T-Mobile is planning to deploy LTE-Unlicensed in small cells by the end of the year, but it doesn't see the mini-RANs as more than a niche play in its broader network plans.
The US carrier has spent the last few years building out its LTE network at an unprecedented speed, and Grant Castle, T-Mobile US Inc. 's VP of engineering services and quality assurance, says he feels pretty confident with where it's at today. (See Q&A: The Castle in T-Mobile's LTE Network .)
The carrier has been aggressive the past ten years in macro-siting density in major cities to make up for its lack of low-band spectrum in these markets, as well as being "smart" with its mid-band spectrum portfolio, which is sizable thanks to AT&T Inc. (NYSE: T)'s required divestitures when the merger failed in 2011, Castle says. T-Mobile also has ample AWS holdings, allowing it to fill in "small holes" in its mid-band portfolio. The wireless carrier plans to expand its low-band portfolio throughout the year. (See T-Mobile Loads Up LTE Spectrum Ammo and T-Mobile: Going Bananas for Low-Band .)
All told, Castle says its network isn't "screaming for small cells." (See T-Mobile: Small Cells? We're Dense Already.)
"We like our site density," he continues. "There is a niche solution for small cells in some areas, but it's definitely not all, in what we need to be successful. That's how we see them at this point."
Where T-Mobile does need the most help is outside of major cities. Here its coverage really drops off, because of its relative lack of low-band spectrum. Small cells would be well-suited to help in these areas, though Castle says that's not his main concern. T-Mobile is planning to use low-band spectrum to "really end the map wars" and show people it has coverage everywhere. T-Mobile will close the gap between itself and Verizon, known for its coverage, with 700MHz spectrum, but he contends that states like North Dakota and South Dakota -- while beautiful -- don't make a huge difference to its customers. (See T-Mobile Boss Asks Consumers to Pressure FCC on Low-Band.)
Instead, T-Mobile will use small cells as "one tool in its toolbox" in cities where it still needs additional help. It's working with Ericsson AB (Nasdaq: ERIC) and Nokia Corp. (NYSE: NOK) on both, and is talking to other suppliers as well, Castle says. It has already started very limited deployments with Nokia. The carrier might deploy 3G/4G small cells in some spots, he says, but will primarily focus on LTE-only devices. (See T-Mobile Customers Use the Most LTE Data.)
T-Mobile will also work with both vendors to bring LTE to 5GHz unlicensed band, or LTE-U, by the end of the year. Here again, Castle sees this more as a spectrum play than a way to justify investment in small cells. (See T-Mobile Gets Small & Unlicensed With Nokia.)
"We see areas where we can take existing LTE sites -- generally in more urban areas with a smaller cell radius and more density -- and add LTE on top of that as an additional spectrum that can add speed and capacity, but not something you can fully count on," he says. "Given the vast amount of unlicensed spectrum and the way we think we can play it smartly, we think we can get to a position where we get a lot of benefit from it, where it makes sense, but not spending lots of money on spectrum acquisition. It will be pretty niche, not deployed across the US."
T-Mobile isn't waiting on standards to get started with LTE-U. Castle says that, as with voice-over-WiFi, voice-over-LTE and most technologies it deploys, the company is impatient. CTO Neville Ray's team wants to roll it out as fast as it can and go from there. (See Ericsson Preps LTE-U for Verizon, T-Mob & SK Telecom.)
"We are going to continue to push the technology envelop because we need to," he says. "We take the things that advantage us and push them forward in the industry."
Ahead of this week's Mobile World Congress, Castle caught up with Light Reading to provide an update on the carrier's small cell plans, as well as a range of other topics, including RCS, 5G, VoWiFi, VoLTE and more. To read the full Q&A, go to the Prime Reading feature section here on Light Reading. (See Q&A: The Castle in T-Mobile's LTE Network .)
— Sarah Thomas, , Editorial Operations Director, Light Reading