Hardware Reference
In-Depth Information
The current solution for maximum flexibility is to use dual-band hardware. Dual-band
hardwarecanworkwitheither802.11aor802.11b/gnetworks,enablingyoutomovefrom
an 802.11b/g wireless network at home or at Starbucks to a faster 802.11a office network.
802.11g
IEEE 802.11g, also known to some as
Wireless-G
, is a standard that offers compatibility
with 802.11b along with higher speeds. The final 802.11g standard was ratified in
mid-2003.
Although 802.11g is designed to connect seamlessly with existing 802.11b hardware,
early 802.11g hardware was slower and less compatible than the specification promised.
Insome cases, problems with early-release 802.11ghardware can be solved through firm-
ware or driver upgrades.
Note
Although802.11b/g/nwirelesshardwarecanusethesame2.4GHzfrequenciesandcancoex-
ist onthe same networks, when mixing different standards onthe same network, the network
willoftenslowdowntothelowestcommondenominatorspeed.Topreventtheseslowdowns,
you can configure access points to disable “mixed mode” operation, but this will limit the
types of devices that can connect. For example, you can configure a 2.4GHz Wireless-N ac-
cess point to allow 802.11b/g/n connections (full mixed mode), or to only allow 802.11g/n
(partialmixedmode)connections,ortoonlyallow802.11nconnections.Thelatteroffersthe
highest performance for Wireless-N devices. Similarly you can configure Wireless-G access
points to allow 802.11b/g (mixed mode) operation, or to only allow 802.11g connections.
Restricting or disabling the mixed mode operation offers higher performance at the expense
of restricting the types of devices that can connect.
802.11n
The latest wireless network standard, 802.11n (also known as
Wireless-N
), was published
in October 2009. 802.11n hardware uses a technology called
multiple input, multiple out-
put (MIMO)
to increase throughput and range. MIMO uses multiple radios and antennas
totransmitmultipledatastreams(alsoknownas
spatial streams
)betweenstations.Unlike
earlier 802.11 implementations, in which reflected radio signals slowed down throughput,
reflected radio signals can improve throughput as well as increase useful range.
802.11n is the first wireless Ethernet standard to support two frequency ranges or bands:
• 2.4GHz (same as 802.11b/g)
• 5GHz (same as 802.11a)
Thus, depending on the specific implementation of 802.11n in use, a dual-band 802.11n
device may be able to connect with 802.11b, 802.11g, and 802.11a devices, whereas a
