Subject: Location Requirements - Data Details

From: "Rosen, Brian" <[email-masked]>
Date: Wed, 17 Jul 2002 07:29:50 -0400

The current requirements are pretty sparse in describing what has
to be carried in a location.  I'd like to see some specificity,
so that the following are accommodated:

1. There must be formats for both lat/lon/altitude and "civil"
locations

2. Time of sighting (mentioned, but not a requirement)

3. Motion and direction vectors

4. Precision (there is a more appropriate term, I forget what
it is)

Brian

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From: "James M. Polk" <[email-masked]>
Date: Wed, 17 Jul 2002 19:15:52 -0500

>1. There must be formats for both lat/lon/altitude and "civil"

You mean "Postal", as in the street address? Shouldn't this be a valid
optional *additional* LO in the reply?
>2. Time of sighting (mentioned, but not a requirement)

I firmly believe the timestamp should be a requirement (using NTP)

>3. Motion and direction vectors

This is a good idea, but shouldn't be mandatory

>4. Precision (there is a more appropriate term, I forget what

fuzziness, or fudge-factor.... I agree with this

>Brian

cheers,
James 

              *************************************
"People generally demand more respect for their own rights than 
                         they are willing to allow for others"

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 17 Jul 2002 20:29:41 -0400

> optional *additional* LO in the reply?

I'm not an addressing expert, but I believe that there is a difference 
between the two in some cases. The difference is that postal addresses 
are often "logical", i.e., expressed as PO boxes, APO/FPO, zip code 
only, etc.

Military addresses are also an example. (see 
http://www.airbornerecce.com/train/security.htm)

We often find this as the difference between the postal address and the 
"courier" address.

As a random example courtesy of Google, see 
http://www.unites.uqam.ca/tourisme/anglais/coordonnees.htm

The format is probably the same (except for PO box and similar), but we 
may need to mark what it is.

Henning

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From: Randall Gellens <[email-masked]>
Date: Thu, 18 Jul 2002 10:22:39 +0900

>  I firmly believe the timestamp should be a requirement (using NTP)

I'm not sure we should require use of NTP.

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From: Henning Schulzrinne <[email-masked]>
Date: Wed, 17 Jul 2002 21:34:07 -0400

Maybe James means the use of the 64-bit NTP timestamp format, as in 
RTCP. That, I believe, is a more reasonable requirement. Whether this is 
better than the alternative of a time-zone based spec (Wednesday, July 
17, 2002 17:45 +500) is debatable, but probably way beyond the detail 
justified in a requirements document. (Since the latter may accidentally 
leak timezone information, the NTP format may have privacy advantages.)

I agree that requiring a particular synchronization method is not 
appropriate. For example, a GPS -based beacon won't have NTP, but it 
will have time that's much more accurate than your average NTP-synced 
clock.

---

From: "James M. Polk" <[email-masked]>
Date: Wed, 17 Jul 2002 20:48:47 -0500

>I'm not sure we should require use of NTP.

Can you name a more appropriate time mechanism that the Big I Internet
uses/should use in this case?

Standalone devices within internal clocks are inherently highly inaccurate
- including the problem of timezones, even ones where the timezone shift is
in 15 or 30 minute increments.  

And *if* we go down the path (that I don't agree with BTW) of delta, the
inaccuracies of timing compounds the problem ...

cheers,
James

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From: "James M. Polk" <[email-masked]>
Date: Wed, 17 Jul 2002 20:51:31 -0500

At 09:34 PM 7/17/2002 -0400, Henning Schulzrinne wrote:
>RTCP. That, I believe, is a more reasonable requirement. 

I was purposely being inaccurate  for the sake/pun of this WG  ;-)  but
yes, this was what I was referring to

cheers,
James

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From: Randall Gellens <[email-masked]>
Date: Thu, 18 Jul 2002 11:06:30 +0900

>  uses/should use in this case?

Some classes of devices have access to very accurate time already 
(for example, CMDA mobile stations).  Some classes of device wouldn't 
have any reason to implement NTP, and a requirement that they do so 
in order to use geopriv seems unwarranted, in my opinion.

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From: Kenji Takahashi <[email-masked]>
Date: Thu, 18 Jul 2002 11:19:05 +0900

GPS gives you the pretty accurate absolute time too.

Kenji

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From: "James M. Polk" <[email-masked]>
Date: Wed, 17 Jul 2002 21:20:45 -0500

>in order to use geopriv seems unwarranted, in my opinion.

So the requirement is to use the "best" the Target has access to....

Absolute inaccuracies will follow

we should work on this because I think this is really important 

cheers,
James

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From: Carl Reed <[email-masked]>
Date: Tue, 23 Jul 2002 17:57:37 -0600

Hi -

I might such looking at the Location Interoperability Forum Mobile Location
Protocol API. It deals with all these questions. Also, the most recent
public release of the LIF MLP specification has now incorporated the OpenGIS
Consortium terminology and schemas for coordinate reference systems and
geometry. If anyone is interested, I can provide the references.

Regards

Carl Reed

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From: Anuket Bhaduri <[email-masked]>
Date: Mon, 29 Jul 2002 09:21:11 -0700 (PDT)

Hi Mr. Reed,
My name is Anuket Bhaduri and I'm a Graduate Student
in Spatial Information Engineering at the University
of Maine. My research topic is Privacy in
Location_Based Service Environments. It would be very
helpful if you could send me the references you
mention below. My advisor and I are working towards
the problem from a slightly different angle, which we
will be describing in the near future. The refereces
or the documents will be very useful to us.
Thank you,
Sincerely,

Anuket Bhaduri.
Graduate Research Assiatant
Dept. of Spatial Information Science & Engineering
University of Maine
5711 Boardman Hall, Rm 234
Orono, ME 04469
Phone - (207) 581-3683, fax - (207) 581-2206
E-mail [email-masked]
Website http://www.spatial.maine.edu/~anuket

> > 4. Precision (there is a more appropriate term, I

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