Price aside, femtocells have some limitations. For one thing, you can use a femtocell only at the address where it is registered. To enforce that restriction, the FCC stipulates that all femtocells must be equipped with GPS receivers, and that they either must be placed close enough to a window to receive GPS signals directly or must be connected to a GPS antenna that can pick up the signals.
David Nowicki, marketing vice president for femtocell vendor Airvana and for the Femto Forum trade association, says that the FCC imposed the location restriction to enable carriers to track the femtocell's position and disable its operation in areas where the carrier doesn't own the frequencies that the femtocell supports and where, consequently, using the femtocell might interfere with another carrier's network. Even so, forum posts suggest that femtocells sometimes hurt neighbors' regular network reception when deployed in close proximity.
Then again, it’s not necessarily a bad thing that femtocells are aware of their location. That, coupled with the device's ability to recognize when an authorized phone is nearby, could enable carriers to offer customers additional services that go beyond improving reception, including 911 services.
Network handoff issues are another concern. You can start a call on femtocell service and then hand it off to the regular network as you leave the femtocell's coverage area (assuming that the nearest cell tower is close enough). But calls initiated on the regular network can't be handed off to a femtocell.
And finally, critics complain about having to pay for a service that essentially deliver what the wireless network is supposed to have provided all along. "It's a fair point," Nowicki concedes. But carrier spokespeople say that no carrier can provide coverage in all locations of its service area. Verizon Wireless spokesperson Thomas Pica describes the Network Extender as a "niche product," given that the vast majority of Verizon customers don't need one because of the carrier's robust network.
What about the broadband ISP that now gets to carry the wireless carrier's traffic? Nowicki says that the bandwidth consumption of mobile devices is tiny compared to that of most home and office networks. For that reason, femtocells don't impose a significant burden on the ISP, which in some cases is run by the same company as the mobile carrier anyway.
T-Mobile has taken a different approach to improving weak cell signals. Phones that support Wi-Fi Calling use UMA (Unified Mobile Access) technology to route calls over Wi-Fi hotspots. T-Mobile notes that this helps with calls made through any hotspot that its phones can access, and not just at a single location (which is the case with femtocells). However, T-Mobile's Android phones can't hand off calls made using Wi-Fi hotspots to T-Mobile's cellular network; other phones that support Wi-Fi Calling can. T-Mobile has no announced plans to introduce femtocells, but a spokesperson says that the carrier continues to review customer equipment options for improving coverage.
Repeaters and Boosters
Repeaters (also called "boosters")--the other class of products designed to improve poor cell reception--depend on at least a weak cell tower signal to amplify and rebroadcast. They work with specific frequencies, independent of carrier; some support more than one frequency. On the frequencies they support, repeaters improve both voice calls and data speeds.
Many repeaters have multiple parts, starting with an antenna that you place as close as possible to the strongest cell tower signal--typically, near a window or even outdoors. The antenna transmits signals over a cable connected to an amplifier, which boosts the signal and retransmits it indoors. In some cases, the amplifier and indoor antenna are integrated; in others, the amplifier hooks up to a separate, centrally located indoor antenna in the home or office. The area of coverage depends on the strength of the amplifier and of the signal being amplified.
Unlike femtocells, repeaters can't be configured to recognize specific phones. Consequently, the amplified signals benefit any mobile device within range that operates on the supported frequencies--though obviously the owner's devices are more likely to benefit than a neighbor's devices located farther away from the indoor antenna. It's up to you (with the help of your reseller) to ensure that your repeater kit amplifies the frequency or frequencies that your carrier uses in your area. You can get help in choosing the right repeater kit from specialty retailers such as wpsantennas.com or RepeaterStore.
Repeaters Don’t Come Cheap
Repeater kits can be more expensive than femtocells. Pricing depends on how large an area you want to cover. Wi-Ex's ZBoost line includes SoHo products that range in price from $169 to $399, and you can spend up to $600 for kits that cover areas larger than 2500 feet--the maximum handled by femtocells. On the other hand, Wi-Ex marketing vice president Sharon Cupett notes, there are no monthly fees for repeaters--and of course, no broadband service is involved.
Though repeaters rebroadcast over carrier-owned frequencies, they are legal if they don't interfere with cell tower signals (which is why repeater signals have limited strength). One way to avoid problems is to look for FCC-certified repeaters; some are still awaiting approval, however. Check with the reseller.
Repeater vs. Femtocell
Should you get a repeater or a femtocell? Generally, femtocells are a good match for cell phone customers with broadband service who don't want to pay $300 or more for equivalent repeater coverage and who want to avoid many of the antenna-positioning hassles that repeaters entail. You do need a GPS signal, but those are available pretty much everywhere. Cell tower sites with signals that repeaters can work with are probably less common. But if your carrier doesn't offer a femtocell, a repeater may be the only way to improve your indoor coverage.