%------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------%
%                               This Program is Designed To Simulate The  Smart Antenna System  On A BTS Receiver ( Uplink )                               %
%                                                             General Constraints For Using This Software                                                                                                     %
%Antenna Array Of Four Elements Operating On 2 GHz With A Separation Distance 0.075 Meters                                                                %
%Narrowband ( Uncorrelated Or Partially Correlated ) Signals Are Assumed                                                                                                         %
%An Authentication Code Of 10 Bits Is Sent First                                                                                                                                                               %
%Two Users Are Served Only In The Presence Of Additive White Gaussian Noise Only                                                                                      % 
%Operation Is Subdivided Into Three Stages : Angle Of Arrival Estimation ( ESPRIT ) , Adaptive Beamforming , Signal Regeneration %
%--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------%
%Input Received Signals Arrival
P = input ('The Channel Signal To Noise Ratio : ') ;
for I = 1 : 2
    A ( I ) = input ('The Signal Arrival Phase Angle : ') ;
    A ( I ) = A ( I ) * pi / 180 ;
end
H = randint ( 2 , 10 ) ;
%Estimation of The Covariance Matrix
S = zeros ( 4 , 2 ) ;
R = zeros ( 4 , 4 ) ;
ZZ = zeros ( 4 , 10 ) ;
for K = 1 : 10
    for J = 1 : 2
        for I = 1 : 4
            S ( I , J ) = exp ( i*( pi  * ( I - 1 ) * cos ( A ( J ) ) ) )  ;  
        end
    end
    S = awgn ( S * H ( : , K ) , P ) ;
    ZZ ( : , K ) = S ;
    R = R + S * S' ;
end
R = R / 10 ;
[ V , E ] = eig ( R , 'nobalance' ) ;
%ESPRIT Algorithm Estimation
VV = V ( : , [ 3 4 ] ) ;
VV1 = VV ( [ 1 2 3 ] , : ) ;
VV2 = VV ( [ 2 3 4 ] , : ) ;
Cv = [ VV1' ; VV2' ] * [ VV1  VV2 ] ;
[ Vc , Ec ] = eig ( Cv , 'nobalance' ) ;
G1 = Vc ( [ 1 2 ] , [ 3 4 ] ) ;
G2 = Vc ( [ 3 4 ] , [ 3 4 ] ) ;
Lg = -G1 * inv ( G2 ) ;
Eg = eig ( Lg ) ;
G  = asin ( angle ( Eg ) / pi) ;
%Estimation The Weight Vector of A Null Steering Beamformer
for I = 1 : 2
   for J = 1 : 4
       SS ( I , J ) = exp ( i*( pi * ( J-1 ) * cos ( G ( I ) ))) ;
  end
end
B = eye ( 2 ) ;
for J = 3 : 4
    Z = B ( J-2  , : ) ;
    W = SS \ Z' ;
    MM = 0 ;
    %Plot of The Output Radiation Pattern And The Output Valid Digital Data of The Null Steering Beamformer
    TT = 0 : 0.005 : pi ;
    for I = 1 : 4
       HH = exp ( i*( pi * ( I-1 )*cos ( TT ))) ;
       MM = MM + ( HH * W(I) ) ;
    end
    TT = ( TT * 180 ) / pi ;
    MM = 20 * log10 ( abs ( MM )/ max ( abs ( MM ) ) ) ;
    for K = 1 : 10
       OO ( K ) = W.' * ZZ ( : , K ) ;
    end
    OO = abs ( OO / max ( OO )) ;
    OO ( 11 ) = 0 ;
    U = J - 2  ;
    UU =  J  ;
    UUU = J + 2 ;
    figure ( U ) , plot ( TT , MM ) , xlabel ('Phase Angle In Degrees') , ylabel ('Electric Field In dB') , title ( 'A Choice Radiation Pattern Of A Spatial Beamformer') ,  axis ( [ 0 180 -10 0 ] ) , grid on ;     
    figure ( UU ) , stairs ( OO , 'linewidth' , 2 ) , title ('A Choice Output Digital Data') ,  xlabel ('The Bit Transition Period') , ylabel  ('The Output Digital Signal') , grid on ;
    %Comparator Operation
    for I = 1 : 10
        if OO ( I ) > 0.5 OO ( I ) = 1 ;
        else OO ( I ) = 0 ;
        end
    end
    figure ( UUU ) , stairs ( OO , 'linewidth' , 2 ) , title ('The Output Valid Digital Data') ,  xlabel ('The Bit Transition Period') , ylabel  ('The Output Digital Signal') , grid on ;
end