Patent ID: 8385395

Claim:
A method for determining a codebook entry in a terminal of a Multiple Input Multiple Output communication system, the method comprising: determining a codebook entry by maximizing a Signal-to-Interference-and-Noise Ratio over all possible codebook entries and receiver weights, wherein the codebook comprises a plurality of quantized channel vectors, and wherein the codebook entry is a quantized channel vector of a channel between a base station and a terminal of a Multiple Input Multiple Output communication system; and selecting the codebook entry and receiver weights corresponding to the largest Signal-to-Interference-and-Noise Ratio; wherein determining the codebook entry is done based on g ^ k ′ = argmax g ^ k ∈ C ⁢ ⁢ max w k ∈ { C N :  w k  = 1 } ⁢ w k H ⁢ A ⁡ ( g ^ k ) ⁢ w k w k H ⁢ B ⁡ ( g ^ k ) ⁢ w k , ⁢ with A ⁡ ( g ^ k ) = ( P Tx M ⁢ H k * ⁢ g ^ k ⁢ g ^ k H ⁢ H k T ) , ⁢ and B ⁡ ( g ^ k ) = [ I + P Tx M ⁢ H k * ⁡ ( I - g ^ k ⁢ g ^ k H ) ⁢ H k T ] , wherein ĝ′ k is the codebook entry to be determined, ĝ k is a codebook entry of a plurality of codebook entries, w k is a receive filter vector and relates to a linear receive filter of the terminal, N is a number of receive antennas, P tx is a transmit power, H k is a channel matrix of the terminal, I is an identity matrix, and M is a number of antennas of the base station.