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

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The 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.

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 1Gbps, though real-world speeds are generally far slower than that. LTE was developed as a long-term alternative to DSL, cable, and other wired forms of internet.

All major networks in the U.S. currently offer LTE connections.

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, so it’s 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.

What about LTE Advanced?

LTE Advanced is the latest and greatest incarnation of 4G technology, and it’s widely regarded as a stepping stone towards 5G. It’s often abbreviated to LTE-A, and uses what’s called “carrier aggregation” to work properly. To understand carrier aggregation, you have to understand that phones download data through radio waves, which exist in different frequencies. 4G exists across multiple different frequency bands, and that’s where LTE-A comes in. Instead of connecting on one frequency band, LTE-A downloads data through multiple frequency bands.

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), 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.

So what’s next?

Contrary to popular belief, 4G is unlikely to be totally replaced by 5G at any point in the near future. Most suggest that instead 4G and 5G will work together to offer a seamless experience. That’s because of the fact that 5G is likely to be an extremely short-distance technology, and will likely only really work when you’re near a building with a 5G radio, or near a 5G-enabled tower.

In any case, carriers will continue to invest in 4G in the near future, and will be rolling out LTE-A as part of that investment — so your internet connection will likely get a whole lot better over the next few years.

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