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What are Femtocells?Femtocells are fully featured but very low power mobile phone basestations, connected using standard broadband DSL or Cable service into the mobile operator's network. They offer excellent mobile phone coverage at home for both voice and data, but at lower cost than outdoor service.
The femtocells themselves look very much like WiFi broadband modems, and some vendors are planning to incorporate all three features into a single box (WiFi, DSL and Mobile). Unlike WiFi, these devices use licenced radio spectrum, so must be operated and controlled by a mobile phone company. Thus it will work with only one mobile phone operator, and thus encourages all users in a household to switch to the same network operator. When in range of the femtocell at home, the mobile phone will automatically detect it and use it in preference to the outdoor cellsites. Calls are made and received in exactly the same way as before, except that the signals are sent encrypted from the femtocell via the broadband IP network to one of the mobile operators main switching centres. Making and receiving calls uses the same procedures and telephone numbers, and all the standard features (call divert, text messaging, web browsing) are available in the same way - indeed data services should operate more quickly and efficiently due to the short range involved. Femtocells operate at very low radio power levels - less than cordless phones, WiFi or many other household equipment. This substantially increases the battery life, both on standby and talktime. Units can handle up to 3 or 4 simultaneous calls from different users depending on the model. Restrictions can be applied on who can use the femtocell service. In extreme cases, there may be additional charges for DSL broadband supplier where a quota applies - however this would equate to many long voice calls or data service. Thus, whilst operators will hope that most femtocell users are willing to provide open access to other users, they usually offer the facility to restrict service to a whitelist of up to 50 specified telephone numbers. The femtocell encrypts all voice and data sent and received from mobile phones and would normally not allow access to the home computer network, so external users cannot break into your computer. In order to reduce cost, these units are self installing and use a variety of clever tricks to sense which frequency to transmit on and power level to use. They are compatible with existing standard mobile phones, although in future some minor enhancements would allow clear indication of when the phone is using the local femtocell (and thus using a free call allowance) - currently this can be provided by tones at the start of each call. Most of the excitement is based around the new 3G UMTS mobile phone system, which includes the ability for high speed data services. However, vendors have developed femtocells for 2G GSM phones which are the most common globally, and also CDMA systems popular in the US. So if anyone asks you what femtocells are, you can now confidently reply. Read more about the various femtocell system architectures, vendors and operators on the rest of this site.
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