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4G explained: A guide to LTE, WiMax, HSPA+, and more

Jeffrey Van Camp

If you’ve seen or heard an ad about a cell phone or wireless plan lately, you may have noticed that a lot of new buzzwords are being thrown around. Words like 4G, LTE, and WiMax seem to have replaced the last set of words we barely understood: 3G, GSM, and CDMA. But what does it all mean? Is it all a bunch of marketing nonsense or are these words you should know and understand? We’ve got the scoop in our official mobile broadband FAQ.

Read on to learn what 4G is, why you should want it, and which carriers and devices are already pushing forward into the next generation of mobile data where your phone’s Internet may actually run faster than your home Wi-Fi.

The basics of 4G

What is 4G?


Don’t let this surprisingly intuitive naming scheme spin you around: 4G simply means “fourth generation.” It’s the next step up in mobile Internet speed from 3G, which is a term you started hearing a few years back. 3G is what you use if you browse the Web on your smartphone right now. It uses the networks built by wireless carriers and transfers data over them at speeds up to 2 megabits per second (Mbps), making it possible to load a website and stream videos… just not very fast. 4G networks will change that, offering download speeds comparable, if not faster than, the broadband Internet you get on your laptop at home — all over the airwaves.

4G networks will eventually reach speeds of up to 100Mbps, but at launch they’ll likely offer actual speeds around 1Mbps to 12Mbps, which puts them about on par with Wi-Fi 802.11b networks. For example, my current cable Internet download speed at 5 p.m. in Chicago, IL is about 6Mbps. Your Internet speed is probably no greater than 15Mbps on a good day. Want to know your connection speed? Test it.

Do I have a 4G-capable phone?

Probably not, unless you just bought it recently. Wireless carriers and cell phone manufacturers are using the word 4G like it’s the holy grail, so even if your phone blatantly says it’s 4G, it may just be marketing lingo. Most 4G phones are smartphones, so if you have an older flip phone, you’re out of luck.

Does my wireless carrier offer 4G?

All four major carriers — AT&T, Verizon, Sprint, T-Mobile — are offering services they call “4G,” but their actual speeds and availability vary wildly. For the most part, 4G access on most carriers is limited to a handful of major cities around the United States, but coverage is expanding fast. To attain 4G speeds, carriers are spending billions of dollars to upgrade (or replace) their wireless networks. In our 4G carrier breakdown below, we’ll go into specifics on each carrier’s current 4G status and compatible handsets.

What is the ITU?

The ITU, or International Telecommunications Union, is an agency of the United Nations that sets telecommunication standards for the world. The ITU coined the terms 3G and 4G and establishes which technologies meet the requirements to qualify for the labels. Initially, the ITU claimed that HSPA+ technology didn’t qualify as 4G, but reversed its decision in December 2010.

The three flavors of 4G

What is WiMax?


WiMax stands for “Worldwide Interoperability for Microwave Access.” It is an ITU-approved, fourth-generation mobile broadband technology that attempts to mimic the abilities of Wi-Fi wireless Internet, but over a mobile phone network using an open protocol (802.16m). Think of it as a patchwork of Wi-Fi hotspots that, instead of reaching for a few hundred feet, can stretch for miles and overlap, eliminating coverage gaps. It provides fixed and mobile Internet access for compatible devices with less interference than traditional Wi-Fi. Theoretically, a WiMax tower could provide broadband wireless Internet over a 30-mile range, though most stations currently achieve much less. Current WiMax users can realistically expect about 3Mbps to 6Mbps download speeds.

If you’ve heard of WiMax, it’s probably due to Sprint, which is working with Clearwire to develop an extensive WiMax network. It is currently available in select cities. More on this in our Sprint section later on.

What is LTE?


LTE stands for “Long Term Evolution,” and is an ITU-approved 4G mobile broadband technology. It is a direct competitor to WiMax. LTE is more of a successor to current mobile 3G standards than WiMax. However, instead of transmitting data using microwaves, LTE uses radio waves. Theoretically it can attain speeds up to 100Mbps, though real-world speeds on Verizon’s network are around 6Mbps to 12Mbps. LTE was developed as a long-term alternative to DSL, cable, and other wired forms of Internet.

