Sunday, November 15, 2009

why Routing Area is a subset of Location Area in UMTS.

Both LA and RA are collection of cells.

RA and LA are identified by the below variables:

LAI = MCC+ MNC + LAC ==> LAC is configured by operator
Location Area Identifier = ( Mobile Country Code + Mobile Network Code + Location Area Code)
RAI = LAI + RAC ==> RAC is configured by operator
Routing Area Identifier = Location Area Identifier + Router Area Code

The reason for either LA or RA logical boundary is to ensure MS does updates only occasionally and not at every cell boundary.
In GPRS session, there is no “permanent connections” but bearers are dynamically created and destroyed.
In voice call, when there is silence in communication after call connect, the connection still exists, but in data, when you are browsing, a silence in data transfer will lead to idle mode, which means you will have to be paged.
So potentially there are more pages compared to voice calls.
Paging is also resource, the finer the granularity of knowledge to the network better. So having smaller RA may be beneficial by paging in less no. of cells compared to LA which will be larger no. of cells.
But anyway, there can be only one RA in a LA and nobody stops it

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