Lack of Coverage
Some rural or developing areas don't have enough people or population density for operators to justify the cost of installing base stations except at wide intervals. In these areas the signal strength from the base station or the mobile phone may be too low to create or maintain a connection. This results in "dead zones" or dropped calls.
Solutions to Poor Signal Quality
Operators know that dead zones, dropped calls, and poor voice quality are big problems, and that re-dialing while driving can be unsafe. Operators also are concerned about subscribers' ability to make emergency calls. They understand that people rely on mobile phones for business and connecting with family. As mobile phones replace landlines, operators are especially aware that mobile signal quality is critical. Operators also see that wireless data is increasingly important for personal and business use. To help, operators work with phone and base station manufacturers to improve antenna performance. They invest in new base stations in growth areas. They invest in technologies that enable more connections per base station. Operators have even provided refunds for dropped calls.
However, many factors causing poor signal quality can't be controlled by operators. Therefore products have emerged to help, provided by operators or companies who sell to either operators or subscribers.
Femtocells Operators can provide femtocells to subscribers with poor signal quality at home. Usually the subscriber pays for hardware, installation, or a monthly fee. Femtocells are carrier grade, and are like small base stations that communicate with operators by using the home Internet connection as a "backhaul". They often can't be moved after installation, must be installed by a skilled technician in order to work properly and to avoid causing network problems. Many femtocells provide only a voice connection, not data. Lastly, femtocells usually only work with phones from one operator, so families with phones from multiple operators may have to request multiple femtocells.
Repeaters are usually carrier-grade equipment and are programmed for a specific operator. They extend cellular networks into buildings and small offices. As with femtocells, installation is complex and if not done properly they can cause network problems. Unlike femtocells, repeaters do not use the local Internet connections, but rather receive and re-transmit the signals between base stations and mobile phones.
Boosters are usually sold online and through retail. They vary widely in amplification power, quality of amplification, and power balance. For example, these products amplify signals at 1, 3, 5, or even 10 watts all the time. Using power over 1 watt increases the probability that a booster will interfere with surrounding mobile devices. Also, it would be more energy efficient to adapt amplification power as needed, rather than to simply use the same wattage constantly. Many boosters don't support balanced power in both directions between base station and mobile phone. This may result in only solving the signal quality problem in one direction. Since communication is bi-directional, this doesn't actually solve the problem. Varying quality of amplification also introduces noise, which can interfere with surrounding devices.