1. Issues with LCI Date: 2010-05-09 Authors: January, 2010 November 2005
doc.: IEEE /0499r1
January, 2010
Issues with LCI
Date:
Authors:
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Gabor Bajko

2. Original use cases Describe the location of an AP
November 2005
doc.: IEEE /0499r1
May, 2010
Original use cases
Describe the location of an AP
Usually fixed or portable, but may be mobile as well
Describe the location of a STA
Mobile
Definition of mobile: operates while in motion (changes location)
Gabor Bajko

3. Location Encoding … is always preceded by location determination
January, 2010
Location Encoding
… is always preceded by location determination
Location determination is the process when the location of an entity is measured and approximated
It is not a deterministic procedure
Results in an area where the subject is probably located (with a confidence level=95%)
The resulted location is then encoded
LCI aims to encode the probable location of an entity
Gabor Bajko

4. LCI LCI has been copy-pasted from RFC3825 and azimuth appended to it
November 2005
doc.: IEEE /0499r1
January, 2010
LCI
LCI has been copy-pasted from RFC3825 and azimuth appended to it
RFC3825 uses a 9+25 bit fixed point number for WGS84 coordinates
It can only be used to describe circles/ellipses with specific radiuses (34 values for Radius is allowed – k*2x with x=0 … 34)
It can not be used to specify custom location boundaries: eg, it can not specify a location having latitude values [ to ], a full or partial arcband, a polygon, etc.
See and related discussion for further details
Gabor Bajko

5. When does location determination result in an irregular shape?
January, 2010
When does location determination result in an irregular shape?
Yellow: coverage of APs
Blue: probable location of the STA
Green: smallest circle containing the blue area
Purple: contour of the circle which can be encoded with LCI
Result: STA location is anywhere within the external contour of the purple circle; much bigger area than the blue one
Gabor Bajko

6. January, 2010
Proposal
Define a new Location Measurement Request and Report (in addition to LCI) which uses:
the encoding defined in RFC3825bis (binary)
RFC3825bis can be used to describe a rectangle, or
The encoding defined in RFC5194 (XML)
RFC5194 encoding can be used to describe multiple type of shapes
An irregular shape can always be approximated with a polygon
It may not fit into an MPDU, fragmentation may be necessary
Can use the fragmentation defined in u for GAS Responses
to describe the geodetic location of a STA
Gabor Bajko

7. November 2005
doc.: IEEE /0499r1
January, 2010
RFC3825bis
It was agreed in IETF to make an update of RFC3825, for a limited applicability: the update will provide a means to describe a location in a form of a rectangle, by mostly reusing the fields defined in RFC3825
point
Uncertainty X
Uncertainty Y
Gabor Bajko

8. Location encoding with RFC3825bis
November 2005
doc.: IEEE /0499r1
January, 2010
Location encoding with RFC3825bis