There are two uses of measurement configuration and reporting , first while making "handover decision" and second one for "Automatic Neighbor Relationship" (ANR) . So many events like A1, A2, A3, A4, A5, A6, B1 and B2 are defined.
A1 : This event is triggered to indicate eNodeB that UE detects serving cell strength better than the configured threshold. In other words, UE is moving towards cell centre.
A2: This event is triggered to indicate eNodeB that UE detects serving cell strength worst than the configured threshold. In other words, UE is going far way from cell centre.
A3: Neighbor becomes offset better than primary cell.
A4: Neighbor becomes better than threshold.
A5: This event is triggered to indicate eNodeB that source cell is worse than threshold1 and neighbor cell is better than threshold2.
A6: Neighbor becomes offset better than Scell.
B1: Inter RAT neighbor becomes better than threshold.
B2: PCell becomes worse than threshold1 and inter RAT neighbor becomes better than threshold2
There are various types of measurement configuration that can be requested by UE as following:
3. Inter-RAT measurements of UTRA frequencies
4. Inter-RAT measurements of GERAN frequencies
5. Inter-RAT measurement of CDMA2000 frequencies
Following terms are used under measurement configuration:
1. Measurement Objects
2. Reporting Configurations
3. Measurement Identities : A list of measurement identity, each measurement identity is associated with one measurement object and one report configuration.
4. Quantity configuration: It is configured per RAT type and it is used to evaluate events
5. Measurement gaps: It tells when UE will perform measurement and no UL/DL transmission will be performed.