دانشگاه صنعتي اصفهان دانشكده برق و كامپيوتر Various Beamformer Structures Suitable For Smart Antennas ارائه کننده: آرش میرزایی ( ) ارائه مقاله تحقيقي در درس “ SDR ” مدرس: دکتر جواد امیدی نيمسال بهار

What Will We See? Introduction Signal model Various beamformers Comparison Comparison in presence of look direction errors

Introduction Output If and then

Introduction Output power: So if x(t): stationary & zero-mean Then where

Introduction Output components If Then Output components power then SNR Or where

Signal Model Delay due to origin: Delay in linear array:

Signal Model The signal induced on the reference element due to the kth source: the signal induced on the lth element due to the kth source: the total signal induced due to all M directional sources and background noise on the lth element: so

Steering Vector Representation steering vector associated with the kth source: Signal vector: Output: array correlation matrix when directional sources are uncorrelated:

Conventional Beamformer also known as the delay-and-sum beamformer S 0 denoting the steering vector in the look direction, the array weights are given by: Source in look direction: Random noise environment:

Conventional Beamformer Directional interference: where ρ depends on the array geometry and the direction of the interference relative to the look direction. So if no interference then:

Conventional Beamformer

Null Steering Beamformer Is used to cancel a plane wave arriving from a known direction. S0 : the steering vector in the direction. S1, …, Sk : k steering vectors associated with k directions. So Using matrix notation, this becomes where and for k=L-1 else

Optimal Beamformer No require acknowledge of directions and power levels of interference. Maximize the output SNR. The weights are the solution of: The weights are: When no directional interference, then optimal : conventional and If one directional interference and then output SNR

Optimization Using Reference Signal Minimize mean squared error between the array output and the reference signal ξ(w). For minimizing So where

Beam Space Processor Main beam: Interference beam: and Output: Output power:

Beam Space Processor No signal in interference beam So Signal power independent of w. Maximizing SNR with minimizing output power:

Postbeamformer Interference Canceler (PIC) Signal beamformer: and Interference beamformer: Output: Output power:

PIC With Conventional Interference Beamformer Interference beamformer weights: So:

PIC With Orthogonal Interference Beamformer Interference beamformer weights: where So No signal suppressing.

PIC With Improved Interference Beamformer Full suppression of the interference. So And Signal power and noise power at the output are independent of interference power. Output signal power When & when, depend on

Comparison Comparison of Normalized Signal Power, Interference Power, Uncorrelated Noise Power and SNR at the Output of the Optimal PIC Forming Interference Beam with CIB, OIB and IIB,,

Comparison Uncorrelated noise power: in PIC using OIB P n > in PIC using IIB depend on if then P n > else P n < for,P n =

Comparison ESP With PIC In The Presence Of Look Direction Error