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7/15/2019 GSM Handbook Optimize
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GSM OPTIMISATION
HANDBOOK
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1. Introduction....................................................................................................32. Support Arrangement ....................................................................................43. Optimisation Team Structure .........................................................................54. Bad Perfromance FisH Bone diagram ...........................................................6
5. Information Preparation .................................................................................76. General Optimisation Proceedure..................................................................87. Alarm Analysis...............................................................................................98. Statistics Investigation Procedure................................................................109. Drive Test ....................................................................................................12
9.1. Drive Test Reminder ................................................................................129.2. Drive Test Log Investigation Consideration..............................................12
10. Frequeny Planning.......................................................................................1310.1. BCCH and BSIC planning criteria.........................................................1310.2. Frequency Assignment Criteria ............................................................1310.3. Frequency Retune Procedure...............................................................14
11. Add Neighbor Criteria ..................................................................................1412. High Rise Building Coverage.......................................................................1513. Maximum System Configuration..................................................................1514. HDPC Setting Template ..............................................................................17
14.1. TX Power and Power Control ...............................................................1714.2. Handover ..............................................................................................2014.3. Multiband..............................................................................................2214.4. Miscellaneous.......................................................................................22
15. Tools Available .............................................................................................2416. Problem Root Cause ...................................................................................25
16.1. High SDCCH Blocking..........................................................................2516.2. High TCH Blocking ...............................................................................2616.3. SDCCH Access Failure Rate................................................................2716.4. Handover Failure & Loss ......................................................................2816.5. MSC Connection Rate .........................................................................2916.5. SDCCH and TCH RF Loss ...................................................................3016.6. Power Control.......................................................................................3116.7. Handover Problem................................................................................3116.8. Others...................................................................................................32
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1. INTRODUCTION
Teamwork, “listen to order”, cycle time reduction and follow procedure are criticalto every successful optimisation.
Below is the optimisation flow chart:
No
Yes
Data Analysis
Data Preparation
Com lete
Optimisation
Data Collection
Satisfactory
Result?
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2. SUPPORT ARRANGEMENT
PEG ArrangementOptimisation Flow
Monthly performancemeeting to identifyoptimisation targets.
Account Team suppliesrequired information
PEG preparesINFORMATION FOR
OPTIMISTION
PEG audits network in
Beijing
PEG arrives localoffice to discuss the
optimisation plan with Account Team and
Customer
Start optimisation
PEG derivesoptimisation plan
Start optimisation and skilltransfer and acquisition
