Cellular Fills Gap Between Hotspots

Let's face it, Wi-Fi has spoiled us. Nothing less than broadband everywhere is good enough any more. When was the last time you fired up the 56K modem in your laptop and made a dial-up connection? Most users would rather drive 15 miles to the nearest hotspot than deal with a phone jack. But what if you can't find a nearby spot, or simply need to get connected NOW? The solution may be no further than the smartphone in your pocket. Many new models have high-speed 3G data capability, and the big providers have finally loosened up their restrictions on using phones as laptop modems by offering reasonably priced add-on plans. Or if you need a heavier duty solution, a dedicated cell data card may be the answer. While older cell data networks could be painfully slow, 3G technology offers true broadband speeds and coverage in most urban areas.

That's not to say cell data can replace Wi-Fi. High-speed cellular service and Wi-Fi go hand-in-hand: Wi-Fi is available primarily in indoor locations like airports and hotels that may not have great cell reception, while cellular data services will get you online in places where Wi-Fi can?t reach. That's one reason big cell carriers like AT&T/Cingular, Sprint and T-Mobile all have high-profile Wi-Fi hotspot networks as well, and offer them as add-ons to their cell subscribers. In this article, we?ll show you how to find the right service plan and network to stay connected no matter where you go.

The Contenders

When you start looking at cellular data services, you?ll be confronted with a confusing array of terms like GPRS, EDGE, UMTS, HSDPA 1xRTT, and EV-DO that the cellular carriers use to describe their networks. And now there's even EV-DO "Rev. A" and HSUPA to contend with. To understand where these terms come from, here's a brief overview.

Current US digital cell phone networks are based on two underlying standards: GSM (Global System for Mobile communications) and CDMA (Code Division Multiple Access). Carriers using GSM include AT&T (the rebranded Cingular) and T-Mobile, while most others (such as Verizon Wireless) use CDMA. Sprint uses a standard called PCS, which is based on CDMA but uses different frequencies. These standards were originally designed to carry voice traffic efficiently, but they aren?t able to support high-speed data connections.

To better handle data traffic, GSM networks added a standard called GPRS (General Packet Radio Service) that could carry data at up to 56Kbps -- about the same speed as a dial-up connection. Next came an upgrade called EDGE (Enhanced Data rates for GSM Evolution) that increased transmission speeds to 144Kbps. About the same time, CDMA networks upgraded to 1xRTT (Radio Transmission Technology), which also runs at 144Kbps. EDGE and 1xRTT are known as "2.5G" technologies, and many current handsets are based on them. T-Mobile still offers EDGE as its top-end service.

The sea change for cell data came with the introduction of 1xEV-DO Rev. 0 (Evolution-Data Only), a "3G" enhancement to CDMA networks which can carry data at a theoretical maximum of several megabits per second -- as fast as DSL or cable Internet connections. Verizon was the first major CDMA carrier with EV-DO; Sprint has now drawn even coverage-wise. This year, both companies are ramping up EV-DO Rev. A, a further enhancement to the standard that boosts real-world download speeds from Rev. 0's 400-700Kbps to 600Kbps-1.4Mbps, but more importantly revs upload speeds from 50-70Kbps all the way to 500-800Kbps and improves latency all around. This increase is designed to enable high-bandwidth two-way services like VoIP and videoconferencing, real-time gaming, and push-to-talk.

AT&T/Cingular was late to the 3G party, but is now actively expanding its HSDPA (High-Speed Downstream Packet Access) network, which matches EV-DO Rev. 0 in real-world transmission speeds of 400-700Kbps. Even as it does so, the company is already looking forward to adding HSUPA (High-Speed Upstream Packet Access), which will boost the upload speeds of its high-speed network similarly to EV-DO Rev. A. Unlike EV-DO Rev. 0, HSDPA allows for simultaneous voice and data, a crucial feature for users who don't want to be cut off from making and receiving calls while surfing with their laptops. Furthermore, AT&T/Cingular's quad-band EDGE/HSDPA cards and phones can roam around the world, unlike U.S.-bound EV-DO devices. T-Mobile will finally be rolling out its 3G HSDPA service later this year.