Satellitewireless wireless systems pro vided by earth

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Unformatted text preview: . Farzad, “The Truth abo ut Bandwidth,” BusinessWeek, February 3, 2010. We’re in the midst o f transitio ning f ro m third generatio n (3G) to f o urth generatio n (4G) wireless netwo rks. 3G systems o f f er access speeds usually less than 2 Mbps (o f ten a lo t less).K. German, “On Call: Welco me to 4G,” CNET, March 9, 2010. While variants o f 3G wireless might emplo y an alphabet so up o f techno lo gies—EV-DO (evo lutio n data o ptimized), UMTS (universal mo bile teleco mmunicatio ns systems), and HSDP A (high-speed do wnlink packet link access) amo ng them— 3G standards can be narro wed do wn to two camps: tho se based o n the do minant wo rldwide standard called GSM (glo bal system f o r mo bile co mmunicatio ns) and the runner-up standards based o n CDMA (co de divisio n multiple access). Mo st o f Euro pe and a go o d chunk o f the rest o f the wo rld use GSM. In the United States, AT&T and T-Mo bile use GSM-based 3G. Verizo n Wireless and Sprint use the CDMA 3G standard. Typically, handsets designed f o r o ne netwo rk can’t be used o n netwo rks suppo rting the o ther standard. CDMA has an additio nal limitatio n in no t being able to use vo ice and data at the same time. But 3G is being replaced by high-bandwidth 4G (f o urth-generatio n) mo bile netwo rks. 4G techno lo gies also f all into two standards camps: LTE (Lo ng Term Evo lutio n) and WiMAX (Wo rldwide Intero perability f o r Micro wave Access). LTE lo o ks like the glo bal winner. In the United States, every majo r wireless f irm, except f o r Sprint, is betting o n LTE victo ry. Bandwidth f o r the service rivals what we’d co nsider f ast cable a f ew years back. Average speeds range f ro m 5 to 12 Mbps f o r do wnlo ads and 2 to 5 Mbps f o r uplo ad, altho ugh Verizo n tests in Bo sto n and Seattle sho wed do wnlo ad speeds as high as 50 Mbps and uplo ad speeds reaching 25 Mbps.K. German, “On Call: Welco me to 4G,” CNET, March 9, 2010. Co mpeting with LTE is WiMAX; do n’t co nf use...
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This document was uploaded on 01/31/2014.

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