TDMA, FDMA, and CDMA
TDMA, FDMA, and CDMA
TDMA, FDMA, and CDMA
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s<br />
DS-<strong>CDMA</strong>: a case study<br />
s<br />
Digital binary signal<br />
t =<br />
j<br />
a<br />
k k t<br />
() j () <br />
() ( kT)<br />
DS-<strong>CDMA</strong>-coded signal<br />
N<br />
() j () () j () j<br />
t = a c [ m]<br />
(<br />
t mT kT)<br />
DS<strong>CDMA</strong><br />
N DS : length of the codeword<br />
T C : chip time<br />
() j () () j<br />
t = 2P<br />
s () t<br />
TX<br />
TX<br />
k k<br />
=<br />
m<br />
DS<br />
1<br />
( ) ( () ) j<br />
g<br />
( t)<br />
sin 2f<br />
t +<br />
s <br />
DS<strong>CDMA</strong><br />
() j () () j () () j () () j () j () j<br />
s RX<br />
t<br />
=<br />
s<br />
TX<br />
t<br />
h<br />
t<br />
=<br />
L<br />
<br />
l=<br />
1<br />
<br />
0<br />
l<br />
s<br />
TX<br />
Spreading Signal<br />
P<br />
( t )<br />
l<br />
C<br />
Transmitted<br />
signal<br />
Signal after<br />
propagation over a<br />
multipath channel<br />
41
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