Wireless and Cellular

Wireless technologies, including cellular systems, provide a mobile access method. Typically,
these technologies offer substantially lower bandwidth than wire line services.
For wireless solutions (wireless LAN), the current standard is based on IEEE 802.11, with
interoperability between systems certified by the Wi-Fi committee. This technology is well
suited for short-range deployments within a building or campus environment, and provides for
bandwidths up to 54Mbps. Security, a long-time stumbling block for deployment (the original
security provided by wireless LANs, Wired Equivalent Protocol (WEP), was relatively poor and
subject to hacking), has been addressed by vendors and will be part of the 802.11i specification
when ratified. Current solutions include Temporal Key Integrity Protocol (TKIP), and it is likely
that 802.1
x
(an authentication model) and Advanced Encryption Standard (AES) will be found
in both wireless LAN and wired solutions.
Three standards are available for wireless LAN installations, as described in Table 22.2.
Because wireless LAN is outside of the scope of the Remote Access exam, it is presented here
only as an introduction. This technology could be deployed as part of remote access solutions
in the future. For further information, we suggest that you consult the 802.11 Planet website at
www.80211-planet.com
.
Another area not addressed on the current Remote Access exam is cellular communications.
Although historically used in voice communications, the latest Global System for Mobile Communications
(GSM) and code division multiple access (CDMA) technologies provide sufficient
bandwidth for lower demand applications. Although the technical characteristics and benefits of each technology are beyond the scope of this text, this technology is important for real-world
application of remote access design. Not only will cellular-based systems provide for roaming
and small form factor connectivity, but they will ultimately link small offices and other services
while removing the last mile that is typically the most costly and time-consuming portion of a
remote access link. The term
last mile
refers to the connection between the telecommunications
providers and the end customer.

802.11 Standards
Standard Frequency Used
Bandwidth Available
(Maximum Rated) Range Features
802.11b 2.4GHz 11Mbps Longest Original specification
and most
widely used today.
Provides three nonoverlapping
channels
of 11Mbps, but
prone to interference
from cordless
phones and microwave
ovens.
802.11a 5.0GHz 54Mbps Shortest Uses frequency
space that is
less prone to
interference.
802.11g 2.4GHz 54Mbps (standard
ratified at 22 Mbps)
Medium to long Backward compatible
with 802.11b.