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technologies being developed for 4G services are WiMAX
and 3GPP Long Term Evolution (LTE) with some interest in
WiBro, iBurst, and 3GPP2 Ultra Mobile Broadband (UMB).
Naturally, carriers want to offer 4G services without disrupting
service to their existing subscribers. In order to provide
backward compatibility for users of legacy services, the
various groups developing 4G standards are aiming to support
most of the standards used by 2G, 2.5G, and 3G services
today. However, 4G infrastructure will be completely based
on IP technology, so new infrastructure must be integrated
carefully. This has several implications for carriers planning
to upgrade their networks to support 4G services.
Coverage
4G services will require higher-quality coverage in more
places. Earlier wireless networks were based on the idea of
blanketing an outdoor area with frequency from cell towers
and rooftops, but 4G services will often use frequencies of 2
GHz and higher which will attenuate faster. So, more antennae
will be required and wireless signals will have to be boosted
inside buildings, in urban canyons, underground facilities and
other locations where traditional macro coverage won’t reach.
At the same time, interference will be an even greater issue
than it is today. Even in areas with an abundant supply of
rooftop cell towers, users often find that signal strength
tails off toward the lower floors of tall buildings. On the
upper floors, subscribers can experience poor service
because signals from multiple towers may be visible and
the phone constantly hunts from one signal to another.
Because 4G services will require more antennae in more
locations, carriers will have to engineer systems more
carefully to minimize interference from the multiple antennae
that any given device may be able to ‘see’ at a time.
Capacity
Macro networks that were designed to support an average
user base five or ten years ago cannot support current
call volumes or the need for higher-speed data support
let alone mobile video. Many users have been unable to
make or sustain a call in stadiums, on bridges or even
on crowded highways or in city streets simply because
These services require significant changes to the the nearest macro towers are overloaded. 4G wireless
underlying wireless infrastructure and carriers face cells will be much smaller than today’s cell areas not only
several issues in choosing the right migration path. because of the need for better coverage (due to signal
attenuation), but also the need for higher per-user capacity.
The term ‘4G wireless’ generally describes the next evolution of
wireless communications. While 3G systems like EVDO, HSPA Backhaul costs and options
and UMTS deliver enough bandwidth for some applications,
the goal of 4G networks is to support voice, data and streamed 4G networks delivering from 100 to 1000 times as much
multimedia for all users in all locations. This means 4G systems bandwidth per user will require much larger and more
must be capable of delivering from 100Mbps to 1Gbps of cost-effective backhaul networks. Most of today’s macro
bandwidth to each subscriber, both indoors and out. The main cellular networks still rely on 1.5Mbps E1 lines and these

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