OMC Engineer arrives localoffice to setup datacollection platform
Contractor preparesoptimisation informationin Beijing
Engineers perform brief
audit in Beijing tounderstand REAL situation
PEG discuss with account
teams to identifyoptimisation targets.
All engineers return toBeijing to derive plan
Best engineeringarrangement arrives at localoffice
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3. OPTIMISATION TEAM STRUCTURE
Job FunctionBSS Controller - Understand fully on BTS maintenance, BSS configuration
Alarm Monitoring,- Monitor daily alarm
Statistics Monitoring- Investigate problem from statistics
D.B. & Feature Controller
- Check database and monitor feature deployment process
Drive Test Log Investigator - Investigate problem from drive test log
D.B. & FeatureController
Drive Test LogInvestigator
AlarmMonitoring
StatisticsMonitoring
BSSController
MONITORING ACTION
Team Leader
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4. BAD PERFROMANCE FISH BONE DIAGRAM
FrequencyPlan
NetworkTopology
Signaling Mobile
Bad Performance
DatabaseSetting Coverage
Software HardwareCapacity
ExternalInterferenceNeighbor Calculation
Statistics Peggingand Retrieval
CableConnection
Documentation
Example of each major problems:a. Database Setting – improper HOPC settingsb. Neighbor – wrong external neighbor’s BCCH or BSIC values, missing
neighbor c. Coverage – weak, highly overlapped, improper antenna downtilt and
orientationd. External Interference – microwave, repeater, faulty alarme. Calculation – incorrect statistics equationsf. Cable Connection – no/cross connectiong. Statistics Pegging and Collection – SW problem on statistics pegging, or
retrievalh. Capacity – lack of TRCU, improper channel configuration, lack of RSL, MTL
linksi. Frequency Plan – co-channel, adj-channel, improper BSIC planning
j. Software – bugk. Hardware – wrong cable connection, faulty combiner and filter, PCM link
downl. Network Topology – bad site location selection, redundant site deployedm. Signaling – Improper cause value and message sequencen. Mobile – faulty mobile in term of signaling or frequency hopping capabilityo. Documentation – wrong feature/parameter usage description
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5. INFORMATION PREPARATION
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6. GENERAL OPTIMISATION PROCEEDURE
Data Collection & CheckLocal Office NetPlan
Information
1 day
Data Preparation &NetPlan Information
Correction
Network Audit from1. Alarm2. Statistics3. Database4. Check customer statistics equations
1. Suggest Better Database Setting (Channel Reconfiguration,Standard HOPC, Blocking Timer , Congestion Relief)
2. Capture External Interference3. Frequency Retune for high IOI, BER and TCH_RF_LOSS4. Audit External Neighbor 5. Improper ARFCN:BSIC Planning6. GPROC loading7. RSL & MTL Usage
Statistics & DB. mainly ona. SDCCH Access Failureb. CSFRc. Drop Calld. TCH_RF_Losse. HO_Lossf. HO_Failureby ARFCN retune, neighor change and coverage
Hardware
Capacity
Database,Interference& Capacity
NetworkTopology
FP, Neighobr andCoverage
2 days
2 days
12 days
2 days
2 days
2 days
Solve Blocking by:
a. BCCH Optimisationb. Neighor Optimisationc. Add Radiod. Site Reconfiguratione. Add Sitef. Antenna Refinement
Network Topology Problem
due to no available ARFCN isfound by:a. Site Replacementb. Coverage Optimisationc. Capacity Dimensioning
TEMS Log & FP. mainly ona. Undecoded BCCHb. Missing Neighbor c. HO Failured. Incorrect External Neighbor e. Weak Coveragef. High Overlappingg. use non-dominant server by ARFCN retune, neighor change and coverage
1. Hardware Fix (Sleeping Cell, OOS TCU, OOS TS2. Path Balance Issue, Faulty TCU from TCH_RF_Loss Issue)
3. GCLK shift and frequent Phase Lock Loop failure from Alarm
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7. ALARM ANALYSIS
Below lists some important alarms that we focus,
a. Critical and major alarmb. Alarms affect voice quality like MSI, KSW, RXCDR, DRIM, DRIc. GCLK affects HOd. Link alarms affect site availability and voice qualitye. XBL alarm affects acknowledgement of OOS CIC
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8. STATISTICS ANALYSIS PROCEDURE
Statistics Tree Diagram
BAD GOOD
Paging No Response SDCCH Access Failure Rate
MSC Assignment Attempt Rate(MA_REQ_FROM_MSC)
CONN Refused
SD RF Loss
Cipher Mode Fail
(TSMI, IMSI)
TCH Blocking
TCH Assignment Success
Call Setup Sucess Rate
TCH RF Loss Rate
Inter-BSS HO Loss
Intra-BSS HO Loss
Intra-cell HO Loss
HO Loss Rate
Drop Call Rate
Call Sucess Rate
MSC TCH Connection Rate
Firstly, we need to understand account teams and customer performanceequation.
