Patent ID: 8873664

Claim:
A method for transmission beamforming in an Orthogonal Frequency Division Multiplexing (OFDM) based wireless system employing multiple antennas, the method comprising: receiving a pilot signal from a transmitter and calculating channel correlation information in a time and frequency domain using the pilot signal; estimating a current beam weight using previous beam weights and the channel correlation information; calculating a difference vector between an actual current beam weight and the estimated beam weight and quantizing the difference vector; selecting an optimum index from a predefined codebook for the quantized difference vector; and generating a quantized transmission beam weight using the optimum index, wherein the quantized transmission beam weight is calculated by [Equation 6]: w ~ ⁡ ( k , t ) = α ⁢ w ~ ⁡ ( k , t - Δ ⁢ ⁢ t ) + β ⁢ ⁢ w ~ ⁡ ( k - Δ ⁢ ⁢ k , t ) + γ ⁢ ⁢ z ^ i ^  α ⁢ w ~ ⁡ ( k , t - Δ ⁢ ⁢ t ) + β ⁢ ⁢ w ~ ⁡ ( k - Δ ⁢ ⁢ k , t ) + γ ⁢ ⁢ z ^ i ^  , [ Equation ⁢ ⁢ 6 ] where {tilde over (w)}(k,t−Δt) and {tilde over (w)}(k−Δk,t) respectively denote previous quantized beam weights in the time and frequency domain, {tilde over (w)}(k,t) denotes the quantized transmission beam weight, α and β are coefficients related with the channel correlation information, {circumflex over (z)} i denotes a normalized vector of the quantized difference vector, γ denotes a magnitude of the difference vector, î denotes the optimum index, and ∥·∥ denotes a vector norm operator.