DavidC wrote:
Have you noticed that those horrible pulsing noises (rat-a-tat-tat) are absent these days
Unfortunately, no!
There seems to still be plenty of places where you only get 2G (I wish I had an option to disable 2G on my phone, there’s only an option to disable 4G)
Also 4G causes audio interference (I thought those days would be gone), I’ve noticed audio noise being caused by my phone with a different characteristic to the GSM noises if I leave the phone near my mixer or microphone cables or speakers (with the phone showing a solid 4G connection). I still have to put the phone in airplane mode (with WiFi on) if it’s near that stuff.
I wonder whether there are external antennas for mobile phones such as the Samsung lines. Have not found anything useable so far but I could imagine that with an antenna on the underside of the plane, you might get much better connections.
I have to imagine that doppler effect is taken into account (at least to some extent) or is not significant enough for 4G networks since I could get a perfectly good and usable 4G connection on the AVE between Zaragoza and Barcelona at >300km/hr (pretty much Bonanza cruising speed). Given that most European countries have ~300km/hr high speed rail these days I would have to imagine it’s a design consideration.
Interesting [ local copy ] but I agree with alioth.
I have known a number of people who work deep in the “3G” business but have never managed to get any of them to talk to me, let alone openly, about what they do. It all seems to be rather confidential, and one can see why. Some are (or have been) on EuroGA but don’t post.
If I was in that business, my biggest concern would be an airliner taking off with say 300 people, of whom say 250 will have their phones on, and I will suddenly get 250 phones up there, climbing to some altitude and trying to negotiate connections to 1000s of towers. Multiply this by say 10-30 for any given country’s network, plus all those arriving, in holding patterns. And this process isn’t just the phone connecting to the one tower, or multiple towers. It involves communication between the towers – normally this is done with underground (often fibre) links but in the countryside it is done with tower-to-tower microwave links. These links can be easily saturated and this can cap the bandwidth. I recall reading about this a few years ago, by one specialist in Usenet. It actually gets really complicated because the system maintains very dynamic databases of where each phone is so that incoming calls and sms can be routed to it.
So, if I was doing this, I would put in some really aggressive software which simply kills all phones trying to connect to too many towers, for some time – say a few mins. Nobody will actually complain because everybody is used to phones sometimes not working.
And I see some manifestation of this when flying. When entering some country, I get connectivity briefly (and a strong signal), but after a few minutes the connectivity vanishes totally (but the signal is still as strong as before). It’s kind of pretty obvious what they did… and it is exactly what I would have done too. This happens regularly e.g. entering France from the UK and it remains the case (with sporadic connectivity every say 30 mins) until I am approaching the Alps and then (as expected) connectivity returns, and again this is predictable because anybody skiing on top of some mountain will create the “airliner problem” but this time they do expect their phone to work… plus there is the public policy requirement for emergency usage. Everybody knows about this issue and everybody can think of the way to solve it. And nobody on an airliner expects their phone to work, anyway… And different countries work this differently. For example I get instant and total zero connectivity over Belgium (Vodafone) and it never returns, even briefly… note that I almost never land there and overfly at FL090 minimum.
So I suspect the answer is simpler than some technology issue. I think the system is hacked to protect itself 
4G works a lot better but it seems to be known that they had to replace most of the ground system for that too. But 4G is still killed in the same places.
