Accidental Roaming
Mark C
Posts: 20,899 Forum Member
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This is bollocks surely, if you're beyond 35km from a base station, you may well see
the networks listed, but the time delay for GSM is too long to allow authentication ?
http://www.bbc.co.uk/news/technology-26513546
the networks listed, but the time delay for GSM is too long to allow authentication ?
http://www.bbc.co.uk/news/technology-26513546
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No, it's a well known phenomenon.
It's been happening for decades and somehow it manages to bubble up into the news every few years.
If the BTS has extended range then up to 120km is possible, though I doubt this is the case here.
Screenshot: https://pbs.twimg.com/media/A2s6QlPCAAA1Iyh.jpg
That's pretty impressive and at least 150km coast to coast
I have picked up signals from IOM and Ireland in a high spot in North Wales
Yes, yes, I know, I've seen the same on my phone, but my question was how can anybody manage to authenticate, and therefore log on to the network over a distance that exceeds the GSM delay period, which is exceeded normally at a distance of 35km ?
Well wiki says:
By implementing the Extended Range feature, the BTS is able to receive the uplink signal in two adjacent timeslots instead of one. When the mobile station reaches its maximum timing advance, i.e. maximum range, the BTS expands its hearing window with an internal timing advance that gives the necessary time for the mobile to be heard by the BTS even from the extended distance. This extra advance is the duration of a single timeslot, a 156 bit period. This gives roughly 120 km range for a cell.[3] and is implemented in sparsely populated areas and to reach islands for example.
http://en.wikipedia.org/wiki/Timing_advance
Could that explain it?
I wasn't saying it was?
120 km is pretty impressive.
Indeed it could, in which case the French could be asked to to reduce the advance, and prevent any risk of logging on (at least for Dorset/Devon). Of course, It's unlikely
they'd respond to such a request !!
On the beach in Lincolnshire I connected to BEN NL (again, a long time ago!)
Often at Porthcurno in Cornwall my phone switches to French time, and connects briefly to Orange F, but just for a few seconds.
On a semi related note - I picked up a German freeview multiplex for a whole evening last summer through my tv aerial in Aberdeen. Presumably atmospheric conditions....
Surely 3G networks using the WCDMA standard are not limited to the timeslot theory that is prevalent with TDMA networks such as GSM?
I have a friend not a million miles from Porthcurno who had fairly reliable reception of several French TV multiplexes.
I'm a bit further up and I've never been able to duplicate it nor ever roam onto a different network, but French and Irish FM radio isn't uncommon for me to pick up.
I've even see tmobile NL in Norwich on one occasion!
Wow, that's amazing! I certainly wouldn't expect to see O2 coverage there.
I don't know, tell us more please ?
Nobody said it was GSM, nor is it mentioned anywhere in the article.
This.
Although 3G has other limitations that aren't directly dependent on distance.
Also boats, with transmitters on board...
Also, if you look at the coverage maps of some UK networks that like to inflate the appearance of their coverage you can see some large blobs reaching dozens of miles out to sea all around the coast - often the ends of these blobs are not so much the maximum range of the mast but the maximum range configured in the coverage map rendering software beyond which it doesn't bother calculating anymore. Indeed you often even see perfect circles of coverage bounded this way inland in some conditions.
That is preety cool! It really is a funny thing with wireless signals because the conditions have to be just precise and perfect and at the right time for such extemeties ;-)
There's a calculator here. Says 22.6km for a 40m mast. Of course most (all?) mobile masts will be above see level so line of site will be further, but conversely will often have higher ground in the way,
http://www.hamuniverse.com/lineofsightcalculator.html