|
|
 |
|
 |
| |
Important Issues for Wireless
As with any relatively new technology, there
are many issues that affect implementation and utilization
of wireless networks. There are both common and specific
issues depending on the type of wireless network. Some
of the common factors include electromagnetic interference
and physical obstacles that limit coverage of wireless
networks, while others are more specific, such as standards,
data security, throughput, ease of use, etc.
-
Standards
-
Coverage
-
Security
Standards
A major obstacle for deployment of wireless
networks is the existence of multiple standards. As it
was mentioned previously, there are analog and digital
standards in wireless telephony. While GSM is the only
widely supported standard in Europe and Asia, multiple
standards are in use in the U.S. As a result, the U.S.
has lagged in wireless networks deployment.Just recently,
organizations have been formed to ensure network and device
interoperability. For example, the adoption of the 802.11b
standard has made wireless data networks one of the hottest
newcomers in the current wireless market.
Coverage
Another issue is coverage. Coverage mainly depends on
the output power of the transmitter (FCC regulated), its
location and frequency used to transmit data. For example,
lower frequencies are more forgiving when it comes to
physical obstacles (walls, stairways, etc.), while high
frequencies require clear line of sight. For each particular
application, throughput decreases as distance from the
transmitter or access point increases.
Security
Data security is a major issue for wireless due to the
nature of the transmission mechanism (electromagnetic
signals passing through the air). It is commonly believed
that voice applications are less secure than data applications.
This is due to limited capabilities of existing technologies
to protect information that is being transmitted. For
example, in metropolitan areas, users are at risk that
simple scanning devices can highjack cell phone numbers
and be maliciously used. In WLANs, authentication and
encryption provide data security. Current implementations
include:
-
MAC address-based access
lists on access points, where only registered and recognized
MAC addresses are accepted and allowed to join the network.
-
A closed wireless system,
where users have to know non-advertised the network
name to be able to join.
-
RADIUS server based authentication,
where users are authenticated against a centralized
RADIUS server based on their MAC address or their username
and password.
-
Wireless Equivalency
Privacy (WEP) utilizes data encryption with 40-bit or
128-bit keys that are hidden from users. WEP provides
three options, depending on the level of security needed:
no encryption of data, combination of encrypted and
non-encrypted data, and forced data encryption.
-
High security solutions
for encryption are proprietary: Cisco AP-350 and Lucent/Agere
AS-2000. Both offer per user/per session encryption
keys and authenticate users based on username/password
scheme.
It is important to understand that in WLANs, data is
encrypted only between the wireless adapter and the access
point. Data travels through a wired LAN unencrypted. Therefore,
data transmitted by wireless is not more secure than data
transmitted through the wire, but probably not less secure.
Application level encryption mechanisms, like secure web
transactions (SSL), SSH, etc. are responsible for further
protection of data.
|
|
 |
|
 |
|
|