The two largest carriers in the United States, AT&T and Verizon, are both investing in LTE networks, though Verizon has already launched its network. MetroPCS is also working on a LTE network.

What’s the difference between LTE and WiMax?

WiMax is based on IEEE (Institute of Electrical and Electronics Engineers) standards, meaning it uses an open protocol that has been debated and approved by a large community of engineers. LTE, on the other hand, is a standard that was cooked up by the 3GPP (Third Generation Partnership Project), which is an organization consisting of wireless agencies and telecommunications companies. The 3GPP organization came up with 3G standard for GSM some years back, which was adopted by a majority of wireless carriers around the world (except here in the U.S. where Verizon and Sprint chose to use CDMA).

However, LTE and WiMax aren’t enemies like CDMA and GSM have been. Both technologies use OFDM (Orthogonal frequency-division multiplexing), which means that unlike competing 3G networks like CDMA and GSM, WiMax and LTE are more like siblings. They aren’t entirely incompatible. Hopefully, it will be easier and cheaper to design devices that incorporate both technologies.

Similarities: Both use SIM cards, both are backward compatible with existing CDMA and GSM networks, both use OFDM and MIMO (Multiple In, Multiple Out), both have similar speeds, and both are IP-based.

Okay, then what is HSPA+?

HSPA+ stands for “Evolved High-Speed Packet Access.” It has been touted by some carriers as a 4G mobile broadband network type, and the ITU recently changed its 4G definition to put HPSA+ under the 4G umbrella, but really, it is merely an upgrade to existing 3G GSM technologies. Think of it as a stopgap or bridge between 3G and 4G. Though it offers download speeds that can theoretically reach 84Mbps (possibly even higher in the future), it is not a next-generation network. It still uses the old interface and standards implemented years ago for 3G, and lacks the response time of LTE and WiMax. It’s like comparing a Formula 1 race car to a souped-up Toyota Camry; the Camry may move fast, but it wasn’t designed to race. HSPA+ is the definition of an old dog that has learned new tricks. LTE has a lot of small back-end improvements to its core technology that better suit it for the future, but many carriers may stick with HSPA+ for a couple years due to the savings. HSPA+ networks will likely feature download speeds from 1Mbps to 7Mbps at first, though performance may vary wildly.

T-Mobile has been a big proponent of HSPA+, touting itself as “America’s largest 4G network.” More on that below. Since it is relatively cheap and speedy to upgrade a GSM network to HSPA+, both T-Mobile and AT&T have implemented HSPA+ in a large number of major markets and are quickly rolling the service out across the country. AT&T is also developing a next-generation LTE network.

4G carrier breakdown

In this section, we will detail each carrier’s current and future 4G plans, including what network technologies they’ve chosen, what 4G devices are available, in what geographical regions 4G coverage is accessible, how fast they’re network is, and how much they’re charging.

AT&T’s 4G network

AT&T Logo

Summary: If you’re on AT&T, you aren’t terribly far behind, but the carrier was caught off-guard by 4G. In fact, AT&T was actually mad at Verizon and T-Mobile for discussing 4G services back in May 2010. Since then, the carrier has done a complete 180, and now flaunts the 4G label more than any other carrier, plastering it on every phone with HSPA+, and some that don’t even have that. AT&T claims its strong implementation of HSPA+ will allow it to have a strong backup if customers move out of LTE range. Two LTE devices have been announced for the network (not phones), and AT&T hopes to cover 15 cities by the end of 2011.

Technology: AT&T is currently using a standard called HSPA+ 21, which allows for theoretical maximum download speeds of up to 21Mbps, though actual rates are said to be around 1Mbps to 7Mbps. We do not yet know much about AT&T’s planned LTE roll-out later this year, but it is coming.

