Historic Pprune posting from on board LH418
Join Date: Sep 2000
Location: SE England
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
A cell phone at altitude can be 'seen' by too many base stations and it starts to swamp the system. The base stations and channels allocated to them are v carefully thought out to provide the maximum spectrum use - topographics, buildings, output power, anticipated phone density and use are all considered. Stick a phone 5 miles up and all this network planning goes out the window, it'll block whatever channel its operating on on umpteen base stations, possibly hundreds in cities where a base station might be designed to cover just a section of a single street.
Title? What title?
Join Date: Dec 2002
Location: In the dog house
Posts: 347
Likes: 0
Received 0 Likes
on
0 Posts
Stick a phone 5 miles up and all this network planning goes out the window, it'll block whatever channel its operating on on umpteen base stations,
hang on, lets not forget, a mobile phone does not stick to one channel during operation, not even during a call. Going from cell A to cell B does not require the same channel to available on the new cell. It can and will hop channels, even within one cell. After all, going from one cell to another may take it into a different MSC. Add to this that putting a phone 5 miles in the air, inside an aluminium tube reduces the range of the transmissions from both handset & cell site.
What ever reason a mobile cannot be used in an aircraft does not lie with the mobile operators !
hang on, lets not forget, a mobile phone does not stick to one channel during operation, not even during a call. Going from cell A to cell B does not require the same channel to available on the new cell. It can and will hop channels, even within one cell. After all, going from one cell to another may take it into a different MSC. Add to this that putting a phone 5 miles in the air, inside an aluminium tube reduces the range of the transmissions from both handset & cell site.
What ever reason a mobile cannot be used in an aircraft does not lie with the mobile operators !
Last edited by phnuff; 29th Jan 2003 at 12:33.
Join Date: Sep 2000
Location: SE England
Posts: 275
Likes: 0
Received 0 Likes
on
0 Posts
Phnuff, I was just pointing out, perhaps badly, that whatever the airlines say about phones, the cell phone companies really don't want people using phones in aircraft either.
Yes phones 'hop' channels, and adjacent base stations never use the same channels [goes against the whole design philosophy of 'cell' phones], but the whole network is designed on the basis of phones being at or near ground level. The base stations often have surprisingly little spare capacity - they're typically designed for 1 - 10% phone usage, as people discover when they ring their friends at midnight on New Years eve
.
As for the attenuation caused by being in an aluminium tube, dunno what that is, but the phone tries its hardest to overcome it by cranking its power up. Hence a phone which should be 'visible' to no more than 4 or 5 base stations all using different channels, suddenly is seen by hundreds of base stations, many using the same channels which are all blocked by the call, and this does put a lot of extra strain on the system. If airlines allowed people to use phones on aircraft entire networks would have to be upgraded and we'd all pay even more for our calls.
Yes phones 'hop' channels, and adjacent base stations never use the same channels [goes against the whole design philosophy of 'cell' phones], but the whole network is designed on the basis of phones being at or near ground level. The base stations often have surprisingly little spare capacity - they're typically designed for 1 - 10% phone usage, as people discover when they ring their friends at midnight on New Years eve
. As for the attenuation caused by being in an aluminium tube, dunno what that is, but the phone tries its hardest to overcome it by cranking its power up. Hence a phone which should be 'visible' to no more than 4 or 5 base stations all using different channels, suddenly is seen by hundreds of base stations, many using the same channels which are all blocked by the call, and this does put a lot of extra strain on the system. If airlines allowed people to use phones on aircraft entire networks would have to be upgraded and we'd all pay even more for our calls.
