Page 8 Wireless RF Introduction
Wireless RF Introduction
There are currently four widely adopted standards for 802.11
wireless network types: a, b, g, and n. Although 802.11n is the
newest and highest capacity standard, each of the four
standards has its own strengths and weaknesses. This section
provides overviews of these standards.
The following section provides a brief overview of RF
technologies:
• Frequency Bands and Channels - page 8
• 802.11 Comparison Chart - page 8
• Radio Frequency Barriers - page 9
• RF Interference - page 9
Frequency Bands and Channels
To allow multiple separate wireless networks in a shared and
confined space, the RF medium is divided into channels. For
devices in the 5GHz range (802.11a), this means the possibility
of up to 23 discrete channels. For devices using the 2.4GHz
range (802.11b, 802.11g), the wireless space is limited to a
maximum of 14 overlapping channels. As a result of these
overlapping channels, 2.4GHz technology provides only a total
of three discrete channels.
The newer 802.11n technology does not fit into either of these
categories, as it is capable of using both 2.4GHz and 5GHz, but
is limited to 14 overlapping channels for backward compatibility.
802.11 Comparison Chart
The following table compares signal characteristics as they
apply to the current 802.11 standards:
802.11a 802.11b 802.11g 802.11n
# of Channels in USA 23 11 11 11
# of Channels in EU 23 13 13 13
# of Channels in Japan 15 14 14 14
Frequency Band 5GHz 2.4GHz 2.4GHz 2.4/5GHz
Max. Data Rate 54Mbps 11Mbps 54Mbps 150Mbps
300Mbps
a
a. Full 300Mbps throughput is possible only in environments free from
2.4Ghz interference.
Note: Although 802.11b/g/n standards provide between 11
and 14 channels, only 3 of those channels are fully
discrete (non-overlapping) channels.
For more information on this topic, refer to the
SonicWALL Secure Wireless Networking Integrated
Solutions Guide.
Radius (Range) 90ft/25m 120ft/
35m
120ft/
35m
300ft/90m
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