3G Intra-Frequency Measurement

UTRAN uses the measurement control message to inform the UE what events need to trigger measurement reporting. All intra-frequency measurement report events are identified with 1X. 

Event 1A: A primary pilot channel enters the reporting range

If the network, in the measurement report mechanism field, requires the UE to report event 1A while the UE has entered the Cell_DCH state, then when a primary pilot channel enters the reporting range, the UE will send a measurement report.

In order to reduce the signaling traffic flow of the measurement report, the TIME-TO-TRIGGER parameter is used so that the UE will not trigger measurement reporting before the primary pilot enters the reporting range and is maintained for a certain period of time. This parameter is also used in other events. An example of measurement reporting triggered by event 1A is given below:

Figure 1     Example of Event 1A and Trigger Delay

Generally, if event 1A is triggered, the UE will send a measurement report to UTRAN, and UTRAN will deliver an ACTIVE SET UPDATE signaling message to update the active set. However, UTRAN may give no response after the UE sends the measurement report (for example, due to insufficient capacity). In this case, the UE will shift from event reporting to periodic reporting mechanism, and the content of the measurement report includes the information of the cells in the active set and the cells in the monitored set that has entered the reporting range. The UE will not stop sending periodically the measurement report until this cell is successfully added into the active set or leaves the reporting range, as shown below:

Figure 2     Periodic Reporting Triggered by Event 1A 

Event 1B:  A primary pilot channel leaves the reporting range

If several cells satisfy the reporting condition simultaneously after the trigger delay, the UE will sort the cells according to the measurement values and report all the measurement results.

Event 1C: The primary pilot channel in a non active set is better than the primary pilot channel in an active set

This event can be described through the following example:

Figure 3     Example of Event 1C

In this example, the cells where P CPICH 1, P CPICH 2 and P CPICH 3 are belong to an active set, while that of P CPICH 4 does not. This event is used to replace the poor cells in the active set, if the number of cells in the active set reaches or exceeds active set replacement threshold.

Event 1D: The best cell changes

Figure 4     Example of Event 1D

In order to prevent frequent triggering of event 1D due to signal fluctuations when the channel difference is small, which results in unnecessary increase of the air interface signaling traffic flow, we can use the hysteresis parameter, as shown below:

Figure 5     Restriction of measurement reporting by means of hysteresis

As we can see, as the hysteresis condition is not met at the second time, event 1D reporting is not triggered. This parameter can also be used in other events.

Event 1E: The measurement value of a primary pilot channel exceeds the absolute threshold

Figure 6     Example of Event 1E

Event 1E can be used to trigger the measurement reports of cells including those detected by the UE before it receives the adjacent cell list.

Event 1F: The measurement value of a primary pilot channel is lower than the absolute threshold

Figure 7     Example of Event 1D1F

PLUR
Putri Touor,,si Smith Delvis