2g_kpi presentation and optimization techniques
TRANSCRIPT
KEY PERFORMANCE INDICATORS
Call Drop Rate (%) = No. of Drop Calls / No. of Calls
= Rate of Drop Calls (system+radio+handover) over the total amount of calls with a
successful end.
Call Setup Success Rate (%) = (1-SDCCH Drop Rate) * (1-RTCH Assign Unsuccessful Rate)
= Rate of calls going until RTCH successful assignment
( from SDCCH seizure to RTCH seizure )
Handover Incoming = HO Incoming Success / HO Incoming Request
Success Rate (%) = Rate of Incoming External and Internal Intercell RTCH and SDCCH HO
successes over the total amount of Incoming External and Internal Intercell HO
requests.
DEFINITION OF TERMS
CALL DROP RATE
Main Causes of Call Drop
1. Drop Call due to Radio Problem
2. Drop Call due to Handover Problem
3. Drop Call Due to System Problem
GSM RadioProblem
Bad Settingsfor HO
Algorithm
Isolated Cell
ClockProblem
CommunicationDuration
Unbalanced
InterferedFrequency
BadAdjacencyP lanning
W rongHandov er
CALL DROP DUE TO RADIO PROBLEM
CALL DROP DUE TO HANDOVER PROBLEM
GSMHandoverProblem
DuplicateBCCH,BSIC
Target CellCongested
CELLInterfered
WrongHandover
Declaration
CoverageProblem
Bad Settingsof PowerControl
Algorithm
ClockProblem
Too much TCHTraffic
RTCH always busy
FU Blocked
Loss of TCHresources
Some Planned Adjacencies arenot declared at OM CR
Some Operational Adjacenciesare not Planned
Adjacencies not declared onboth side
InterferedFrequency
CALL DROP DUE TO SYSTEM PROBLEM
GSMSystemProblem
RemoteTranscoder
Problem
BSS InternalFailures
SystemProblem on
BSC
SystemProblem on
Cell
CALL SETUP SUCCESS RATE
Main Causes of Call Setup Problem
1. RTCH Assignment Failure Problem
2. SDCCH Drop Problem
TCHAssignment Fail
Problem
TCH AssignFail System
TCH AssignFail Radio
RadioEquipment
Problem
AbisProgramming
Problem
FU Blocked
CALL SETUP PROBLEM DUE TO RTCH ASSIGNMENT FAIL
CALL SETUP PROBLEM DUE TO SDCCH DROP PROBLEM
SDCCH DropProblem
SDCCH DropSystem
SDCCH DropHO
SDCCH DropRadio
Link Failure
ProcessorRestart
BSS Int.Problem
SDCCH HO notActivated
TCH RadioProblem
StandaloneSDCCH HO
Problem
TCH HOProblem
HANDOVER SUCCESS RATE
TOPICS TO BE DISCUSSED:
• Few Handovers on Better Cell
• Intra Cell Handover Problem
• Incoming Handover Problem
• Outgoing Handover Problem
FEW HANDOVERS ON BETTER CELL
FewHandoverson Better
Cell
Too manyHO onQuality
Too manyHO on Level
InterferedFrequency
PotentialInterferer
AdjacentInterferer
Co-channelInterferer
ExternalInterferer
Problem ofUplink
Reception
Problem ofDownlink
Transmission
INTRACELL HANDOVER PROBLEM
Main Causes of Intracell Handover Problem
1. Congestion Problem
2. HO Failure with Reversion to Old Channel
3. HO Fail with Drop Call
INTRACELL HANDOVER PROBLEM DUE TO CONGESTION PROBLEM
Problem ofCongestion
RTCH alwaysBusy
FU Blocked
Loss of TCHResource
Too M uch TCHTraffic
INTRACELL HANDOVER PROBLEM DUE TO REVERSION TO OLD CHANNEL
HO Fail withReversion to Old
ChannelInterfered Cell
InterferedFrequency
INTRACELL HANDOVER PROBLEM WITH CALL DROP
HO Fail withDropped Call
SystemProblem on
BSC
Bad Settings ofIntracell HO
Timer
Dropped Calldue to System
Failure
Dropped Calldue to Radio
Failure
SystemProblem on
Cell
InterferedFrequency
Interfered Cell
PROBLEM OF UNSUCCESSFUL INCOMING HANDOVER
Main Causes of Incoming Handover Problem
1. Problem of HO Congestion
2. HO Failure Problem
PROBLEM OF UNSUCCESSFUL INCOMING HANDOVER DUE TO CONGESTION
Problem ofHO
Congestion
Problem ofToo M uch
TCH Traffic
RTCH AlwaysBusy
FU Blocked
Loss of TCHResources
Problem ofHO Failures
HO Failure -System
HO Failure -Radio
Wrong HORelationship
OutgoingProblem onServing Cell
Outgoing Problemon Internal Serving
Cell
Outgoing Problemon External Serving
Cell
DuplicateBCCH, BSIC
ClockProblem
InterferedCell
SystemProblem on
BSC
SystemProblem on
Cell
InterferedFrequency
InterferedFrequency
InterferedCell
CoverageProblem
Bad Settings ofHO Algorithm
Bad Settings ofPower Control
Algorithm
InterferedCell
InterferedFrequency
CoverageProblem
Bad Settings ofHO Algorithm
Bad Settings ofPower Control
Algorithm
PROBLEM OF UNSUCCESSFUL INCOMING HANDOVER DUE TO HANDOVER FAILURE PROBLEM
PROBLEM OF UNSUCCESSFUL OUTGOING HANDOVER
Main Causes of Unsuccessful Outgoing Handover
1. Problem of High Handover Reversion
2. Problem of Drop Calls
PROBLEM OF UNSUCCESSFUL OUTGOING HANDOVER DUE TO HIGH HANDOVER REVERSION
Pb of High HOReversion
Congestion onTarget Cell
Incoming Pb onTarget Cell
Congestion onInternal Target Cell
Incoming Pb onInternal Target Cell
Congestion onExternal Target Cell
Incoming Pb onExternal Target Cell
Too M uch TCHTraffic
FU Blocked
Loss of TCHResources
RTCH Always Busy
Congestion onTarget Cell
Congestion onTarget Cell
Congestion onTarget Cell
Congestion onTarget Cell
Interfered Cell
Duplicate(BCCH,BSIC)
Clock Problem
Wrong HORelationshipDeclarations
System Drop duringExternal HO
System Drop duringInternal HO
PROBLEM OF UNSUCCESSFUL OUTGOING HANDOVER DUE TO DROP CALLS
Pb of Drop Calls
HO Drop Radio
HO Drop System
Radio Drop duringExternal HO
Radio Drop duringInternal HO
System Drop duringExternal HO
System Drop duringInternal HO
OPTIMIZATION TECHNIQUES
1 2
Channel Request Channel Request
Imm Assignment Imm Assignment
Service Request Service Request
Signalling SDCCH Signalling: :
Signalling SpeechTCH
RLT = 0 ; DROPS RLT = 0 ; DROPSSDCCH DROP ! TCH DROP !
