This is my first/. posting. For my sins, I was the Zingo project director. I thought it was a pretty cool idea, but then I'm biased. I'm flattered the project attracted some attention on these hallowed pages!
The technology currently deployed by most UK networks is enhanced (to one degree or another)cell identity. Essentially they plot a 'splash map' of where each cell will dominate, and look up the predicted coverage for the cell the phone is camped onto. This works quite well in cities (cell density is driven by capacity requirements - cells can reach 35Km radius in rural areas). My experience is that you can expect to locate to 500-600m in city centres (particularly where there's a microcell layer), 1500-2000m in the suburbs and 3Km or so in rural areas.
Timing Advance is a refinement that uses the synchronisation of timeslots to work out the distance between the handset and base station. Each TA band equates to around 550m and as macro cells are usually configured in 3 120 degree segments, you get this banana shaped area (which is still reported as a point and radius of error).
TA doesn't really help much in city centres, as microcells are omni-directional and typically 500-600m radius. It can be used to discount (or confirm you're in) rogue patches of RF dominance in more suburban environments, but it really scores in rural areas.
There are a coupele of triangulation techniques - Enhanced Observed Time Difference and Uplink Time of Arrival - vying for attention, but I'm not convinced they'll actually be deployed on 2/2.5G networks in Europe. Its more likely we'll be pushed to 3G, where our shiny new handsets will include Assisted GPS. This might change with the recent E112 legislation (similar to the US E-911 requirements).
Slashdot Mirror
The technology currently deployed by most UK networks is enhanced (to one degree or another)cell identity. Essentially they plot a 'splash map' of where each cell will dominate, and look up the predicted coverage for the cell the phone is camped onto. This works quite well in cities (cell density is driven by capacity requirements - cells can reach 35Km radius in rural areas). My experience is that you can expect to locate to 500-600m in city centres (particularly where there's a microcell layer), 1500-2000m in the suburbs and 3Km or so in rural areas.
Timing Advance is a refinement that uses the synchronisation of timeslots to work out the distance between the handset and base station. Each TA band equates to around 550m and as macro cells are usually configured in 3 120 degree segments, you get this banana shaped area (which is still reported as a point and radius of error).
TA doesn't really help much in city centres, as microcells are omni-directional and typically 500-600m radius. It can be used to discount (or confirm you're in) rogue patches of RF dominance in more suburban environments, but it really scores in rural areas.
There are a coupele of triangulation techniques - Enhanced Observed Time Difference and Uplink Time of Arrival - vying for attention, but I'm not convinced they'll actually be deployed on 2/2.5G networks in Europe. Its more likely we'll be pushed to 3G, where our shiny new handsets will include Assisted GPS. This might change with the recent E112 legislation (similar to the US E-911 requirements).