GSM - Paging Success Rate (PSR) Analysis

Paging success rate can be degraded due to increase in MOC/MTC attempts, low TCH availability of source and neighboring cells, high LAC/BSC utilization. Following steps should be taken to analyze the root cause:

• Check for MOC/MTC trend - increase may cause high PPS (Paging Per Second) causing paging discards, indicating paging capacity limitation. LAC splitting could be done to resolve the issue
• Examine TCH Availbility of sites in the affected BSC
• Inspect cell level paging stats from the core network to zero in on the problematic LACs
• Parameter discrepancy between BSC and MSC can cause degradation - check parameters such as Location Update Timer, paging retransmissions by MSC, paging times etc.
• Interference, low coverage due to large distance or dense areas, path balance issues contribute to PSR degradation

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. 

UMTS CE Consumption - Uplink and Downlink

Uplink CE consumption is more than that of downlink. The reason is that CEs are not utilized  by HSDPA being a shared channel. HSUPA and R99, on the other hand, consume dedicated CS resources for their respective sessions.