Hardware Reference
In-Depth Information
a desktop using a USB or PCI adapter, the high expense and low performance compared
tootherbroadbandservicesmakescellular modemsapoorchoiceforastationarydesktop
system.
Whereas most cellular broadband connections are made with a dedicated cellular modem,
in many cases you can also connect through your existing cell phone by attaching the
phonetothesystemviaUSBorBluetooth(called
tethering
)andthenusingthephoneasa
high-speed modem connection. Some phones only allow tethering via USB, whereas oth-
ers support both USB and Bluetooth. For example, using my laptop, I can link to the cell
phone in my pocket via Bluetooth and then instruct the cell phone to connect to the Inter-
net, in essence creating a double-wireless connection.
3G Mobile Broadband Service
The connection speeds available depend on the carrier and services offered, but so-called
3G (Third Generation) technologies offer speeds in the 400Kbps-700Kbps range. Al-
though this is quite a bit less than the 11MBps provided by the most basic Wi-Fi hotspots,
this type of service is available anywhere you can get a cell phone signal. Note that con-
nectionsviaatetheredcellphonearegenerallymuchlowerinperformance(dependingon
the phone) than via dedicated cards.
”4G” Mobile Broadband Service
There are three competing technologies marketed as “4G” in the US: WiMax, long term
evolution (LTE), and evolved high speed packet access (HSPA+). WiMax and LTE are
also widely used in international markets.
WiMAX(WorldwideInteroperability forMicrowaveAccess)canbeusedforbothmobile
and fixed-base wireless broadband. However, WiMax is being positioned primarily as a
mobilesolution.WiMaxisbasedonthe802.16estandard,withsupportformaximumdata
rates of up to 12Mbps. However, current speeds are far slower: up to 4Mbps download
speed and 0.4Mbps upload speed. WiMAX uses orthogonal frequency division multiple
access(OFDMA)signaling,whichusessimultaneousbroadcastofradiowavesacrossdif-
ferent frequencies to avoid interference. In the US, WiMAX is the basis for Sprint's 4G
network.
LTEisbasedonGSMandUTMScellularsystems,henceitsname.LTEusesthe700MHz
radio frequency and is designed to reach a theoretical peak speed of around 100Mbps. In
the US,Verizon is the major user ofLTE, and in real-world tests performed byComputer-
World in February 2011, LTE averaged around 13.1Mbps download—or about 3×faster
than WiMAX and about 5.5Mbps upload speed (over 100 times faster than WiMAX).
