A comparison of wi-fi and wimax with case studies - Florida State ...
A comparison of wi-fi and wimax with case studies - Florida State ...
A comparison of wi-fi and wimax with case studies - Florida State ...
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Figure 4-7<br />
Coverage<br />
<strong>and</strong> Capacity<br />
for Diffferent<br />
Wireeless<br />
Accesss<br />
Technique es<br />
Bas sically, thee<br />
applications<br />
<strong>of</strong> themm<br />
are different,<br />
althouugh<br />
they hhave<br />
some features in n<br />
commoon.<br />
WiMax is develooped<br />
for MANs; M Wi-Fi<br />
is for LANs <strong>and</strong>d<br />
3G is tthe<br />
cellularr<br />
commuunication<br />
sta<strong>and</strong>ard.<br />
Thuus,<br />
the relaationships<br />
aamong<br />
themm<br />
should bbe<br />
<strong>of</strong> coope eration, nott<br />
competition.<br />
The sservices<br />
<strong>of</strong> 33G<br />
are phon ne service a<strong>and</strong><br />
limited internet serrvice<br />
in a lo ow mobility y<br />
environnment.<br />
Wi-FFi<br />
providess<br />
broadb<strong>and</strong> d <strong>wi</strong>reless sservice<br />
in a <strong>fi</strong>xed envvironment,<br />
most likelyy<br />
indoorss.<br />
WiMax iis<br />
going to provide a large rangge<br />
broadbannd<br />
<strong>wi</strong>reless service in a <strong>fi</strong>xed orr<br />
mobility y environmment.<br />
They can<br />
cover eaach<br />
other’s ddrawbacks.<br />
[54][133]<br />
In an urban arrea,<br />
IEEE 8802.16<br />
has sseveral<br />
commpetitors<br />
suuch<br />
as DSL, , cable, or f<strong>fi</strong>ber.<br />
Thesee<br />
<strong>wi</strong>red cconnectionss<br />
have highher<br />
speed a<strong>and</strong><br />
are moore<br />
stable. MMost<br />
<strong>of</strong> timme,<br />
they ha ave alreadyy<br />
existed when a buuilding<br />
was built. Evenn<br />
through w<strong>wi</strong>reless<br />
commmunicationn<br />
has been improved a<br />
lot; <strong>wi</strong>rred<br />
communnication<br />
is sstill<br />
more reeliable<br />
<strong>and</strong> safer. The maximum speed that WiMax W cann<br />
reach iss<br />
about 70 Mbps, but <strong>wi</strong>th <strong>fi</strong>ber, it can achieve<br />
at least t 1 Gbps! TTherefore,<br />
users u wouldd<br />
choose <strong>wi</strong>red ratheer<br />
than <strong>wi</strong>relless.<br />
[58]<br />
Annother<br />
probllem<br />
is the ttopography.<br />
. In a highlly<br />
developeed<br />
city, thesse<br />
tall builddings<br />
wouldd<br />
interfere<br />
<strong>wi</strong>th the ttransmissionn<br />
<strong>of</strong> radio. For high frequency<br />
miicrowaves,<br />
it requires a clear pathh<br />
to reachh<br />
the terminnal;<br />
other<strong>wi</strong>se<br />
the base station musst<br />
set on a bbuilding<br />
thaat<br />
is higher tthan<br />
others.<br />
On the other h<strong>and</strong>, , lower-freqquency<br />
micrrowave<br />
usinng<br />
non-linee-<strong>of</strong>-sight<br />
(NNLOS)<br />
tech hnology still l<br />
has a pr roblem; a signal<br />
is diff <strong>fi</strong>cult to locck<br />
on becauuse<br />
<strong>of</strong> manyy<br />
reflectionss<br />
<strong>of</strong>f mason nry walls. Inn<br />
59
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