用于WBAN的Matlab中BER计算的路径损耗因子

1 回答

• 1

  我认为零是可以接受的，因为源 - >中继 - >目标路径有时会有0位错误，而直接路径有> 0.当以对数刻度绘制时，这会导致数据点出现在-Inf（离开情节） .

  

  Edit ：我稍微修改了你的代码以绘制更高的SNR（参见更新的图表） . 另外，我认为pathloss的原始用法是不正确的 . 我假设给定的路径损耗常数以dB为单位 . 在将它们（相乘）应用于发送信号之前，需要将它们转换为线性标度 . 此外，路径损耗值应为负dB . 原始代码实质上是给信号增益而不是损失 . 这是修改后的代码：

  format long; 
  
  bit_count = 1000000;
  
  Eb_No = 20: 1: 100;
  
  SNR = Eb_No + 10*log10(2);  % not sure about the 10*log10 part, ??
  BER = zeros(size(SNR));
  BER1 = zeros(size(SNR));
  BER2 = zeros(size(SNR));
  for aa = 1: 1: length(SNR)
  
     T_Errors = 0;
  
     T_bits = 0;
  
     T_Errors1=0;
  
     T_Errors2=0;  
  
     while T_Errors < 10 && T_Errors1 < 10 && T_Errors2 < 10
  
        uncoded_bits  = round(rand(1,bit_count));
  
        B1 = uncoded_bits(1:2:end);
  
        B2 = uncoded_bits(2:2:end);
  
        qpsk_sig = ((B1==0).*(B2==0)*(exp(1i*pi/4))+(B1==0).*(B2==1)...
        *(exp(3*1i*pi/4))+(B1==1).*(B2==1)*(exp(5*1i*pi/4))...
        +(B1==1).*(B2==0)*(exp(7*1i*pi/4)));        
  
        h = sqrt(0.5*((randn(3,length(qpsk_sig))).^2+(randn(3,length(qpsk_sig))).^2));
  
        d1=50;
  
        % Path losses in dB
        PL1=-23.22;
  
        PL2=-27.77;
  
        PL3=-49.8; 
  
        n=0.6^(SNR(aa)/0.6); 
  
        n1=0.7^(SNR(aa)/0.7); 
  
        n2=1/10^(SNR(aa)/10);  
  
        % Since we are multiplying pathloss by the input, pathloss needs to
        % be linear (not dB).  If we keep P.L. in dB, then we would subtract
        % P.L. from the signal (which would also need to be in dB).
        rx = (qpsk_sig.*h(1,:)*(10^(PL1/10)))+ sqrt(n/2)*(randn(1,length(qpsk_sig))+1i*randn(1,length(qpsk_sig)));  % Source to  Relay
  
        rx_re = real(rx);
        rx_im = imag(rx);  
  
        rxHat = zeros(size(rx));
  
        rxHat(find(rx_re < 0 & rx_im < 0)) = exp(5*1i*pi/4); %-1 + -1*j;
  
        rxHat(find(rx_re >= 0 & rx_im > 0)) = exp(1i*pi/4); % 1 + 1*j;
  
        rxHat(find(rx_re < 0 & rx_im >= 0)) = exp(3*1i*pi/4); % -1 + 1*j;
  
        rxHat(find(rx_re >= 0 & rx_im < 0)) = exp(7*1i*pi/4); % 1 - 1*j;
  
        % Same as above, convert pathloss from dB to linear
        rx1 = (rxHat.*h(2,:)*(10^(PL2/10))) + sqrt(n1/2)*(randn(1,length(qpsk_sig))+1i*randn(1,length(qpsk_sig)));  %Relay to Destination
  
        rx2=(qpsk_sig.*h(3,:)*(10^(PL3/10))) + sqrt(n2/2)*(randn(1,length(qpsk_sig))+1i*randn(1,length(qpsk_sig)));  % Source to Destination
  
        %---------------------------------------------------------------
  
        rx = rx./h(1,:);
  
        rx1 = rx1./h(2,:);
  
        rx2 = rx2./h(3,:);
  
        B4 = (real(rx)<0);
  
        B3 = (imag(rx)<0);
  
        uncoded_bits_rx = zeros(1,2*length(rx));
  
        uncoded_bits_rx(1:2:end) = B3;
  
        uncoded_bits_rx(2:2:end) = B4;
  
        % Calculate Bit Errors
  
        diff = uncoded_bits - uncoded_bits_rx;
  
        T_Errors = T_Errors + sum(abs(diff));
  
        T_bits = T_bits + length(uncoded_bits);
  
  
        B8 = (real(rx1)<0);
  
        B7 = (imag(rx1)<0);
  
        uncoded_bits_rx1 = zeros(1,2*length(rx1));
  
        uncoded_bits_rx1(1:2:end) = B7;
  
        uncoded_bits_rx1(2:2:end) = B8;
  
  
        % Calculate Bit Errors
        diff1 = uncoded_bits - uncoded_bits_rx1;
        T_Errors1 = T_Errors1 + sum(abs(diff1));
        T_bits = T_bits + length(uncoded_bits);
  
        B6 = (real(rx2)<0);
        B5 = (imag(rx2)<0);
  
        uncoded_bits_rx2 = zeros(1,2*length(rx2));
        uncoded_bits_rx2(1:2:end) = B5;
        uncoded_bits_rx2(2:2:end) = B6;
  
  
        % Calculate Bit Errors
        diff2 = uncoded_bits - uncoded_bits_rx2;
        T_Errors2 = T_Errors2 + sum(abs(diff2));
        T_bits = T_bits + length(uncoded_bits);
  
     end
  
     % Calculate Bit Error Rate
     BER(aa) = T_Errors / T_bits;
     BER1(aa) = T_Errors1 / T_bits; 
     BER2(aa) = T_Errors2 / T_bits;
  end
  
  %------------------------------------------------------------ 
  
  figure(1); 
  
  subplot(2,1,1);
  
  semilogy(SNR,BER1,'bs-','LineWidth',2');
  
  hold on;
  
  xlabel('SNR');
  
  ylabel('BER');
  
  grid on;
  
  figure(1);
  
  semilogy(SNR,BER2,'*r');
  
  hold on;
  
  xlabel('SNR');
  
  ylabel('BER');
  
  grid on;
  
  legend('Relay','Direct');
  
  title('Bit Errors (log)')
  
  xlim([min(SNR) max(SNR)])
  
  subplot(2,1,2)
  
  plot(SNR,BER1,'bs-');
  
  hold on
  
  plot(SNR,BER2,'*r')
  
  hold off
  
  title('Bit Errors (linear)')
  
  xlabel('SNR')
  
  ylabel('BER')
  
  xlim([min(SNR) max(SNR)])
  

  回复于 2024-04-19T01:33:05+08:00