Any bandwidth is limited, although slightly differently depending on if closer to 400MHz than 3-4GHz.
"behind" and "below" *or (above) all this modulation gobble-gobble sits the frequency band guys and those
who decides on what modulation to use on what band, new or old, lower or higher.
And once again, GSM and GPRS does not use linear RF-parts, same as deep space satellites, as
that saves battery.
CDMA and EDGE use linear RF parts (except that QCDMA which Q could not deployed in Europe
because it didn't have those filters limiting the sidebands), one reason that there is already almost enough
masts close by, not like satellites in outer space, the other that RF technology is improving, handsets
do not need to be as expensive as satellites.
From this point of view one can say
- old bands reserved for satellite modulations, nonlinear, battery saving RF parts.
- new bands reserved for linear, battery wasting RF parts.
as well as
- old (nonlinear) bands built the base of mast grids needed for new (linear) bands
- old (nonlienar) bands can then be updated to the new (linear) bands (EDGE)
Additionally this process started from old, lower bands and continues to new, higher bands
as the coverage also decreases with higher center frequencies.
The question on GSM/EDGE/WCDMA is minor compared to this, the battery power
and mast density needed plus how higher carrier frequencies behave cmprd to lower ones.
Ilmarinen
One reason Nokia is in both EDGE, WCDMA and WLAN, but from the point of view
the bands from 400MHz through 1-2GHz up to 3GHz, the specific modulation used is
not that important. |