3 SDCCH / TCH
Handover Command
Hand Access
Handover Failure
HANDOVER FAILURE DROP !
DROP CALL PROBLEM ANALYSIS
• SDCCH Drops - Causes
– Coverage
– Interference & Multipath
– BTS performance
• TCH Drops - Causes
– Coverage
– Interference & Multipath
– BTS performance
• Handover Failure - Causes
– Threshold parameters
– Missing neighbors
DROP CALL PROBLEM CAUSES
DROP CALL PROBLEM SOLUTIONS
– Optimize Coverage– Interference Management– Optimize neighbors– Optimize handover
parameters– Effective Frequency Hopping– Use of DTX & Power control
1
Channel RequestRACH .
:RACH
max_retransNO RESPONSE FROM N/WACCESS FAILURE !
2
Channel RequestRACH
Imm Assign Reject
SDCCH BLOCKED !
3
Channel Request
Imm Assignment
Service Request
Signalling:
Signalling
NO TCH ASSIGNMENTMobile Returns To IdleTCH BLOCKED !
CALL SETUP PROBLEM ANALYSIS
`̀
– Optimize Coverage– Interference Management– Optimize Capacity– Effective Frequency Hopping– Use of DTX & Power control
CALL SETUP PROBLEM SOLUTIONS
MOBILE A BTS A BSC A MSC BSC B BTS B MOBILE B
SYS INFO 5 & 6 BTS MEAS. RESULT
MEASUREMENT REP MS MEAS. RESULT
SACCH
HANDOVER REQ’D
HANDOVER RQSTCHANNEL ACT.
ACT. ACK.
HO RQST ACK
HANDOVER ACCESSHANDOVER DETECT
FACCH
HO COMMANDHO COMMAND DATA REQUEST
RELEASE RQST PHYSICAL INFO
PHYSICAL INFO
SABM EST INDICATION
UA
HO COMPLETE DATA INDICATION HO COMPLETE
CLEAR CMD
CLEAR CMPLT
RELEASE RF CHNL RELEASE
RF CHNL REL. ACK. RELEASE CMPLT
INTER - BSC HANDOVER
HANDOVER PROBLEM SOLUTIONS
– Optimize Coverage– Interference Management– Optimize Neighbors– Optimize Handover
parameters
ADDITIONAL INFORMATION
SYSTEM INFORMATION TYPE 5
- Neighbour cells description which gives the ARFCN’s of the neighbour cells to be monitored and reported by the mobile. Note that this also an offset and a bit map listing up to 124 ARFCN’s.
SYSTEM INFORMATION TYPE 6
1. Cell Identity (CI) to identify any cell in a given location area.2. Location Area Identification including:
• The Mobile Country Code (MCC)• The Mobile Network Code (MNC)• The Location Area Code (LAC)
3. Cell Options including• Power Control Enabled• DTX Enabled• The value of the Radio Link Timeout counter
4. PLM permitted which lists the network color codes (NCC’s) which the mobile can use.
ADDITIONAL INFORMATION
TYPES OF HANDOVERS
• PREVENTATIVE HO
- Improve Call Quality or Minimize Interference
1. Power Budget – Based on Downlink Signal Levels - Uses Power Budget HO Margin - If Neighbor is better than Serving Cell by more than the margin, initiate HO.
2. Timing Advance – Based on Timing Advance - If Serving Cell Timing Advance is greater than a set distance and Neighbor Cell is better than the serving cell by more than the margin then initiate HO.
ADDITIONAL INFORMATION • RESCUE HO
- Prevent Dropped Calls or Poor Quality Calls
1. Level – Intended to HO a call before the signal level gets so low that quality is affected
- Triggered on both UPLINK and DOWNLIK
- Uses HO Level Margin
- If Serving Cell RXLev ( UL or DL ) is lower than a set value, and Neighbor Cell is better than the serving cell by more than the margin, then initiate HO.
2. Quality – Intended to HO the Call Before the Quality level gets so low that the customer notices
- Triggered on both UPLINK and DOWNLIK
- Uses Quality HO Margin
- If Serving Cell RXQual ( UL or DL ) is lower than a set value, and Neighbor Cell is better than the serving cell by more than the margin, then initiate HO.
END OF PRESENTATION