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KPI
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GSM KPI Improvement Process / Guidelines
Limited Internal NPI Training - Retainability 2005-09-302
Key Performance Indicators - KPIs
SDCCH Blocking
SDCCH Drop
TCH Drop Rate
Handover Success Rate
Limited Internal NPI Training - Retainability 2005-09-303
Accessibility DefinitionCall to an MS
9805024
BSC
MSC/VLR
TRC
BTS
BTS
1
2
4
5
2
2
2
3
1
4
356
1. MSC/VLR sends paging command to all BSCs belonging to the location area (LA) where MS is located
2. BSC forwards the paging command to all BTSs in that LA, and the BTSs in their turn page the MS on the PCH
3. The MS responds to the BTS on the RACH and the BTS forwards the response to the BSC (forward to MSC)
4. The BSCs checks with the BTS if it has an SDCCH available and the BTS grants the MS an SDCCH by using the AGCH
5. The MS and the BTS signal on the SDCCH, measurement reports sent on SACCH are forwarded from the BTS to the BSC and once the signalling is done the BSC decides which TCH to use
6. TCH connection established between MS and BTS
Accessibi lit y
Limited Internal NPI Training - Retainability 2005-09-304
SDCCH Congestion – Overview
SDCCH Activities:
Mobility Management– Normal Location update– Periodic Registration– IMSI Attach / Detach
Connection Management– Call setup– SMS Point to Point– Fax Setup– Supplementary Services
Limited Internal NPI Training - Retainability 2005-09-305
SDCCH Congestion – Overview
Channel Configuration:
Channel Configuration can be done as follow– Combined BCCH/SDCCH on 1 TS (SDCCH/4)– Non-Combined BCCH and SDCCH on 2 TS (SDCCH/8)
Cell Broadcast Channel (CBCH)– The Cell Broadcast service provides the transmission of an SMS from a
message-handling centre to all MSs in the serving area of the BTS. – If the Cell Broadcast service is active in a cell, one signaling sub-channel is
replaced by one CBCH resulting in a SDCCH/7
Limited Internal NPI Training - Retainability 2005-09-306
SDCCH Congestion – Overview
SDCCH Channel Allocation Profile (CHAP)
Channel Allocation is the feature that selects and allocates suitable channels when one or more channels are required
Channel Allocation Profile (CHAP) is the parameter that provides different channel allocation strategies
For SDCCH assignments, CHAP 8 prioritize new assignments as follows:
1. OL/SDCCH2. UL/SDCCH (if OL/SDCCH is congested)
Limited Internal NPI Training - Retainability 2005-09-307
SDCCH Congestion – Overview
OL (CHGR 0)
UL (CHGR 1)TT T T T T T T
ST T T T T T T
TT T T T T T T
SB T T T T P P
A new assignment will use the SDCCH in OL first
OL (CHGR 0)
UL (CHGR 1)TT T T T T T T
ST T T T T T T
TT T T T T T T
SB T T T T P P
If the OL is congested, the SDCCH in UL will be used
NoteSDCCH congestion in the OL will increment, but this is not customer perceived since the SDCCH in UL will then be utilized
B
S
T
P
BCCH timeslot
SDCCH timeslot
TCH timeslot
PDCH timeslot
Limited Internal NPI Training - Retainability 2005-09-308
SDCCH Dimensioning Strategy
GOS Approach:
SDCCH should be dimensioned for better GOS compare to TCH. Typical range is 0.5% - 1%.
Immediate Assignment of TCH with “TCH as last option strategy” is recommended.
It is recommended to add SDCCH when 0.5 Erlang of signaling traffic is carried by TCH.
Half Rate penetration, usage of Extended Range cell and HSCSD should be taken into consideration.
STS Approach:
Accurate dimensioning is achieved by using STS cell statistics
Limited Internal NPI Training - Retainability 2005-09-309
SDCCH Congestion Optimization
Analyze the following issues that could be possible reasons for SDCCH Congestion:
SDCCH Dimensioning Incorrect use of SDCCH capacity features such as
Adaptive Configuration of Logical channels TCH Congestion Location Areas not optimized SMS usage and Cell Broadcast channel SDCCH Availability
Limited Internal NPI Training - Retainability 2005-09-3010
SDCCH Congestion Optimization
The following recommendations will have a positive impact on SDCCH congestion
Try not to use combined BCCH/SDCCH (SDCCH/4) Use the optional SDCCH capacity features such as the Adaptive
Configuration of Logical Channel feature when available. Use Immediate Assignment on TCH, SDCCH first. For manual dimensioning, use STS cell statistics Configure one SDCCH on the BCCH carrier and the others on the
hopping layer (Non-BCCH) Use the Ericsson SDCCH Dimensioning guideline.
