GPS Meets PCS

The Donald writes: "According to an article at News.com, Sprint PCS will be starting to implement E911 calls in Rhode Island sometime in October. The FCC required that all cell phone providers have an improved E911 system in place by October first. This is the first step in making the E911 a reality, with Sprint being the first major company to actually put a phone on the market that will work with E911; instead of just filing papers with the FCC saying the implementation is just to hard. The Samsung N300 phone will use GPS to track the people down. I like the idea, I just hope the phone will display the GPS information, and there is a way to opt-out for all of the location based advertisements you will get with your GPS enabled phone."

Comments

Not quite the first..

[PenguinX]

Disclaimer: I work for TeleCommunication Systems Inc. - we provide nationwide E-911 service.

During the FCC mandate for Phase I - which most carriers still have not fully deployed was based on cellsite/sector / some other general location. For Phase II E-911 the requirement is a PDE. As there are literally hundreds of ways to get this information (GPS handsets are only one). Under the TCS solution for Phase II we query a "pluggable" PDE for the location information - so the only time that anyone gets your specific location information is only when it is needed (as in during a 911 call). The only real difference with the Sprint solution is that they have brought the PDE functionality in-house.

Just to try to help clarify...

GPS Coverage

[Detritus]

I see one big problem with using GPS. It only works when you have a clear view of the sky. It doesn't work inside buildings or other places where the view is obstructed.

911 service can also be screwed up by PBX systems. I know of several cases where someone called 911 and the ambulance responded to the company headquarters building, where the PBX was located, instead of the building where the emergency occurred.

Re:GPS Coverage

[PatJensen]

Good post. Let me see if I can clarify why this is (as a PBX rookie of course) PBX's do not send location data unless your company has what is called a CAMA trunk. It is a special trunk that connects directly to 911 call centers to pass in-building location information that is in your switch translations.

I think digital PRI trunks can pass this information as well. When an emergency call is made, switch translations are read to find all sorts of useful information about your location. i.e. campus building, room number, office number, wiring jack number or whatever is programmed.

This information then shows on the screen of the 911 call center person that gets the call, so that office 911 calls can be routed properly. Hope that helps, that is what I learned in my Avaya training. Woohoo.

-Pat

Re:Why not cell triangulation?

[morcheeba]

That's the other method people are proposing.

GPS advantages/disadvantages:
+ precise
+ works great outdoors
- extra cost, extra weight, extra bulk (another antenna), less battery life
- doesn't work indoors or in cars

Triangulation advantages/disadvantages:
+ low cost
+ phones remain the same size/weight/battery life (triangulation can be mostly done in infrastructure)
- generally less precise
- in urban environments, multipath interference and distortion caused by buildings is a problem
- in rural environments, you're lucky to get a signal from one tower, much less 3!, so it doesn't work too well.

Note that the GPS implemntation doesn't need to be a full one-- some of the processing smarts can be located in the cell towers. Unfortuantly, this doesn't buy you much as the radio section is still the major size and power draw.

Performance of gps phone / Privacy protection

[morcheeba]

Here's a very-old press release (12-Apr-99) from the people who did the GPS portion of the phone. Some highlights:

Using prototype handsets from Motorola and Samsung, more than 8,000 test calls were made over a period of days and under a variety of conditions including clear skies, inside moving automobiles, inside homes and large buildings, and in wooded areas. The tests were conducted on GTE Wireless' 800MHz network and on Sprint PCS' 1900MHz network. Preliminary results show SnapTrack typically located callers with an accuracy under 25 meters. In optimal conditions, callers were located within five meters. In calling environments with extreme signal blockage, such as indoors where conventional GPS will not work, SnapTrack located callers within 90 meters, well below the FCC's 125-meter accuracy requirement.
...
A variety of miniature antennae also are being tested with each phone, and testing is conducted at all times of day in order to measure effects from GPS satellite constellation variation.

On their site, they have a spiel about privacy protection. Here's a quote:

Only when a subscriber dials 9-1-1 or requests a location service will the location be determined. Callers can initiate location requests the same way they control other phone functions.

Of course, who knows if this will be respected by the OEM's who implement the snaptrack technology in the phones. There's always the tin-foil-over-the-gps-antenna solution... maybe those people with the tin foil hats are on to something!