Problem Identification from Statistics1. per carrier on HW, external interference, channel interference, coverage
a. PATH_BALANCE for faulty hardware (Every 3 days) b. IOI for external interference and bad channel assignment (Every Day) c. BER for external interference and bad channel assignment (Every Day)
d. TCH_RF_LOSS for faulty hardware and bad channel assignment (Every Day) e. CHAN_REQ_FAIL_ROLL for faulty hardware and BCCH and SDCCH coverage footprint
difference (Every Day) 2. per cell on usage
a. AVAILABLE_TCH and AVAILABLE_SDCCH (Every Day) b. BUSY_SDCCH_MAX, SDCCH Blocking for faulty hardware (Every Day) c. SDCCH_CONGESTION and BUSY_SDCCH_MEAN for phantom RACH (Weekly) d. BUSY_TCH_MAX, TCH Blocking for faulty hardware (Every Day) e. OK_ACC_PROC_SUC_RACH for sleeping cell (Every Day) f. No TOTAL_CALL, OUT_INTRA_BSS_ATMPT, OUT_INTER_BSS_ATMPT (Every Day) g. CONN_REFUSED { - IMSI_DETACH} for CIC blocking (Weekly) h. cell without any statistics for OOS cell (Every Day)
3. per cell on dual band mobile usage
a. MA_ACCESS_BY_TYPE (Weekly) b. MS_TCH_USAGE_BY_TYPE (Weekly) 4. per cell on Cipher Mode
a. CIPHER_MODE_FAIL (Weekly) 5. per cell on loading
a. BSS GPROC loading mean 70% (Weekly) b. MSC Processor Loading and Subscriber (Weekly) c. RSL TX, RX Utilisation mean 25% (Weekly) d. MTL TX, RX Utilisation mean 20% (Weekly) e. Pages per second (Weekly)
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f. ALLOC_SDCCH, ALLOC_SDCCH_FAIL ,OK_ACC_PROC relationship (Weekly) g. HO per call (Weekly)
6. per cell on paginga. PCH_PAGE_Q_DISCARD (Weekly)
7. per cell for BCCH and BSIC planninga. INV_EST_CAUSE_RACH and BAD_HO_REFNUM_MS (Weekly)
8. per cell inter-BSS HO monitor inga. OUT_INTER_BSS_MS_FAIL + OUT_INTER_BSS_MS_LOST = HP_MSC_REQ_FAIL
(not include blocking) (Weekly) b. OUT_INTER_BSS_MS_ATMPT = HO_MSC_REQ_FAIL + HO_MSC_REQ_OK (Weekly)
Below all are daily task:9. evaluate target
a. calculate system total call, total loss, ho loss, rf loss, drop call%b. calculate how many total loss reduction is required to achieve the goalc. do (b) again for other statistics
10. select worst cells and BSCsd. pick worst 20 cells and worst 5 BSCs
11. per cell on TCH Assignmenta. CONN_REQ_TO_MSC
b. MA_REQ_FROM_MSC, CONN_REFUSED { - IMSI_DETACH}, if CONN_REFUSED ishigh, MSC procedure is required.
c. MA_CMD_TO_MS_BLKD, MA_CMD_TO_MSd. MA_FAIL_FROM_MS, MA_COMPLETE_TO_MSC (same as TOTAL_CALL)
12. per cell on HO Causea. OUT_HO_CAUSE
13. per cell on HO Failurea. OUT_INTRA_BSS_HO_FAIL, OUT_INTER_BSS_HO_FAIL, IN_INTRA_BSS_HO_FAIL
and IN_INTER_BSS_MS_NO_SEIZE for ho failues14. per cell on TCH_RF_LOSS, SD_RF_LOSS, HO Loss
a. TCH_RF_LOSS, OUT_INTRA_BSS_HO_REQ, OUT_INTRA_BSS_HO_ATMPT,OUT_INTER_BSS_HO_REQ, OUT_INTER_BSS_HO_ATMPT
b. SD_RF_LOSS and HO_LOSS relationship on cell coverage
c. OUT_INTER_BSS_HO_LOSTMS, OUT_INTRA_BSS_HO_LOSTMS,OUT_INTRA_CELL_HO_LOSTMS
For hardware fix, it usually takes 3 days to fix, hence we suggest to review those statistics every3 days. For system loading and usage, we will visit them once in a week.Weekly and every 3 days statistics should be reviewed when that corrective action is done.
Special RequestFor growth planning per cell on blocked call setup, we can use ALLOC_TCH_FAIL –HO_FAIL_NO_RESUORCES_INTRA_BSS - HO_FAIL_NO_RESUORCES_INTER_BSS -HO_FAIL_NO_RESUORCES_INTRA_CELL to estimate expanded network total calls.
For coverage analysis and improve MSC connection rate, we can use per LAC
ACCESS_PER_RACH – PAGING_RESPONSE. Difference tells us how many no page reponses.
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9. DRIVE TEST
9.1. Drive Test Reminder
i. prepare cell definition fileii. 2mins per calliii. 10-15mins per log fileiv. force to appropriate band (GSM only, DCS only or Dual)v. mark benchmark route per log file in mapvi. mark on maps about (a) drop call (b) weak coverage (c) lot of rxquality (d)
bad coveragevii. fill in drive test problem sheet
9.2. Drive Test Log Investigation Consideration
General TEMS Log Investigation Concern1. check undecoded BCCH – this affects RF loss and creates log of ping pong
handover 2. decoded neighbor but no handover is attempted – due to missing neighbor or
incorrect external neighbor path3. focus on drop call and rxqual greater than 4 for non-hopping, 5 for hopping for
at least 4 seconds4. look for handover failure – investigation target cell assigned ARFCN/MA from
ASSIGNMENT COMMAND and HANDOVER COMMAND5. mark down weak coverage area, no dominant server, say less than –85dBm6. mark down highly overlapped area
Besides, be careful that when you see a decoded cell, that cell is not definitely aneighbor of serving, it can be due to serving cell having a neighbor which hassame BCCH as decoded cell.
Note: (a) Focus on new site database(b) Due to CCB, no SFH can be deployed(c) Dedicated ARFCN/MA is different from BCCH(d) After Assignment and Handover, the cell ID may not be updated yetdue to serious rxquality at DL.
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10. FREQUENY PLANNING
10.1. BCCH and BSIC planning criteria
a. Cells have same BCCH and BSIC that increases TEMS log review
troublesome.b. Nearby cells have same BCCH:BSIC with ARFCN:BSIC.c. Nearby cells have adjacent BCCH with ARFCN and same BSIC.
10.2. Frequency Assignment Criteria
Non-hopping Case
Hopping Case for non-BCCH
servingcell
servingcell
can’t be co- or ad -cahannel adjacent
channelco-
channel
adjacentchannel
co-channel
BCCH in hopping case is same as the non-hopping case.
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10.3. Frequency Retune Procedure
Frequencies can be grouped into 5 types, they are:-a. same site co- and adj-channel to BCCHb. adjacent site co- and adj-channel to BCCH
c. adjacent site co-channel to ARFCNd. same site co-channel to ARFCNe. same site adj-channel to ARFCNf. adjacent site adj-channel to ARFCNg. others ARFCN
Priority of ARFCN retune is from g. to e. for fix and BBH, from g. to d. for SFH. If no available ARFCN can be found, site planning need to be reviewed.Besides, 400k separation is required for CCB.58, 70 shouldn’t be used for BCCH.MCell generates UL interference on channel 50 and 56.
11. ADD NEIGHBOR CRITERIA
In general, LOS and 2nd Round Interferer will be added as neighbor; however, for 3rd Round, this is very network dependant. field knowledge is required to makethe decision.
servingcell
LOS interferer 3
r Round
Interferer 2
nRound
Interferer
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12. HIGH RISE BUILDING COVERAGE
Introduce high rise building coverage must make sure to have good streetcoverage.
High Rise Building – provide high level (likely above 8th floor) high rise buildingcoverage
盄 High Rise Building
Macro
Micro
Macro – provide low floors and street level coverageMicro – provide street level and indoor coverage
13. MAXIMUM SYSTEM CONFIGURATION
It is important to understand how system grows from phase to phase. It can bedescribed in 3 phases.
Phase 1: Only macro layer, antenna located at tower top with small downtilt. Antenna uses large vertical beam-width.
Phase 2: Start to introduce micro layer, and increase macro cell downtilt andlower macro cell height of macro antenna.
Phase 3: Introduce high rise building coverage to office building and hotel. Beforedeploying this kind of coverage, street level coverage MUST be strong enough
(likely more than –75dBm) to protect interference from high rise buildingcoverage.
For a mature network which its system rxlevel has reach average –75dBm, it istime for us to deploy SFH to expand system capacity.
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14. HDPC SETTING TEMPLATE
14.1. TX Power and Power Control
TX Power Parameter
CurrentSetting
SuggestSetting
Reason
max_tx_ms
max_tx_bts
Downlink Power Control due to Level
Parameter CurrentSetting
SuggestSetting
Reason
decision_alg_num
bts_power_control_allowed
bts_p_con_ack(TIMER)
bts_p_con_interval(TIMER)
pow_inc_step_size
pow_red_step_size
rxlev_dl_pc, hreqave
rxlev_dl_pc, hreqt
decision_1_dl_rxlev_av_p
l_rxlev_dl_p
u_rxlev_dl_p
decision_1_n1
decision_1_p1
decision_1_n2
decision_1_p2
Downlink Power Control due to Quality
Parameter CurrentSetting
SuggestSetting
Reason
decision_alg_num
bts_power_control_allowed
bts_p_con_ack(TIMER)
bts_p_con_interval(TIMER)
pow_inc_step_size
pow_red_step_size
rxqual_dl_pc, hreqave
rxqual_dl_pc, hreqt
rxqual_dl_pc,qual_weight
decision_1_dl_rxqual_ av_p
l_rxqual_dl_pu_rxqual_dl_p
decision_1_n3
decision_1_p3
decision_1_n4
decision_1_p4
w_qual
Uplink Power Control due to Level
Parameter CurrentSetting
SuggestSetting
Reason
decision_alg_num
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ms_power_control_allowed
ms_p_con_ack
ms_p_con_interval
pow_inc_step_size
pow_red_step_size
rxlev_ul_pc, hreqave
rxlev_ul_pc, hreqt
decision_1_ul_rxlev_av_p
l_rxlev_ul_p
u_rxlev_ul_p
decision_1_n1
decision_1_p1
decision_1_n2
decision_1_p2
Uplink Power Control due to Quality
Parameter CurrentSetting
SuggestSetting
Reason
decision_alg_num
ms_power_control_allowed
ms_p_con_ack
ms_p_con_intervalpow_inc_step_size
pow_red_step_size
rxqual_ul_pc, hreqave
rxqual_ul_pc, hreqt
rxqual_ul_pc,qual_weight
decision_1_ul_rxqual_ av_p
l_rxqual_ul_p
u_rxqual_ul_p
decision_1_n3
decision_1_p3
decision_1_n4
decision_1_p4
w_qual
Data and Hopping Quality Power Control
Parameter CurrentSetting
SuggestSetting
Reason
data_qual_flag
l_rxqual_dl_p_data
l_rxqual_ul_p_data
hop_qual_enabled
l_rxqual_dl_p_hopping
l_rxqual_ul_p_hopping
Standard MS HO Power, MS Ho Power Level based on Path Loss Calculations (GSR3)
Parameter CurrentSetting
SuggestSetting
Reason
handover_power_level
use_derived_ho_power 0 1 Reduce MS UL power and interference
Optimised Power Control (GSR4)
Parameter CurrentSetting
SuggestSetting
Reason
dyn_step_adj
dyn_step_adj_fmpr
pow_inc_step_size_dl
pow_inc_step_size_ul
pow_red_step_size_dl
pow_red_step_size_ul
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Oscillation Prevention for MS Power Control
Parameter CurrentSetting
SuggestSetting
Reason
mspwr_alg
Rapid MS Power Down
Parameter
Current
Setting
Suggest
Setting Reasonrpd_pwr_down
rpd_period (TIMER)
rpd_trigger
rpd_offset
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14.2. Handover Inter-cell Handover
Parameter CurrentSetting
SuggestSetting
Reason
inter_cell_handover_allowed
Intra-cell Handover
Parameter CurrentSetting
SuggestSetting
Reason
intra_cell_handover_allowed
ho_ack (TIMER)
hop_count
hop_count_ timer
Uplink Quality
Parameter CurrentSetting
SuggestSetting
Reason
ul_rxqual_ho_allowed
rxqual_ul_ho, hreqave
rxqual_ul_ho, hreqt
