In a series of interviews with the New York Times, Wall Street Journal and USA Today, Steve Jobs and Randall Stephenson used nearly identical talking points as they defended their decision to rely on AT&T's sluggish EDGE network rather than the faster 3G network that AT&T sells corporate customers. "It's good enough," Jobs told the Journal. "But you wish it was a little faster."
Jobs described the iPhone's network strategy as a "sandwich": it connects to fast Wi-Fi networks where they are available and switches back to the slower EDGE network when they're not -- which is the case for most of the U.S.
"We think we made a pretty good doggone decision," said Jobs.
So what exactly are these acronyms -- EDGE, 3G and Wi-Fi -- and how do they compare? A primer:
2G: Second generation (2G) cell phone and data standards differ primarily from first generation (1G) in that they are digital, not analog. They come in two main flavors: GSM, used by roughly 2 billion people in the world, and CDMA, used by fewer than 300 million.
3G: There are a dozen variations of s0-called third generation (3G) standards, which have been widely deployed in the Far East and to a lesser extent in Europe. But coverage in the U.S. is spotty. Jobs said he looked at 3G chipsets, but decided they were too bulky and drained batteries too quickly or use in the first generation iPhone. He hinted broadly that that might change in future versions.
EDGE: An acronym for Enhanced Data Rates for GSM Evolution, this is what experts call a bolt-on enhancement of GSM. It takes a second generation (2G) network and makes it roughly 2.75G. EDGE can carry data speeds up to 236.8 kbit/second for 4 timeslots. AT&T's EDGE network was delivering roughly 40 kbit/s before it was upgraded in advance of iPhone's launch. Today several sites are reporting download speeds of better than 200 kbits/s over the same network.
HSDPA: An acronym for High-Speed Download Packet Access, this is the protocol AT&T uses to deliver 3G data speeds. In its current form, HSDPA supports download speeds of 1.8 Mbit/s, 3.6 Mbit/s, 7.2 Mbit/s and 14.4 Mbit/s. It can eventually be upgraded to 42 Mbit/s.
Wi-Fi: Thought to stand for Wireless Fidelity, Wi-Fi is usually used to deliver wireless connections to local area networks to computers, but it can also be used for phone calls over so-called VoIP (Voice Over Internet Protocol). In its various flavors it can deliver from 4 Mbits/s to 74 Mbits/s over relatively short distances (from 30 to 100 meters). Many commercial establishments (like Starbucks) offer Wi-Fi for a price, but computer owners often share their Wi-Fi connections and several U.S. cities have started blanketing public areas with free Wi-Fi.
Source: http://blogs.business2.com/apple/2007/06/bandwidth-101-w.html
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