Femtocells Capable of Delivering More Capacity Than Macro Networks: Study

Femtocells (News - Alert) are low-power wireless access points that operate in licensed spectrum to connect standard mobile devices to a mobile operator’s network using residential digital subscriber line (DSL) or cable broadband connections. Lack of standards and complexity in technology are hampering femtocell deployments around the world. However, according to market intelligence reports, volume shipments for femtocells could begin in 2010 if existing technical challenges are met.

 

“Femtocells have the potential to deliver an order of magnitude more capacity than the macro network alone when used in dense deployments, even when occupying the same radio channel as the macrocells,” says a study from Femto Forum, an independent industry and operator association that supports femtocell deployment worldwide.

 

To address the technological challenges surrounding femtocell deployments and enable wide-scale deployment of the technology, Femto Forum also identified a number of technological solutions that mitigate potential interference with the macro network.

 

To explore the co-existence issues surrounding femtocell deployment, the research assessed the impact of femtocells on a mobile network in a wide range of deployment scenarios.

 

To analyze the issues such as interference, Femto Forum analyzed both femtocells using a separate carrier to the surrounding macro network and those using the same carrier – which pose the greatest interference challenge, but also the greatest opportunity for increased spectrum efficiency.

 

The study found although femtocells using a separate carrier were able to provide a simple means to essentially eliminate interference, many third generation (3G) operators are not having enough spectrum for their deployments.

 

The new solutions identified by Femto Forum mitigate potential interference where femtocells share the same carrier as the macro network. According to the agency, these methods are already being developed for pre-standard femtocell solutions, and they will be soon included in within the standard framework.

 

One of the solutions, Adaptive Pilot Power Control, lets the femtocell dynamically adjust its transmit power in response to the current level of signals from surrounding cells and the desired coverage area.

 

The Extended Tests for Dynamic Range ensures that femtocell designs are able to operate reliably even in the presence of nearby high power mobile phones connected to the macro network

 

With uplink power capping of the mobile phone when operating in the femtocell environment, the technology ensures that even in difficult radio conditions, the phone hands-off to the macro network before its transmit power increases to the point where macro noise rise is a problem.

 

By offering dynamic receiver gain management in the femtocell, femtocells can offer good service to both near and far mobile phones without unnecessarily increasing the phone transmit power, therefore keeping the noise rise to a minimum.

           

“At a time when mobile operators are seeing data usage rocket, femtocells offer an economic and effective way to deal with demand,” said Professor Simon Saunders, chairman, Femto Forum, in a statement. “By utilizing the identified interference management techniques it has been shown that femtocells offer operators an effective method to increase capacity and coverage within their existing networks through dense cell deployments.”

 

This particular study from Femto Forum relates to Wireless Code Division Multiple Access (WCDMA), but the Femto Forum represents the full range of radio standards and similar studies are underway for other air interfaces, the Forum said.