B. P. Lathi, Zhi Ding - Modern Digital and Analog Communication Systems-Oxford University Press (2009)

10.12 MATLAB Exercises 595
set (figwave l, 'Linewidth ' , 2) ;
subplot (212 )
figwave2=plot (t,xorth ( delayrt : delayrt+l99) );
title ('(b) Orthogonal modulation .')
set ( figwave2 , 'Linewidth ' , 2);
% Find the signal length
Lrcos=length (xrcos) ;Lrect=length (xorth) ;
BER= [ l ;
noiseq=randn(Lrcos,l) ;
% Generating the channel noise (AWGN )
for i=l:12,
Eb2N (i)= i;
%(Eb/N in dB)
Eb2N_num=l0 A (Eb2N(i)/10) ; % Eb/N in numeral
Var_n=l/ (2*Eb2N_num) ; %1/SNR is the noise variance
signois=sqrt (Var_n) ;
% standard deviation
awgnois=signois*noiseq;
% AWGN
% Add noise to signals at the channel output
yrcos=xrcos+awgnois/sqrt (2) ;
yorth=xorth+awgnoi s(l:Lrect) ;
% Apply matched filters first
zl=conv (yrcos, pcmatch) ;clear awgnois, yrcos;
z2=conv (yorth, phmatch) ;
z3=conv (yorth , psmatch ) ;clear yorth;
% Sampling the received signal and acquire samples
zl=zl (delayrc+l: f_ovsamp:end) ;
z2=z2 (delayrt+l: f_ovsamp :end-f_ovsamp+l) ;
z3=z3 (delayrt+l: f_ovsamp :end-f_ovsamp+l) ;
% Decision based on the sign of the samples
decl=round ((sign(zl(l:L)-0.5)+1)*.5) ;dec2=round( (sign(z2-z3)+1)*.5) ;
% Now compare against the original data to compute BER for
% the three pulses
BER= [BER;sum(abs ( s_data-decl) )/L sum (abs ( s_data-dec2))/L ] ;
Q(i)= 0.5* erfc ( sqrt (Eb2N_num/2) ); % Compute the Analytical BER
end
figure (2)
subplot (ll l)
figber=semil ogy (Eb2N,Q, 'k-',Eb2N,BER( : ,l) , 'b-*' , Eb2N,BER(: ,2) , 'r-o') ;
fleg=legend ('Analytical ', 'Root-raised cosine on/off', 'Orthogonal
signaling');
fx=xlabel ('E_b/N (dB) ');fy=ylabel ('BER ' );
set ( figber, 'Linewidth' , 2) ;set ( fleg, 'FontSize' , 11) ;
set (fx, 'FontSize' , 11) ;
set(fy, 'FontSize' , 11) ;
% We can plot the individual pulses used for the binary orthogonal
% signaling
figure (3)
subplot (111) ;
pulse=plot ((0:f_ovsamp )/f_ovsamp , [psinh 0] , 'k-', ...
(0:f_ovsamp )/f_ovsamp , [psine 0 ] , ' k-o' );
pleg=legend ('Half-sine pulse ', 'Sine pulse');
ptitle=title ('Binary orthogonal signals');