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标题：OFDM信号调制仿真源码程序
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所属分类: 文档资料 资源类型：文档 文件大小: 71.27 KB 上传时间: 2016-06-07 19:55:33 下载次数: 36 资源积分：1分 提 供 者: xiaopeng2 OFDM信号调制仿真源码程序
内容：
fprintf ('OFDM Analysis Program\n\n');
defaults = input('输入1');
%
if defaults == 1
    IFFT_bin_length = 64;  
    carrier_count = 3;        
    bits_per_symbol = 1;        
    symbols_per_carrier = 2;   
    SNR = 10;                                             
else
    IFFT_bin_length = input('IFFT bin length = ');
    carrier_count = input('carrier count = ');
    bits_per_symbol = input('bits per symbol = ');
    symbols_per_carrier = input('symbols per carrier =');
    SNR = input('SNR = ');
end
band_out_length =  carrier_count * symbols_per_carrier * bits_per_symbol; 
carriers = (1:carrier_count) + (floor(IFFT_bin_length/4) - floor(carrier_count/2));
conjugate_carriers = IFFT_bin_length - carriers + 2;
the band signal which is to be transmitted.
%
band_out = round(rand(1, band_out_length));
figure(11),stairs( band_out);
axis([1 band_out_length -2 2]);
%
convert_matrix = reshape( band_out, bits_per_symbol, length( band_out)/bits_per_symbol);
for k = 1:(length( band_out)/bits_per_symbol)
    modulo_ band(k) = 0;
    for i = 1:bits_per_symbol
        modulo_ band(k) = modulo_ band(k) + convert_matrix(i,k)*2^(bits_per_symbol-i);
    end
end
%
carrier_matrix = reshape(modulo_ band, carrier_count, symbols_per_carrier)';
%
%
carrier_matrix = [zeros(1,carrier_count);carrier_matrix];
for i = 2:(symbols_per_carrier + 1)
    carrier_matrix(i,:) = rem(carrier_matrix(i,:)+carrier_matrix(i-1,:),2^bits_per_symbol);
end
%
carrier_matrix = carrier_matrix * ((2*pi)/(2^bits_per_symbol));
%
[X,Y] = pol2cart(carrier_matrix, ones(size(carrier_matrix,1),size(carrier_matrix,2)));
complex_carrier_matrix = complex(X,Y);
%
IFFT_modulation = zeros(symbols_per_carrier + 1, IFFT_bin_length);
IFFT_modulation(:,carriers) = complex_carrier_matrix;
IFFT_modulation(:,conjugate_carriers) = conj(complex_carrier_matrix);
%
figure (1)
stem(0:IFFT_bin_length-1, abs(IFFT_modulation(2,1:IFFT_bin_length)),'b*-')
grid on
axis ([0 IFFT_bin_length -0.5 1.5])
ylabel('Magnitude')
xlabel('IFFT Bin')
('OFDM Carrier Frequency Magnitude')
figure (2)
plot(0:IFFT_bin_length-1, (180/pi)*angle(IFFT_modulation(2,1:IFFT_bin_length)), 'go')
hold on
stem(carriers-1, (180/pi)*angle(IFFT_modulation(2,carriers)),'b*-')
stem(conjugate_carriers-1, (180/pi)*angle(IFFT_modulation(2,conjugate_carriers)),'b*-')
axis ([0 IFFT_bin_length -200 +200])
grid on
ylabel('Phase (degrees)')
xlabel('IFFT Bin')
('OFDM Carrier Phase')
%
time_wave_matrix = ifft(IFFT_modulation');
time_wave_matrix = time_wave_matrix';
%
figure (3)
plot(0:IFFT_bin_length-1,time_wave_matrix(2,:))
grid on
ylabel('Amplitude')
xlabel('Time')
('OFDM Time Signal, One Symbol Period')
 
colors = ['r' 'g' 'b' 'k' 'r' 'g' 'b' 'k' 'r' 'g' 'b' 'k' 'r' 'g' 'b' 'k'];
for f = 1:carrier_count
   temp_bins(1:IFFT_bin_length)=0+0j;
   temp_bins(carriers(f))=IFFT_modulation(2,carriers(f));
   temp_bins(conjugate_carriers(f))=IFFT_modulation(2,conjugate_carriers(f));
   temp_time = ifft(temp_bins');
   figure(4)
   plot(0:IFFT_bin_length-1, temp_time,colors(f))
  hold on
end
grid on
ylabel('Amplitude')
xlabel('Time')
('Separated Time Waveforms Carriers')
%
for i = 1:symbols_per_carrier + 1
    %windowed_time_wave_matrix(i,:) = real(time_wave_matrix(i,:)) .* hamming(IFFT_bin_length)';
    windowed_time_wave_matrix(i,:) = real(time_wave_matrix(i,:));
end
%
ofdm_modulation = reshape(windowed_time_wave_matrix', 1, IFFT_bin_length*(symbols_per_carrier+1));
%
temp_time = IFFT_bin_length*(symbols_per_carrier+1);
figure (5)
plot(0:temp_time-1,ofdm_modulation)
grid on
ylabel('Amplitude (volts)')
xlabel('Time (samples)')
('OFDM Time Signal')
 
