Today, I read prof. Simon Saunder article on Femtocell and the following struck me.
A major technical challenge that femtocell designers initially faced was the need to manage potential interference. It takes up to two years to install conventional base stations, during which time radio engineers meticulously plan a station's position and radio characteristics to avoid interference. However, such an approach is not viable in the case of femtocells, deployed potentially in their million at random. Automating a process conducted by radio engineers was no mean feat and simply would not have been possible a few years ago.
Fortunately, the fact that the walls of buildings keep 3G signals out and keep the femtocell’s signals in provides strong inherent interference mitigation for indoor femtocells. Extensive studies have shown that proper implementation of a few key techniques to reduce interference can take advantage of this attenuation in an intelligent manner. Such techniques include frequent monitoring of the cell’s surrounding radio environment combined with adaptive power control. Indoor users gain faster data rates, as do outdoor users who now operate on less congested cells, while it costs less for operators to deliver higher overall network capacity. Large-scale, real-world deployments are demonstrating that these techniques work in practice and even allow new approaches, such as operating 3G networks in the same spectrum as 2G networks.
AT&T has deployed femtocells on the same frequencies as both the hopping channels for GSM macrocells and with UMTS macrocells. They have tested thousands of femtocells, and found that the mitigation techniques implemented successfully minimise and avoid interference. The more femtocells are deployed, the more uplink interference is reduced.
It is very interesting to see that the interference is not causing any problems in real life.
(From today, I will try to introduce more information about femtocell Interference as possible as I can. ^~^ .)
No comments:
Post a Comment