Verizon Wireless BroadbandAccess (EV-DO)
April 12, 2007
The good, the bad and the ugly in testing the laptop 3G capabilities of one of America's biggest mobile operators.
A word problem: suppose you are riding in a car going 70 mph and your destination is 300 miles away how fast can you download a 1 megabyte file?
Chances are, you cant, unless you subscribe to a mobile data service. It has long been possible to dribble sluggish bits of data by tethering your cell phone to a portable computer with a supported data subscription plan, but the solution is painfully slow and can be expensive. Enter cellular broadband services, also known as 3G (third generation)
In the U.S., the major 3G providers are Sprint Nextel
, Verizon Wireless (a joint venture of Verizon
), and to a lesser extent, Cingular (the new AT&T
). Both Sprint Mobile Broadband and Verizon BroadbandAccess use the technology called Evolution-Data Optimized (EV-DO)
Whether you have access to Verizons original Rev 0 EV-DO network or the newer Rev A version, BroadbandAccess delivers on its promise of mobile connectivity.
Typical download speeds on the Rev A network average 600 Kbps to 1 Mbps with strong signal strength, although even better performance can be seen on lightly-loaded towers and through TCP/IP configuration tweaks. Rev 0 users typically see somewhat (but not dramatically) slower downstream throughput.
The more significant advantages of Rev A over Rev 0 come in upstream throughput and network latency. Whereas Rev 0 users typically experience upload speeds under 150 Kbps, Rev A users can enjoy a bump of several multiples, reaching 300-400 Kbps under good conditions. And like the download speeds, these numbers can be bumped as much as 50% higher with network configuration tweaks and, again, depending on conditions.
Latency is reduced considerably between Rev 0 and Rev A. On the Rev 0 network, average network latency is measured at approximately 200ms but can often spike as high as 400-500ms. In contrast, the Rev A network regularly delivers ping results below 100ms, although it too is subject to higher spikes.
The BroadbandAccess network has proven robust through a wide variety of signal strength conditions. The strongest signals measured run in the -50 to -60 dBm range and produce a full four bars in the software display. I extensively tested BroadbandAccess in a fringe coverage area in fact, at least 2-3 miles outside the edge of Verizons official coverage area in my region (Ithaca, New York). Without the help of an external antenna, I managed only -100 to -105 dBm nearly as faint a signal as you can get before the service drops out completely. In spite of the marginal signal, the service continued to deliver Rev 0 access with speeds averaging 300 Kbps down and 10-15 Kbps up nowhere near its maximum capability, but better than no service at all.
With the help of an el-cheapo external directional antenna rated at 7dBm and careful placement in a high location, I improved the fringe signal to about -95dBm. Oscillating between one and two bars on the software display, download speeds average 500 Kbps with spikes as high as 700 Kbps, and upload speeds range widely from 15 Kbps to 64 Kbps.
While BroadbandAccess delivers only a fraction of its rated speeds in areas of weak signal strength, it does continue to deliver, which may be the most important quality of all for the highly mobile subscriber.
In spite of Verizons contractual Terms of Service (see The Ugly below), they do not seem to block most popular network services. Clients are assigned a publicly routable IP address.
The USB720 Adapter
My evaluation was performed using Verizons new Rev A-compatible USB720 adapter ($129 with a two-year contract), made by Novatel Wireless. As its name implies, this EV-DO modem plugs into a USB port rather than a PCMCIA slot as most EV-DO adapters do.
In fact, the USB720 may require two USB ports on some systems. The adapter includes a USB Y-cable, designed to plug into two USB ports to provide extra power to the modem. Using the Y-cable offers the additional benefit of letting you place the adapter a couple of feet away from the computer, reducing interference and maximizing signal strength. On the other hand, for mobile use, the Y-cable can be awkward to tote around.
You can plug the bulky USB720 directly into a USB port without the cable, but some machines may not supply enough power from a single port. I found that a newer Toshiba portable powered the USB720 without difficulty, with or without the Y cable -- but an older ThinkPad T21 could not deliver enough USB-based juice to drive the modem. Whats more, the old ThinkPad had only one USB port, making the Y cable moot -- meaning that the USB720 could not be used at all with this older machine.
The USB720 includes a small flip-up antenna. When open, it exposes an external antenna jack, which can be especially useful in fringe signal areas.