Lessons From Your Friendly Neighborhood Small Cells
LONDON -- Small Cells World Summit 2014 -- Despite reservations among many mobile operators about deploying public access small cells in urban areas, some operators have already ventured into outdoor deployments. AT&T, Orange, and Vodafone shared their experiences from trials and commercial deployments at the small cells gathering here in London. (See Urban Jungle Is Still Too Wild for Small Cells and Small Cell Forum Tackles Urban, Virtualization.)
AT&T Inc. (NYSE: T), for example, has deployed HSPA+ small cells to fill in coverage gaps in some residential neighborhoods in an effort to improve customer experiences in areas where the natural landscape degrades or impedes wireless signals.
"Most of our need is still coverage based, and we're also looking at congested outdoor environments," said David Orloff, director of small cells platforms, radio access and devices. "There are some cases where the cost of [deploying] a macro site is too high or you can't get [planning] permission; then, small cells make sense."
Orloff discussed three of AT&T's deployments. The first involved installing a cluster of 15 small cells in a high-income, residential neighborhood at the edge of five macrocells that provided poor coverage. In another rollout, the operator placed 22 small cells in a suburban area near a school where dense foliage and the terrain blocked macro coverage. And in the third example, 13 small cells were deployed at the edge of 13 macrocells located in a difficult terrain that, again, did not provide good coverage.
Each of these clusters of small cells is carrying live 3G traffic today.
The key with these deployments is designing and optimizing the small cell clusters for interacting with the nearby macrocells, noted Orloff. "For small cells, it's the interaction with the macro network that largely enables good customer experience," he said.
AT&T has deployed small cells in more than 30 states, according to Orloff. While he didn't specify the number of units deployed, he said the total includes indoor, outdoor, public, private, residential, large and small enterprise varieties. (See AT&T Gets 'Opportunistic' With 4G Small Cells and AT&T Readies LTE-Only Small Cells, Eyes Multimode by 2015.)
Orange cools on hotspots for now Over in Europe, Orange (NYSE: FTE) has also deployed some outdoor small cells for addressing coverage needs, although the numbers are "quite moderate," said Benoit Graves, the operator's small cell project manager. "It's definitely part of our mid-term strategy."
"A well-located outdoor small cell provides great coverage indoor," he added.
But when it comes to using outdoor small cells to improve network performance in congested environments, Graves said that access to sites and backhaul were still big challenges, particularly in Western Europe. "Once this is sorted, there is a clear place for outdoor small cells."
Also, in Orange's case, the rollout of LTE in its European markets will likely add capacity in some of those congested areas, which would delay the need for an additional capacity boost from small cells. "It's still cheaper to use all the spectrum you have first, then deploy outdoor small cells," he said. "We intended to deploy more 3G small cells a couple of years ago, but now there's 4G."
Vodafone's Dutch experience Vodafone Netherlands has been rolling out various flavors of small cells over the last four years. Jinglong Zhou, the operator's small cell program manager, explained that it all started with 3G femtocells, an experience that taught the operator that small cells are not only about radio, but the whole network.
About two years ago, the operator deployed 3G small cells in outdoor rural and city areas. "The deployment was fast and cheap, so we were really happy internally," said Zhou. "However, from a quality point of view, it was not a good experience because the handover ratio was not good."
Zhou said this was primarily due to different protocol support in the small cells and the macrocells at that time. Put simply, the operator didn't have the right product available when it first tried outdoor 3G small cells two years ago.
Now, the situation is different and the operator has been trialling an outdoor HetNet of 3G, 4G, and WiFi small cells in a joint project with the City of Maastricht.
So far, Zhou said that the initial result is promising and that a combination of outdoor 3G and 4G small cells can improve network performance.
Vodafone first publicly proposed the concept of deploying small cells outdoors -- dubbed "metro femto" at the time -- at the Small Cell Forum's annual gathering six years ago. (See Vodafone Dreams of Metro Femto.)
A lot has changed since then, but some fundamental challenges (such as backhaul and site acquisition) remain the same for outdoor public access small cells.
Michelle Donegan, contributing editor