log_map_bound.asv

短波信道抗多音干扰的性能分析及其仿真

function Pb=log_map_bound(BPH,number_of_states,rho_in_db)
%this function computes the MAP demodulation
%bit error bound

%G(D)=3NJ^3D^3+9N^2J^5D^5+27N^3J^7D^7+...
%G(D)=3D^3+18D^5+
%fanout=2^BPH;
rho=10^(rho_in_db/10);
beta=BPH*rho/2;
namda=(sqrt(1+6*beta+beta^2)-(1+beta))/2;
%L=floor(log(number_of_states)/log(fanout));
%Pb=(fanout/4)*(exp(-2*beta*(namda/(1+namda)))/(1-namda^2))^(L+1);
D=exp(-2*beta*(namda/(1+namda)))/(1-namda^2);
G=(3*D^3+9*D^5+27*D^7)/2;