Cryptography Reference
In-Depth Information
the bandwidth in 802.11g. The development of 802.11n took a step forward in
August 2004, when it passed the proposal posting stage at the IEEE meeting.
Yet the 802.11n specifications may take anywhere from late 2005 to early 2007
to finalize. Essentially, TGn is in the nascent stage of developing its standard.
They are entertainingproposals from various groups, after which they will decide
what to include and exclude. Below we will delineate a couple of the sets of
proposals by certain consortiums and analyze the potential outcomes. The
802.11n standard will have the potential of increasingWLAN speeds to at least
100 Mbps throughput rates, 9.12 but could be as high as 500 Mbps. These high
bandwidths are very important for consumer applications such as HDTV and
streamingvideo, as well as significant updates for business environments such as
high-density corporate networks. The push for higher bandwidth is also driven
by real and increasingmodern-day needs. For instance, the number of mobile
users is increasing, as are the number of business employees with handheld
devices. Moreover, in their private lives, individuals are increasingly connecting
computers to TVs and audio systems in order to move digital sound and video
from one device to another. Lastly, these applications are becomingincreasingly
more complex and demandingof higher bandwidth.
Proposals for 802.11n
The WWiSE Proposal
One of the consortiums layingout proposals for the proposed TGn standard
is called World Wide Spectrum E ciency (WWiSE), consisting12 companies,
includingAiro Networks, Bermai, Broadcom, Conexant, SIMicroelectronics,
and Texas Instruments; with system members: Mitsubishi and Motorola, the
latter of which uses ECC in their wireless phones (see page 190).
1. Bandwidth : There should be compulsory employment of already existing
(and approved) 20-MHz bandwidth channels; and to maximize data rates,
these channels should employ four MIMO 9.13 antennas. Optionally, higher
rates may be achieved with 40-MHz channels usingtwo MIMO antennas.
2. Interoperability : There should be obligatory modes accommodating in-
teroperability with devices in the 5-GHz and 2.4-GHz bands.
3. Number of Channels : There should be 14 channels in the 5-GHz band.
Perhaps equally matched in their power to influence the outcome of TGn's
standardization process is the consortium (originally founded by Agere Sys-
9.12 A throughput is the measure of the capacity of a (digital) network. The rate is provided
as a ratio of bits transmitted per unit of time (such as the 100 Mbps, cited above). The more
popular term for throughput is bandwidth .
9.13 MIMO stands for Multiple-Inputs, Multiple-Outputs. Essentially, MIMO is a technique
which increases bandwidth on an individual channel by creating more air paths for data
transmission. By employing multiple antennas, both transmitters and receivers, each such
path can carry differing kinds of data at the same frequency. Currently, only a single set of
antennas is employed in each wireless connection. (Note that once a signal is received, it is
interpreted by a demodulator that separates the data from the carrier wave, and translates
the information backinto its original form.)
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