3G/UMTS Inter-frequency, Intra-frquency and Inter-RAT handover events

Intra-frequency Handover Events:

Event 1a: A Primary CPICH enters the Reporting Range (FDD only).
Event 1b: A Primary CPICH leaves the Reporting Range (FDD only).
Event 1c: A Non-active Primary CPICH becomes better than an active Primary CPICH (FDD only).
Event 1d: Change of best cell (FDD only).
Event 1e: A Primary CPICH becomes better than an absolute threshold (FDD only).
Event 1f: A Primary CPICH becomes worse than an absolute threshold (FDD only).
Event 1g: Change of best cell in TDD.
Event 1h: Timeslot ISCP below a certain threshold (TDD only).
Event 1i: Timeslot ISCP above a certain threshold (TDD only).
Event 1j: A Non-active E-DCH but active DCH Primary CPICH becomes better than an active E-DCH Primary CPICH (FDD only).

When an Event 1C is received, Handover procedure will be started in the NodeB.

Inter-frequency Handover Events:

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.
Event 2c: The estimated quality of a non-used frequency is above a certain threshold.
Event 2d: The estimated quality of the currently used frequency is below a certain threshold.
Event 2e: The estimated quality of a non-used frequency is below a certain threshold.
Event 2f: The estimated quality of the currently used frequency is above a certain threshold.

Event 2B will trigger the inter-frequency handover procedure in the Node B. Event 2D will start the compressed mode scanning and Event 2F will stop the compressed mode.

Inter-RAT Handover Events:

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.
Event 3b: The estimated quality of other system is below a certain threshold.
Event 3c: The estimated quality of other system is above a certain threshold.
Event 3d: Change of best cell in other system.

Event 3A will trigger the inter-frequency handover procedure in the Node B
 

UMTS: Traffic Volume Measurement (HSDPA, HSUPA)

Traffic Volume Measurement is used for purpose of Rate reallocation at UE. The monitored traffic volume corresponds to the amount of data in number of bytes that is available for transmission and re-transmission in RLC layer- Buffer Occupancy.
When an UE supporting Release 5 and below release is used then rate adaptation can be achieved. As the buffer occupancy goes lower than the threshold, Timer will be started. If the buffer occupancy goes above the threshold then it will stopped. If the timer expires then data rate will be adapted to lower rate for the UE.
Event 4a: Transport Channel Traffic Volume exceeds an absolute threshold.
Event 4b: Transport Channel Traffic Volume becomes smaller than an absolute threshold.

Traffic volume measurements may be configured by RRC to assist with dynamic radio bearer control. In general, RLC buffer payload, Average of RLC buffer payload or Variance of RLC buffer payload will be configured to report.

Traffic volume measurement reports can be triggered periodically and event triggered based on the reporting criteria specified in the measurement control message.

Traffic volume measurement information will be communicated in SIB11 and during the radio bearer setup stage.

Live wireshark/pcap collection and log rotation/round robin

Most of the live system requires PCAP/Wireshark log collection on the network interfaces. But logs needs to be rotated to avoid disk space consumption. Using simple script and tcpdump command, it is very easy to achieve this goal. tcpdump has an option to set the rotation of log files by specifying the number of log files and size of each log file. tcpdump command can be run in the background using these options. Writing a script to perform this task in the background is the best option.

Below is the Syntax:

tcpdump -nni <network interface> <filter if any> -s0 -w - | ( tcpdump -nn -r - -W <Number of files> -C <Size of each file> -w <Log file name> > <Logfile.output> 2> <Log.error> )


Below is the Example for keeping last 50 pcap files for eth0 interface, each file of size 20MB:
tcpdump -nni eth0 not arp and not port 22 -s0 -w - | ( tcpdump -nn -r - -W 50 -C 20  -w WS_ETH0.pcap > log.output 2> log.error )