Main purpose of Service Areas in 3G

[drJaser]

copy/paste from one of the 3g books:
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Service Area (SA)
The SA identifies an area of one or more cells of the same LA (Location Area). And is used to indicate the location of a UE (User Equipment) to the CN (Core Network).The combination of SAC (Service Area Code), PLMN -Id (Public Land Mobile Network Identifier) and LAC (LocationArea Code) is the Service Area Identifier.
SAI = PLMN-Id + LAC + SAC
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I would like to clarify what is direct/main purpose of CN to know where the UE is located?
Is it only for government to track your way? :)
or is it mainly for location based services ? (like example: .. you are traveling via highway, suddenly you get (free) sms message "Hi, you are approaching Las Vegas city .. please find SuperDuper hotel on your right side, check-in in next 30 minutes and you get 30% discount and lunch for free.." )

any other idea?


BR,
drJ.

[riyantoyadi]

i think not just related to this, but to make always connected n paging your UE coz in 3G UE need always to be page in that's way 3G UE more consume battery then other, any related with government issue depend on your political region :p

[RFDude_PMA]

Umm

The CN Page PS to a RA or a URA or LA if the connection is CS. the 3Gpp introduce this concept for LBS.
This SAI is sent in a RANAP Initial Direct transf mess when a Location Update Request is triger by a x-Area change.

You are right drJaser... Depending on the type of phone you have LBS can be precise with LAT/LON or base in distance and SA data.