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How Measurement Report Triggering in LTE UE

Depending on the type of measurement, the UE can measure and report any of the following:

  • serving cell;
  • list of cells (e.g., cells shown as part of the object of measurement);
  • cells are found at the frequency set (ie cells are the cells that are not listed, but found UE).

For some rats, the UE measures and reports submitted by the cells (eg, white list list), while the other RAT UE report also found the cell. In addition, E-UTRAN can configure the PCI ranges in which the UE can send a measurement report (especially for teaching support UTRAN cell broadcast CSG identity).
For LTE, the following criteria specified reporting and events:

  • The event A1. Serving cell becomes better than an absolute threshold.
  • Event A2. The serving cell becomes less than the absolute.
  • A3 event. The neighboring cell is greater than the difference in comparison to the serving cell.
  • Event A4. Neighbor cell becomes better than an absolute threshold.
  • Event A5. Serving cell becomes worse than an absolute threshold and the neighboring cells is better than another absolute threshold.

For inter-RAT mobility are the following criteria for reporting and events:

  • The event B1. Neighbor cell becomes better than an absolute threshold.
  •  B2 event. Serving cell becomes worse than an absolute threshold and the neighboring cells is better than another absolute threshold.

UE raises an event when one or more cells to meet the “conditions of entry” is specified. E-UTRAN may affect the input condition setting configurable parameters used in these circumstances – for example, one or more thresholds, the displacement and / or hysteresis. Input condition must be met for at least the period corresponding “response time” setting is configured E-UTRAN for the event to be enabled.

The UE scales the time To Trigger parameter depending on its speed .Figure illustrates the A3 triggering event for the start time and the offset configured.

Event triggered report condition

UE can be configured to provide a series of periodic reports after a trigger event. This is the “regular reporting event” is configured using parameters compared Amount “and” Report Interval “, which define respectively the number of periodic reports and the time between them. If an event is set for periodic reporting, Earl UE number of messages sent is reset every time a new cell corresponds to the initial state. same cell can not serve as a pretext for a new set of periodic reports, if it does not respond at first, “leaving specified state” .

In addition to event-triggered reporting, the UE can be configured for periodic measurement reports. In this case, the same parameters can be set as an event triggered reporting, except that the reporting UE starts immediately and not only when an event occurs.

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