AT&T network technology executive Kris Rinne told a packed crowd yesterday that the operator's early small cell deployments showed promise, but some hurdles still remain.
"There's still a lot of optimization that needs to be done," Rinne said, citing interference management, backhaul, and issues related to local zoning and regulations. AT&T has begun its initial deployment of small cells in "several venues" and is still doing final field testing.
Rinne, who serves as senior vice president of network technologies at AT&T Labs, said self-organizing network (SON) technology has been an "important tool" to maximize the benefits of femtocells, picocells and metrocells. AT&T finished its nationwide SON rollout earlier this year using technology from Intucell, a company it began working with in 2011 at its Silicon Valley development center.
"SON is used to improve network quality by detecting when we have cell sites that are overloaded and working with neighboring cell sites to offload that tower," Rinne said, adding that initial SON deployments in California and Georgia have resulted in a 10 percent improvement in call “retainability” and throughput.
Wi-Fi hotspots are another part of AT&T's plan to address continual increases in data traffic, which it reports has risen 20,000 percent between the time it got the iPhone in 2007 and last year. The operator has a network of more than 30,000 Wi-Fi hotspots that it is leveraging to move data off of its cellular network.
When asked whether AT&T would be able to extend its SON platform past its cellular network to incorporate Wi-Fi, Rinne said additional capabilities were needed to "optimize Wi-Fi as just another layer within our network."
Rinne described the 3GPP's cellular standards and Wi-Fi standards as "overlapping circles where we still need to fill in some gaps."
"We're driving to be able to use that in a more integrated basis," she said.
In addition to small cells and Wi-Fi, AT&T is also leveraging distributed antenna systems in high-traffic venues like stadiums and convention centers.
It even rolled out what Rinne called “DAS on wheels” at this year's Democratic National Convention in Charlotte, N.C., wheeling in a movable antenna ray to better cope with the surge of traffic during the event. Five terabytes of data were sent over AT&T's network during the event, Rinne said, calling the results of the antenna installations "impressive."
Carrier aggregation is another one of the tools AT&T plans to use to keep ahead of the capacity crunch. The technology works by bonding together different bands of spectrum into a single, larger channel, essentially creating a fatter pipe.
Rinne touted carrier aggregation as a way of bonding together AT&T's various frequencies, including the WCS spectrum it is currently in the process of acquiring from Comcast, Horizon Wi-Com and its buyout of NextWave Wireless. The FCC recently cleared use of the band for LTE after AT&T managed to sort out issues with interference to satellite radio services.
Rinne did not list exactly which channels AT&T plans to stick together for LTE, but the operator has previously stated that it plans to combine the 700 MHz spectrum it bought from Qualcomm with its 1900 MHz and 850 MHz holdings to supplement capacity on its LTE network.
AT&T is not the only U.S. operator planning to use carrier aggregation to supercharge LTE. Sprint has said it plans to use the technology to merge its 800 MHz and 1900 MHz spectrum into a single channel for LTE.
Verizon Wireless and T-Mobile USA have been less vocal about their plans to use carrier aggregation. The technology is part of the specifications for LTE Advanced, a standard both Verizon and T-Mobile have publically embraced as the next evolution of their LTE networks. However, neither operator has specifically named carrier aggregation as part of their implementations of LTE Advanced.
AT&T’s LTE network now covers 135 million people, behind Verizon’s formidable coverage across more than 250 million people. Sprint’s LTE deployment lags behind both its larger competitors, but it is working to catch up with the addition of more than 100 new markets by year-end. T-Mobile has yet to get its LTE service off the ground but plans to light up the network next year.