GSM OPTIMIZATION HANDBOOK
03/30/11
1/33
1. Introduction.........................................................................................................3 2. Support Arrangement..........................................................................................4 3. Optimisation Team Structure..............................................................................5 4. Bad Perfromance FisH Bone diagram................................................................6 5. Information Preparation......................................................................................7 6. General Optimisation Proceedure......................................................................8 7. Alarm Analysis....................................................................................................9 8. Statistics Analysis Procedure...........................................................................10 9. Drive Test..........................................................................................................13 9.1. Drive Test Reminder..................................................................................13 9.2. Drive Test Log Investigation Consideration...............................................13 10. Frequeny Planning .........................................................................................14 10.1. BCCH and BSIC planning criteria............................................................14 10.2. Frequency Assignment Criteria................................................................14 10.3. Frequency Retune Procedure..................................................................15 11. Add Neighbor Criteria.....................................................................................15 12. High Rise Building Coverage..........................................................................16 13. Maximum System Configuration.....................................................................16 14. HDPC Setting Template.................................................................................18 14.1. TX Power and Power Control...................................................................18 14.2. Handover..................................................................................................21 14.3. Multiband..................................................................................................23 14.4. Miscellaneous...........................................................................................23 15. Tools Available................................................................................................25 16. Problem Root Cause ......................................................................................26 16.1. High SDCCH Blocking.............................................................................26 16.2. High TCH Blocking...................................................................................27 16.3. SDCCH Access Failure Rate...................................................................28 16.4. Handover Failure & Loss..........................................................................29 16.5. MSC Connection Rate ............................................................................30 16.6. SDCCH and TCH RF Loss.......................................................................31 16.7. Power Control...........................................................................................32 16.8. Handover Problem...................................................................................32 16.9. Others.......................................................................................................33
03/30/11
2/33
1. INTRODUCTION Teamwork, “listen to order”, cycle time reduction and follow procedure are critical to every successful optimisation. Below is the optimisation flow chart:
Data Preparation
Data Collection
Data Analysis
Satisfactor y Result?
No
Optimisation
Yes
Complete
03/30/11
3/33
2. SUPPORT ARRANGEMENT Optimisation Flow Monthly performance meeting to identify optimisation targets.
Account Team supplies required information PEG prepares INFORMATION FOR OPTIMISTION
PEG audits network in Beijing
PEG derives optimisation plan
PEG arrives local office to discuss the optimisation plan with Account Team and Customer
Start optimisation
03/30/11
PEG Arrangement PEG discuss with account teams to identify optimisation targets.
OMC Engineer arrives local office to setup data collection platform Contractor prepares optimisation information in Beijing
Engineers perform brief audit in Beijing to understand REAL situation
All engineers return to Beijing to derive plan
Best engineering arrangement arrives at local office
Start optimisation and skill transfer and acquisition
4/33
3. OPTIMISATION TEAM STRUCTURE Team Leader
Alarm Monitoring
Statistics Monitoring
BSS Controller
MONITORING
D.B. & Feature Controller
Drive Test Log Investigator
ACTION
Job Function BSS 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
03/30/11
5/33
4. BAD PERFROMANCE FISH BONE DIAGRAM Database Setting
Neighbor
Coverage
External Calculation Interference
Capacity
Frequency Plan
Software
Hardware
Cable Connection
Statistics Pegging and Retrieval
Bad Performance
Network Topology
Signaling
Mobile
Documentation
Example of each major problems: a. Database Setting – improper HOPC settings b. Neighbor – wrong external neighbor’s BCCH or BSIC values, missing neighbor c. Coverage – weak, highly overlapped, improper antenna downtilt and orientation d. External Interference – microwave, repeater, faulty alarm e. Calculation – incorrect statistics equations f. Cable Connection – no/cross connection g. Statistics Pegging and Collection – SW problem on statistics pegging, or retrieval h. Capacity – lack of TRCU, improper channel configuration, lack of RSL, MTL links i. Frequency Plan – co-channel, adj-channel, improper BSIC planning j. Software – bug k. Hardware – wrong cable connection, faulty combiner and filter, PCM link down l. Network Topology – bad site location selection, redundant site deployed m. Signaling – Improper cause value and message sequence n. Mobile – faulty mobile in term of signaling or frequency hopping capability o. Documentation – wrong feature/parameter usage description
03/30/11
6/33
5. INFORMATION PREPARATION
03/30/11
7/33
6. GENERAL OPTIMISATION PROCEEDURE Data Collection & Check Local Office NetPlan Information
1 day 2 days
Data Preparation & NetPlan Information Correction
1. 2. 3. 4.
1. 2. 3.
Hardware Fix (Sleeping Cell, OOS TCU, OOS TS Path Balance Issue, Faulty TCU from TCH_RF_Loss Issue) GCLK shift and frequent Phase Lock Loop failure from Alarm
1. 2. 3. 4. 5. 6. 7.
Capacity
Network Audit from Alarm Statistics Database Check customer statistics equations
Hardware
Suggest Better Database Setting (Channel Reconfiguration, Standard HOPC, Blocking Timer , Congestion Relief) Capture External Interference Frequency Retune for high IOI, BER and TCH_RF_LOSS Audit External Neighbor Improper ARFCN:BSIC Planning GPROC loading RSL & MTL Usage
Solve Blocking by: a. BCCH Optimisation b. Neighor Optimisation c. Add Radio d. Site Reconfiguration e. Add Site f. Antenna Refinement
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
03/30/11
2 days
Network Topology Problem due to no available ARFCN is found by: a. Site Replacement b. Coverage Optimisation c. Capacity Dimensioning
2 days
Database, Interference & Capacity
Network 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
2 days
2 days
FP, Neighobr and Coverage
g.
use non-dominant server by ARFCN retune, neighor change and coverage
8/33
12 days
7. ALARM ANALYSIS Below lists some important alarms that we focus, a. Critical and major alarm b. Alarms affect voice quality like MSI, KSW, RXCDR, DRIM, DRI c. GCLK affects HO d. Link alarms affect site availability and voice quality e. XBL alarm affects acknowledgement of OOS CIC
03/30/11
9/33
8. STATISTICS ANALYSIS PROCEDURE Statistics Tree Diagram
M P
a
g
i n
g
N
o
R
e S s Dp
oC n C s He C M
a
S ( M B
A S
C
C
T
c c e
l l
e
s s
t u
p
O
S
N
D
ip h ( T S
N
R
R
F
H
S
u
c e
o
n
n
o s sT
s s
R
e n t T A C t Ht e R O M _ M O
e f u s e
L
C
e
F C a a i l ul l r S e u R c ea
G
D C
C
C
A s s i g n m _ R E Q _ F
A A
S
O dT
C
e r M o d e F M I , I M S I )
n
st e s
R
t e
mR S
D
R
H
A
i l
B
r o
p
g
e n t
S
t e
t e
Fp t L R o a s t s e C )
lo c k in
s s ig n m
a
a
D C
H
a
a
c t io
C
a R
l l Ha
R
tO e
a
t e
L
o
s s
R
t e
I n t e r - B
S
S
H
O
L
o s s
I n t r a - B u c c e s s
S
S
H
O
L
o s s
I n t r a - c e ll
H
Firstly, we need to understand account teams and customer performance equation. Problem Identification from Statistics 1. 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) 03/30/11
a
10/33
O
L o
s s
b. c. d. e. f. g.
MSC Processor Loading and Subscriber (Weekly) RSL TX, RX Utilisation mean 25% (Weekly) MTL TX, RX Utilisation mean 20% (Weekly) Pages per second (Weekly) ALLOC_SDCCH, ALLOC_SDCCH_FAIL ,OK_ACC_PROC relationship (Weekly) HO per call (Weekly) 6. per cell on paging a. PCH_PAGE_Q_DISCARD (Weekly) 7. per cell for BCCH and BSIC planning a. INV_EST_CAUSE_RACH and BAD_HO_REFNUM_MS (Weekly) 8. per cell inter-BSS HO monitoring a. 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 goal c. do (b) again for other statistics 10. select worst cells and BSCs d. pick worst 20 cells and worst 5 BSCs 11. per cell on TCH Assignment a. CONN_REQ_TO_MSC b. 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_MS d. MA_FAIL_FROM_MS, MA_COMPLETE_TO_MSC (same as TOTAL_CALL) 12. per cell on HO Cause a. OUT_HO_CAUSE 13. per cell on HO Failure a. OUT_INTRA_BSS_HO_FAIL, OUT_INTER_BSS_HO_FAIL, IN_INTRA_BSS_HO_FAIL and IN_INTER_BSS_MS_NO_SEIZE for ho failues 14. 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 every 3 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 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 LAC ACCESS_PER_RACH – PAGING_RESPONSE. Difference tells us how many no page reponses.
03/30/11
11/33
03/30/11
12/33
9. DRIVE TEST 9.1.
Drive Test Reminder
i. ii. iii. iv. v. vi. vii.
prepare cell definition file 2mins per call 10-15mins per log file force to appropriate band (GSM only, DCS only or Dual) mark benchmark route per log file in map mark on maps about (a) drop call (b) weak coverage (c) lot of rxquality (d) bad coverage fill in drive test problem sheet
9.2.
Drive Test Log Investigation Consideration
General TEMS Log Investigation Concern 1. 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 path 3. focus on drop call and rxqual greater than 4 for non-hopping, 5 for hopping for at least 4 seconds 4. look for handover failure – investigation target cell assigned ARFCN/MA from ASSIGNMENT COMMAND and HANDOVER COMMAND 5. mark down weak coverage area, no dominant server, say less than –85dBm 6. mark down highly overlapped area Besides, be careful that when you see a decoded cell, that cell is not definitely a neighbor of serving, it can be due to serving cell having a neighbor which has same 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 yet due to serious rxquality at DL.
03/30/11
13/33
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
serving cell
can’t be co- or adjcahannel
adjacent channel
co-channel
Hopping Case for non-BCCH
serving cell
adjacent channel
co-channel
BCCH in hopping case is same as the non-hopping case.
03/30/11
14/33
10.3. Frequency Retune Procedure Frequencies can be grouped into 5 types, they are:a. same site co- and adj-channel to BCCH b. adjacent site co- and adj-channel to BCCH c. adjacent site co-channel to ARFCN d. same site co-channel to ARFCN e. same site adj-channel to ARFCN f. adjacent site adj-channel to ARFCN g. 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 make the decision.
serving cell
03/30/11
LOS interferer
2nd Round Interferer
3rd Round Interferer
15/33
12.
HIGH RISE BUILDING COVERAGE
Introduce high rise building coverage must make sure to have good street coverage.
盄 High Rise Building
Macro
Micro
High Rise Building – provide high level (likely above 8th floor) high rise building coverage Macro – provide low floors and street level coverage Micro – provide street level and indoor coverage
13.
MAXIMUM SYSTEM CONFIGURATION
It is important to understand how system grows from phase to phase. It can be described 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 and lower macro cell height of macro antenna. Phase 3: Introduce high rise building coverage to office building and hotel. Before deploying this kind of coverage, street level coverage MUST be strong enough (likely more than –75dBm) to protect interference from high rise building coverage. For a mature network which its system rxlevel has reach average –75dBm, it is time for us to deploy SFH to expand system capacity.
03/30/11
16/33
03/30/11
17/33
14.
HDPC SETTING TEMPLATE
14.1. TX Power and Power Control TX Power Parameter
Current Setting
Suggest Setting
Reason
max_tx_ms max_tx_bts Downlink Power Control due to Level Current Suggest Parameter Setting Setting decision_alg_num bts_power_control_all owed 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_a v_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 Current Suggest Setting Setting decision_alg_num bts_power_control_all owed 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 Parameter
Uplink Power Control due to Level Current Setting decision_alg_num Parameter
03/30/11
Suggest Setting
Reason
Reason
Reason
18/33
ms_power_control_all owed 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_a v_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 Current Parameter Setting decision_alg_num ms_power_control_all owed 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
Suggest Setting
Data and Hopping Quality Power Control Current Parameter Setting 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
Reason
Suggest Setting
Reason
Standard MS HO Power, MS Ho Power Level based on Path Loss Calculations (GSR3) Current Suggest Parameter Reason Setting Setting handover_power_level use_derived_ho_power 0 1 Reduce MS UL power and interference Optimised Power Control (GSR4) Current Setting 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 Parameter
03/30/11
Suggest Setting
Reason
19/33
Oscillation Prevention for MS Power Control Current Suggest Setting Setting mspwr_alg Parameter
Reason
Rapid MS Power Down Parameter
Current Setting
Suggest Setting
Reason
rpd_pwr_down rpd_period (TIMER) rpd_trigger rpd_offset
03/30/11
20/33
14.2. Handover Inter-cell Handover Parameter
Current Setting
Suggest Setting
Reason
Current Setting
Suggest Setting
Reason
Current Setting
Suggest Setting
Reason
inter_cell_handover_a llowed Intra-cell Handover Parameter intra_cell_handover_a llowed ho_ack (TIMER) hop_count hop_count_ timer Uplink Quality Parameter 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
Current Setting
Suggest Setting
Reason
Suggest Setting
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
Current Setting
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, 03/30/11
21/33
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
Current Setting
Suggest Setting
Reason
Current Setting
Suggest Setting
Reason
Current Setting
Suggest Setting
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 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 Parameter 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
Current Setting
Suggest Setting
Reason
ms_distance_allowed rel_tim_adv, hreqave rel_tim_adv, hreqt decision_1_tim_adv_av_a lg ms_max_range decision_1_n8 decision_1_p8 03/30/11
22/33
poor_initial_assignment timing_advance_period (TIMER)
Define the interval between timing advance changes
Power Budget Parameter
Current Setting
pwr_handover_allow ed rxlev_dl_ho, hreqave rxlev_dl_ho, hreqt surround_cell, hreqave decision_1_pbgt_rxl ev_av_h decision_1_ncell_rxl ev_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
Suggest Setting
Reason
1
Data and Hopping Quality Handover Control Current Suggest Setting Setting 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 Parameter
Reason
14.3. Multiband Multiband Handover Current Setting
Parameter
Suggest Setting
Reason
mb_preference phase2_classmark_ allowed early_classmark_sending early_classmark_delay interband_ho_allowed band_preference band_preference_mode multiband_reporting
14.4. Miscellaneous Criteria 1 Parameter
Current Setting
rxlev_min_def rxlev_min_cell
Suggest Setting 5 5
Reason rxlev_min_def (internal neighbor default) rxlev_min_cell (external neighbor)
Criteria 2 Parameter ho_margin_def 03/30/11
Current Setting
Suggest Setting 4,5
Reason
23/33
Neighboring Cell Processing Current Setting ncell_pro disuse_cnt_hreqave ho_only_max_pwr neighbor_journal worse_neighbor_ho Parameter
Suggest Setting 0 0 1 0 0
Alternative Processing of Rxqual Measurements Current Suggest Setting Setting alt_qual_proc 0 0 Parameter
Reason
Reason Quality Band Unit
Broadcast Control Channel Allocation (BA) Reinitialization Current Suggest Reason Setting Setting ba_alloac_proc 1 Parameter
Missing Report Parameter missing_rpt
Current Setting 0
Suggest Setting 0
Current Setting
Suggest Setting
Reason
Current Setting
Suggest Setting
Reason
Reason Waiting for the actual data
Handover Timer Parameter handover_recongniz ed_period bssmap_t7 Link Disconnection Parameter radio_link_timeout rr_t3109 link_about_to_fail link_fail full_pwr_rfloss
03/30/11
24/33
15.
TOOLS AVAILABLE
COP – Event Counting Tool, Call Trace Product, Generic Look Up, Cell Analysis Tool 2 TEMS and Safco K1103 Web Statisitcs NetPlan BSS Database GEP
03/30/11
25/33
16.
PROBLEM ROOT CAUSE
16.1. High SDCCH Blocking HIGH SD BLOCKING
N
BUSY_SD_MAX =MAX CONFIGUREDSD
Y
Find faulty TS from BER stats or check alarm
Y
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)
N
Check Neighbor BCCH being Interfered
Missing Neighbor or incorrect neighbor DB Path, TOTAL_CALL/ALLOC_TCH may be used
Neighbor Cell Outage or own cell carrier outage (l carrier can have max 2 SD)
Coverage Hole
Review OK_ACC_PROC like CM_SERVICE_REQ_CALL, PAGE_RESPONSE,LOCATION UPDATE
N
Lot of location Update?
END
Y LAC BORDER REDESIGN ， check t3121
Is out_INTRA_BSS_HO_RETURN AND out_INTER_BSS_HO_RETURN A LOT?
Y
N END
No TCH BLOKING, ENABLE CHANNEL RE CONFIGUPATION
Neighbor 磗 tx power reduced
Check neighbor in_intra_BSS_ho_return and in_inter_bss_ho_Seize, if high, Check neighbor 磗 fp
03/30/11
26/33
16.2. High TCH Blocking HIGH TCH BLOCKING
N
BUSY_TCH_MAX =MAX_CONFIGURED_TCH
Find faulty TS From BER Stats or check alarm
Y
3. Its GCLK SHIFT causes neighbor 磗 bsic undecoded
2. Missing Neighbor or incorrect Neighbor BSIC
1. Any neighbor 磗 BCCH interfered
4. Long timer setting intra_BSS HO_rrt3103 channel release_rrt3109
6. Check any co-located or close micro-cell,see whether traffic offload is possible by optismisig DB 5. check out_intra_bss_no_return and out_inter_bss_ho_return, it is high
N END 7. If SD has no blocking. May reconfigure channels or enable channel reconfiguration feature
Y 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 11. Increase of single or dualband MSs.
8. check adjacent cell busy_tch_max, if the busy_tch_max8>configured TCH
Y
Reduce ho margin and enable congestion relief
N Site reconfiguration
12. Inappropriate congestion HO setting
03/30/11
27/33
16.3. SDCCH Access Failure Rate Note: 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
4. HW Problem, check per carrier chan_req_ms_fail stats. or check alarm
03/30/11
5. UL Interference External check night line IOI High cell site High UL Path Loss Co. or adj. �channel interference
3. Link balance, DB power setting
6. Excessive TA
28/33
16.4. Handover Failure & Loss High HO Loss / Failure
1. Poor serving cell HDPC setting
5. HO Failure - Incorrect External Neighbor Database
2. Short rr_t3103
6. Handover_power_level is max?
8. HW (DRCU, Filter� Fault
03/30/11
3. MSC Problem
4. Bad fp or external Interference -find % of UL/DL Quality by out_ho_cause
7. HO failure - Check target cell fp
9. Radio Calibration
29/33
16.5. MSC Connection Rate
Low 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 Fail
7. Proper setting on ms_txpwr_max_cch and ms_txpwr_max_def
03/30/11
8. MSC Connection Refused (MTL Congested)
9. Call clearing timer (t3109<
30/33
16.6. SDCCH and TCH RF Loss
High SD & TCH RF LOSS
a. Neighbor´s BCCH Interfered b. External Interference c. Use guard band d. 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
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
Missing Neighbor, usually by drive test or trace-call 7. SD RF LOSS Inconsistent coverage Not enough overlapping No SDCCH HO 5.
Coverage hole, check UL Path Loss
8.
9. Is out_intra_bss_ho_return and out_inter_bss_ho_return a lot?
N
Poor HDPC setting
END
Y
Check neighbor in_intra_bss_ho_return and in_inter_bss_ho_seize if high, check neighbor′ s fp 03/30/11
31/33
16.7. Power Control Sudden Power Drop 1. Incorrect call clearing timer setting 2. Faulty hardware Slow Power Control 1. ho_only_max_pwr is turned on 2. Bad xx_p_con_ack and xx_p_con_interval Power Control Window 1. Any external interference 2. Frequency planning technique 3. Speed of power down and up 4. Street or indoor coverage
16.8. Handover Problem Ping Pong Handover 1. Bad radio calibration 2. Hardware fault 3. Negative handover allowed 4. Quality handover without turning on qual_pwr flag 5. Especially air combing, one of TX, RX antenna is blocked by building Negative Handover 1. Neighbor journal 2. qual_margin_flag=0 3. Bad radio calibration between BCCH and non-BCCH 4. Turn on ho_magrin_rxqual feature with default value No and Delay Handover 1. Inappriorate hreqave, hreqt and N & P voting 2. Negative handover margin 3. Improper setting on handover_recognised_period and bssmap_t7 4. Improper HO algorithm (Type 4, 6) 5. Blocking
03/30/11
32/33
16.9. Others Low Erlang Usage 1. Inappropriate C1, C2 and handover criteria High Rxqual 1. Adjacent site interference 2. Same site MAIO assignment problem 3. High internal same site hit rate 4. External interference like cordless phone, alarm, BTS hardware Undecode BSIC 1. GCLK shift 2. BCCH interfered Spurious Coverage 1. Coverage optimization 2. TA control Killed Paging 1. Too many access grant block reserved 2. Location area too large No Paging After Mobile is on certain time period 1. MSC Location Update Timer < BSS Location Update Timer No Call Setup 1. LACI is different between BSS and MSC 2. Cell BAR Immediate Assignment Reject 1. NO SDCCH
03/30/11
33/33
