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Ask Maggie: On what 4G is and isn't

Ask Maggie is a weekly technology column that answers readers' questions. This week, CNET's Maggie Reardon answers readers questions about 4G wireless broadband and white spaces.

Almost everywhere you turn, one major wireless carrier or another is talking about its 4G wireless network.

Verizon Wireless says it will launch its 4G network by the end of the year. Sprint Nextel has been touting its 4G network for more than a year. And now all of a sudden T-Mobile, which on a few years ago didn't even have 3G service, is talking about 4G speeds on its network.

Ask Maggie

One reader wants to know what it all means. Another reader wants to know when Verizon will actually start selling 4G wireless smartphones. And finally I try to explain how the new "white space" spectrum might be used to create new wireless broadband services.

Ask Maggie is a weekly advice column that answers readers' wireless and broadband questions. If you've got a question please send me an email to me at maggie dot reardon at cbs dot com. And please put "Ask Maggie" in the subject header.

What's 4G really mean?

Dear Maggie,

Will T-Mobile USA, provide wireless Internet at 4G speeds anytime soon? I know Verizon Wireless and Sprint Nextel are already building 4G networks.



Dear Jonathan,

The short answer is yes.

The last 18 months have been very confusing for consumers when it comes to understanding what 4G really means. Marketing masters at the major wireless operators have been throwing around the term pretty loosely the past several months in an effort to one-up each other. To corporate spin artists, 4G is a term used to describe the latest wireless upgrade to faster speeds. But to the International Telecommunications Union, the standards body that defines network technologies, the term 4G has not actually been defined yet.

Part of the requirements for a network to be considered 4G by the ITU is that it needs to be IP-based and it needs to use orthogonal frequency-division multiplexing (OFDM). The other main requirement is that it needs to support aggregate mobile data speeds of 100 Mbps.

Technically, none of the carriers today claiming to offer 4G services are really offering 4G services. Clearwire, which is building the network that Sprint Nextel is using, uses a technology called WiMax, and Verizon is using a technology called long term evolution, or LTE. These technologies satisfy some of the ITU's requirements for 4G but not all.

T-Mobile uses an extension of its existing 3G technology called HSPA+, which also doesn't satisfy the technical definition of 4G.

But this doesn't mean that these new networks don't represent a new evolution in wireless technology. They do. Each of these network technologies offers a considerable jump in speed over older-generation 3G technologies and data speeds.

Average 3G services offer between 700Kbps and 1.5Mbps. Sprint's WiMax service, built by Clearwire, offers average download speeds around 6Mbps, the company has said. And Verizon claims that tests indicate it is getting download speeds between 6Mbps and 12Mbps on its pre-commercial LTE network.

Just as WiMax and LTE have improved data rates for Sprint and Verizon customers, HSPA+ offers a significant boost in performance for T-Mobile subscribers too. Average download speeds range between 3Mbps and 7Mbps.

(Actual download speeds of wireless networks vary depending on how heavily loaded the network is. Wireless is a shared medium, so the more users you have, consuming more bandwidth, the less capacity is available to go around.)

So what does this mean to the average consumer? In a nutshell, comparing the technologies purely on download speeds, WiMax (Sprint), LTE (Verizon Wireless) and HSPA+ (T-Mobile) are all comparable.

The real competitive difference for these carriers will likely come down to coverage. Clearwire, which is building the WiMax network Sprint is using, is in over 55 markets today and is adding more each week. Its goal is to reach 120 million potential customers by the end of 2010.

Verizon said earlier this week it plans to be in 38 markets across the country and offer service to 110 million potential customers by the end of 2010. And within three years it will be everywhere its 3G service is available today and it will cover 285 million potential customers.

T-Mobile's HSPA+ networkis in 65 metro areas today and is available to 120 million potential customers. And by the end of 2010, the company has said it will be available in 100 markets to more than 200 million potential customers.

To get the full benefit of these improved networks, consumers need to get a device that supports the new network technologies. Sprint currently sells two "3G/4G" WiMax smartphones. T-Mobile will soon offer two devices that support its HSPA+ network, the new G2 and HTC myTouch. Verizon hasn't yet announced "4G" devices, but Verizon COO Lowell McAdam said it would announce several new smartphones at the Consumer Electronics Show in January with products in stores in the first quarter.

But consumers also need to be careful when buying supposed "4G" smartphones. Not every device that has a "4" after its name can take advantage of these new networks. For example, the iPhone 4 does not operate on a new generation of AT&T's network. It is simply the fourth version of the iPhone. It operates over the same 3G network that the iPhone 3G and the iPhone 3GS also use.

I hope that helps!

Verizon LTE handsets ?

Dear Maggie,

I am a Verizon Wireless customer and I live in one of the markets where Verizon will launch 4G service later this year. My question is when will 4G smartphones be available? A specific month would be appreciated. Also, Motorola just announced the Droid Pro, Verizon's first Android-based world phone. I've been waiting for a phone I can use overseas. Would this phone be 4G compatible when the LTE is rolled out, or would I need to purchase a new "global" phone in 2011? Thanks in advance for seeking the answers to these questions.



Dear Jason,

I asked Verizon's COO Lowell McAdam when Verizon LTE devices will hit store shelves. He wouldn't give me a specific date but said that LTE smartphones would definitely be for sale in the first quarter of 2011. The company plans to introduce several LTE smartphones and tablets at the CES trade show in Las Vegas in early January.

Any device that Verizon is launching now, including the Motorola DroidPro, will not be able to take advantage of the new LTE network that will be launched later this year. And at this point, it's hard to know whether any of Verizon's LTE smartphones will have the necessary radio technology to be used overseas.

Verizon's 3G network is based on CDMA technology, but much of the world's carriers use GSM. This is why when you travel abroad with most Verizon phones you can't roam onto another carrier's network. Verizon's "world phones" have a CDMA radio for the Verizon domestic network and a GSM radio that allows the device to roam onto other networks. So unless Verizon offers phones with LTE, CDMA, and GSM, a new "4G" may not necessarily be a world phone.

White spaces

Hey Maggie,

I was considering the recent news of the FCC allowing wireless Internet broadcasts over unused television frequencies. Would these devices be called wireless broadband phones? Or, would they be called something different?



Dear Enrique,

It's too early to say what types of devices or services will be built using the "white space" frequencies. So I am not sure what the devices will be called. But my guess is that there will likely be a whole range of devices and services that use the spectrum. "White spaces" are slivers of unused spectrum that sit between TV channels. The FCC recently authorized this spectrum to be used without a license for wireless broadband services.

Given that the frequencies that will be available for unlicensed use do not stretch across the entire U.S., it's unlikely that any company would use it exclusively to develop a nationwide voice or data service to compete with the major wireless players. But the spectrum could be used regionally to help existing service providers augment or offload traffic from their existing networks. Or it could be used for entirely new applications.

For example, in Wilmington, NC, the city tested technology that used white space spectrum to monitor traffic at intersections to regulate the traffic lights in order to reduce congestion, fuel consumption, travel time, support local law enforcement, and assist with hurricane and disaster evacuations.

It was also used to wirelessly connect cameras in city parks to police for surveillance. Radios are also set up in city parks to provide free Wi-Fi access to residents and city workers.

And finally, the city and county used the spectrum to remotely monitor and manage wetland areas to comply with EPA regulations. Because these areas are hard to get to, there is no fiber optic network that can be used to transmit data from sensors in the field. So people go out in boats and canoes to collect the data from the monitors. Now using the white space network, the data can be transmitted wirelessly.

These are just a few applications that have already been tested using white spectrum. And there are likely to be many more as device makers and service providers think of new ways to use the technology.