract
To realize a GDFE precoder for multi-user MIMO systems, which significantly reduces the computational cost while resulting in no capacity loss, one method comprises obtaining an effective downlink (DL) channel matrix H for the DL channel after receiver processing at the user terminals; computing an uplink (UL) covariance matrix D by assuming there are as many user terminals as a number of rows in the effective DL channel matrix H; computing a filter matrix C based on the UL covariance matrix D; computing a feedforward filter matrix F based on the filter matrix C; computing an interference pre-cancellation matrix G, based on the feedforward filter matrix F and the filter matrix C, used in a transmitter at an interference pre-cancellation stage of the GDFE precoder; and processing user symbols by a decision feedback equalizing stage of the GDFE precoder to produce filtered vector symbols.
9 Citations
20 Claims
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1. A method for processing user symbols with a generalized decision feedback equalizer (GDFE) based precoder in a base station of a multi-user multiple-input multiple-output (MU-MIMO) wireless system having K user terminals (UTs) which communicate with the base station via an uplink (UL) channel and a corresponding downlink (DL) channel, the method comprising:
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a processor obtaining an effective downlink (DL) channel matrix H for the DL channel after receiver processing at the user terminals; computing an uplink (UL) covariance matrix D by assuming there are as many user terminals as a number of rows in the effective DL channel matrix H, the UL covariance matrix D being a diagonal matrix; computing a filter matrix C based on the UL covariance matrix D; computing a feedforward filter matrix F based on the filter matrix C; computing an interference pre-cancellation matrix G, based on the feedforward filter matrix F and the filter matrix C, used in a transmitter at an interference pre-cancellation stage of the GDFE precoder; and processing by the processor user symbols by a decision feedback equalizing stage of the GDFE precoder to produce filtered vector symbols; wherein the effective downlink (DL) channel matrix is H=
H=[Ĥ
1H,Ĥ
1H, . . . , Ĥ
KH],where Ĥ
k is an effective DL channel sub-matrix for the kth UT
Ĥ
k=SkVkH,where Sk and Vk are matrices obtained from a singular value decomposition (SVD) of and estimated DL channel matrix Hk for the kth UT
Hk=UkSkVkH. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A generalized decision feedback equalizer (GDFE) based precoder in a base station (BS) of a multi-user multiple-input multiple-output (MU-MIMO) wireless system having K user terminals (UTs) which communicate with the base station via an uplink (UL) channel and a corresponding downlink (DL) channel, the GDFE precoder comprising:
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a processor for calculating; a feedforward path; a feedback path; and an interference pre-cancellation block denoted by I-G disposed in the feedback path, I being an identity matrix, G being an interference pre-cancellation matrix; wherein the interference pre-cancellation matrix G is computed based on a feedforward filter matrix F and a filter matrix C, the feedforward filter matrix F is computed based on the filter matrix C, the filter matrix C is computed based on an uplink (UL) covariance matrix D, the UL covariance matrix D is computed by assuming there are as many user terminals as a number of rows in an effective downlink (DL) channel matrix H, the UL covariance matrix D is a diagonal matrix, and the effective DL channel matrix H is obtained after receiver processing at the user terminals; wherein the effective downlink (DL) channel matrix is
H=[Ĥ
1H,Ĥ
2H, . . . , Ĥ
KH]where Ĥ
k is an effective DL channel sub-matrix for the kth UT
Ĥ
k=SkVkH,where Sk and Vk are matrices obtained from a singular value decomposition (SVD) of and estimated DL channel matrix Hk for the kth UT
Hk=UkSkVkH. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A generalized decision feedback equalizer (GDFE) based precoder in a base station (BS) of a multi-user multiple-input multiple-output (MU-MIMO) wireless system having K user terminals (UTs) which communicate with the base station via an uplink (UL) channel and a corresponding downlink (DL) channel, the GDFE precoder comprising:
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a decision feedback equalizing stage for processing, by a processor, user symbols to produce filtered vector symbols, the decision feedback equalizing stage including an interference pre-cancellation stage having an interference pre-cancellation matrix G used in a transmitter at the interference pre-cancellation stage; and a transmit filter represented by a transmit filter matrix B for processing the filtered vector symbols after the decision feedback equalizing stage to produce an output of transmitted signals to be directed to the DL channel represented by the effective DL channel matrix H through which communications occur in the wireless system with the user terminals; wherein the interference pre-cancellation matrix G is computed based on a feedforward filter matrix F and a filter matrix C, the feedforward filter matrix F is computed based on the filter matrix C, the filter matrix C is computed based on an uplink (UL) covariance matrix D, the UL covariance matrix D is computed by assuming there are as many user terminals as a number of rows in an effective downlink (DL) channel matrix H, the UL covariance matrix D is a diagonal matrix, and the effective DL channel matrix H is obtained after receiver processing at the user terminals; wherein the effective downlink (DL) channel matrix is
H=[Ĥ
1H,Ĥ
2H, . . . , Ĥ
KH]where Ĥ
k is an effective DL channel sub-matrix for the kth UT
Ĥ
k=SkVkH,where Sk and Vk are matrices obtained from a singular value decomposition (SVD) of and estimated DL channel matrix Hk for the kth UT
Hk=UkSkVkH. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification