UMTS - Types of congestion

UMTS cells can have below congestion types:

1. CE (Channel Elements) Congestion:  This happens when resources on the hardware are fully utilized. One solution is to add extra cards/boards in the Node B to increase capacity. For example, ZTE has BPK1 and BPKd cards that comprises of 384 and 768 CE respectively. CE congestion is always monitored by observing UL CE (since UL CE consumption is always greater than that in the DL)
2. Code Congestion:  High number of users could result in code congestion. Parameters such as minHSDPA users can be decreased to make room for cell DCH users. Carrier expansion can be done to accommodate larger  number of users.
3. TCP Congestion:  This represents that Total Carrier Power limit has been reached. Addition of Power Amplifier, new nodes/sites, decreasing CPICH power, or increasing cell transmission power are some of the remedial steps for rectification. 
4. Iub Congestion:  Congestion results due to fully utilized transmission media which can be increased to resolve the issue. 

BS PA MFRMS - PSR Alcatel-Lucent

Improvement in PSR (Paging Success Rate) can be achieved by tuning of BS_PA_MFRMS and reducing Paging discards. Paging discards are mostly due to congestion in the BSC, on the Abis link and/or on the PCH (Paging Channel) ie Air interface.

Parameter:

• BS_PA_MFRMS

Target Cells: Cells with higher number of paging discards

Theory: 

• This parameter defines the the number of 51 multiframes between two consecutive occurrences of Paging group (a number of pagings)
• Higher value means less number of pagings will be transmitted in a given interval thereby conserving lesser power of the MS
• Reducing this parameter increases number of pagings per paging group (for a given value of MSC paging timer T3113) and therefore probability of no paging response decreases

High SDCCH Blocking Statistical Analysis

SDCCH Blocking is a critical KPI that depicts the quality of optimization in a network as this KPI is mostlty controlled via soft optimization. The considerations for maintaining this KPI are as follows:

1. SDCCH/TCH Availability %
1. Many times, the SDCCH traffic is enough to be carried in defined channels, but still the blocking is high. This could be mostly due to momentary surge in traffic or site fluctutation causing blocks for a small portion of an hour, thereby averaging the traffic/availability in the hour.
2. SDCCH Drops
1. TA Analysis
2. Interference (Co/Adjacent)
3. TCH Congestion
4. Equipment Failure
5. Low output power
3. SDCCH Channels/Traffic/Blocking (Erlang Table)
1. SDCCH Addition (Static/Dynamic)
2. SDCCH/TCH Conversion Timer
3. Maximum SDCCH Channels Threshold
4. Penalty Timer (Set PT = 31 of cell)
5. Increase CRH (Cell Reselect Hysteresis) if cell is on LAC Boundary
6. Directed Retry (Forced)