WLANs

LANs mostly make use of the Internet IP. The growth in wireless and the benefits
it provides has brought forward changes in the world of LANs in recent years.
WLANs provide much higher data rates as compared to WWANs for slow mobile
or static systems. The IEEE 802.11b-based WLANs are already widely being used
while the IEEE 802.11g and IEEE 802.11a are also available.
WLAN technologies are mainly used for wireless transmission of IP packets.
Until now, in contrast to the WWANs, the WLANs provided network access as a
complement to the wireline LANs. In the near future QoS-based WLANs are
expected to come onto the market. IEEE 802.11e is working towards MAC enhancements. The purpose of the
MAC enhancement is to enable the present MAC, CSMA/CA, to provide QoS. The
current draft has accepted two variations for QoS enhancements: central controland
distributed control-based. For security in IEEE 802.11i, the main direction is
towards applying the IEEE 802.1X-based solution with stronger and more choice
of encryption algorithms. The IEEE 802.11 Working Group (WG) has also
accepted a mobility solution known as Inter Access Point Protocol (IAPP), IEEE
802.11f. Another group in IEEE 802.11 is working on radio resource management
(IEEE 802.11j); The IEEE 802.11 committee has approved IEEE 802.11h,
dynamic frequency assignment, and transmit power control. Due to the success of
the standard there are several other study groups looking at higher data rate
solutions (IEEE 802.11n 110 Mbps+) and next generation technologies including
standardization work with 3G standardization committees.
WiFi Alliance, an industry alliance, is providing interoperability specifications
and tests of the IEEE 802.11 products for better acceptance in the market. This
alliance also provides recommendations for roaming between different WISPs so
that a user, or customer of one WISP, can access WLAN services when in another
WISP’s hotspot and still receive one bill.
Other known WLAN technologies are HIPERLAN Type 2 and HomeRF.
HIPERLAN Type 2 is already standardized; it provides hooks for QoS and security
for different environments. HomeRF developed several solutions but since the
beginning of 2003 HomeRF has been thought to be dead.
The direction for WLANs at present would be to move towards a common
international standard. Harmonization in 5-GHz band technologies is a must so as
to avoid making the 5-GHz band a garbage band. Although harmonization is a
solution it is possible that the market will be a deciding factor and choose one
technology. For the time being the success of a standard will depend on pricing,
performance, availability, and marketing of the standards.
Besides the work being done by the standardization committees there should
be a study on providing top-to-bottom mapping. The correct mapping of higher
layer protocols to lower layer protocols is a must to provide optimum service.
Especially in the case of IEEE 802.11 where the standard only defines the bottom
two layers, relations must be created with IETF, the committee developing layer
three, and some higher layer protocols.
Basically most of the current development will lead to providing users
different services within WLANs; in other words it is the integration of services
within one system. Another step currently becoming visible is towards integration
with WWAN technologies like 3G.