Remember those telltale twisty antennas on
the roofs of cars in the 1980s? Those cool customers on their
car phones were using Advanced Mobile Phone Service, or AMPS.
This first-generation analog network may have been cutting edge
at the time, but it soon became notorious for its iffy call
quality. Even worse, anyone with a police radio scanner can
easily eavesdrop on AMPS calls, which travel through the air
without any scrambling or encryption. AMPS still is available
today on some CDMA phones from Sprint and Verizon, but it is
largely fading as a technology.
The evolution of 3G
| |
1980s |
1990 to 1995 |
1995 to 2000 |
2000 to 2005 |
1G
Analog: voice only |
AMPS |
|
|
|
2G
Digital: voice and limited data
(less than 20Kbps) |
|
CDMA
GSM |
|
|
2.5G
Data at dial-up speeds
(30Kbps to 90Kbps) |
|
|
GPRS
1xRTT |
EDGE |
3G
DSL speeds
(144Kbps to 2Mbps) |
|
|
|
UMTS
1xEV-DO |
The 1990s marked the arrival of two digital networks:
CDMA, popular in the United States and a few other countries;
and GSM, the dominant technology overseas. These
second-generation (2G) networks spread voice calls across
several wireless spectrums, making for more reliable connections
that are much harder--though not impossible--for hackers to
intercept. More importantly, CDMA and GSM networks are also
capable of sending a sliver of data along with voice signals,
making possible for such features as text messaging (SMS),
caller ID, and conference calling.
Though the move to 2G was a great leap in terms of the
technology, the splintering of the CDMA and GSM camps created a
mess. At the time, AT&T Wireless, Cingular, and VoiceStream (now
T-Mobile) opted for GSM. This required the carriers to adopt the
now largely defunct TDMA technology before moving on to GSM. On
the other hand, Sprint, Verizon, and a number of smaller
carriers chose CDMA. While each side says it has the advantage,
the schism resulted in two competing networks with little
incentive to create a unifying 3G standard. Conversely in
Europe, 3G arrived much more quickly because all carriers were
working off a government-mandated standard.
Of course, there were other factors working against 3G's
adoption in the United States. Rolling out the new networks was
very expensive, and customers had to be sold on the services.
Furthermore, the move also involved technological constraints.
Carriers had to bridge the gap between slow-as-molasses 2G
service and zippy 3G with "2.5G" network enhancements. In
operation a couple years now, 2.5G networks let you download
ring tones, listen to short audio clips, send multimedia
messages (MMS), or surf the Web, albeit slowly. These services
include GPRS, which is capable of transmitting and receiving
data at an average of about 30Kbps to 40Kbps, or a little slower
than standard 56K dial-up service and EDGE, another GSM
enhancement that manages about 90Kbps on an average day, or
almost twice as fast as dial-up. On the CDMA side is 1xRTT, an
early version of CDMA2000, which squeaks in about 60Kbps to
80Kbps. The next step, of course, is 3G and beyond. But some
important differences remain. |
