In short, LTE-U simply means LTE in unlicensed spectrum and is a technology originally designed by Qualcomm. Unlicensed spectrum means those parts of the airwaves where no one operator has an exclusive license, which means technology products (and ultimately companies) must co-operate in order for LTE-U to work. This is of particular importance because LTE-U operates in the same 5.0 GHz frequency spectrum that some 802.11 Wi-Fi hotspots operate in, and it would not be a great experience should a LTE-U broadcaster effectively disable Wi-Fi hotspots. LTE-U is considered to be an important technology as it may be used to provide coverage in areas where otherwise the signal is weak, or more likely congested. However, as one might imagine, this is a potential recipe for disaster because it’s possible that a number of different companies may build their own slightly tweaked variant of LTE-U that could block out other products. Last year, we reported on a number of developments designed to allow LTE-U to cooperate and co-exist in the same spectrum as local Wi-Fi hotspots.
The current LTE-U standard as defined by the 3GPP is known as “release 12.” It requires that the LTE-U spectrum is “anchored” in licensed spectrum and is currently suitable for deployment by carriers into selected markets (most notably including the United States of America). This means that where a carrier already has licensed coverage, it may also be permitted to broadcast in the unlicensed spectrum. This implementation of the technology means that LTE-U may be used to boost capacity over coverage; carriers may not roll out LTE-U coverage into areas where there is no anchor signal. However, it does mean that for compatible devices, they should be able to enjoy a better quality of connection. Sophisticated networking control will mean that the carrier is able to use the LTE-U spectrum for those devices able to use it, keeping the licensed spectrum free for those customers using devices unable to benefit from LTE-U. This is known as “data offloading” and is designed to ensure the best possible service for all customers.
There are several manufacturers already building small cell sites designed to broadcast in unlicensed spectrum, and there are also a number of modems and chipsets that work with the technology. LTE-U may be deployed in areas of high network congestion on either a permanent or temporary basis: the recent Super Bowl stadium and surrounding area is the sort of event that could well benefit from LTE-U deployment and we understand that Verizon Wireless is planning on trialing LTE-U in the third quarter of 2016 and China Mobile has already completed field trials with plans to deploy the technology this year.
Release 12 is actively supported across the industry and both LTE-U and Wi-Fi are seen as important standards for the mobile industry: it is important that the two technologies supplement rather than compete. The next iteration of LTE-U technology contains a technology called Licensed-Assisted Access, known as LAA, which is something of a redesign of LTE-U designed to ensure global compatibility for operating LTE networking over the 5.0 GHz spectrum. LAA is a core part of the 3GPP standard, which is not expected to be established until 2017 although some manufacturers are already supporting the technology. There is also another implementation of the technology whereby LTE operates exclusively in unlicensed spectrum, such as Qualcomm’s MulteFire, which has widespread support across the industry. Ultimately, next generation (known as 5G) radio technology is likely to rely on operating in both licensed and unlicensed bands, too; the foundations being set for LTE-U should provide good experience for implementing 5G technologies in the coming years.
LTE-U is not without its drawbacks, and indeed Google has in the past protested the technology. The main reason for complaints is how LTE-U operates in the same frequencies as Wi-Fi and as such, the technology could degrade the performance of Wi-Fi networking. Another issue surrounds how a carrier may increase its coverage using LTE-U over and above a technology such as Hotspot 2.0, which is not restricted by carrier but instead is readily available for more devices. Nevertheless, for some of our readers, LTE-U may be deployed in your market in the coming months and providing the technology works as designed, this should improve how responsive our cellular networks are.