Tuesday, November 10, 2009

Handovers in UMTS

There are 3 types of Handovers in UMTS
1) Soft Handover
2) Hard Handover
3) Softer Handover

Both Soft and Softer handover follows, make before Break uproach. So, data transfer will be seam less to the UE. But for Handover it follows Break before Make approach. So here call will be dropped.

Soft Handover:
UE maintains Utran connectionw ith one/more nodeBs and all these BSs are using same frequency.
Both base stations will be in UE active set.
These are managed by Active_set_Update message sent by N/w
UE will update its active set with the contents of this message.
Here all participating NodeBs belongs to same RNC, so signal will be combined at RNC and send to MSC

Hard Handover:
This is break before Make approach
in general during handovers between UMTS to GSM/GPRS
This triggers all procedures: Physical channel reconfig, radio bearer est, RB Recof, RB Releae and Transport channel reconfiguration.

Softer Handover:
This HO occurs between sectors under same NodeB then the combining the data happens at NodeB. This intern saves IuB and RNC work load.
The combining technologies are different than RNC.

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