The document summarizes different 3G events that can trigger handover procedures in UMTS networks. It describes 7 categories of events related to primary pilot channel, frequency, quality, channel traffic volume, CRCs, Rx-Tx parameters, and location/position. Each category contains multiple specific events that are monitored and can trigger handovers based on thresholds being passed for radio frequency parameters. The events monitor factors like signal quality, interference levels, traffic loads, transmission power, and device location to determine when a UE should hand over to a better serving cell.

1. 3G Based Events
BY: M ISMAIL RAZA

2. Event Range Count Relation
1 A-I Primary Pilot Channel
2 A-F Frequency
3 A-D Quality
4 A-B Channel Traffic Volume
5 A-A CRCs
6 A-G Rx-Tx
7 A-C Location / Position
RRC Reporting events or Handover events are sent from RBS or UE to trigger the different
handover procedures in the RNC.
The generation of handover events depend on the different RF parameters and thresholds.

3. Event 1A
• A Primary CPICH (Primary Pilot Channel) enters the reporting range; addition of a
radio link.
Event 1B
• A primary CPICH (Primary Pilot Channel) leaves the reporting range; removal of
a radio link.
Event 1C
• A non-active primary CPICH (Primary Pilot Channel) becomes better than an active
primary CPICH; replacement of the worst cell in AS.
Event 1D
• Change of best cell
Primary Pilot Channel

4. Event 1E
• A Primary CPICH (Primary Pilot Channel) becomes better than an absolute
threshold.
Event 1F
• A primary CPICH (Primary Pilot Channel) becomes worse than an absolute
threshold
Event 1G
• Change of best cell (TDD)
Event 1H
• Timeslot ISCP below a certain threshold (TDD)
Event 1I
• Timeslot ISCP above a certain threshold (TDD)
Primary Pilot Channel

5. Event 2A
• Change of best frequency
Event 2B
• The estimated quality of the currently used frequency is below a certain threshold
and the estimated quality of a non-used frequency is above a certain threshold;
handover to inter-frequency neighbors
Event 2C
Event 2D
• The estimated quality of the currently used frequency is below a certain threshold;
start compressed mode to measure inter-frequency WCDMA or GSM neighbors.
Event 2E
• The estimated quality of a non-used frequency is below a certain threshold.
• The estimated quality of a non-used frequency is above a certain threshold
Event 2F
• The estimated quality of the currently used frequency is above a certain threshold;
stop compressed mode & stop measure inter-frequency WCDMA or GSM
neighbors
Frequency

6. Event 3A
• The estimated quality of the currently used UTRAN frequency is below a certain
threshold and the estimated quality of the other system is above a certain threshold;
handover to GSM neighbors
Event 3B
• The estimated quality of other system is below a certain threshold
Event 3C
Event 3D
• Change of best cell in other system
• The estimated quality of other system is above a certain threshold
Quality

7. Event 4A
• Transport Channel Traffic Volume becomes larger than an absolute threshold
Event 4B
• Transport Channel Traffic Volume becomes smaller than an absolute threshold
Channel Traffic Volume

8. Event 5A
• A predefined number of bad CRCs is exceeded
CRCs

9. Event 6A
• The UE Tx power becomes larger than an absolute threshold; start compressed
mode
Event 6B
• The UE Tx power becomes less than an absolute threshold; stop compressed mode
Event 6C
Event 6D
• The UE Tx power reaches its maximum value
Event 6E
• The UE RSSI reaches the UE's dynamic receiver range
• The UE Tx power reaches its minimum value
Event 6F
• The UE Rx-Tx time difference for a RL included in the active set becomes larger
than an absolute threshold
Event 6G
• The UE Rx-Tx time difference for a RL included in the active set becomes less
than an absolute threshold
Rx-Tx

10. Event 7A
• The UE position changes more than an absolute threshold
Event 7B
• SFN-SFN measurement changes more than an absolute threshold
Event 7C
• GPS time and SFN time have drifted apart more than an absolute threshold
Location / Position

11. References
• http://www.telecomsource.net/showthread.php?1441-
What-are-the-events-1a-1b-1c-etc

12. THE END 