Eb/N0 and SNR

来源：互联网发布：整治网络传销可丽金编辑：程序博客网时间：2024/04/29 23:07

http://blog.sina.com.cn/s/blog_68f81b8b0100jtse.html

Eb/N0中的N0的定义，可参照wiki里的描述，具体需要注意到是，当计算单边带和双边带动时候，乘积上有(1/2)的区别。

If the noise is one-sided white noise, i.e., constant with frequency, then the total noise power N integrated over a bandwidth B is N=BN₀ (for double-sided white noise, the bandwidth is doubled, so N is BN₀/2). This is utilized in signal-to-noise ratio calculations.

Eb/N0的计算，对于实信号来说，

s           = signal;L           = length(s);% Convert SNR from dBSNRdB       = 10;SNR         = 10^(SNRdB/10);% Measure average power of signalPs          = sum(s.^2)/L;% Calculate wanted noise powerPn          = Ps/SNR;% Generate random vector and ensure 0-mean w           = randn(1,L);w           = w-sum(w)/L;% Scale to wanted powerPw          = 1/L*sum(w.^2);w           = sqrt(Pn/Pw).*w;% Measure resulting SNRPw_meas     = 1/L*sum(w.^2);SNRdB_meas  = 10*log10( Ps/Pw_meas ); % Gives 10.0000

对于复信号来说，

%signal energycalculate the mean symbol energy% Bit energy for each symbolEb   = Es/bit_per_symbol;EbNo = 10^(EbNo_dB/10);% Noise variance   No   = Eb/EbNo;                             noise = sqrt(No/2)*(randn(1,length(symbol))+j*randn(1,length(symbol))); noise_symbol = symbol + noise;

以上代码来自于 https://dsp.stackexchange.com/questions/8580/power-spectral-density-and-snr-for-awgn

SNR与Eb/N0的关系，总结如下：

SNR = (Eb/N0) * (Rb/W)

对于W来说，是信号的带宽。这个是要随着调制方式不同，而相应改变的。比如采取BPSK调制的时候，Null-to-Null bandwidth是2×Rb；而采取QPSK的时候，Null-to-Null带宽是1×Rb。具体可以参考<Tutorial on Basic Link Budget Analysis> AN9804。

0 0