As a father of two kids, I am the happiest when they self organize their things without my intervention. Well, that might be a bit of a stretch when it comes to kids, but it’s actually a reality for unplanned, plug-and-play femtocells, thanks to Qualcomm’s UltraSON (Ultra Self Organizing Network).
As I have explained in a previous blog, femtocells bring enormous benefits. No wonder, their popularity is growing by the day. As reported by Informa in June this year, the number of deployed 3G femtocells, has now surpassed that of 3G macrocells. Femtos are designed to be user deployable. Which means, there is no network planning or network optimization involved, nor do the operators control where and how are they deployed. Again, as I’ve previously mentioned, this poses challenges.
The good news is that Qualcomm’s UltraSON, which is part of our FSM chipset solution, is here to the rescue! It is comprised of many, advanced algorithms that ensure femtos operate in a way that will not adversely affect the larger macro networks, while still providing excellent coverage, capacity and data rates to users.
At the very outset, there are four things that would be of concern when femtos are being deployed en masse, especially, in “restricted access:” mode
1) femto users get best possible coverage/data rates;
2) femto users are not affected by macro users around them;
3) macro users are not affected when they are around femtos; and
4) the larger macro network is not affected adversely by the presence of femtos.
UltraSON uses mainly two levers to make all the above happen: femto transmit power that controls interference on the downlink; and femto-user transmit power that limits interference in the uplink.
Looking at the first lever, if femto transmit power is too low, the coverage might be limited, affecting data rates and user experience.
If too high, the coverage may leak out and create interference to nearby macro users. So, UltraSON ensures that transmit power is maintained at an optimal level, by learning the RF environment and usage pattern (usage locations within the coverage area) and periodically fine-tuning the output power to meet it.
The second lever achieves the objective of reducing uplink interference to macrocells by controlling the absolute power of femto-users, as well as by managing their data rates.
There is a location aspect as well. For example, femtos located away from the macrocells toward the cell-edge, may need higher limits for femto-user transmit power, so as to overcome the effect of higher transmit power of surrounding macro users. By the same token, the limits may be lower for the femtos closer to macrocell.
The bottom line is that UltraSON is a one-stop solution that takes care of all of your concerns about femto and macrocell interference, while providing an excellent user experience.
If you need more information about UltraSON algorithms and femtocells as a whole, please visit our website www.qualcomm.com/femto. Also, I am conducting a session titled “The Big World of Small-Cells” at Mobilize in San Francisco on 26th Sep at 10am, which will discuss femtocells and their evolution in detail. Hope you join me.