How Handover Filtering by UE in LTE ?
If the IE “Filter coefficient” is received the UE applies filtering of the measurements for that measurement quantity according to the formula below.
This filtering is performed by the UE before UE event evaluation. The UE filters also the measurements reported in the IE “Measured results”.
The filtering is performed according to the following formula:
Fn = (1 − a) * Fn-1 + a * F −Mn
The variables in the formula are defined as follows:
Fn is the updated filtered measurement result step n.
Fn−1 is the old filtered measurement result step n – 1.
Mn is the latest received measurement result from physical layer measurements.
The unit used for Mn is the same unit as the reported unit in the MEASUREMENT REPORT message or the unit used in the event evaluation.
In order to initialize the averaging filter, Mn is set to M~0 when the first measurement
result from the physical layer measurement is received.
The measurement period is 200 ms.