Walt Mossberg

4G or Not 4G: A Guide to Cut Through All the “Fast” Talk

Of all the confusing technology terms used in consumer marketing today, perhaps the most opaque is “4G,” used to describe a new, much faster generation of cellular data on smartphones, tablets and other devices. It sounds simple, but there are many varieties of 4G and conflicting claims.

AT&T claims “The nation’s largest 4G network,” and T-Mobile says it has “America’s largest 4G network.” Verizon Wireless boasts “America’s fastest 4G network,” and Sprint says it had the first 4G network.

Yet the technology used by T-Mobile, and mostly comprising AT&T’s 4G network, isn’t considered “real” 4G at all by some critics, and the one used by Sprint has proven to be a dead end and is being abandoned. The flavor being used by Verizon is now being adopted by its rivals, but won’t be interoperable among them.

PTECH-JUMP

Verizon offers LTE, which is the fastest variety of 4G.

It’s a headache for consumers to grasp. So here’s a simplified explainer to some of the most common questions, based on interviews with top technical officials at all four major U.S. wireless carriers.

What is 4G?

It’s the fourth and latest generation technology for data access over cellular networks. It’s faster and can give networks more capacity than the 3G networks still on most phones. There’s a technical definition, set by a United Nations agency in Europe, and a marketing definition, which is looser, but more relevant to most consumers.

Who needs 4G?

It’s mostly for people with smartphones, tablets and laptops who often need fast data speeds for Web browsing, app use and email when they’re out of the range of Wi-Fi networks. It can give you the same or greater data speeds as home or office Wi-Fi when you’re in a taxi. In hotels and airports, it’s often faster than public Wi-Fi networks.

How does 4G differ from another term being advertised, ‘LTE’?

LTE, which stands for “Long Term Evolution,” is the fastest, most consistent variety of 4G, and the one most technical experts feel hews most closely to the technical standard set by the U.N. In the U.S., it has primarily been deployed by Verizon, which offers it in over 200 markets. AT&T has begun deploying it, offering LTE in 28 markets so far. Sprint and T-Mobile are pivoting to LTE, though they have no cities covered by it yet.

What are these other versions of 4G?

Sprint uses a technology called WiMax. T-Mobile and AT&T deployed a technology called HSPA+, a faster version of 3G that they relabeled as 4G, and which many technical critics regard as a “faux 4G.” Sprint will begin switching to LTE later this year, and T-Mobile in 2013.

PTECH-JUMP

Sprint uses a 4G technology called WiMax.
How fast is 4G?

Claims vary and performance depends upon the type of device, location, and time. In my tests, 4G phones, tablets and data modems for laptops typically deliver from three to 20 times the download speeds of 3G devices. The speed king is LTE. The LTE devices I’ve used have typically averaged download speeds of between 10 and 20 megabits per second, with frequent instances of over 30 megabits per second. The other forms of 4G have generally produced download speeds well under 10 mbps in my tests. But all of these are better than 3G, which in my tests on all networks and many devices, averages download speeds of under 2 mbps.

How does LTE compare with common wired home Internet speeds?

Although it is wireless, LTE is often faster than most Americans’ wired home Internet service. According to Akamai, a large Internet company, the average broadband speed in the U.S. in the third quarter of 2011 was a mere 6.1 mbps.

How does LTE compare with Wi-Fi?

Wi-Fi is usually a wireless broadcast of a wired Internet service, so, if the average U.S. broadband speed is 6.1 mbps, that’s around what the average Wi-Fi speed is. But, in public places, the shared Wi-Fi is often much, much slower than LTE. In tests I did this week at Dulles Airport near Washington, and at a hotel outside Boston, the public Wi-Fi networks delivered well under 1 mbps on the new iPad. But the Verizon LTE cellular network on the iPad averaged over 32 mbps in both places.

PTECH-JUMP

T-Mobile and most of AT&T’s network use HSPA+.
Is LTE only faster at downloads? What about uploads?

It’s faster at both than 3G, in my experience.

Will these speeds drop as more people adopt LTE?

Probably, but it’s hard to say by how much, since LTE also offers more capacity, as well as speed. Verizon’s LTE network is believed to be used by less than 10% of its total subscribers.

What does LTE cost?

Prices vary by carrier and device. Verizon and AT&T use tiered pricing, where you pay escalating prices for larger and larger buckets of data. So far, they haven’t raised these prices for LTE, though people with LTE may find they use more data, and thus will need bigger buckets. One example: On the Verizon version of the new LTE iPad, prices range from $20 a month for 1 gigabyte of data to $80 a month for 10 gigabytes.

If I have an LTE phone or tablet, will I use more data faster than if I have 3G?

Quite possibly. The same amount of content, received at the same quality, won’t use more data on LTE than it does on 3G. However, because LTE is so much faster, users may be tempted to download or stream more data, like video, than with 3G. And they may choose to view higher quality video, which uses more data. Also, some apps and websites, sensing the higher LTE speed, will automatically send down larger, higher quality, data files, especially video.

PTECH-JUMP

AT&T is starting to roll out LTE.
How does LTE affect voice calls?

It doesn’t. It’s all about data, so far. Voice calls are handled by other, parallel networks. But companies are hoping to move voice traffic to LTE.

What if I have an LTE phone or tablet, but I move into an area without LTE coverage?

On Verizon, you fall back to a 3G network. On AT&T, you fall back to HSPA+, which is a slower 4G network, but still faster than 3G.

Who has the biggest 4G network in the U.S.?

Even if you accept all the carriers’ definitions of 4G, it’s hard to tell. Carriers measure the size of their networks differently — sometimes by the number of people to whom it is theoretically available, and sometimes by the number of cities and markets, which can be defined differently. Verizon has the largest LTE network. Both AT&T and T-Mobile claim the biggest 4G network, but the first has only a limited LTE deployment and the second has none.

Does LTE work overseas?

Yes, but there is less LTE rollout going on overseas than in the U.S. So, in most countries, your shiny new American LTE device may wind up falling back to slower networks.

Will an LTE phone from AT&T work on Verizon, and vice versa?

No. The technology is the same, but the networks use different bands, or frequencies. So, at least today, LTE devices aren’t interoperable among networks.

Email Walt at walt.mossberg@wsj.com.


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