3G Wireless Networks Come of Age

Wireless data networks are finally growing into the speedy 3G networks we've heard so much about the past few years.

Enterprise applications have grown dependent enough on Internet access that its presence is virtually mandatory if users are going to get their work done—a fact that doesnt change just because workers happen to be out of reach of the corporate LAN.

Widened penetration of broadband access in homes and businesses—combined with the spread of inexpensive Wi-Fi access points—has resulted in an environment in which its increasingly easy to reach the Internet. However, the spots that dont have connectivity still far outnumber those that do.

For now and the near future, the best bet for far-reaching Internet connectivity is the data networks of wireless telephone carriers. These networks are finally beginning to grow into the speedy 3G (third-generation) networks that weve heard so much about during the past few years.

/zimages/1/28571.gifClick here to read Labs reviews of three wireless data services.

Current 3G networks break down into two digital wireless technology families: GSM (Global System for Mobile Communications) and CDMA (Code Division Multiple Access).

GSM is the worlds most popular standard for mobile communications, employed by U.S. carriers T-Mobile USA Inc., AT&T Wireless and Cingular Wireless. (Cingular recently acquired AT&T Wireless, and the merging of the companies service offerings is ongoing.)

/zimages/1/28571.gifFor more on how the merger is proceeding, click here.

GPRS (General Packet Radio Service) is a wireless network technology built atop GSM. GPRS networks are packet-switched and deliver higher speeds than 2G—or digital, circuit-switched—GSM data connections.

However, GPRS networks, which typically manage speeds of 30K bps to 40K bps, are too slow to be considered 3G. In fact, GPRS is often called a 2.5G technology. It makes use of space left over from voice communications, and performance can suffer noticeably when the network is busy.

GPRS networks are the most widely accessible of the cellular data networks, with coverage over most metropolitan areas in the United States and networks maintained by major carriers.

EDGE (Enhanced Data for Global Evolution) builds atop GSM and GPRS networks to deliver speeds of about 100K bps to 130K bps. AT&T Wireless and Cingular currently cover most metropolitan areas with EDGE service, with the option of falling back to GPRS in areas that lack EDGE coverage.

Even further up the GSM chain is UMTS (Universal Mobile Telecommunications System), which theoretically supports transfer rates approaching 2M bps, but in real-world conditions is advertised to deliver transfer rates of about 220K bps to 320K bps. UMTS connections experience markedly lower latency than their EDGE or GPRS predecessors, which makes for a much better interactive network operation. UMTS also allows for simultaneous voice and data connections, provided ones hardware supports this feature.

At this point, AT&T Wireless is the only U.S. carrier to have deployed a UMTS network, with service available in the San Francisco Bay area, San Diego, Seattle, Dallas, Detroit and Phoenix.

The next step for high-speed Internet access in the GSM clan is UMTS/HSDPA (High Speed Downlink Packet Access), an extension to UMTS that boosts downlink transfer rates to 2M bps to 3M bps and uplink rates to 384K bps—speeds that make this wireless technology competitive with fixed broadband links such as DSL. UMTS/HSDPA service currently is not available in the United States, but Cingular has announced plans to test such a network.

Next page: CDMA.