AT&T to Test Femtocells to Improve Network Coverage

Despite vast improvements in cell phone coverage, there remain areas that just don't get decent coverage. Though that statement may bring to mind remote or rural areas where tower deployment has yet to occur, it also includes lots of metropolitan areas, particularly indoors. Natural topography and even man-made obstacles can interfere with cell signals even when in close proximity to cell towers.



To improve cell phone signal availability to customers' homes, AT&T, the largest wireless carrier in the U.S., has announced that it plans to test market femtocell technology in a city sized test in the second quarter of 2009. It has already been testing the technology in some employees' homes. Femtocells, once known as Access Point Base Stations, are essentially personal cell phone towers that can provide strong cell service to about 5-thousand square feet such as a home or small business. The device resembles a wireless router and works in much the same way. It's plugged into existing broadband internet service, DSL or cable, and then relays signals between the base station and cell phones within its limited range. The result is superb cell phone reception in an area that previously had a weak or non-existent signal.

The technology is already being used in select markets by Sprint under the brand name Airave. Sprint's service is currently limited to voice and narrow band data connections while AT&T indicates that its version will be fully 3G, allowing for broadband data. T-Mobile offers a similar product called HotSpot@Home. Whereas the Sprint and AT&T products use the gateway to connect to the cellular network, T-Mobile's program allows some phones to connect to the gateway using Wi-Fi connectivity, then, through the internet connection, to the cell network.

Femtocell technology which provides connectivity to the UMTS cellular network is currently getting the bulk of the notoriety because of its potential for short term implementation; however, as the T-Mobile interface with Wi-Fi demonstrates, broader applications are just as feasible. The concept is applicable to other standards including 4^th generation, 4G, ones that will evolve.

The biggest obstacle for femtocells is the difficulty of interacting seamlessly with traditional cell towers. Interference with other wireless devices can also be problematic because voice signals must have top priority or the communication is lost. Complicated algorithms to avoid these conflicts are in the works.

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