Patent ID: 8737199

Claim:
A method of using differential precoding for highly correlated channels in a wireless network, comprising: using a differential codebook optimized for highly correlated antennas that comprises: measuring the short term channel covariance matrix by a mobile station (MS) operable in said wireless network and determining feedback based on the following criteria: measuring by said MS a short term channel covariance matrix R=H H H(1); determining by said MS the feedback with the following criteria: θ ^ = arg ⁢ ⁢ max θ ^ ∈ θ s ⁢ ⁢ det ( I + γ N s ⁢ Q ⁡ ( θ ^ ) H ⁢ RQ ⁡ ( θ ^ ) ) , w ⁢ here ⁢ ⁢ θ s ∈ [ θ b - α ⁢ : ⁢ 2 ⁢ α 15 ⁢ : ⁢ θ b + α ] , Q ⁡ ( θ ^ ) = [ 1 exp ⁡ ( - jπcos ⁡ ( θ ^ ) ) exp ⁡ ( - j2πcos ⁡ ( θ ^ ) ) exp ⁡ ( - j3πcos ⁡ ( θ ^ ) ) ] , θ b = arg ⁢ ⁢ max θ ∈ [ 0 , π ) ⁢  a ⁡ ( θ ) H ⁢ V ⁡ ( 0 )  2 , ⁢ a ⁡ ( θ ) = [ 1 ⅇ - j2π ⁢ d λ ⁢ cos ⁡ ( θ ) ⅇ - j2π ⁢ 2 ⁢ d λ ⁢ cos ⁡ ( θ ) … ⅇ - j2π ⁢ ( N t - 1 ) ⁢ d λ ⁢ cos ⁡ ( θ ) ] , and θ s is a set of predefined angles in a range of [−α,α] degrees; and wherein the index of {circumflex over (θ)} is then fed back to a base station (BS) and based on said {circumflex over (θ)} that is fed back from said MS, said BS reconstruct a precoding vector V(t)=Q ({circumflex over (θ)}).