Another Barrier Broken: LTE Coming to Unlicensed Spectrum

Carl Weinschenk
Slide Show

Fifteen Wi-Fi Predictions for 2015

One of the great dividing lines between wireless technologies is which spectrum they use. The distance over which different frequencies are effective and how they deal with challenges as diverse as hair dryers, file cabinets and rain varies greatly.

Perhaps the biggest differentiator, however, has nothing to do with the unique properties of a particular spot in the electromagnetic spectrum. It has to do with money. Some frequencies are licensed, as in the government awards them to users and collects fees from them, and some are unlicensed, and hence, free.

This toll road versus “free”-way approach has led the two types of spectrum to evolve differently. They play host to different types of users and, due to the crowding in the free spectrum, have different usage characteristics.


Wi-Fi is unlicensed and cellular is licensed. The rapid evolution of the wireless world has led carriers, including phone companies, cable operators and others, to work out clever ways to use licensed and unlicensed spectrum in concert. For instance, the IP Multimedia Subsystem (IMS) is an emerging way of efficiently using all available networks to traffic data.

Another emerging trend is using unlicensed spectrum to accommodate LTE, which usually traverses the toll roads. The possibility, called LTE-U, is intriguing to network owners, because it could reduce both congestion and costs. 

WirelessWeek, in the most recent installment of its video conversations with Recon Analytics’ founder Roger Entner, Tuesdays with Roger, looked at the prospects of LTE-U. The upshot of the conversation between Entner and Alex Shanahan was that there is a lot of interest in the approach, but there will be challenges.

The unlicensed nature of the Wi-Fi spectrum means that it is crowded and competitive. Entner said that it is likely better used by carriers as sort of a safety valve for their more ordered and calm licensed spectrum than as a primary conduit. It is also better used for short distances and, for that reason, may be an enabler of the nascent small cell industry.  

Work aimed at enabling Wi-Fi and LTE to coexist is ongoing. Patrick Moorhead, a regular contributor to Forbes, reported on what he saw at Mobile World Congress in Barcelona. The news could be good for all players: vendors, carriers and, ultimately, end users:

Qualcomm’s small cell and mobile SoC solutions for LTE-U are specifically designed to both complement and coexist with Wi-Fi in ways that benefit everyone. The carriers get more spectrum to work with which ultimately results in faster speeds for consumers and it also can help reduce Wi-Fi interference, which admittedly isn’t much of a problem right now in the 5 GHz band, but will be in the future as more than more APs transition to 802.11ac. This will result in better speeds for the Wi-Fi users as well as those that are connected to an LTE network and are using LTE-U for supplemental bandwidth.

LTE Network

Big companies such as Verizon Wireless and T-Mobile will use the technology.

The LTE-U Forum, which was formed last year by Alcatel-Lucent, Ericsson, Qualcomm and Samsung, has released its first technical recommendations. They include coexistence specifications and minimum performance specs for base stations and consumer devices operating in the 5 GHz unlicensed spectrum, the press release said.

The telecom world is struggling to support the exploding amount of wireless traffic traversing networks today and to prepare for the greater loads that are coming. LTE-U can be a key approach to driving the efficiencies necessary to succeed.

Carl Weinschenk covers telecom for IT Business Edge. He writes about wireless technology, disaster recovery/business continuity, cellular services, the Internet of Things, machine-to-machine communications and other emerging technologies and platforms. He also covers net neutrality and related regulatory issues. Weinschenk has written about the phone companies, cable operators and related companies for decades and is senior editor of Broadband Technology Report. He can be reached at cweinsch@optonline.net and via twitter at @DailyMusicBrk.



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