vus_stbc_4_32.m

BER of the VUS-MUMIMO-SM Uplink System

% BER of the VUS-MUMIMO-SM Uplink System - Rayleigh () 
% 8 Real Users - 16 Virtual Users - 4 Best Virtual Users
clc
clear all
close all

R_users = 6; % Number of real users
Tx = 2;      % Number of Tx antennas for each real user
V_users = R_users * Tx; % Number of virtual users
N = 4 * 10 ^ ( 4 ); % Number of bits
Ns = N / 2; % Number of symbols
SNR = -5 : 2.5 : 10; % in dB
snr = 10 .^ ( SNR / 10 );

% % Map-H matrix index array and Greate Sk input array --??????????????
load X_index_snr_4_32_20000_Final
user_index = zeros( R_users, Ns, length( SNR ) );
for i = 1 : length( SNR )
    for t = 1 : Ns
        for k = 1 : R_users
            if ( X_index_snr( ( 2 * k - 1 ), t, i ) + X_index_snr( ( 2 * k ), t, i ) ) > 0
               user_index( k, t, i ) = 1;
            end
        end
    end
%     users6( i ) = ( Ns - length( find( sum( user_index( :, :, i ) ) - 4 ) ) ) / Ns;
end

% Create Inputs
for n = 1 : V_users
    sk_bin( n, : ) = randint( 1, N );
    sk_polar = sk_bin( n, : ) * 2 - 1;
    for i = 1 : Ns
        sk_complex( n, i ) = ( 1 / sqrt( 2 ) ) * complex( sk_polar( 2 * i - 1 ), sk_polar( 2 * i ) );
    end
end

load H_4_32_20000

% STBC Encoding
% Assume the H matrix of time slot 1 and time slot 2 are identical
ErrorTxbits = zeros( 1, Ns, length( SNR) ); 
for p = 1 : length( SNR )
    for t = 1 : Ns
        if ( sum( user_index( :, t, p ) ) ) == 2 % 2 selected users
            u = find( user_index( :, t, p ) );  % find the selected 2 users from four users
            h2 = [ H( :, ( 2 * u( 1 ) - 1 ) : ( 2 * u( 1 ) ), t ), H( :, ( 2 * u( 2 ) - 1 ) : ( 2 * u( 2 ) ), t ) ];
            x2 = [ sk_complex( ( 2 * u( 1 ) - 1 ) : ( 2 * u( 1 ) ), t ); sk_complex( ( 2 * u( 2 ) - 1 ) : ( 2 * u( 2 ) ), t ) ];
            ET = STBC_R4_T4_ED( h2, x2, SNR( p ) );
            ErrorTxbits( 1, t, p ) = ET( 1, 1 );
            ErrorTxbits( 2, t, p ) = ET( 2, 1 );
        end
        if ( sum( user_index( :, t, p ) ) ) == 3 % 3 selected users
            u = find( user_index( :, t, p ) );  % find the selected 3 users from four users
            h3 = [ H( :, ( 2 * u( 1 ) - 1 ) : ( 2 * u( 1 ) ), t ), H( :, ( 2 * u( 2 ) - 1 ) : ( 2 * u( 2 ) ), t ), H( :, ( 2 * u( 3 ) - 1 ) : ( 2 * u( 3 ) ), t ) ];
            x3 = [ sk_complex( ( 2 * u( 1 ) - 1 ) : ( 2 * u( 1 ) ), t ); sk_complex( ( 2 * u( 2 ) - 1 ) : ( 2 * u( 2 ) ), t ); sk_complex( ( 2 * u( 3 ) - 1 ) : ( 2 * u( 3 ) ), t ) ];
            ET = STBC_R4_T6_ED( h3, x3, SNR( p ) );
            ErrorTxbits( 1, t, p ) = ET( 1, 1 );
            ErrorTxbits( 2, t, p ) = ET( 2, 1 );
        end
       if ( sum( user_index( :, t, p ) ) ) == 4 % 4 selected users
            u = find( user_index( :, t, p ) );  % find the selected 3 users from four users
            h4 = [ H( :, ( 2 * u( 1 ) - 1 ) : ( 2 * u( 1 ) ), t ), H( :, ( 2 * u( 2 ) - 1 ) : ( 2 * u( 2 ) ), t ), H( :, ( 2 * u( 3 ) - 1 ) : ( 2 * u( 3 ) ), t ), H( :, ( 2 * u( 4 ) - 1 ) : ( 2 * u( 4 ) ), t ) ];
            x4 = [ sk_complex( ( 2 * u( 1 ) - 1 ) : ( 2 * u( 1 ) ), t ); sk_complex( ( 2 * u( 2 ) - 1 ) : ( 2 * u( 2 ) ), t ); sk_complex( ( 2 * u( 3 ) - 1 ) : ( 2 * u( 3 ) ), t ); sk_complex( ( 2 * u( 4 ) - 1 ) : ( 2 * u( 4 ) ), t ) ];
            ET = STBC_R4_T8_ED( h4, x4, SNR( p ) );
            ErrorTxbits( 1, t, p ) = ET( 1, 1 );
            ErrorTxbits( 2, t, p ) = ET( 2, 1 );
        end       
    end
    BER_VUS_MIMO_STBC_4_32_Final( p ) = sum( ErrorTxbits( 1, :, p ) ) / sum( ErrorTxbits( 2, :, p ) );
end

save BER_VUS_MIMO_STBC_4_32_Final BER_VUS_MIMO_STBC_4_32_Final

figure,
semilogy( SNR, BER_VUS_MIMO_STBC_4_32_Final, 'g-*' )
axis( [ -5 10 10 ^ ( -6 ) 10 ^ 0 ] );
title( ' The BER of VUS-MUMIMO-STBC-4-32 (20000 Time Slots) ' )
xlabel( ' SNR in dB ')
ylabel( ' BER ' )
legend( ' MLD-STBC-4-32 - Monte Carlo ')
grid on