rxqual_ul_ho,qual_weight
rxqual_ul_ho,qual_pwr_flag
rxqual_ul_ho,qual_margin
rxqual_ul_ho,adj_qual_margin
decision_1_ul_rxqual_ av_h
l_rxqual_ul_h
u_rxqual_ul_h
decision_1_n6
decision_1_p6
w_qual
Uplink Interference
Parameter CurrentSetting
SuggestSetting
Reason
interfer_ho_allowed
rxlev_ul_ho, hreqave
rxlev_ul_ho, hreqt
rxlev_ul_ho,qual_margin
rxlev_ul_ho,adj_qual_margin
decision_1_ul_rxlev_ av_ih
u_rxlev_ul_ih
decision_1_n7
decision_1_p7
Downlink Quality
Parameter CurrentSetting
SuggestSetting
Reason
dl_rxqual_ho_allowed
rxqual_dl_ho, hreqave
rxqual_dl_ho, hreqt
rxqual_dl_ho,qual_weight
rxqual_dl_ho,qual_pwr_flag
rxqual_dl_ho,
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qual_margin
rxqual_dl_ho,adj_qual_margin
decision_1_dl_rxqual_ av_h
l_rxqual_dl_h
u_rxqual_dl_h
decision_1_n6
decision_1_p6
w_qual
Downlink Interference
Parameter CurrentSetting
SuggestSetting
Reason
interfer_ho_allowed
rxlev_dl_ho, hreqave
rxlev_dl_ho, hreqt
rxlev_dl_ho,qual_margin
rxlev_dl_ho,adj_qual_margin
decision_1_dl_rxlev_ av_ih
u_rxlev_dl_ih
decision_1_n7
decision_1_p7
Uplink Level
Parameter CurrentSetting
SuggestSetting
Reason
ul_rxlev_ho_allowed
rxlev_ul_ho, hreqave
rxlev_ul_ho, hreqt
decision_1_ul_rxlev_ av_h
l_rxlev_ul_h
u_rxlev_ul_h
deicion_1_n5decision_1_p5
Downlink Level
Parameter CurrentSetting
SuggestSetting
Reason
dl_rxlev_ho_allowed
rxlev_dl_ho, hreqave
rxlev_dl_ho, hreqt
decision_1_dl_rxlev_ av_h
l_rxlev_dl_h
u_rxlev_dl_h
decision_1_n5
decision_1_p5
Distance
Parameter CurrentSetting
SuggestSetting
Reason
ms_distance_allowed
rel_tim_adv, hreqave
rel_tim_adv, hreqt
decision_1_tim_adv_av_alg
ms_max_range
decision_1_n8
decision_1_p8
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poor_initial_assignment
timing_advance_period(TIMER)
Define the interval between timing advance changes
Power Budget
Parameter CurrentSetting
SuggestSetting
Reason
pwr_handover_allow
edrxlev_dl_ho, hreqave
rxlev_dl_ho, hreqt
surround_cell,hreqave
decision_1_pbgt_rxlev_av_h
decision_1_ncell_rxlev_av_h_calc
max_tx_ms (servingcell)
ms_tx_pwr_max_def (internal neighbor default)
ms_tx_pwr_max_cell(external neighbor)
use_neighbor_pbgt_ hreqave
1
Data and Hopping Quality Handover Control
Parameter CurrentSetting
SuggestSetting
Reason
data_qual_flag
l_rxqual_dl_h_data
l_rxqual_ul_h_data
hop_qual_enabled
l_rxqual_dl_h_hopping
l_rxqual_ul_h_hopping
14.3. Multiband
Multiband Handover
Parameter CurrentSetting
SuggestSetting
Reason
mb_preference
phase2_classmark_ allowed
early_classmark_sending
early_classmark_delay
interband_ho_allowed
band_preference
band_preference_mode
multiband_reporting
14.4. MiscellaneousCriteria 1
Parameter CurrentSetting
SuggestSetting
Reason
rxlev_min_def 5 rxlev_min_def (internal neighbor default)
rxlev_min_cell 5 rxlev_min_cell (external neighbor)
Criteria 2
Parameter CurrentSetting
SuggestSetting
Reason
ho_margin_def 4,5
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Neighboring Cell Processing
Parameter CurrentSetting
SuggestSetting
Reason
ncell_pro 0
