gsm_network_optimisation_handbook_
TRANSCRIPT
GSM OPTIMISATION
HANDBOOK
1. Introduction 32. Support Arrangement 43. Optimisation Team Structure 54. Bad Perfromance FisH Bone diagram 65. 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 25
16.2. 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
1. IntroductionTeamwork, “listen to order”, cycle time reduction and follow procedure are critical toevery successful optimisation.
Below is the optimisation flow chart:
Data PreparationData Collection
Data Analysis
Satisfactory Result?No
Optimisation
Yes
Complete
2. Support ArrangementBest engineering arrangement arrives at local office
All engineers return to Beijing to derive plan
PEG arrives local office to discuss the optimisation plan with Account Team and Customer
Start optimisation
Engineers perform brief audit in Beijing to understand REAL situation
Contractor prepares optimisation information
in Beijing
OMC Engineer arrives local office to setup data collection platform
PEG derives optimisation plan
PEG audits network in Beijing
PEG prepares INFORMATION FOR OPTIMISTION
Account Team supplies required information
Optimisation FlowPEG Arrangement
PEG discuss with account teams to identify optimisation targets.
Monthly performance meeting to identify optimisation targets.
Start optimisation and skill transfer and acquisition
3. Optimisation Team StructureTeam Leader
BSS ControllerStatistics Monitoring
Alarm MonitoringD.B. & Feature Controller
Drive Test Log Investigator
MONITORINGACTION
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
4. Bad Perfromance FisH Bone diagramFrequency
Plan
Network Topology
Signaling
Mobile
Bad Performance
Database
Setting
Coverage
Software
Hardware
Capacity
External
Interference
Neighbor
Calculation
Statistics Pegging and Retrieval
Cable
Connection
Documentation
Example of each major problems:a. Database Setting – improper HOPC settingsb. Neighbor – wrong external neighbor’s BCCH or BSIC values, missing
neighborc. 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 planningj. Software – bugk. Hardware – wrong cable connection, faulty combiner and filter, PCM link
downl. Network Topology – bad site location selection, redundant site deployed
m. Signaling – Improper cause value and message sequencen. Mobile – faulty mobile in term of signaling or frequency hopping capabilityo. Documentation – wrong feature/parameter usage description
5. Information PreparationInformation from Account Team Output Generated from Left Column DataBSS Scripts Cell, Site, BSC, RTF. Neighbor, External
Neighbor Check, TEMS Cell DefinitionsCurrent and planning site map with main road,site location, antenna height, orientation anddown tilt in NetPlan format
NetPlan ARFCN plots
Nighttime Full Power Drive Test TEMS log withLat., Lon., both directions need to be driven
NetPlan rxlevel, rxqualilty, overlapping routemaps
Latest 1 week Informix statistics NetPlan Erlang, Blocking %, Drop Call %, TotalLoss, Call Setup Failure % Plots
Antenna configuration informationBusy area, VIP spots and main route marked oncity mapProject in last 3 and coming 3 months
Site outage listTools and network features availabilityLast 3 month system performance historyLast 2 day event and alarm log
6. General Optimisation Proceedure1 day
Data Collection & Check Local Office NetPlan Information
2 daysData Preparation & NetPlan Information Correction
2 daysNetwork Audit from
1. Alarm
2. Statistics
3. Database
4. Check customer statistics equations
1. Hardware Fix (Sleeping Cell, OOS TCU, OOS TS
2. Path Balance Issue, Faulty TCU from TCH_RF_Loss Issue)
3. GCLK shift and frequent Phase Lock Loop failure from Alarm
Hardware2 days
2 daysDatabase, Interference & Capacity
1. Suggest Better Database Setting (Channel Reconfiguration, Standard HOPC, Blocking Timer , Congestion Relief)
2. Capture External Interference
3. Frequency Retune for high IOI, BER and TCH_RF_LOSS
4. Audit External Neighbor
5. Improper ARFCN:BSIC Planning
6. GPROC loading
7. RSL & MTL Usage
Solve Blocking by:
a. BCCH Optimisation
b. Neighor Optimisation
c. Add Radio
d. Site Reconfiguration
e. Add Site
f. Antenna Refinement
Network Topology Problem due to no available ARFCN is found by:
a. Site Replacement
b. Coverage Optimisation
c. Capacity Dimensioning
2 daysCapacityNetwork Topology
TEMS Log & FP. mainly on
a. Undecoded BCCH
b. Missing Neighbor
c. HO Failure
d. Incorrect External Neighbor
e. Weak Coverage
f. High Overlapping
g. use non-dominant server
by ARFCN retune, neighor change and coverage
Statistics & DB. mainly on
a. SDCCH Access Failure
b. CSFR
c. Drop Call
d. TCH_RF_Loss
e. HO_Loss
f. HO_Failure
by ARFCN retune, neighor change and coverage
12 daysFP, Neighobr and Coverage
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
8. Statistics Analysis Procedure
Statistics Tree Diagram
Firstly, we need to understand account teams and customer performance equation.
