To meet customers' requirements for high quality networks, LTE trial networks must be optimized during and after project implementation. Radio frequency (RF) optimization is necessary in the entire...
Check for hardware availability by comparing: RTCH_nb (TCRRN) with RTCH_available_avg (TCAVAN) (TCAVAN)
Any TRXs down or not carrying traffic?
Report to BSS support team
Yes
NO
Check through thematic map TCH load BH on cell neighbors. HO Inc congestion on neighbors.
NO
All neighbors neighbors are loaded (> 80%) + High Inc HO con con esti estion on
Yes
NO
Any neighbor site(s) down not carrying traffic?
Check with RNP if planned coverage overlap with neighbors is sufficient for smooth HO flow.
NO
Yes
Yes
Check better condition parameters for each couple. Check High HO Inc execution failure on neighbors, if yes follow same investigation in call drop HO sheet. Check through drive test (RMS) coverage for serving loaded cell vs. neighbor free cell. Antenna optimization needed? Hardware check needed?
Traffic sharing Enable FDR on serving cell Enable Traffic HO for each couple and adjust relevant parameters according to drive test analysis. (or leave default values according to # of TRX) Enable Fast traffic HO, but monitor HO/call rate and call drop HO specially for cells with many inter BSC adjacencies
Request for upgrades, Calculate # of combiners needed and check with RNP if there will be no coverage problem if additional combiner is used Request for Densification sites RNP
Densification sites needed
SDCCH drop rate Problem detection: High SDCCH drop rate > 0.5 % Investigation:
BSS drop > 40% of total drops
Radio drops > 40% of total drops
NO
Check for Extreme queueing Situation i.e.: RTCH_assign_queued_rate >50%? T11 is set to values higher than default ( > 6 seconds) ? High SD duration average (> 5 s)
Check TRX carrying SD TS for alarms
Check TCU handling TRX with SD TS for alarms
High TCH call drop HO
Yes
Reset TCU Extreme queueing ?
Check if TRX carrying SD is problematic , if Yes move SD TS to another good TRX
Check value of cell_reselect_hyst, see if it was set previously to high values (> 6db) (to reduce # of LU, but can increase SD Drop)
LU procedure leads to higher duration on SD (4s). Apply # LU reduction procedure in SDCCH Congestion sheet
Yes
Yes
Yes
HO drops > 40% of total drops
NO
NO
NO
High TCH drop radio
NO
Yes
Reduce queuing Solve TCH blocking prob. (refer to TCH congestion solving sheet) Reduce T11 value (TCH congestion should be monitored)
Yes Call drop radio investigation should be followed
Same investigation should be followed
Enable SD HO Reduce averaging window Reduce HO margin (optional)
Disable SDCCH HO, but with careful monitor of SD drop radio
Move SDCCH TS to another TRX preferably handled by different TCU
Recalculate SD/TCH time slots needed using traffic model to reach optimum situation.
Check the value of BTS_Q_LENGTH: for values > default 2 TRX 4 TRX 6 TRX 4 6 10 Check % RTCH requests queued: high percentage (> 40%) can lead to SDCCH resources blocking for T11 period of time.
High % LU (> 50%) Action: Check HO flow to study if cell needs to be downtilted to reduce overlap with neighbors in different LAC Increase cell_reslect_hyst on LAC border cells to reduce # of LU (monitor of SDCCH drop radio is necessary)
Check with architecture the possibility to re-design LAC plan to minimize as much as possible LU
Check value of T3101 and see if it is set to default value
High % other services: a) IMSI attach b) IMSI detach c) SMS d) Supplementary services Action: 1-Increase SD capacity if possible: Consider TCU load Consider TCH blocking 2- Make sure all neighbor relations are defined handover and reselection 3- Use the parameter cell_reselect_offset to increase neighbor’s re-selection. 4- Densification site – Request for RNP study.
Call drop radio Problem detection: 1. High call drop rate on the cell > 1 %. 2. % Radio drops > 40% of total dropped calls on the cell. Investigation:
No
Isolated cell
Yes
NO
Densification sites are needed
Yes
Hardware Problem
Check HO causes
No
Check adjacencies for missing relations
Report to BSS team
Yes
High % UL level
Check if No HO if possible due to
1. congestion on neighbors 2. High rate of outgoing HO failures (follow HO drop investigation)
Yes
HO per call rate (>10%)
High % DL level
NO
NO NO High % DL quality Check Frequency plan Check drive test for overshooting problem
High %UL interference & quality Check for antenna, feeder or connections prob. Check external interferer (idle interference) UL level threshold
HO per call rate = number of “outgoing Handovers success / TCH seizures”
Yes
*Check for coverage problems (holes) *Check missing neighbors
Check for unbalanced path loss (RMS)
Call drop HO Problem detection: 1. High call drop rate on the cell > 1 %. 2. % HO drops > 30% of total dropped calls on the cell. Investigation:
No
High HO out execution failure rate? >40 %
Yes
Identify critical pair of cells, (with Out HO drop > 5 %) using Type 26 (on demand counter)
NO
Good % of better condition (>40%)
*Check better conditions parameters. *Check for severe interference on serving cell * Check for coverage continuity
NO
Yes Check DL Qual / UL Qual on target cell to locate interference problem. Check DL Lev /UL Lev on target cell for coverage problem
High % ROC?
Yes
NO
Check DL Qual / UL Qual on both serving & target cell to locate interference problem. Check DL Lev /UL Lev on both serving & target cell for coverage problem
Majority of failure is Inter BSC?
Yes
Check for BCCH/BSIC duplication in cell adjacencies
Check for database inconsistency between OMC-R and BSC
Check for BCCH/BSIC duplication in cell adjacencies For neighbors in different OMC-R , check if relation is defined correctly (external cells) Check for synchronization problems
Check neighbor plan for unnecessary (Far) neighbor declarations.
