At 10:57 AM 3/10/2010, Henning Schulzrinne wrote:
Something like
The US Federal Communications Commissions (FCC) has established a
requirement [in 19XX] that cell phones using GPS can be located
within 100 m with 95% confidence. This requirement is generally met
by current deployments in North America.
I have to back Henning's offered text here. His text offers the
requirement as a goal - which it is - rather than something that's
already been technically proven to be achievable 95% of the time -
which it hasn't been. In other words, the FCC is stating where they
want things, not where we already are.
james
The current wording implies a verifiable fact, which none of the
citations I provided come close to supporting. References to unknown
documents from the pre-SA-abolishment era aren't all that helpful to
an outside reader. (For example, the "urban canyon" problem isn't
likely to affect Paris and Amsterdam all that much, and Iceland
doesn't have to worry about leaves...) Also, as far as I know, there
isn't any great new technology on the horizon that will magically
shrink this from 100 m to 3 cm. The only thing that will help a bit
in the next few years is more satellites (part of the Galileo
effort) and, in some limited cases, differential GPS. (See
http://en.wikipedia.org/wiki/Galileo_(satellite_navigation)#Services)
Henning
On Mar 10, 2010, at 10:49 AM, Brian Rosen wrote:
> The current text is:
> As of the date of this memo, typical assisted GPS uncertainty in mobile
> phones with 95% confidence is 100 m. As technology advances, the accuracy
> requirements for location will need to be tightened.
>
> That is a statement of fact that is backed up by the U.S.
Regulatory docket.
>
> Above this text is a requirement (3 cm).
>
> How would you suggest rewording?
>
> Brian
>
>
>
>
> On 3/10/10 10:43 AM, "Henning Schulzrinne" <[email protected]> wrote:
>
>> I would simply state it as a requirement, rather than a statement of fact,
>> which is very likely is not (or only with a long list of caveats).
>>
>> On Mar 10, 2010, at 10:27 AM, Brian Rosen wrote:
>>
>>> The citation is the U.S. Regulatory spec, which is (barely) achievable.
>>> There is a very long record available that documents the back
and forth with
>>> experts arguing on both sides. The conclusions of even the
PSAP folks, who
>>> really want a tighter spec, is that 100 meter 95% measured at
county level
>>> is as good as we can get right now. For this document, that's
good enough.
>>>
>>> Brian
>>>
>>>
>>>
>>>
>>> On 3/10/10 10:22 AM, "Henning Schulzrinne" <[email protected]> wrote:
>>>
>>>>
>>>> On Mar 10, 2010, at 9:41 AM, Brian Rosen wrote:
>>>>
>>>>> This is a (probably pointless) discussion on the 100 meter uncertainty
>>>>> number that is found in -framework. It is a realistic number
today, and a
>>>>> much smaller number is not, in my opinion, realistic.
>>>>
>>>> I'd prefer citations to opinions :-)
>>>>
>>>>
>>>
>>>
>>>
>>
>
>
>
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