Imagine you are in a shopping mall, trying unsuccessfully to connect with your phone or tablet over Wi-Fi. Eventually you give up and connect using LTE over your data plan. The mall’s businesses also find they cannot reliably connect over their Wi-Fi networks, which interferes with everything from point of sale systems and mobility apps to secured financial transactions and streaming video.
Are these scenarios the fault of the on-site Wi-Fi? No. It’s due to a much larger, more systemic problem – one which may become commonplace starting in the first half of 2016 unless regulators intervene.
Welcome to the world of LTE-U
LTE-U, or LTE in unlicensed spectrum, allows today’s cellular carriers to boost coverage of LTE in unlicensed spectrum such as the 5 GHz band already used by Wi-Fi. LTE-U is designed to let cell networks boost data speeds over short distances, without requiring login to a separate Wi-Fi network. Additionally, because no additional rights have to be purchased, LTE-U would allow carriers to extend their core networks at a fraction of the cost of their existing systems.
The problem centers on the ability of the upper unibands to allow up to 1 watt or more for outdoor usage. Testing shows that in public locations, an LTE-U network often “drowns out” any Wi-Fi signal in the area, creating enough interference to block nearby corporate networks and public Wi-Fi hotspots.
Unless LTE carriers agree to fairly share the 5 GHz spectrum with Wi-Fi, this level of interference could be the new reality. Proponents of LTE-U argue that it is a legitimate competitor to Wi-Fi technology and should therefore be allowed to operate in the same spectrum.
Bluntly, I disagree. Why?
LTE-U costs the user: LTE technologies offer standard cell connections made as part of the user’s data plan. This means that, unlike in a free public hot spot, every time the user connects, they pay. The cost of connecting using LTE-U will add up very quickly, every time for every user.
LTE-U is not a good fit for business: Seriously, do any of us imagine that companies are willing to foot the bill for cell-based connectivity when they can run a cost-efficient corporate Wi-Fi network that allows their workers to connect without paying individual charges? Wi-Fi suits businesses better as a cost-effective way to connect.
Wi-Fi can be secure: One of the claims I hear is that LTE-U provides better security than Wi-Fi. Granted, public Wi-Fi may have security problems when they are improperly deployed or used. IT administrators should set up their networks with a separate encryption key for each user. Such technologies are already available and can be seamlessly deployed at each location.
Efficient spectrum use: Supporters may also talk about LTE’s greater spectral efficiency over Wi-Fi. This was true – five years ago. Now, the data rates and capacity of 802.11ac far outstrip LTE, and 802.11ax will move that needle another 10 times.
And, by the way, users will need to buy a new device that is LTE-U compatible.
Regulation for co-existence
To attest to the impact of LTE-U on Wi-Fi installations, the LTE-U Forum and other coalitions have conducted research for both indoor and outdoor deployments. They all show when LTE is simply deployed in unlicensed spectrum without any coexistence mechanism, LTE causes significant performance degradation on Wi-Fi networks.
Despite these findings, carriers position Wi-Fi and LTE-U as competing technologies in the 5 Ghz band. However, as we can see they actually do not compete. Wi-Fi provides the local area networking capabilities businesses and public hot spots need, while LTE-U can offer for-pay wide area networking in larger public areas. The only issue revolves around how we can assure these two technologies do not interfere with each other.
Wi-Fi currently uses an 802.11 listen-before-talk contention-based protocol, while LTE-U relies on an arbitrary duty cycle mechanism. To resolve this dichotomy, LTE-U needs to adopt the LBT protocol and fairly share the medium. The United Kingdom has already successfully conquered this problem by regulating the 5 GHz spectrum.
Given the significant drawbacks to LTE-U, an attempt to grab the unlicensed spectrum in the United States without a fair-sharing mechanism becomes a zero-sum game. Carriers are rushing LTE-U into the market in an effort to get the product out before the Federal Communications Commission has a chance to rule. If this occurs, not only will consumers become frustrated with problems such as latency on their devices, but traditional Wi-Fi vendors will be forced to look for clean spectrum. Similar to the European model, the FCC and industry leaders need to take steps now to regulate the 5 GHz band.
Editor’s Note: The RCR Wireless News Reality Check section is where C-level executives and advisory firms from across the mobile industry share unique insights and experiences.