Limited Internal NPI Training - Retainability 2005-09-3011
SDCCH Congestion Optimization
The following issues are worth taking into account when analyzing SDCCH Congestion:
Use LAPD STS statistics to evaluate LAPD congestion and optimize the LAPD Concentration factor
Analyze border cells with a large amount of random access attempts resulting in SDCCH congestion.
– Use Random Access optimization to solve the SDCCH congestion
Take into account Timeslot priority when deciding where to configure SDCCH/8
Limited Internal NPI Training - Retainability 2005-09-3012
SDCCH Congestion Optimization
S D C C H C o n g e s t i o n
C h e c k s i t e p o s i t i o n
L o c a t i o n a r e a
b o r d e r ?C h a n g e L o c a t i o n
A r e a B o r d e r
C h e c k a n d i n c r e a s eC R H
C h e c k T C H t r a f f i c
T C HC o n g e s t i o n ?
C h e c k S M S a c t i v i t y
M a n y S M Sm e s s a g e s ?
E
C h e c k p e r i o d i cr e g i s t r a t i o n
T o o f r e q u e n tr e g i s t r a t i o n ?
C h e c k H W a v a i l a b i l t y
L o wa v a i l a b i l i t y ?
S e e T C H & S D C C H
A v a i l a b i l i t y
A d d T C Hc a p a c i t y
R e d i m e n s i o n S D C C H
C h a n g e r e g i s t r a t i o ni n t e r v a l t i m e r s
N O
Y E S
N O
N O
N O
Y E S
Y E S
Y E S
N O
Y E S
Y E S
Limited Internal NPI Training - Retainability 2005-09-3013
SDCCH Congestion Optimization
C h e c k c h a n n e l c o n f i g u r a t i o n
C o m b i n e dS D C C H ?
C h e c k t r a f f i c t r e n d
S h o r t t e r mt r a f f i c g r o w t h ?
C h e c k S D C C H d i m e n s i o n i n g
E
U n d e r d i m e n s i o n e dS D C C H ?
C h e c k S D C C H m e a n h o l d i n g t i m e
L o n g m e a n h o l d i n gt i m e ?
I s c e l l b r o a d c a s tu s e d ?
A v o i d c e l l b r o a d c a s t i fp o s s i b l e
M a k e c h a n n e ln o n - c o m b i n e d
N o a c t i v i t y
C h e c k H W a n d n u m b e ro f F a l s e A c c e s s e s
R e d i m e n s i o nS D C C H
E N D
N O
N O
Y E S
Y E S
Y E S
Y E S
Y E S
N O
N O
N O
C h e c k A d a p t i v e c o n f i g u r a t i o n o fl o g i c a l c h a n n e l a n d p a r a m e t e r s
A C S T A T E o f f ? S w i t c h o nY E S
Limited Internal NPI Training - Retainability 2005-09-3014
SDCCH Drops – Overview
SDCCH Drops are classified into one of the following categories:
SDCCH Drops because of Timing Advance SDCCH Drops because of Low Signal Strength SDCCH Drops because of Bad Quality SDCCH Drops due to Other Reasons
Limited Internal NPI Training - Retainability 2005-09-3015
SDCCH Drops – Overview
MSMSC BSC BTSChannel Request
Channel Required
1
2
3
Immediate Assignment RejectY
4 Channel Activation
5n6
Channel Activation Ack.
Channel ActivationChannel Activation Ack.
6n
Chan. Neg. Ack.
Chan. Neg. Ack.Immediate Assignment
Establish IndicationSCCP Conn. ReqSCCP Conn. Conf.
SABM, UA
Signaling Connection Set-up
5
N
Too high TA ?Wrong Cause Code?
Y
NToo high processor load ?
Step related RA counter
Free ch. Available?
YNActivation of channel successful?
Y
N
Random Access
Step CMSESTAB counter
Limited Internal NPI Training - Retainability 2005-09-3016
SDCCH Drops – OverviewAssignment: Assignment to Serving Cell
MSC BSC BTS MS
Assignment Request
N
Y
SABMUAEstablish Indication
Assignment Command
Assignment Complete
Assignment Compl.
Channel Activation
XChannel Act. Ack.
Channel Act. Neg. Ack.
RF Channel Release, old channel
RF Channel Release Ack.
Possible to assign channel?
If TCH Congestion CNRELCONG is stepped (time out).
Limited Internal NPI Training - Retainability 2005-09-3017
SDCCH Drops – OverviewConnection Release, Normal Disconnection
MSC BSC BTS MS
Clear Command
Channel ReleaseClear Complete
Deactivate SACCH
DISC
UARelease Indication
RF Channel Release
RF Channel Release Ack
SCCP Rel.
