Re: [Ecrit] Location Protocols in Phone BCP

["Thomson, Martin" <Martin.Thomson at andrew.com>]

Good point.  

In general, it might not even be necessary to assume a single reference frame.  To the extent possible, we should try to avoid making unsafe assumptions either way.  However, when it is unavoidable we need to be clear.

>From the perspective of general advice to device manufacturers (the original topic), I believe that the only necessary advice is to note that location might change and the device MUST allow for that possibility.  While urn:service:sos.fire on the cruise ship might not perceive movement; urn:service:sos.terrorist might [1].  Better avoid the assumptions on the device end altogether.

The consumer of location information might define their own means of handling these special cases.  Within such closed systems, conventions are possible.  On the plane, the filter rules might ignore lat/long.

Ta,
Martin

[1] Speed 2 was two hours of my life that I want back.

> -----Original Message-----
> From: Henning Schulzrinne [mailto:hgs at cs.columbia.edu]
> Sent: Friday, 21 November 2008 2:51 PM
> To: Thomson, Martin
> Cc: Roger Marshall; ecrit at ietf.org
> Subject: Re: [Ecrit] Location Protocols in Phone BCP
> 
> While I think this is generally true, there are reasonably-common
> exceptions. For example, on a cruise ship, the fire warden or EMT
> cares about the cabin the emergency is in, not the current longitude
> and latitude the cabin happens to be located at, which would be
> utterly useless. Same is probably true for other "closed" systems,
> such as large buildings or an underground mine. Even on a plane, the
> flight attendant finds you by seat number when you press that orange
> button, not by longitude and latitude, so it doesn't matter whether
> you can determine the latter.
> 
> Henning
> 
> On Nov 21, 2008, at 2:29 PM, Thomson, Martin wrote:
> 
> > Hi Roger,
> >
> > To answer this question, you have to first answer the question: how
> > many reference frames exist?  My answer is one.
> >
> > It helps to only have a single reference frame for this purpose.
> > That is, earth-centred, earth-fixed is the single reference frame we
> > use to determine movement.  Anything moving in that reference frame
> > is moving.  Establishing ad hoc reference frames increases the
> > complexity of any solution that we develop.
> >
> > In the plane example, you might use a complex of the geodetic
> > location of the plane with uncertainty, plus a civic address with
> > SEAT=34C.  However, this would be considered to be moving at 3500m/s.
> 

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