What are Femtocells?

Femtocells are low-power access points that can combine mobile and Internet technologies within the home. The femtocell unit generates a personal mobile phone signal in the home and connects this to the operator’s network through the Internet. This will allow improved coverage and capacity for each user within their home.

Femtocells have an output power less than 0.1 Watt, similar to other wireless home network equipment, and will typically allow up to about 4 simultaneous calls/data sessions at any time. Mobile phones connected to a femtocell will typically operate at levels similar to other wireless phones used in the home.

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.

Typically, a single femtocell will deliver voice services simultaneously to at least four users within the home, while allowing many more to be connected or ‘attached’ to the cell, accessing services such as SMS. Additionally, femtocells will deliver data services to multiple users, typically at the full peak rate supported by the relevant air interface technology, currently several megabits per second and rising to tens and hundreds of megabits per second in the future. But by removing the capacity hungry indoor mobile users from the outdoor network, femtocells also in effect improve performance for consumers outside. Indeed, for each additional indoor femtocell user, system resources are freed to serve about ten outdoor users. The femtocell behaves like a normal base station in that as users enter or leave the home their voice or data services are seamlessly handed over from or to the outdoor network as required.

Subscribers benefit from perfect cellular coverage and faster mobile broadband in the home as well as a more competitive voice and data tariff. Operators get optimum cellular coverage and more mobile usage in the home and dramatically reduced operating costs especially through backhaul - their single largest OPEX - and power savings. Equally importantly the cellular operators’ capital expenditure will significantly drop because accelerating data usage means they will inevitably have to heavily invest in their outdoor network in terms of new cell sites and backhaul to meet expected demand - something femtocells do at a fraction of the cost. In fact, Paul Jacobs, Qualcomm’s CEO, recently said that the gains in throughput available to femtocell users are “equivalent to that brought by the cell phone’s shift from analogue to digital.”

Finally, as mobile operators look beyond 3G to LTE or WiMAX, femtocells offer a new, dramatically lower-cost model for network rollout. For example, LTE femtocells could be employed using higher frequencies to deliver targeted intense high bandwidth requirements inside buildings - exactly where subscribers most demand it. Operators can then use their existing networks outdoors as demand slowly builds up and then use the scarce lower frequency spectrum to provide good quality LTE coverage across entire markets with the minimum number of outdoor network cells. As we have seen, the simple proposition of lower costs, for both operators and consumers, combined with improved coverage and services is compelling. Yet there are also challenges which must be overcome before widespread commercial deployments can become a reality.