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Femto cells or femtocells are small cellular telecommunications base stations that can be installed in residential or business environments either as single stand-alone items or in clusters to provide improved cellular coverage within a building. It is widely known that cellular coverage, especially for data transmission where good signal strengths are needed is not as good within buildings. By using a small internal base station - femtocell (femto cell), the cellular performance can be improved along with the possible provision of additional services.

In order to link the femtocells with the main core network, the mobile backhaul scheme uses the user's DSL or other Internet link. This provides a cost effective and widely available data link for the femtocells that can be used as a standard for all applications.

There are many advantages for the deployment of femtocells to both the user and the mobile network operator. For the user, the use of a femto cell within the home enables far better coverage to be enjoyed along with the possible provision of additional services, possible cost benefits, and the use of a single number for both home and mobile applications. For the network operator, the use of femtocells provides a very cost effective means of improving coverage, along with linking users to their network, and providing additional revenue from the provision of additional services.

Although there are advantages and disadvantages to the use of femtocells, their use has many advantages for both user and network provider.

Femtocell issues

There are a number of issues that needed to be resolved in terms of the basic system design and set-up.

  • Femto cell interference issues:   One key issue associated with femtocells is that of interference. There is only limited spectrum on which the cellular systems can run. Some 3G operators for example may only have one channel in some places. Therefore it is necessary that femtocells are able to operate within the normal spectrum shared with many other cellular base stations. There are a number of ways in which this can be achieved: the use of cognitive radio technology; the use of systems that are tolerant to interference (3G and 4G are able to tolerate interference and single channel working); spectrum planning where possible.
  • Femtocell spectrum issues:   radio spectrum is a particularly scare resource, especially when large amounts of data are required. Planning the available spectrum so that it can be used with the possible huge numbers of femtocells can require careful attention, although in some instances single channel operation with main base stations may be required.
  • Femtocell regulatory issues:   Femtocells operate in licensed or regulated spectrum. Unlike Wi-Fi which operates in unlicensed spectrum, femtocells need regulatory approval. The spectrum and radio regulations vary from one country to the next and therefore regulations may need to be changed in each country. International agreement may also be required, because private individuals may take femtocells from one country to the next.
  • Femtocells and health issues:   With a large public awareness of the possible dangers of RF radiation, one key issue has been that of health and safety. As a femtocell is a cellular base station, there could be public concern regarding the levels of RF radiation received. However the power levels emitted by femtocells are small - no greater than most Wi-Fi access points which are common in very many homes. As a result it is not believed by the industry in general that there are any health issues that should cause any concern.


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