有人可以指导我如何在Matlab中的无线体域网络的BER计算中包含路径损耗值吗? 我正在使用qpsk调制和瑞利信道。
如果我只是将带有路径损耗值的通道乘以:
y=x*(h*PL)+n
结果是大多数值变为零。
代码(参见rx,rx1和rx2的计算):
format long; bit_count = 1000000;
Eb_No = 0: 1: 30;
SNR = Eb_No + 10*log10(2);
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(i*pi/4))+(B1==0).*(B2==1)...
*(exp(3*i*pi/4))+(B1==1).*(B2==1)*(exp(5*i*pi/4))...
+(B1==1).*(B2==0)*(exp(7*i*pi/4)));
h = sqrt(0.5*((randn(3,length(qpsk_sig))).^2+(randn(3,length(qpsk_sig))).^2));
d1=50;
PL1=43.22;
PL2=67.77;
PL3=69.8;
n=0.6^(SNR(aa)/0.6);
n1=0.7^(SNR(aa)/0.7);
n2=1/10^(SNR(aa)/10);
rx = (qpsk_sig.*h(1,:)*PL1)+ sqrt(n/2)*(randn(1,length(qpsk_sig))+i*randn(1,length(qpsk_sig))); % Source to Relay
rx_re = real(rx);
rx_im = imag(rx);
rxHat(find(rx_re < 0 & rx_im < 0)) = -1 + -1*j;
rxHat(find(rx_re >= 0 & rx_im > 0)) = 1 + 1*j;
rxHat(find(rx_re < 0 & rx_im >= 0)) = -1 + 1*j;
rxHat(find(rx_re >= 0 & rx_im < 0)) = 1 - 1*j;
rx1 = (rxHat.*h(2,:)*PL2) + sqrt(n1/2)*(randn(1,length(qpsk_sig))+i*randn(1,length(qpsk_sig))); %Relay to Destination
rx2=(qpsk_sig.*h(3,:)*PL3) + sqrt(n2/2)*randn(1,length(qpsk_sig))+i*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); 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');
axis([0 30 10^-10 0.1])
请帮忙。 谢谢你
答案 0 :(得分:1)
我认为零是可接受的,因为源 - &gt;中继 - &gt;目标路径有时会出现0位错误,而直接路径有> 0。 0.以对数刻度绘图时,这会导致数据点显示在-Inf(关闭绘图)。
编辑:我稍微修改了您的代码以绘制更高的SNR(请参阅更新的图表)。另外,我认为路径损失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)与发射信号相对应之前,需要将它们转换为线性标度。此外,路径损耗值应负 dB。原始代码基本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)])