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About Pilot tones

Started by Bavithi April 24, 2006
Hi All,

I have a basic doubt about pilot tones. I am working with OFDM systems and
I am trying to implement pilot tones for a 64 subcarrier system. I set aside
4 tones for pilot data in frequency domain.
However, according to a fwe books I've read, I learn that pilot tones ,
which are used for channel estimation ,change their position according to
some pattern (discussed in the literature) over various OFDM symbols(each
symbol has 64 sucarriers) . This has to be preserved to preserve the nature
of pilot tones.

Also, there is a mention of the average power on pilot tones. Some
literature on Pilot Tone Amplitude Modulation state that the average power
of pilot tone has to be greater than the average power of data tone AND the
pilot tones have to be qually spaced - to preserve their purpose.
But I also read that the average power on pilot tones & data tones have to
be equal.

Also, some literature says that "pilot tones" & "pilot symbols" are
different in the sense that pilot tones are frequency domain equvivalent of
pilot symbols(time domain) & the insertion of pilot symbols or pilot data
can cause a change in PAPR of the signal.

I am very confused on how to go about simulating pilot tones for a 64
subcarrier , 1000 OFDM symbols case.
I would really appreciate it if someone can send me some information
required to know more about pilot tones . If someone can send me a
simulation of pilot tones in MATLAB , that would be very helpful.

Thank you.

Bavithi.