A small idea here: I once saw an app note on a "tunnel information
system" designed for
the old MW AM band. The designer clocked a rom at a modulus of 9 khz (
channel spacing)
and produced a sum of sines, 500 khz to 1.5 Mhz, i.e. a carrier on every
possible AM frequency.
The entire waveform was modulated by the "tunnel information broadcast",
i.e. modulation all
carriers with the same information. Since the length of the waveform
table was "9 khz", all carriers
had an integer number of cycles, and was thus phase continous.
Enough rambling, the point was that all these carriers "added up"
causing high PAPR , the solution was to "randomize"
the PHASE, and minimize "adding up". Perhaps something similar could be
done here, i.e. each carrier
has a certain phase offset that is constant, but different from all
carriers?
Would that be cumbersome? I do not think I have seen anything that
mandates a particular absolute phase
for a carrier, but I will gladly back off given a reasonable explanation
why this would not work.
Gullik
On 06/05/2013 10:33 PM, Frank Palazzolo wrote:
Hi Bruce,
Actually, I almost added that one - we will certainly find out if it
is an issue. :)
I think I've convinced myself that all multicarrier methods suffer
from this same issue, and probably to the same degree. If you add a
bunch of sine waves, most of the time they average out, but once in a
while they all add up.
I do see the same "12dB PAPR" number kicking around in multiple
references with regard to both FDM and OFDM.
Now, I don't know how or even if the problem get worse with more carriers.
-Frank
NQ8N
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