Small Cell Forum says 75% of macrocell traffic can be offloaded to 10 small cells

NEW ORLEANS--Small cells could eventually offload the majority of mobile user traffic from local macro networks, but challenges stemming from interference and backhaul issues must be mitigated, according to a new report from the Small Cell Forum, which is also pushing a new API and emulator for small cell applications.

"Public access small cells could play a key role in providing additional mobile coverage, capacity and new services in both urban and rural areas," said the group, which released its report at the CTIA show. "With a ratio of one public access small cell per macrocell, 21 percent of users would be offloaded; this rises to 56 percent with four small cells and 75 percent with 10 small cells," the forum said.

The report said self-organizing network, or SON, technology will be required regardless of whether an operator or a third-party deploys open access small cells because the networks must be made permanently aware of their surroundings. Many of these capabilities are included in 3GPP Release 10.

The group's report suggests that rather than rolling out open access small cells, operators might prefer to opt for hybrid access, promising premium service to certain subscribers or organizations.

Downlink and uplink interference problems as well as potential impacts from mobile connections in fast-moving vehicles that quickly pass through small cells are also addressed in the report. It concludes that these challenges can be mitigated using techniques such as inter-frequency and intra-frequency handover, active hand-in, as well as recalibrating transmit power and scheduling.

The forum assessed various backhaul options for public access small cells. It noted that in rural areas, in particular, satellite and DSL have been successfully employed. The group, which created a backhaul task force at the end of 2011, promises to publish an extensive paper on backhaul in coming months.

The Small Cell Forum is also helping developers create a range of new applications that can be made possible with public access small cells. The FemtoZonal Awareness API created within the forum is now being supported by the GSMA OneAPI initiative, said Simon Saunders, chairman of the Small Cell Forum, in an interview with FierceBroadbandWireless.

In addition, the forum is launching an emulator that will let developers test their app "in an environment that replicates what a femtocell network will do before the app goes live on a real carrier's network," said Saunders. This means that mobile developers anywhere in the world can build small cell-enabled applications using the GSMA's OneAPI and then test them using the forum's emulator. The emulator is designed and hosted by platform provider Aepona.

The forum is continuing its push for more collaboration among industry groups, an effort it started at the Mobile World Congress earlier this year. "Many vendors today are launching access points that combine Wi-Fi and picocell, for example, in one box. We want to help them make the most of that," said Saunders. "It's not about Wi-Fi or femtocell. It's about how you combine the two together in an intelligent fashion."

"3GPP doesn't recognize the idea that you've got an LTE and 3G and Wi-Fi-capable device in one box. 3GPP treats them as separate devices. The Wi-Fi Alliance [and] the Wireless Broadband Alliance are working on aspects of the problem. What we really want to do is work together with all those peers across the industry to get the best of both technologies," said Saunders.

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