Thursday, 5 November 2009

Femtocell trial: update

Well, I have placed the femtocell at a greater distance from the router - but given the limitations of where to put routers and the length of cables this is still not an ideal scenario, I would say.

I was talking to an executive from Nokia Siemens about this yesterday, and he said the spectrum filters in current femtocells are still quite poor and really need to be further refined - although this would make them more expensive initially.

I'm no engineer, but as a consumer my view is that it's not good enough to just ask consumers to locate a femtocell six feet away from their router. Sometimes that's just not always that feasible, and it's hardly user friendly. It might be OK for the early adopters to do this - but what about the mass market? I can't help but think that if femtos are to take off as a mass-market solution for indoor coverage or even data offloading then these interference issues need to be eliminated. I'm just trialling a femtocell; not sure I would buy one just yet.


Anonymous said...


I have heard similar.

But if the problem is that your WiFi fails when your femtocell works, I would suspect it is the filters in the WiFi (not the femto).

ie the opposite of your Nokia Siemens contact's suggestion.

Most of the femtocells today are still early & (arguably) over-engineered. The companies who make them have the handset & basestation mindset.

In contrast, it is the WiFi boxes which have had ten years of "oh, if we take that out it makes it cheaper and it doesn't break". Then try making it even cheaper... That is why they are cheap (good) but why they fail when they meet something new, like a femto (less good).

That does not make your experience any less frustrating, and unfortunately I doubt it makes fixing it any better.

But maybe blaming the right box is a good thing.

Anonymous said...

Thinking on it further:

There are legal rules on transmsission, so the femto must be obeying those to be legally sold.
Not least because otherwise it would impact other operator's expensive 3G spectrum even more tha it affects WiFi.
Then both Voda and ALU would be in serious (££££) trouble with carrier and OFCOM.
In contrast there are no rules or laws on receive beyond "does it work" - a bad receiver does not hurt anyone else.

That doesn't help you, although I'd suggest finding a better informed source than your friend at NSN (maybe they were deliberately mischievious?)

One suggestion: put something between the WiFi and the femto. You said you were on virgin so the nice hefty cable modem would be great if it is convenient?

Anonymous said...

WiFi spectrum is in 2.4 GHz range, whereas 3G Femtocell spectrum is around 1.8-2.1 GHz - I wonder how they can interfer with each with other even though the transmit, receive filters are poor since they have sufficient guard bands seperating one another. Hmmm...

Anne Morris said...

Hi anonymous, yes which box to blame: I don't know to be honest. But I certainly would not want to blame one or the other; there could be issues with both, or with just one. Anyway, it's been very interesting to do the trial and find out this kind of issue. On the whole I am very happy that the femto allows me to make mobile calls in my home. And I agree that the femtos are more likely to be more strictly tuned in given the rules to which they have to adhere. I did also wonder how they could interfere given the spectrum and certainly did not expect this to happen! All being well it'll get sorted out - what do you think will happen with femtos? Feel free to email me privately!