3G Wireless Networks Come of Age
3G Wireless Networks Come of Age
Enterprise applications have grown dependent enough on Internet access that its presence is virtually mandatory if users are going to get their work donea 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 businessescombined with the spread of inexpensive Wi-Fi access pointshas 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.
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.)
GPRS (General Packet Radio Service) is a wireless network technology built atop GSM. GPRS networks are packet-switched and deliver higher speeds than 2Gor digital, circuit-switchedGSM 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 bpsspeeds 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.
The other major family of cellular network technology, CDMA, is the set of standards on which U.S. carriers Sprint Communications Co. L.P. and Verizon Wireless have built their networks.
The set of 3G network technologies that belong to the CDMA family is known as CDMA2000, which, as with the GSM alternatives, come in successively speedy iterations.
The first and most widely available of these is CDMA2000 1xRTT (Radio Transmission Technology), which delivers transfer speeds of up to 144K bps and straddles the line between whats considered 2.5G and 3G.
The performance that 1xRTT services offer is good enough for most general network access requirements, such as linking to corporate resources over a VPN and interacting with Web-based applications.
Sprint and Verizon Wireless each offer CDMA2000 1xRTT services in most metropolitan areas. Sprint calls its 1xRTT service Sprint PCS Vision, and Verizon calls its 1xRTT service NationalAccess.
The next step beyond 1xRTT is CDMA2000 1xEvDO (Evolution Data Optimized), which boosts typical transfer rates to between 300K bps and 500K bps.
Verizon Wireless offers 1xEvDO service under the product name BroadbandAccess in 16 U.S. cities.
As its name suggests, 1xEvDO supports data transmission only. A follow-on called 1xEvDV will provide for both voice and data transmission, but neither Sprint nor Verizon Wireless has deployed such a network so far.
As with UMTS and UMTS/ HSDPA on the GSM side, the performance that these next-step CDMA2000 networks make possible begins to erase the distinctions that enterprises must now make between the applications they can deploy to mobile users and those they can deploy to fixed broadband users.
Taking a route separate from the GSM or CDMA paths traveled by other major U.S. carriers is Nextel Communications, which offers data services based on IDEN (Integrated Digital Enhanced Network).
Nextel currently offers data services with transfer rates of about 15K bpsawfully poky compared with the competitionalthough Nextel is in the process of upgrading its network with an IDEN extension called WIDEN, which should boost data rates to about 60K bps to 80K bps.
Its unclear at this point whether or how Nextel will boost its data services to 3G speeds. However, the carrier is conducting a network trial using Flarion Technologies Inc.s FLASH-OFDM, which stands for (take a deep breath now) Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiplexing. FLASH-OFDM offers transfer speeds in excess of 1M bps.
Senior Analyst Jason Brooks can be reached at firstname.lastname@example.org.
Check out eWEEK.coms for the latest news, reviews and analysis on mobile and wireless computing.