[MLB-WIRELESS] Mobile phones in remote places.

[Jon Teh]

On Mon, Sep 09, 2002 at 08:15:54PM +1000, evilbunny wrote:
> Hello Nick,
> 
> My parents barely have access to CDMA, you can forget GSM for pretty
> much 30 to 150km depending which way you go, possibly further...

Well, the problem with GSM, is it was not deisgned for Australia; at all.
It was designed for geographically small European countries with very high
population densities, and therefore mobile base station densities.

Due to the fact that that GSM employs TDMA, which breaks communication up
into tiny timeslots (<1ms), there is a theoretical maximum of 36km that the
mobile phone can be away from the base station, due to propogation delay.
So even if you can pick up the signal from that base station 40km away,
it is of no used to your phone.

This is why GSM sucks.

> 
> There is a LOT of places that should whine about now... My parents got
> the royal shafting over cdma phones and the pretty ads they had on TV,
> the analog network was 100x better then CDMA will ever be... (actually
> the network was turned off forcing them to go to CDMA, wasn't by
> choice)
> 

CDMA is a very good system, if the telcos actually implemented it
comprehensively. They threw out the horrible time division scheme, and
instead use the much nicer spread spectrum technology, like 802.11b wireless
cards do. This theoretically allows a lot more users, a lot further away
from the base stations. Distances of 130km, Line of Sight, are meant to 
be possible. Again, this is really a problem of not enough base stations
rolled out. I'm of the opinion telcos should be moving off GSM and to CDMA,
so they can focus their efforts on one technology. Incidentaly, 3G also 
employs CDMA transmission, but who knows when 3G is ever going to be
rolled out from the major three mobile providers...


Just my 2c worth... I wish the mobile networks actually had decent coverage,
but it's a pretty mean feat, if just for the fact that most of Australia
has quite a low population density... and plenty of hills too. 
These are problems which are also a pain when trying to build wireless WANs.


-- Jon Teh

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