Devices (HSPA+): Motorola Atrix 4G, HTC Inspire 4G, Samsung Infuse 4G, HTC Sensation 4G, HP Veer 4G. (To find current listings, check AT&T’s 4G phones page.)

In mid July, AT&T announced its first 4G LTE-powered devices for consumers in the form of a USB modem for notebook computers and a Wi-Fi mobile hotspot.

Coverage: AT&T’s coverage map is right here. Currently, only major cities have actual HSPA+ access. AT&T has announced 4G LTE service in Atlanta, Chicago, Dallas, Houston, and San Antonio. The company plans to have LTE service up and running in at least 15 markets by the end of the 2011.

Sprint’s 4G network

Sprint Logo

Summary: Sprint went all in with WiMax, but now it seems to be having some buyer’s remorse. WiMax has required Sprint to work with Clearwire, which has purchased a chunk of 2.5GHz spectrum needed to run the network, but implementation has been slow. In February 2011, a Sprint executive claimed that the company is not shutting the door on LTE, especially since its current network could be upgraded to the new service. In June, rumors swirled that Sprint may sign a LTE deal with LightSquared to kickstart its service.

Technology: Sprint 4G runs on WiMax in collaboration with Clearwire. It claims that users will get average download speeds around 3Mbps to 6Mbps and peak download speeds of more than 10Mbps. Check out our hands-on test of Clear’s WiMax service (the same network Sprint uses) in Portland, Oregon.

Devices: HTC EVO Shift 4G, HTC EVO 4G, Samsung Epic 4G, HTC Evo 3D, Motorola Photon 4G, Nexus S 4G. (To find current listings, check out Sprint’s 4G phones page.)

Coverage: Sprint’s coverage selector is right here. The service is still available in 76 major cities and the carrier claims there are 120 million people living in areas where its 4G is available.

T-Mobile’s 4G network?

T-Mobile Logo

Summary: T-Mobile has been aggressively rolling out HSPA+ upgrades to its networks. The carrier claims to have the “largest 4G network,” which may be true in overall geographical area covered, though we suspect AT&T will soon catch up with its HSPA+ enhanced network. T-Mobile executives claim that they plan to hold off on LTE upgrades until 2013.

Technology: T-Mobile 4G runs on a version of HSPA+ with theoretical download speeds up to 42Mbps. Realistically, most users will probably get somewhere around 1Mbps to 7Mbps. Check out our hands-on test of T-Mobile’s HSPA+ service in Portland.

Devices: T-Mobile G2x, T-Mobile myTouch 4G, T-Mobile MyTouch 4G Slide, Samsung Exhibit 4G, T-Mobile Sidekick 4G, HTC Sensation 4G, Samsung Galaxy S 4G. (To find current listings, check T-Mobile’s 4G phones page.)

Coverage: T-Mobile’s 4G coverage map is right here. The carrier claims more than 200 million people live in areas where T-Mobile 4G is already available; it is available in more than 191 markets.

Verizon Wireless’s 4G network?

Verizon Logo

Summary: Verizon’s 4G strategy may be the most advanced and forward-thinking of the bunch. The carrier has already launched its LTE network in the States and three 4G LTE phones are available on the market. Verizon also plans to upgrade the quality of its voice calls and video chat in the coming months.

Technology: Verizon believes its LTE network will retain speeds of 5Mbps to 12Mbps, even in congested areas and periods of high usage. We’ve experienced much faster speeds in our testing (20Mbps to 30Mbps), leading us to believe Verizon’s estimates are conservative. No matter which way you slice it, Verizon’s minimum LTE speeds currently outpace other 4G offerings.

Devices: HTC ThunderBoltSamsung Droid Charge, LG RevolutionMotorola Droid Bionic (coming soon). (To find current listings, check Verizon’s 4G devices page.)

Coverage: Verizon’s coverage map is right here. Currently, the service is available in more than 100 markets, 80 major airports, and is expanding quickly. Verizon expects to cover areas containing two thirds of the entire U.S. population by mid 2012, and have complete 4G coverage by the end of 2013.