disuse_cnt_hreqave 0
ho_only_max_pwr 1
neighbor_journal 0
worse_neighbor_ho 0
Alternative Processing of Rxqual Measurements
Parameter CurrentSetting
SuggestSetting
Reason
alt_qual_proc 0 0 Quality Band Unit
Broadcast Control Channel Allocation (BA) Reinitialization
Parameter CurrentSetting
SuggestSetting
Reason
ba_alloac_proc 1
Missing Report
Parameter CurrentSetting
SuggestSetting
Reason
missing_rpt 0 0 Waiting for the actual data
Handover Timer
Parameter CurrentSetting
SuggestSetting
Reason
handover_recongnized_period
bssmap_t7
Link Disconnection
Parameter CurrentSetting
SuggestSetting
Reason
radio_link_timeout
rr_t3109
link_about_to_fail
link_fail
full_pwr_rfloss
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15. TOOLS AVAILABLE
COP – Event Counting Tool, Call Trace Product, Generic Look Up, Cell Analysis Tool 2
TEMS and SafcoK1103
Web StatisitcsNetPlanBSS DatabaseGEP
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16. PROBLEM ROOT CAUSE
16.1. High SDCCH Blocking
HIGH SD BLOCKING
BUSY_SD_MAX=MAX CONFIGUREDSD
Find faulty TSfrom BER statsor check alarm
SD_MEAN_HOCDINGTIME CONVERGES to
T3101
May due to Phantom RACH and HO access burst, checkany same ARFCN and BSICPath Imbalance (SDCCH not on BCCH carrier)
1. Check Neighbor BCCHbeing Interfered
2. Missing Neighbor or incorrectneighbor DB Path,TOTAL_CALL/ALLOC_TCHmay be used
3. Review OK_ACC_PROC likeCM_SERVICE_REQ_CALL,PAGE_RESPONSE,LOCATIONUPDATE
4. Neighbor Cell Outage or own cell carrier outage (l
carrier can have max 2 SD)
5. Coverage Hole Lot of locationUpdate?
END
Is out_INTRA_BSS_HO_RETURN ANDout_INTER_BSS_HO_RETURN A LOT?
END
Check neighbor in_intra_BSS_ho_returnand in_inter_bss_ho_Seize, if high,Check neighbor´s fp
LAC BORDER REDESIGN,
check t3121
8. No TCH BLOKING,ENABLE CHANNEL RECONFIGUPATION
7. Neighbor´s tx power reduced
N
N
N
N
Y
Y
Y
Y
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16.2. High TCH Blocking
HIGH TCH BLOCKING
BUSY_TCH_MAX=MAX_CONFIGURED_TCH
Find faulty TS FromBER Stats or checkalarm
1. Any neighbor´s BCCHinterfered
2. Missing Neighbor or incorrect Neighbor BSIC
3. Its GCLK SHIFT causesneighbor´s bsic undecoded
4. Long timer settinga. intra_BSS HO_rrt3103b. channel release_rrt3109
5. checkout_intra_bss_no_return andout_inter_bss_ho_return, it ishigh
END
6. Check any co-located or closemicro-cell,see whether trafficoffload is possible by optismisigDB
7. If SD has no blocking. May reconfigurechannels or enable channel
reconfiguration feature
Find neighbors which has highin_intra_bss_ho_returnin_inter_bss_ho_seize thencheck its fp
9. Coverage hole and improper DT &orientation
10. Add radio to cell withoutadding new cabinet
8. check adjacent cellbusy_tch_max, if thebusy_tch_max-8>configured TCH
Site reconfiguration
Reduce ho margin andenable congestion relief
N
Y
Y
N
N
Y
11. Increase of single or dualbandMSs.
12. Inappropriate congestion HO setting
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16.3. SDCCH Access Failure Rate
Note: SDCCH blocking is excluded.
