WCDMA Handover

Handover: call transfer one cell to another cell without disconnecting

There are three types of handover used in WCDMA.

1.    Intra frequency Handover (Soft & Softer )

2.    Inter frequency handover

3.    IRAT Handover

Soft Handover:

            WhenHandover between two NodeB within same carrier frequency and add in active set.

Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN. Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time.

Softer Handover:

                        When Handover between two cells within same NodeB and ADD in active set.

IRAT Handover:

                        When handover between WCDMA to GSM and GSM to WCDMA.

What are the three sets in handover?

The 3 sets in handover are:

§ Active set – the list of cells which are in soft handover with UE.

§ Monitored set – the list of cells not in active set but RNC has told UE to monitor.

§ Detected set – list of cells detected by the UE but not configured in the neighbor list.

 

4 events associated with soft (or softer) handover: UE view

•           1A  Add

•           1B  Remove

•           1C  Replace

•           1D  Change of best cell

•          1E   A Primary CPICH becomes better than an absolute threshold

•          1F   A Primary CPICH becomes worse than an absolute threshold Intrafrequency reporting events for TDD