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Wireless Broadband Networks
Frequency
Band & Licensing Requirements For Broadband
Wireless
broadband networks are being deployed in a number of frequency bands –
from the low end 800 MHz ISM band to 38 GHz Wide band. Previous generation
of LAN bridging equipment employed lower frequency band (800- 912 MHz ISM
band). The new generation of broadband network technology utilizes 24-38 GHz
band.
More recently, vendors are also developing the last mile wireless
access solutions in the 2.4-2.6 GHz band.
The advantage in going up the frequency band is the ability to use
higher bandwidth and therefore achieving higher network speed and capacity
– in voice terms, it means more channels and more subscribers.
In
the United States, a license-free spectrum exists through the Federal
Communications Commission (FCC), established to increase competition and
experimentation in the 900 MHz, 2.4 GHz, and 5 GHz range.
Distance
Limitations on Wireless Broadband
Distances
vary with frequency band, technology and vendor implementation. One factor
that users must keep in mind that performance or throughput may become lower
with distance because of signal strength after certain distance may not be
sustainable at higher speeds. Therefore, some vendors offer lower speeds at
greater distances.
Speeds
Speeds
in wireless broadband (mid-2000 circa) can go from sub one megabit (< 1
Mbps) to 45 Mbps range.
The
following table gives some idea of frequency, speed and distance
relationship:
| Type
of Broadband Technology |
Frequency |
Distance |
Range
of Data Speed** |
| MMDS |
2.1
to 2.7 GHz |
30
to 35 miles |
10 Mbps |
| International
WLL |
3.2-3.7
GHz |
25 miles |
10-11 Mbps |
| ISM |
902-928
MHz |
5
to 25 miles
|
5-7
Mbps |
| LMDS |
24
to 38 GHz |
3
to 5 miles |
Up to 45 Mbps |
Note: Wireless Data speed is a
function of bandwidth, the frequency band employed, modulation technology
used, # of channels dedicated, clear line of sight and signal strength, and
other factors. These numbers are purely for general guidance.
In
contrast, DSL and related technologies utilizing the existing copper
infrastructure transfer rates vary from 2.32 MB/second at 3.5 km to 208
kb/second at 7.0 km. It should be pointed out that higher speed DSL
offerings are also becoming available. But these technologies do not address
wireless and mobility needs of users and Internet applications.
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