controlling signal power

Sirs,
I have read in some of the wireless literatures that certain data are
deliberately transmitted with higher power. However, I dont understand what
increasing the signal power means and where exactly happens.

Does increasing power means simoly increasing the amplitude and in case of
wireless applications, does this happen in RF section of the transmission

Thanks, manish

On Sun, 09 Jun 2013 07:09:53 -0500, "manishp" <58525@dsprelated>
wrote:

>Sirs,
>I have read in some of the wireless literatures that certain data are
>deliberately transmitted with higher power. However, I dont understand what
>increasing the signal power means and where exactly happens.
>
>Does increasing power means simoly increasing the amplitude and in case of
>wireless applications, does this happen in RF section of the transmission
>
>Thanks, manish

It depends on what you're talking about.   Are you talking about
something like a pilot tone that has more power than the rest of the
signal or something like that?   Automatic power control for
reliability?  

Changes in power can be made by adjusting the signal amplitude.   This
can be done anywhere in the transmit chain, either digital or analog.
Where it is actually done depends on what you're talking about.
Large changes in power are almost always done in the RF section with a
variable gain amplifier.   Small changes can be, but aren't always,
done digitally.  


Eric Jacobsen
Anchor Hill Communications
http://www.anchorhill.com

Sir, thanks a lot. Yes, I was mainly referring to the pilot sequence. 
But can you let me know what you mean by controlling in digital domain (in
baseband) since all it contains encoded data.

Thank, manish


>

On Sun, 09 Jun 2013 12:05:41 -0500, "manishp" <58525@dsprelated>
wrote:

>Sir, thanks a lot. Yes, I was mainly referring to the pilot sequence. 
>But can you let me know what you mean by controlling in digital domain (in
>baseband) since all it contains encoded data.
>
>Thank, manish

The transmit waveform is PCM, like most signals, so pilot symbols can
be amplified numerically compared to non-pilot symbols during
modulation.    For a single-carrier waveform this would most likely be
done just prior to transmit pulse filtering.   For a multi-carrier
(e.g., OFDM) waveform, this would be done to the subcarrier symbols
prior to the FFT (or IFFT, depending on one's preference) before
transmit.


Eric Jacobsen
Anchor Hill Communications
http://www.anchorhill.com