Problem Identification from Statistics1. per carrier on HW, external interference, channel interference, coveragea. 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 usagea. 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 usagea. MA_ACCESS_BY_TYPE (Weekly)b. MS_TCH_USAGE_BY_TYPE (Weekly)4. per cell on Cipher Modea. CIPHER_MODE_FAIL (Weekly)5. per cell on loadinga. 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)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 monitoringa. 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 targeta. 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_MSCb. MA_REQ_FROM_MSC, CONN_REFUSED { - IMSI_DETACH}, if CONN_REFUSED is high,
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_CAUSE13. per cell on HO Failure
a. OUT_INTRA_BSS_HO_FAIL, OUT_INTER_BSS_HO_FAIL, IN_INTRA_BSS_HO_FAIL andIN_INTER_BSS_MS_NO_SEIZE for ho failues
14. per cell on TCH_RF_LOSS, SD_RF_LOSS, HO Lossa. TCH_RF_LOSS, OUT_INTRA_BSS_HO_REQ, OUT_INTRA_BSS_HO_ATMPT,
OUT_INTER_BSS_HO_REQ, OUT_INTER_BSS_HO_ATMPTb. SD_RF_LOSS and HO_LOSS relationship on cell coveragec. 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 every 3days. 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 Request
For 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 LACACCESS_PER_RACH – PAGING_RESPONSE. Difference tells us how many no page reponses.
9. Drive Test
1. Drive Test Reminder
i. prepare cell definition fileii. 2mins per call
iii. 10-15mins per log fileiv. force to appropriate band (GSM only, DCS only or Dual)v. mark benchmark route per log file in map
vi. mark on maps about (a) drop call (b) weak coverage (c) lot of rxquality (d)bad coverage
vii. fill in drive test problem sheet
2. Drive Test Log Investigation Consideration
General TEMS Log Investigation Concern1. check undecoded BCCH – this affects RF loss and creates log of ping pong
handover2. 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 has sameBCCH 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 yet due toserious rxquality at DL.
10. Frequeny Planning
1. BCCH and BSIC planning criteriaa. 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.
2. Frequency Assignment Criteria
Non-hopping Case
can’t be co- or adj-cahannelserving cellco-channel
adjacent channel
Hopping Case for non-BCCH
co-channeladjacentchannel
serving cell
BCCH in hopping case is same as the non-hopping case.
3. Frequency Retune ProcedureFrequencies can be grouped into 5 types, they are:-
a. same site co- and adj-channel to BCCHb. adjacent site co- and adj-channel to BCCHc. 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 noavailable 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 CriteriaIn 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 make thedecision.
3rd Round Interferer2nd Round Interferer
LOS interfererserving cell
12. High Rise Building CoverageIntroduce high rise building coverage must make sure to have good street coverage.
盄盄Micro
Macro
High Rise Building
High Rise Building – provide high level (likely above 8th floor) high rise buildingcoverageMacro – provide low floors and street level coverageMicro – provide street level and indoor coverage
13. Maximum System ConfigurationIt 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. Antennauses large vertical beam-width.
Phase 2: Start to introduce micro layer, and increase macro cell downtilt and lowermacro 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 (likelymore than –75dBm) to protect interference from high rise building coverage.
For a mature network which its system rxlevel has reach average –75dBm, it is timefor us to deploy SFH to expand system capacity.
14. HDPC Setting Template
1. TX Power and Power ControlTX Power
ParameterCurrent
Setting
Suggest
SettingReason
max_tx_ms
max_tx_bts
Downlink Power Control due to Level
ParameterCurrent
Setting
Suggest
SettingReason
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
ParameterCurrent
Setting
Suggest
SettingReason
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_p
u_rxqual_dl_p
decision_1_n3
decision_1_p3
decision_1_n4
decision_1_p4
w_qual
Uplink Power Control due to Level
ParameterCurrent
Setting
Suggest
SettingReason
decision_alg_num
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
ParameterCurrent
Setting
Suggest
SettingReason
decision_alg_num
ms_power_control_allowed
ms_p_con_ack
ms_p_con_interval
pow_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
ParameterCurrent
Setting
Suggest
SettingReason
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)
ParameterCurrent
Setting
Suggest
SettingReason
handover_power_level
use_derived_ho_power 0 1 Reduce MS UL power and interference
Optimised Power Control (GSR4)
ParameterCurrent
Setting
Suggest
SettingReason
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
Oscillation Prevention for MS Power Control
ParameterCurrent
Setting
Suggest
SettingReason
mspwr_alg
Rapid MS Power Down
ParameterCurrent
Setting
Suggest
SettingReason
rpd_pwr_down
rpd_period (TIMER)
rpd_trigger
rpd_offset
2. HandoverInter-cell Handover
ParameterCurrent
Setting
Suggest
SettingReason
inter_cell_handover_allowed
Intra-cell Handover
ParameterCurrent
Setting
Suggest
SettingReason
intra_cell_handover_allowed
ho_ack (TIMER)
hop_count
hop_count_ timer
Uplink Quality
ParameterCurrent
Setting
Suggest
SettingReason
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
ParameterCurrent
Setting
Suggest
SettingReason
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
ParameterCurrent
Setting
Suggest
SettingReason
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, 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
ParameterCurrent
Setting
Suggest
SettingReason
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
ParameterCurrent
Setting
Suggest
SettingReason
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_n5
decision_1_p5
Downlink Level
ParameterCurrent
Setting
Suggest
SettingReason
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
ParameterCurrent
Setting
Suggest
SettingReason
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
poor_initial_assignment
timing_advance_period
(TIMER)
Define the interval between timing advance changes
Power Budget
ParameterCurrent
Setting
Suggest
SettingReason
pwr_handover_allowed
rxlev_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 (serving cell)
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
ParameterCurrent
Setting
Suggest
SettingReason
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
3. Multiband
Multiband Handover
ParameterCurrent
Setting
Suggest
SettingReason
mb_preference
phase2_classmark_ allowed
early_classmark_sending
early_classmark_delay
interband_ho_allowed
band_preference
band_preference_mode
multiband_reporting
4. MiscellaneousCriteria 1
ParameterCurrent
Setting
Suggest
SettingReason
rxlev_min_def 5 rxlev_min_def (internal neighbor default)
rxlev_min_cell 5 rxlev_min_cell (external neighbor)
Criteria 2
ParameterCurrent
Setting
Suggest
SettingReason
ho_margin_def 4,5
Neighboring Cell Processing
ParameterCurrent
Setting
Suggest
SettingReason
ncell_pro 0
disuse_cnt_hreqave 0
ho_only_max_pwr 1
neighbor_journal 0
worse_neighbor_ho 0
Alternative Processing of Rxqual Measurements
ParameterCurrent
SettingSuggest Setting Reason
alt_qual_proc 0 0 Quality Band Unit
Broadcast Control Channel Allocation (BA) Reinitialization
ParameterCurrent
SettingSuggest Setting Reason
ba_alloac_proc 1
Missing Report
ParameterCurrent
SettingSuggest Setting Reason
missing_rpt 0 0 Waiting for the actual data
Handover Timer
ParameterCurrent
SettingSuggest Setting Reason
handover_recongnized_period
bssmap_t7
Link Disconnection
ParameterCurrent
SettingSuggest Setting Reason
radio_link_timeout
rr_t3109
link_about_to_fail
link_fail
full_pwr_rfloss
15. Tools AvailableCOP – Event Counting Tool, Call Trace Product, Generic Look Up, Cell Analysis Tool 2TEMS and SafcoK1103Web StatisitcsNetPlanBSS DatabaseGEP
16. Problem Root Cause
1. High SDCCH BlockingHIGH SD BLOCKING
BUSY_SD_MAX
=MAX CONFIGUREDSD
Find faulty TS from BER stats or check alarm
SD_MEAN_HOCDING TIME CONVERGES to T3101
May due to Phantom RACH and HO access burst, check any same ARFCN and BSIC
Path Imbalance (SDCCH not on BCCH carrier)
1. Check Neighbor BCCH being Interfered
2. Missing Neighbor or incorrect neighbor DB Path, TOTAL_CALL/ALLOC_TCH may be used
3. Review OK_ACC_PROC like CM_SERVICE_REQ_CALL, PAGE_RESPONSE,LOCATION UPDATE
4. Neighbor Cell Outage or own cell carrier outage (l carrier can have max 2 SD)
5. Coverage Hole
Lot of location Update?
END
Is out_INTRA_BSS_HO_RETURN AND 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
LAC BORDER REDESIGN, check t3121
7. No TCH BLOKING, ENABLE CHANNEL RE CONFIGUPATION
8. Neighbor´s tx power reduced
NN
NNYYYY
2. High TCH BlockingHIGH TCH BLOCKING
BUSY_TCH_MAX
=MAX_CONFIGURED_TCH
Find faulty TS From BER Stats or check alarm
1. Any neighbor´s BCCH interfered
2. Missing Neighbor or incorrect Neighbor BSIC
3. Its GCLK SHIFT causes neighbor´s bsic undecoded
4. Long timer setting
a. intra_BSS HO_rrt3103
b. channel release_rrt3109
5. check out_intra_bss_no_return and out_inter_bss_ho_return, it is high
END
6. Check any co-located or close
micro-cell,see whether traffic
offload is possible by optismisig
DB
7. If SD has no blocking. May reconfigure channels or enable channel reconfiguration feature
Find neighbors which has high
in_intra_bss_ho_return in_inter_bss_ho_seize then
check its fp
9. Coverage hole and improper DT & orientation
10. Add radio to cell without
adding new cabinet
8. check adjacent cell busy_tch_max, if the busy_tch_max-8>configured TCH
Site reconfiguration
Reduce ho margin and enable congestion relief
N
Y
Y
N
N
Y
11. Increase of single or dualband MSs.
12. Inappropriate congestion HO setting
3. SDCCH Access Failure RateNote: SDCCH blocking is excluded.
LOW SDCCH ACCESS SUCCESS RATE
1. Phantom RACH, check any same ARFCN and BSIC
2. Path Balance, BCCH is OK bat SD carrier not OK
3. Link balance, DB power setting
4. HW Problem, check per carrier chan_req_ms_fail stats. or check alarm
5. UL Interference
a. External check night line IOI
b. High cell site
c. High UL Path Loss
d. Co. or adj. – channel interference
6. Excessive TA
4. Handover Failure & LossHigh HO Loss / Failure
1. Poor serving cell HDPC setting
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
5. MSC Connection RateLow MSC Connection Rate
1. Paging Overflow Causing Discard
2. Coverage Hole
3. SD RF loss
4. TCH BLOCKING
5. Infrequent Location Update
6. Cipher Mode Fail8. MSC Connection Refused (MTL Congested)
7. Proper setting on ms_txpwr_max_cch and ms_txpwr_max_def
9. Call clearing timer (t3109<<radio_link_timeout) causing unclear call generating UL interference
SDCCH and TCH RF Loss
High SD & TCH RF LOSS
1. a. Neighbor´s BCCH Interfered
b. External Interference
c. Use guard band
d. Use AMPS frequency
2. Hardware
(a)Path balance
-idea is 108;³120 (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 LOSS
a. Inconsistent coverage
b. Not enough overlapping
c. No SDCCH HO
8. Poor HDPC setting
9. Is out_intra_bss_ho_return
and 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
6. Power ControlSudden Power Drop
1. 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
7. Handover ProblemPing Pong Handover
1. Bad radio calibration2. Hardware fault3. Negative handover allowed
4. Quality handover without turning on qual_pwr flag5. Especially air combing, one of TX, RX antenna is blocked by building
Negative Handover1. 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 Handover1. 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
8. OthersLow Erlang Usage1. Inappropriate C1, C2 and handover criteria
High Rxqual1. 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 Reject
1. NO SDCCH4/32