Embedded mobile broadband: Software-defined radio makes carrier-switching easy

One chip to run them all... or at least many of them

by Daniel P. Dern - All wireless communication, whether it's Bluetooth, cell phone voice service, WiFi, WiMAX, or plain old walkie-talkies and CB radios, needs several things inside each device: a radio transceiver (transmitter/receiver), a radio antenna, and the related protocols and technologies that differentiate some carriers from each other. Even one-way devices like radios and televisions need all this except for the transmitter part.

One challenge, until relatively recently, is that much of the circuitry has had to be specific to a carrier technology, like EV-DO versus HSDPA. This meant if you wanted your mobile broadband "embedded" (included) inside a notebook, you'd have to have your carrier, or at least carrier technology, picked out in advance, and changing your mind later would mean buying a replacement radio module.

[ Paying too much for WiFi, 3G? You have options ]

Thankfully, today, new software-defined radio tech like Qualcomm's GOBI, which provides "Major RF bands and GPS functionality all on one chipset," is doing away with some of this. For example, according to a June 2010 press release, "Qualcomm's latest Gobi-enabled MDM chipsets are compatible with leading mobile connectivity standards, including CDMA2000 1xEV-DO Rev. A and Rev. B, HSPA+, dual-carrier HSPA+, and LTE with integrated backwards compatibility to HSPA and EV-DO."

More and more notebooks (and, over time, netbooks, smartphones and other devices) are using these chips. (Qualcomm's GOBI is the main dog in this race; if there are others, I'm unaware of it.)

So now you can make the carrier decision after buying the notebook, and change carriers without having to buy a new data card or external adapter.

(Vendors and resellers like this, too, as it means fewer SKUs -- versions -- to make and stock.)

Again, just remember that you can't use the different carrier unless you've got a service agreement with them, and the service is available where you're going to be. And GOBI may be flexible, but even it has limits for example, GOBI currently doesn't support WiMAX or other 4G networks; you'd need a separate way to access them.

Software-defined radio tech can also provide other benefits besides carrier-switching. For example, GOBI 2000 provides "assisted GPS" -- using data from cell towers to aid in positioning.

But, cautions mobile expert Chris De Herrera, GOBI may not work with all the carriers you want, for example, it may not work with T-Mobile, because of their implementation of HSDPA, or if the antenna doesn't handle the frequency well enough. "Antennas are cut to a specific length, to optimize for the intended frequency range. An international device may not work as well as you hope." (An external USB antenna might help.)

However, compared to previous inflexibility, software defined radio means you can go shopping for a mobile-broadband-ready notebook or netbook that can, at least, give you some pre and post-purchase choice of carriers... again, as long as the machine you want has or offers a GOBI option.

Daniel P. Dern is a freelance technology writer based in Newton Center, MA. His web site is www.dern.com and his technology blog is TryingTechnology.com.

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