Femtocells are mini mobile radio cells, also known as small cells, which are deployed in buildings and rooms. In the Third Generation Partnership Project( 3GPP), femtocells are referred to as Home NodeB( HNB). The background to femtocell development is that radio transmissions with UMTS or Long Term Evolution( LTE) in buildings are possible via these small cells.
Used in companies or in private households, the femto base stations can be used indoors to communicate via UMTS in 3G networks. In addition to this advantage, the transmission power can also be significantly reduced, since the femto base station only covers a limited area of about 50 square meters and the UMTS cell phones are located at close range to the base station. The transmitting power is about 5 mW.
In a femtocell, several users can make calls at the same time. The distance between the user and the femtocell base station is between 50 m and 200 m. The femtocell base station is located in the immediate vicinity of the base station. The femtocell base station can be connected directly to the Internet via Ethernet or to the Digital Subscriber Line Access Multiplexer( DSLAM) via aDSL modem, or to a broadband cable network via a cable modem. It is connected via the Internet to the radio network controller( RNC) and thus to the UMTS network. The femtocell provides UMTS access points as Internet access points through which the user can send and receive data. This allows the user of a femtocell to work directly on the Internet.
If communication takes place between different femtocells within a building, this also relieves the UMTS network and reduces communication costs. In addition, communication can take place using High Speed Downlink Packet Access( HSDPA), WiMAX and WiBro. If the femto access point is integrated in a DSL modem, communication from the UMTS cell phone can take place via the DSL connection to the Internet.