%PLOT OFDM SIGNAL (spectrum)
symbols_per_average = ceil(symbols_per_carrier/5);
avg_temp_time = IFFT_bin_length*symbols_per_average;
averages = floor(temp_time/avg_temp_time);
average_fft(1:avg_temp_time) = 0;
for a = 0:(averages-1)
   subset_ofdm = ofdm_modulation(((a*avg_temp_time)+1):((a+1)*avg_temp_time));
   subset_ofdm_f = abs(fft(subset_ofdm));
   average_fft = average_fft + (subset_ofdm_f/averages);
end
average_fft_log = 20*log10(average_fft);
figure (6)
plot((0:(avg_temp_time-1))/avg_temp_time, average_fft_log)
hold on
plot(0:1/IFFT_bin_length:1, -35, 'rd')
grid on
axis([0 0.5 -40 max(average_fft_log)])
ylabel('Magnitude (dB)')
xlabel('Normalized Frequency (0.5 = fs/2)')
('OFDM Signal Spectrum')
%
Tx_data = ofdm_modulation;
%
Tx_signal_power = var(Tx_data);
%
linear_SNR = 10^(SNR/10);
noise_sigma = Tx_signal_power/linear_SNR;
noise_scale_factor = sqrt(noise_sigma);
%
noise = randn(1, length(Tx_data))*noise_scale_factor;
Rx_Data = Tx_data + noise;
%
Rx_Data_matrix = reshape(Rx_Data, IFFT_bin_length, symbols_per_carrier + 1);
%
Rx_spectrum = fft(Rx_Data_matrix);%
%
figure (7)
stem(0:IFFT_bin_length-1, abs(Rx_spectrum(1:IFFT_bin_length,2)),'b*-')
grid on
axis ([0 IFFT_bin_length -0.5 1.5])
ylabel('Magnitude')
xlabel('FFT Bin')
('OFDM Receive Spectrum, Magnitude')
figure (8)
plot(0:IFFT_bin_length-1, (180/pi)*angle(Rx_spectrum(1:IFFT_bin_length,2)), 'go')
hold on
stem(carriers-1, (180/pi)*angle(Rx_spectrum(carriers,2)),'b*-')
stem(conjugate_carriers-1, (180/pi)*angle(Rx_spectrum(conjugate_carriers,2)),'b*-')
axis ([0 IFFT_bin_length -200 +200])
grid on
ylabel('Phase (degrees)')
xlabel('FFT Bin')
('OFDM Receive Spectrum,  Phase')
%
Rx_carriers = Rx_spectrum(carriers,:)';
%
figure (9)
Rx_phase_P = angle(Rx_carriers);
Rx_mag_P = abs(Rx_carriers);
polar(Rx_phase_P, Rx_mag_P,'bd');
%
Rx_phase = angle(Rx_carriers)*(180/pi);
phase_negative = find(Rx_phase < 0);
Rx_phase(phase_negative) = rem(Rx_phase(phase_negative)+360,360);
%
Rx_decoded_phase = diff(Rx_phase);
phase_negative = find(Rx_decoded_phase < 0);
Rx_decoded_phase(phase_negative) = rem(Rx_decoded_phase(phase_negative)+360,360);
%
%
_phase = 360/2^bits_per_symbol;
delta_phase = _phase/2;
Rx_decoded_symbols = zeros(size(Rx_decoded_phase,1),size(Rx_decoded_phase,2));
%
for i = 1:(2^bits_per_symbol - 1)  
    center_phase = _phase*i;
    plus_delta = center_phase+delta_phase;
    minus_delta = center_phase-delta_phase;
    decoded = find((Rx_decoded_phase <= plus_delta) & (Rx_decoded_phase > minus_delta));
    Rx_decoded_symbols(decoded)=i;
end
%
Rx_serial_symbols = reshape(Rx_decoded_symbols',1,size(Rx_decoded_symbols,1)*size(Rx_decoded_symbols,2));
%
for i = bits_per_symbol: -1: 1
    if i ~= 1
        Rx_binary_matrix(i,:) = rem(Rx_serial_symbols,2);
        Rx_serial_symbols = floor(Rx_serial_symbols/2);
    else
        Rx_binary_matrix(i,:) = Rx_serial_symbols;
    end
end
band_in = reshape(Rx_binary_matrix,1,size(Rx_binary_matrix,1)*size(Rx_binary_matrix,2));
%
bit_errors = find( band_in ~= band_out);
bit_error_count = size(bit_errors,2);
 

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