LONDON -- LTE/EPC & Converged Mobile Backhaul -- EE shared some of the challenges it faced and lessons it learned from launching the U.K.'s first, and only, 4G Long Term Evolution (LTE) service here at Layer123's industry conference dedicated to LTE and mobile backhaul on Tuesday.

EE launched LTE services on Oct. 30 using the 1800MHz spectrum that it already had for delivering 2G services. By refarming this spectrum for LTE services, the U.K.'s largest mobile operator with 27 million subscribers will be able to offer 4G services for at least seven months ahead of its rivals Telefónica UK Ltd. (O2), Vodafone UK and Three UK , which need to acquire LTE spectrum from the upcoming auction scheduled to start in early 2013. (See How Not to Do 4G, EE-Style, Euronews: 4G Arrives in UK, EE Unveils 4G Price Plans, Brits Braced for 4G and Euronews: Will UK Fast-Track 4G Auction?)

But it wasn't easy, as Mansoor Hanif, EE's director of network integration and LTE, explained.

Among the technical challenges EE faced were lack of device support, uncertainty about voice services and having to support two different legacy networks -- that is, those of Orange UK and T-Mobile (UK) , as EE is the joint venture of Orange (NYSE: FTE)'s and Deutsche Telekom AG (NYSE: DT)'s U.K. operations.

Hanif said that it was particularly difficult to convince device manufacturers to add support for EE's 1800MHz band in LTE smartphones. "To get some of them on board and get 1800MHz on their roadmaps involved endless negotiations, discussions and a lot of drama behind the scenes," he said.

Another issue for EE was how to deliver voice services by using the legacy 2G and 3G networks, which is referred to as circuit-switch fallback (CSFB). The operator knew its 4G service launch would focus on smartphones from the start, so it had to be able to deliver voice. But the problems were that there was no device ecosystem in place, especially for 1800MHz devices, to support CSFB and there were "serious doubts" about performance and call setup times. All this caused a lot of "nervousness" for the operator, Hanif said.

The backhaul network design was yet another challenge, which was made more difficult by the fact that EE has a network-sharing agreement in place with 3 for the transport network. That meant EE had to agree on the network design plans with its rival.

"To agree on best design [for backhaul] is a challenge, to agree on that with your competitor is another challenge," said Hanif.

4G lessons
Given all of those hurdles to clear, it seems a wonder that EE got its service off the ground when it did.

Here's what Hanif said EE has learned from the process:

-- Michelle Donegan, European Editor, Light Reading Mobile