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

720 DIGITAL COMMUNICATIONS UNDER LINEARLY DISTORTIVE CHANNELS
Figure 12.21
Noise-free eye
diagram of the
in-phase (real)
component at the
receiver (after
matched filter)
before sampling:
the eyes are
closed, and ISi
will lead to
decision errors.
3
2
-]
-2
-0.8 -0.6 -0. 4
-0.2 -0 -0.2 -0. 4
-0.6 -0.8
Time, T,
subplot ( 111)
figber=semilogy ( Eb2Naz ,Q, 'k-' ,Eb2N, SERneq, 'b-o ' ,Eb2N, SEReq, 'b-v') ;
axis ([O 26 .99e-5 l] );
legend ('Analytical ', 'Wi thout equalizer', 'With equalizer' );
xlabel ('E_b /N (dB) ') ;ylabel ('Symbol error probability' );
set (figber , 'Linewidth' , 2);
% Constellation plot before and after equalization
figure (3)
subplot (l21)
plot (real (zl (l:min (L,4000) ) ) ,imag (zl (l:min(L,4000) )) , '. ');
axis ( 'square ' )
xlabel ('Real part ')
title (' (a) Before equali zation ')
ylabel ('Imaginary part' );
subplot (l22)
plot (real (dsig (l:min (L, 4000) )) ,imag (dsig (l:min (L,4000) )), '. ');
axis ( ' square ' )
title (' (b) After equalization ')
xlabel ('Real part ')
ylabel ('Imaginary part');
figure (4)
t=length (h) ;
plot([l:t] /f_ovsamp,h) ;
xlabel ('time (in unit of T_s ) ')
title ('Multipath channel impulse response ');
% Plot eye diagrams due to mu ltipath channel
eyevec=conv (xchout, prcos) ;
eyevec=eyevec (delaychb+ l: (delaychb+800)* f_ovsamp ) ;
eyediagram (real ( eyevec ),1 6,2) ;
title ('Eye diagram (in-phase component) ');
xlabel ('Time (in unit of T_s ) ');