Cryptography Reference
In-Depth Information
tems),
nSynch
, backed by Atheros, Cisco, Intel, Nortel, and Philips; with system
members Matsushita, Nokia, Samsung, Sony, and Toshiba.
1.
Bandwidth
: There should be mandatory 10-, 20-, and 40- MHz bandwidth
channels. Moreover, there should be mandatory two-antenna MIMO in
the 40-MHz channels, and optional four-antenna MIMO in the 20-MHz
channels.
2.
Interoperability
: There should be mandatory modes for interoperability
with devices in the 5-GHz band, and optionally in the 2.4-GHz band.
3.
Number of Channels
: There should be twenty-four channels in the 5-GHz
band.
Analysis
: Basically, the general consensus is that the difference between
the two aforementioned proposals amounts to 2
20. Do we want two
MIMO antennas in the 40-MGz channels, or four MIMO antennas in the 20-
MGz channels? The former will produce raw throughput of 250 Mbps (although
usable bandwidth would be approximately 175 Mbps), but will be more di
L
cult
to implement in some areas. The latter will produce raw bandwidth of 216 Mbps
(with usable bandwidth of approximately 162 Mbps), but would be easier to
implement and face less regulatory barriers. The arguments against the former
include that it would reduce the number of available 802.11 channels; while the
arguments against the latter include that it would be unnecessarily complicated,
expensive, and unsuitable for mobile devices. From a strictly mathematical
viewpoint, we see that 2
×
40 vs. 4
×
20, so perhaps both proposals are
really aimingat the same thing. In the final analysis, a compromise may be the
solution.
Whatever the outcome of 802.11n, we will be seeing
Ultra WideBand
(UWB)
in the not-too-distant future. This new TGn standard should result in 20 times
the speeds we currently have at our disposal.
×
40=80=4
×
Wi-Fi
: The generic term for any type of 802.11 network is
Wi-Fi
or
Wireless Fidelity
for high-frequency WLANs. The
Wi-Fi Alliance
was formed in
1999 as a nonprofit international organization to certify interoperability between
WLAN products based on 802.11. Initially, Wi-Fi was used only in reference to
the 802.11b standard (ratified in 1999), but Wi-Fi extended the use of the term
in a deliberate effort to stem the tide of confusion over WLAN interoperability.
However, 802.11b operates with virtually no privacy despite the fact that it
supports
Wired Equivalent Privacy
(WEP), which was created with the aim of
makinga WLAN as secure as a wired network.
WEP
: The WEP protocol is totally insuLcient as a sole means of security
for a WLAN. Part of the problem is that the use of RC4 (see Section 3.7), in
WEP is flawed partly because they reuse the encryption key.
9.14
Given that
9.14
Do not gather from the above that there is a problem with RC4. It is the implementation
of it in WEP, which is problematic. As we have seen previously, the strongest of ciphers is
irrelevant if the implementation is done in an improper fashion that renders its use insecure.
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