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Hi. I have a question regarding time synchronization of bursty =
transmission (e.g. TDMA).
Assuming a typical modulation scheme like QPSK, data-aided (DA) =
technique like correlation of a known sequence is quite commonly used. =
Let's say the decision criterion is Maximum Likelihood (i.e. time sync =
is said to occur at the point where the correlation value is highest), =
and the accuracy requirement is +/- half samples (i.e. exactly the =
optimal sample). In this case, having a high oversampling rate would =
make the task of meeting the accuracy requirement more difficult, since =
practical RRC pulse shaping would make the correlation peak quite broad =
and so just a little noise is sufficient to cause the correlation peak =
to occur at the optimal+/-1 samples. Is there a solution to this? I am =
thinking perhaps the correlation technique is not sufficient to resolve =
this problem, other technique may be needed.
Thks.
--=20
Regards,
Kian Chong
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Hi. I have a question regarding time=20
synchronization of bursty transmission (e.g. TDMA).
Assuming a typical modulation scheme =
like QPSK,=20
data-aided (DA) technique like correlation of a known sequence is quite =
commonly=20
used. Let's say the decision criterion is Maximum Likelihood (i.e. time =
sync is=20
said to occur at the point where the correlation value is highest), and =
the=20
accuracy requirement is +/- half samples (i.e. exactly the optimal =
sample). In=20
this case, having a high oversampling rate would make the task of =
meeting the=20
accuracy requirement more difficult, since practical RRC pulse shaping =
would=20
make the correlation peak quite broad and so just a little =
noise is=20
sufficient to cause the correlation peak to occur at the optimal+/-1 =
samples. Is=20
there a solution to this? I am thinking perhaps the correlation =
technique is not=20
sufficient to resolve this problem, other technique may be =
needed.
Thks.
--
Regards,
Kian=20
Chong
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