LOW SDCCH ACCESS SUCCESSRATE
1. Phantom RACH, check anysame ARFCN and BSIC
2. Path Balance, BCCH is OK batSD carrier not OK
3. Link balance, DB power setting
4. HW Problem, check per carrier chan_req_ms_fail stats. or checkalarm
5. UL Interferencea. External check night line IOIb. High cell sitec. High UL Path Lossd. Co. or adj. – channel interference
6. Excessive TA
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16.4. Handover Failure & Loss
High HO Loss / Failure
1. Poor serving cell HDPCsetting
2. Short rr_t3103 4. Bad fp or external Interference -find %of UL/DL Quality by out_ho_cause
5. HO Failure- Incorrect External Neighbor Database
7. HO failure- Check target cell fp
3. MSC Problem
6. Handover_power_level is max?
8. HW (DRCU, Filter…) Fault 9. Radio Calibration
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16.5. MSC Connection Rate
Low MSC Connection Rate
1. Paging Overflow CausingDiscard
2. Coverage Hole 3. SD RF loss
4. TCH BLOCKING 5. Infrequent Location Update 6. Cipher Mode Fail
8. MSC Connection Refused (MTLCongested)
7. Proper setting onms_txpwr_max_cch andms_txpwr_max_def
9. Call clearing timer (t3109<<radio_link_timeout)causing unclear call generating ULinterference
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SDCCH and TCH RF Loss
High SD & TCH RF LOSS
1. a. Neighbor´s BCCH Interferedb. External Interferencec. Use guard bandd. Use AMPS frequency
2. Hardware(a)Path balance
-idea is 108;≥120 (serious UL Path Loss)
;≤100 (serious DL Path Loss)(b)Radio
-check per carrier RF loss stats(c) Neighbor cell outage(d) GCLK SHIFT
3. Neighbor Blocking-check (OUT_INTRA_BSS_HO_REQ_OUT_INTRA_BSS_HO_ATTEMPT)
or (OUT_INTER_BSS_REQ_TO_MSC_OUT_TNETER_BSS_HO_ATTEMPT)
and check neighbor ′s ALLOC_TCH_FAIL
4. Missing Neighbor, usually by drive test or trace-call
5. Coverage hole, check UL Path Loss
7. SD RF LOSSa. Inconsistent coverage
b. Not enough overlapping
c. No SDCCH HO
8. Poor HDPC setting
9. Is out_intra_bss_ho_returnand out_inter_bss_ho_return
a lot? END
Check neighbor in_intra_bss_ho_return and
in_inter_bss_ho_seize if high, check neighbor ′s fp
N
Y
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16.6. Power Control
Sudden Power Drop1. Incorrect call clearing timer setting2. Faulty hardware
Slow Power Control1. ho_only_max_pwr is turned on2. Bad xx_p_con_ack and xx_p_con_interval
Power Control Window1. Any external interference2. Frequency planning technique3. Speed of power down and up4. Street or indoor coverage
16.7. Handover Problem
Ping Pong Handover 1. Bad radio calibration2. Hardware fault3. Negative handover allowed4. Quality handover without turning on qual_pwr flag5. Especially air combing, one of TX, RX antenna is blocked by building
Negative Handover 1. Neighbor journal2. qual_margin_flag=03. Bad radio calibration between BCCH and non-BCCH4. Turn on ho_magrin_rxqual feature with default value
No and Delay Handover
1. Inappriorate hreqave, hreqt and N & P voting2. Negative handover margin3. Improper setting on handover_recognised_period and bssmap_t74. Improper HO algorithm (Type 4, 6)5. Blocking
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16.8. Others
Low Erlang Usage1. Inappropriate C1, C2 and handover criteria
High Rxqual
1. Adjacent site interference2. Same site MAIO assignment problem3. High internal same site hit rate4. External interference like cordless phone, alarm, BTS hardware
Undecode BSIC1. GCLK shift2. BCCH interfered
Spurious Coverage1. Coverage optimization2. TA control
Killed Paging1. Too many access grant block reserved2. Location area too large
No Paging After Mobile is on certain time period1. MSC Location Update Timer < BSS Location Update Timer
No Call Setup1. LACI is different between BSS and MSC2. Cell BAR
Immediate Assignment Reject1. NO SDCCH