viterbi_awgn_pe.m

实现GSM通信的快速接入控制信道（FACCH）的信道编码的MATLAB仿真

%经卷积编译码后的改善误码率
function sig_err_rate=viterbi_AWGN_pe(snr_in_dB)
E=1;
snr=10^(snr_in_dB/10);
sgma=sqrt((E/snr)/2);%噪声功率
err_num=0;
%信息序列
for i=1:100
coder_input=round(rand(1,224));
G=[1 0 0 1 1;1 1 0 1 1];
k=1;

ch_out=viterbi_encoder(G,k,coder_input);%编码
%经信道加高斯燥声
u=2*ch_out-1;
u=sign(u+sgma*randn(size(u))+eps);
u=(u+1)/2;

[decoder_output,survivor_state,cumulated_metric]=viterbi_decoder(G,k,u);%解码
err_num=err_num+length(find(coder_input~=decoder_output));
end;
%误码率
sig_err_rate=err_num/22400;