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// Exa 9.7
// To determine modulation scheme to be used and Eb/No.
clc;
clear all;
Rb=144; //data rate in kbps
BW=36; //in MHz
Pb=3*10^-5;//probability of bit error
//solution
Seff=Rb/BW; //spectral efficiency in bps/Hz
M=2^(Rb/BW); //since the channel is band limited
disp("16-QAM (refer Equation 9.66) should be used as it is more efficient than 16-PSK (refer Equation 9.50)");
disp("");
//since Q[sqrt(2*Eb_No)]=(1/2)*erfc[sqrt(Eb_No)] // refer page no 257 equ 9.35
deff('y=f(x)','y=(3/8)*erfc(sqrt((2/5)*x))-Pb'); //from eqn 9.66 and 9.35
[x,v,info]=fsolve(0.1,f); //x=Eb_No
printf('For a rectangular constellation (refer Figure 9.12), with a Gaussian channel and matched filter reception, the calculated Eb/No value is %.1f dB\n ',10*log10(x));
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