Information Technology Reference
In-Depth Information
Internationally the ITU encompasses mobile
or fixed technologies that provide connections at
speed higher than the primary rate (e.g., 2 Mbit/s).
However, the definition differs across countries
based on their available technologies and stages of
economic development. There is also a three-part
definition of Broadband Wireless Access (BWA)
in accordance with ITU-R Recommendations as
follows: (ITU, 2006)
Wireless access systems are broadband radio
systems that may be deployed either indoors or
outdoors. These systems include:
of the network to users. Thus, WiMAX can be used
as a complementary service to WLAN (ITU, 2006,
Odinma, Oborkhale, Eng and Kah, 2007, Niyato
and Hossain, 2007). Technical aspects of current
and upcoming wireless broadband applications
are discussed in many existing research works
8
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In the mobile BB technology space, 3G (for
third generation) and LTE marketed as 4G (for
fourth generation) are two well known technolo-
gies in the current generation of mobile networks.
The 3G systems expect to provide data at a mini-
mum of 144 Kbit/s for all radio environments and
2 mbit/s to low-mobility and indoor environment,
though these high speeds may not be available for
all the time in service offerings. The 3G standard
as defined by ITU is International Mobile Tele-
communications or IMT-2000 and the standards
for 4G are currently being defined.
Wi-Fi, WiMAX and 3G cellular are very dif-
ferent from one another but they complement each
other as well as compete with each other under
some situations. WiMAX is expected to provide
fixed and nomadic wireless connections. The
future 4G infrastructure will consists of a set of
various networks using IP (Internet Protocol) as
a common protocol. Ultimately 4G will integrate
fixed, mobile and other BB technologies in order
to provide robust, seamless communications with
high speed data transfer
9
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Regarding the spectrum band for BWA, gen-
erally, 450-500 MHz and 600-1000 MHz bands
could be used for broadband mobile access ser-
vices given the significant enhanced propagation
characteristics of the bands. Many of the bands
between the ranges 1.5 - 2.5 GHz are currently
identified as IMT-2000 bands which could be used
for delivering both fixed and mobile broadband
access services. Sometimes such technological
application is referred as “IMT-2000 and beyond”
(that which is 3.5G or 4G technology). These
bands are identified for hybrid satellite and ter-
restrial wireless systems that permit seamless
continuation of roaming for BWA operation. 3.4
- 3.7 GHz bands are allocated over all regions for
1) Fixed wireless access which may be defined
as wireless access application(s) in which the
location of the end users terminations and
the network access point to be connected to
the end users are fixed.
2) Mobile wireless access which may be defined
as wireless access application(s) in which the
location of end user termination is mobile
3) Nomadic wireless access which may be
defined as wireless access application(s) in
which the location of the end-user termina-
tion maybe in different place but it must be
stationary while in use.
A wireless local area network (WLAN) is
defined as a local area network in which one seg-
ment uses electromagnetic waves to transmit and
receive data over short distances in place of wired
network access. Of all the WLAN technologies,
the most popular and widely known one is IEEE
802.11b, currently redefined as Wireless Fidelity
(Wi-Fi). Wi-Fi coverage is limited to a maximum
of 300 feet radius. On the other hand, World Wide
Interoperability to Microwave Access (WiMAX)
is IEEE 802.16 standard which uses point-to-
multipoint architecture and is capable of delivering
last mile BB connections in a larger radius than
Wi-Fi. WiMAX is seen as a high-speed wireless
backbone or middle-mile technology, linking
different ISPs to the Internet whereas service like
Wi-Fi can be used for connections over the last leg
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