Apparatus and method for determining beamforming vector in a codebook-based beamforming system
First Claim
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1. A receiver in a codebook-based transmission beamforming system, comprising:
- a predictor for generating forthcoming channel values for a forthcoming period using M present and previous channel estimates;
an effective channel gain calculator for calculating effective channel gains for transmission beamforming vectors included in a codebook using the forthcoming channel values generated by the predictor; and
a codebook selector for feeding back a codebook index corresponding to the maximum effective channel gains received from the effective channel gain calculator to a transmitter;
wherein the effective channel gain calculator calculates effective channel gains jk,d(w) for each transmission beamforming vector w by
Jk,d(w)=wHR(k,mP+d)w
R(k,mP+d)≡
{circumflex over (H)}MMSEH(k,mP+d){circumflex over (H)}MMSE(k,mP+d)where Ĥ
MMSE is a forthcoming channel value, k is a subcarrier index, P is a feedback interval, m is a feedback index, and d is a time offset.
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Abstract
An apparatus and method for determining a beamforming vector in a codebook-based transmission beamforming system are provided. In a feedback method for a receiver in a codebook-based transmission beamforming system, forthcoming channel values for a forthcoming period are generated using M present and previous channel estimates. Effective channel gains for all transmission beamforming vectors included in a codebook are calculated using the forthcoming channel values. A codebook index corresponding to the maximum effective channel gains is fed back to a transmitter.
19 Citations
14 Claims
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1. A receiver in a codebook-based transmission beamforming system, comprising:
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a predictor for generating forthcoming channel values for a forthcoming period using M present and previous channel estimates; an effective channel gain calculator for calculating effective channel gains for transmission beamforming vectors included in a codebook using the forthcoming channel values generated by the predictor; and a codebook selector for feeding back a codebook index corresponding to the maximum effective channel gains received from the effective channel gain calculator to a transmitter; wherein the effective channel gain calculator calculates effective channel gains jk,d(w) for each transmission beamforming vector w by
Jk,d(w)=wHR(k,mP+d)w
R(k,mP+d)≡
{circumflex over (H)}MMSEH(k,mP+d){circumflex over (H)}MMSE(k,mP+d)where Ĥ
MMSE is a forthcoming channel value, k is a subcarrier index, P is a feedback interval, m is a feedback index, and d is a time offset. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A feedback method for a receiver in a codebook-based transmission beamforming system, comprising the steps of:
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generating forthcoming channel values for a forthcoming period using M present and previous channel estimates; calculating effective channel gains for transmission beamforming vectors included in a codebook using the forthcoming channel values; and feeding back a codebook index corresponding to the maximum effective channel gains to transmitter. wherein the calculation step comprises calculating effective channel gains jk,d(w) for each transmission beamforming vector w by
jk,d(w)=wHR(k,mP+d)w
R(k,mP+d)≡
{circumflex over (H)}MMSEH(k,mP+d){circumflex over (H)}MMSE(k,mP)+d)where Ĥ
HMMsE is a forthcoming channel value, k is a subcarrier index. P is a feedback interval, m is a feedback index, and d is a time offset. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification