NETWORK SOLUTIONS
SERVICES SOLUTIONS PACKAGES
2G
ACCESSIBILITY
RETAINABILITY
2G
MOBILITY
Gprs/edge
2G
MOBILITY
Basic Sanity
Check [L1]
PARAMETER
RECOMMENDATIONS
[L2]
NEW
FEATURES [L3]
MOBILITY
 Mobility is defined as the ability of a user to move
between neighboring GSM Cells and retain its requested
service once connected
 Definition: The Change of dedicated Radio Channel
(SDCCH or TCH) when an active RR Connection exists
between MS & BTS
 major component of mobility IS Handover Success Rate
 HANDOVER IS A PROCESS IN WHICH, THE SERVICE TO THE
SUBSCRIBER IS TRANSFERRED FROM THE SERVING CELL TO
ANOTHER CELL, DURING THE ACTIVE MODE OF MS AND THE CALL
WILL CONTINUE, TILL THE MS DISCONNECTS THE CALL
Ericsson Internal | 2012-06-22 | Page 5
MOBILITY CALCULATION COUNTER
a. Mobility counters:
›
›
›
›
›
›
SUMOHOSUCC
SUMEOHOSUCC
SUMOHOATT
SUMEOHOATT
SUMOHOLOST
SUMEOHOLOST
B. Mobility formula
Handover Success Rate:
› PERCENTAGE SUCCESSFUL HANDOVERS. SUMMED UP FOR ALL EXTERNAL AND
INTERNAL CELL RELATIONS
H_SUC=100*[(SUMOHOSUCC + SUMEOHOSUCC) / (SUMOHOATT + SUMEOHOATT)]
Handover LOST rate:
› PERCENTAGE MS LOST AT HANDOVERS. SUMMED UP FOR ALL EXTERNAL AND
INTERNAL CELL RELATIONS
H_LOST=100*[(SUMOHOLOST+SUMEOHOLOST) /( SUMOHOATT+SUMEOHOATT)]
Ericsson Internal | 2012-06-22 | Page 6
Mobility failureS POSSIBLE REASONS
Possible Causes for Handover Failures
›
›
›
›
›
›
›
›
Missing Neighbors.
Co-BCCH/BSIC.
TCH Congestion at Target.
Swapped Sectors.
BCCH / TCH interference.
Weak Cell Boundary.
Too Many Neighbors.
Incorrect Handover Parameters.
Recommendations for improvement:
› Use of planning tool and drive tests to identify and add missing
neighbors.
› Audit of the co BCCH/BSIC allocation
› Antenna implementation check.
› Bringing down the average neighbor count per cell.
› Optimization of handover parameters
Ericsson Internal | 2012-06-22 | Page 7
MOBILITY FLOW CHART Cell
Mobility
issueS
Dragged
Ping Pong
Missing
SWAPPED
Handover
effect
Neighbor
SECTOR
Check
Check for
AUDIT AND
parameters
Check cable
Rf coverage
OVERLAP
ADD NEIGHBOR
feeder
issues
connections
Check traffic
volume
handover
H/W PROBLEM
Parameter
Check missing
neighbors
optimization
HANDOVER
Power control
optimization
Ericsson Internal | 2012-06-22 | Page 8
PARAMETERS
Layer1 troubleshooting process –
BASIC Sanity check [L1]
Sanity is the level one check where parameter values are audited to
make sure they are set to the recommended values. If any
discrepancies are observed then those must be corrected
MO
ACCESS
Parameter
SSDESUL
CRO
LCOMPUL
ACCMIN
QCOMPUL
CCHPWR
SSLENUL
Power Control(MS)
INILEN
HOP
QLENUL
HSN
QDESUL
PSSBQ
INIDES
PSSTA
REGINTUL
QLIMDL
SSDESDL
QLIMUL
QDESDL
QOFFSETDL
LCOMPDL
QOFFSETDLAFR
QOFFSETUL
POWER CONTROL
(Bs)
Parameter
ACC
CRH
HANDOVER
MO
Power Control (BS)
QCOMPDL
REGINTDL
QOFFSETULAFR
SSLENDL
SDCCHREG
QLENDL
Note: detailed explanation mentioned in attached excel.
Ericsson Internal | 2012-06-22 | Page 9
Layer 2 troubleshooting process –
parameter RECOMMENDATIONS [L2] CONTD…
FOLLOWING SET OF Parameters can be CONSIDERED FOR IMPROVING
THE Mobility performance
Ericsson Internal | 2012-06-22 | Page 10
Parameter
Default
BQOFFSET
3
BSRXSUFF
-
KHYST
3
KOFFSET
0
LHYST
3
LOFFSET
0
LOHYST
3
MSRXSUFF
-
OFFSET
0
PSSBQ
10
PSSTA
63
QLIMDL
55
QLIMUL
55
TRHYST
2
TROFFSET
0
MOBILITY improvement –
NEW FEATURES [L3]
FOLLOWING SET OF FEATURES can be CONSIDERED FOR IMPROVING THE
MOBILITY PERFORMANCE
LICENSE
FEATURE NAME
FAJ 122 625
Enhanced Handover Success Rate
FAJ 122 181
Handover of Traffic at Channel Blocking
FAJ 122 429
Handover Power boost
Ericsson Internal | 2012-06-22 | Page 11
MOBILITY IMPROVEMENT -
CASE STUDY 1 - Dragged handover
A Quality handover
should happen earlier
Ericsson Internal | 2012-06-22 | Page 12
MOBILITY IMPROVEMENT -
CASE STUDY 2 - MISSING NEIGHBORS
Ericsson Internal | 2012-06-22 | Page 13
MOBILITY IMPROVEMENT CASE STUDY 3 - BCCH COLLISION
Ericsson Internal | 2012-06-22 | Page 14