LTE-U’s Balancing Act

Complementary Coexistence or Incongruous Competitor?

LTE-U_lThe making of mobile standards can be a convoluted business. There’s the pure technology aspect, but that’s often just the tip of the iceberg. Underneath lies a pile of patent issues, lobbying efforts, regional requirements and political motives. In the wild world of wireless, there are more than 100 standardisation bodies. They often cooperate, but sometimes compete to make their technologies the must-have method to connect and communicate.

Every few years a significant specification-making skirmish of some sort appears. The current cause célèbre is LTE-U, with several major players and interest groups rallying for or against one method or another.

The implementation of LTE within unlicensed spectrum is intended to augment the current use of 4G, creating less congestion in licensed – and costly – bands by offloading traffic to the open 5 GHz frequency. This is the same band used by late-model Wi-Fi equipment, prompting concerns about interference between the two connectivity technologies. It also highlights the growing competitive aspect between Wi-Fi and cellular as more service providers look to Wi-Fi to piece together wireless networks without participating in billion-dollar spectrum auctions.

In 2014 a specification-making body called the LTE-U Forum was formed by Verizon together with Alcatel-Lucent, Ericsson, Qualcomm and Samsung to create network and device standards for the use of LTE in the 5 GHz band. Backers say that LTE-U will support more bandwidth at greater distances than Wi-Fi, thus requiring fewer base stations. For a mobile operator looking to reduce costs and increase coverage, it’s a tempting technology.

But its detractors are concerned about interference with Wi-Fi. Google, for example, is lobbying against LTE-U, providing detailed technical reasons to regulate its implementation. Google’s interest, of course, is in unlimited, open access where there is also less risk of wireless operator interception or other limits.

But standards salesmanship is a two-way street, and members of the LTE-U are pushing a message of harmony from the other side. Qualcomm, the original developer and proponent of LTE-U, has released a video showing that Wi-Fi and LTE-U can work smoothly side-by-side. We’ve seen similar demonstrations with similar results. The video’s narrator even hints that LTE-U can improve Wi-Fi performance, though gives no technical details. Qulacomm counters Google’s claims of potential interference by pointing out that Google’s test used lab equipment rather than real-life hardware, and that its own tests have returned very different results.

There’s a risk that this technology development could also become a regional issue: the use of LTE in unlicensed spectrum is being standardised separately within the global 3G Partnership Project (3GPP) with cooperation from the IEEE under the term License Assisted Access (LAA). LAA will implement an anti-interference requirement known as “listen before talk” mandated by some countries.

It appears that LAA could become a method of implementing unlicensed LTE in Europe and Japan, and LTE-U an American-based method. There’s a reminder here of the competition between WCDMA and CDMA2000 from late last century when 3G access was being standardised.

Some operators and equipment makers hope to begin the LTE-U push in 2016, so we expect this to take on a higher profile in the coming months. Historically such competing technologies have tended to find common ground. Current development work is not mutually exclusive and members of the LTE-U Forum are also active participants in 3GPP’s work, so there are strong connections between the two.

LTE-U versus LAA will be the standarisation scuffle to watch during the coming year.

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