WIRELESS INFRASTRUCTURE

  • 05/12/2016
    6:00 AM
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The LTE-U Vs. WiFi Debate

If carriers use unlicensed spectrum, it may not be the WiFi disaster that some expect.

LTE-U, an emerging technology that aims to reduce cell phone data congestion by offloading traffic onto unlicensed spectrum, has been a hot topic in the wireless world. Carriers like AT&T, T-Mobile and Verizon are proponents of rolling out this technology while wireless companies and coalitions like the Wi-Fi Alliance worry that it will degrade WiFi performance. In fact, they have gone so far as to say that LTE-U would be disastrous. Is this just hype, or a valid concern? It may be too early to tell, but let’s look at what we know so far.

LTE or 4G LTE refers to the fourth generation of data technology for cellular networks that most of us use every day. Normally our phone’s data connection relies on specific frequencies that have been licensed by the carrier. But there are other frequencies – parts of the radio frequency (RF) spectrum – that are “unlicensed” and open for anyone to use. These are often used by devices like remote-control toys and walkie-talkies. LTE-U -- short for Long Term Evolution of Unlicensed Spectrum -- allows carriers to transmit data using those unlicensed frequencies. The trouble is, our trusty old WiFi also operates within these unlicensed bands, and the debate is about whether these two technologies are able to share the airwaves amicably.

Since I come from a WiFi background, I’ll admit that my initial reaction was “Hey, keep your licensed technology out of our unlicensed bands -- that’s just not fair!” But as a fair and rational engineer, I try to look at these things with an open mind. The simple fact is that if you deploy an LTE-U base station near a WiFi access point set to the same channel, there will be interference, with a corresponding negative impact on performance. There are technologies in development to help LTE-U and Wi-Fi coexist, but also a lot of doubt on both sides and testing is ongoing. So yes, LTE-U can negatively affect WiFi performance.

However, I’m not convinced that LTE-U will have the dramatic, harmful effect on WiFi that companies like Google, Microsoft and Comcast claim. Adding an LTE-U base station is like adding another wireless access point. In locations like a stadium or convention center with a carefully designed and highly tuned wireless network, it's possible that adding an LTE-U station could disrupt the network. But the carrier could work closely with the venue to mitigate the issue. Given the amount of attention that this debate has attracted already, it’s in each carrier’s best interest to avoid interfering with WiFi.

Data congestion is already a major problem on cellular networks because of skyrocketing usage, and it’s especially bad in high-density areas like stadiums, arenas and downtown areas in big cities. WiFi offloading is already a major goal in these environments, with carriers strongly encouraging venues to provide high-quality WiFi networks at the expense of the venue. This is feasible for fixed venues like football stadiums, but not for events like temporary music festivals, which still suffer from the same high-density network congestion. LTE-U may provide a solution because it puts the financial and operational burden back on the carriers, with obvious benefit to all cellular users. 

The drawback is that the solution is now carrier-dependent. When a venue deploys its own WiFi, everyone benefits. But when an individual carrier deploys LTE-U, only certain customers benefit. If more than one major carrier wants to provide service in the same area, cooperation will be essential to avoid common WiFi problems like co-channel interference, but in the fiercely competitive cellular industry this seems unlikely. Regulation doesn’t seem likely either, since the whole point of an unlicensed spectrum is that it’s not regulated.

In the end, customer experience is key to customer retention. We may find that WiFi access and performance is better when we let a few major carriers address the issue rather than the Wild West of WiFi that we have today. Just visit any airport and try to use the wireless network to experience what unbridled WiFi access does to the user experience. If every cellular subscriber gets LTE-U and pays for it through his or her cellular subscription, then carriers have an incentive to give them better service. Reducing congestion is something that everyone wants.

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