%Performing the QPSK
%b(i),b(i+1)
%x = I+jQ
%wuguangfu
%20081027

B = 1000;
b = randint(1,2*B);
x = zeros(1,B);

for n = 1 : B
    x1 = b(2*n-1:2*n);
    x2 = bin2dec(num2str(x1));
    switch x2
        case 0
            x(n) = 1/sqrt(2) + i*1/sqrt(2);
        case 1
            x(n) = 1/sqrt(2) - i*1/sqrt(2);
        case 2
            x(n) = -1/sqrt(2) + i*1/sqrt(2);
        otherwise
            x(n) = -1/sqrt(2) - i*1/sqrt(2);
    end
end
scatterplot(x);grid on
x