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3G speeds might not cut it for multimedia
 
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Despite the hype surrounding the higher-speed 3G (third-generation) mobile networks now under construction, industry skeptics say that users will not be able to take advantage of rich multimedia content across wireless networks until the arrival of yet another network. You guessed it: the 4G (fourth-generation) wireless network.
While 3G wireless will be able to handle short, low-quality multimedia clips, some say multimegabit 4G speeds will be required to deliver full, rich multimedia experiences.
4G networks are reportedly in development at AT&T Labs and could enable downstream transfer rates of 5M bit/sec to10M bit/sec. However, these networks are not likely to be up and running for another four or five years.
AT&T is building its 3G network based on Enhanced Data for GSM Evolution (EDGE) technology, which reportedly will offer a maximum rate of 384K bit/sec. Some observers, note, though, that such speeds are achieved only in best-case scenarios. For example, if a user is the only person using the network near a cell tower with no interference nearby, that user might see 384K bit/sec speeds. Typically, users are more likely to realize 56K bit/sec speeds, akin to current telephone modem connections.
4G will be a follow-on to 3G and will leverage Orthogonal Frequency Division Multiplexing (OFDM). OFDM uses multiple carriers, or tones, to divide data across the available spectrum. It's similar to the way FDM works. However, in an OFDM system, each tone is considered to be independent to adjacent tones and does not require a guard band. OFDM requires guard bands only around a set of tones, making it more efficient spectrally than FDM. OFDM is made up of many narrowband tones, so narrowband interference will degrade only a small portion of the signal.
The good news is that upgrading from 3G to 4G is expected to be seamless to end users with no device upgrades required.
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Joanie Wexler is an independent networking technology writer/editor in Campbell, Calif., who has spent most of her career analyzing trends and news in the computer networking industry. She welcomes your comments on the articles published in this newsletter, as well as your ideas for future article topics. Reach her at joanie@jwexler.com.
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