SCCP Rel. Ack.
1
Check Cause codes, if not HO successful or Call Control, step drop call counter, CNDROP
Limited Internal NPI Training - Retainability 2005-09-3018
SDCCH Drops – OverviewConnection Release, Abnormal Disconnection
MSC BSC BTS
Clear Command
Channel Release
Clear CompleteDeactivate SACCH
DISC
UARelease Indication
RF Channel Release
RF Channel Release Ack
SCCP Rel.
SCCP Rel. Ack.
Clear Request Step drop call counter, CNDROP
Limited Internal NPI Training - Retainability 2005-09-3019
SDCCH Drop Optimization
Analyze the following issues that could be possible reasons for SDCCH Drops:
Low signal strength Interference Pathloss Imbalance between UL/DL High Timing Advance MS error or Subscriber behavior TCH Congestion Transmission Congestion (LAPD Concentration) Hardware or Transmission failures
Limited Internal NPI Training - Retainability 2005-09-3020
SDCCH Drop Optimization
The following issues are worth taking into account when analyzing SDCCH Drops:
SDCCH Drops and TCH Drops often drop because of the same RF reasons, such as for example insufficient coverage
Only use SDCCH power regulation and SDCCH HO when the network has good coverage
BSC and transmission problems can impact SDCCH drops so investigate Transcoders, A-interface and LAPD
SDCCH Drops on the hopping layer are normally showing worse values than SDCCH on the BCCH
Limited Internal NPI Training - Retainability 2005-09-3021
SDCCH Drop Optimization
C h e c k S D C C H D r o p p e d P e r C e l l
C h e c k d r o pr e a s o n
B a dq u a l i t y ?
• C h e c k I C M• C h e c k f r e q u e n c y P l a n•
F r e q u e n c y s c a n•R u n M R R & F A S
L o wS S ?
• R e f e r t o L o w S Sa n a l y s i s f l o w c h a r t .
H i g hT A ?
• C h e c k s i t e l o c a t i o n& T A L I M
T C HC o n g e s t i o n ?
• C h e c k S _ D R - S _ N T C• I n c r e a s e T C H o r u s i n g
C h e c k B T S e r r o rl o g
H Wf a u l t ?
• S w a p &R e p a i r H W
B
N O
Y E S
Y E S
Y E S
Y E S
Y E S
N O
N O
N O
N O
R a d i o F e a t u r e s , C L S , H C S
Limited Internal NPI Training - Retainability 2005-09-3022
SDCCH Drop Optimization
B
T r a n s m i s s i o n f a u l t ?
• P e r f o r m l i n ki n v e s t i g a t i o n
C h e c k L i n k Q u a l i t y
C h e c k M S f l e e t
P e r f o r m D r i v e T e s t
P e r f o r m M T R / C T R / M R R
P e r f o r m s i t e s u r v e y
C h e c k a n t e n n a i n s t a l l a t i o n
E N D
Y E S
N O
Limited Internal NPI Training - Retainability 2005-09-3023
TCH Drop – Overview
MSC BSC BTS MS
Clear Command
Channel ReleaseClear Complete
Deactivate SACCH
DISC
UARelease Indication
RF Channel Release
RF Channel Release Ack
SCCP Rel.
SCCP Rel. Ack.
1
Check Cause codes, if not HO successful or Call Control, step drop call counter, TFNDROP
Connection Release, Normal Disconnection
Limited Internal NPI Training - Retainability 2005-09-3024
TCH Drop – OverviewConnection Release, Abnormal Disconnection
MSC BSC BTS
Clear Command
Channel Release
Clear Complete
Deactivate SACCH
DISC
UARelease Indication
RF Channel Release
RF Channel Release Ack
SCCP Rel .
SCCP Rel . Ack .
Clear Request Step drop call counter,TFNDROP
Limited Internal NPI Training - Retainability 2005-09-3025
TCH Drop – Drop Call Reasons
The TCH Drop Call reasons has the following priority order:
Excessive TA – TA > TALIM cell parameter
Low signal strength in downlink and/or uplink – SSUL < LOWSSUL (BSC parameter)– SSDL < LOWSSDL
Bad quality in downlink and/or uplink– RxQualUL> BADQUL (BSC parameter)– RxQualDL> BADQDL
Sudden loss of connection– None of the above
Other– Non radio-related
Limited Internal NPI Training - Retainability 2005-09-3026
TCH Drop – Drop Call ReasonsThe TCH Drop Call reasons counters:
-60-110
SS downlink
SS uplink
-115
-110
-60
BTS sensitivity-111
-104
MS
se n
siti
v ity
LOWSSUL
-104
-104
LO
WS
SD
L TxDISSQADLTxDISSQAULTxDISSQABL
TxDISSULTxDISSBL
TxDISSDL
Limited Internal NPI Training - Retainability 2005-09-3027
TCH Drop parameters
RLINKT
STS Workshop43
Radio Link Time -out
Limited Internal NPI Training - Retainability 2005-09-3028
TCH Drop parameters
RLINKT
The MS sends measurement reports regarding the signal strength of neighbor cells every 480 ms
If the BTS does not receive a measurement report the RLINKT timer is decreased by 1.
If a new report is received the timer is increased by 2. Leaky bucket. When reaches 0 call is dropped
Limited Internal NPI Training - Retainability 2005-09-3029
TCH Drop – Optimization
Analyze the following issues that could be possible reasons for poor TCH Drop performance:
– Low Signal strength on Uplink/Downlink– Interference on Uplink/Downlink– Excessive TA– Incorrect/Not optimum Parameter settings for example power
regulation– Missing Ncells or Congestion in Ncells– MS or MS Battery problems– Subscriber Behavior– Antenna/Hardware or Transmission faults– Incorrect Installations
Limited Internal NPI Training - Retainability 2005-09-3030
TCH Drop – Optimization
The following issues often cause TCH Sudden Drops:
– Very sudden and severe drop in signal strength, such as when– subscribers enter into buildings, elevators, parking garages, etc.– Very sudden and severe occurrence of interference or bad
quality.– MS running out of battery during conversation.– Handover Lost– BTS HW faults.– Synchronization or Abis link fault (transmission faults).– MS Faults
Limited Internal NPI Training - Retainability 2005-09-3031
TCH Drop – Optimization
D r o p p e d C a l l s o n T C H
C h e c k r a d i o n e t w o r k f e a t u r e s
P o w e r r e g u l a t i o nu s e d p r o p e r l y ?
D T Xu s e d ?
C h e c k o u t p u t p o w e r
C h e c k l o c a t i n g p a r a m e t e r s
B a d p a r a m e t e rs e t t i n g ?
P o w e rb a l a n c e ?
A d j u s t o u t p u t p o w e r
I n t r o d u c eD T X
C o r r e c t p a r a m e t e rs e t t i n g
F r e q u e n c yh o p p i n g
u s e d ?
A c t i v a t e f r e q u e n c yh o p p i n g
N O
C o r r e c t p o w e r r e g u l a t i o np a r a m e t e r s
Y E S
N O
Y E S
Y E S
N O
N O
Y E S
N O
M i s s i n gn e i g h b o u r s ? Y E S R u n N C S
Y E S
C h e c k d r o p p e d c a l lr e a s o n
B a dq u a l i t y ?
L o w s i g n a ls t r e n g t h
P e r f o r m i n t e r f e r e n c ea n a l y s i s
P e r f o r m l o w s i g n a ls t r e n g t h a n a l y s i sA
N O
N O
Y E S
Y E SN O
Limited Internal NPI Training - Retainability 2005-09-3032
TCH Drop – Optimization
M o s t d r o p p e d C a l l d u r i n g
H O ?
C h e c k l o s th a n d o v e r s
P e r f o r m h a n d o v e ra n a l y s i s
S w a p & r e p a i rH W
C h e c k s i t ep o s i t i o n
D r a g o o ns i t e ?
C h e c k M S f l e e t
B e s t s e r v e re x i s t s ?
C h e c k a n t e n n ai n s t a l l a t i o n
P e r f o r m s i t e s u r v e y
C h e c k B T S E r r o r L o g
H Wf a u l t ?
T r a n s m i s s i o nf a u l t ?
C h e c k l i n k q u a l i t y a n dS y n c h r o n i z a t i o n
R e m o v e s i t e o r c h a n g e
f r e q u e n c y
P e r f o r m l i n ki n v e s t i g a t i o n
A d d s i t e
P e r f o r m M T R / C T Rr e c o r d i n g s
P e r f o r m d r i v e t e s t s
H i g h t i m i n ga d v a n c e
E N D
A
C h e c k s i t e l o c a t i o n
& T A L I MY E S
N O
Y E S
N O
N O
Y E S
N O
Y E S
Y E S
N O
N O
Y E S
C h e c k D r o p p e d C a l l s p e r T S b a s i s
Limited Internal NPI Training - Retainability 2005-09-3033
TCH Drop – Optimization
L o w s i g n a l s t r e n g t ha n a l y s i s
I d e n t i f y b a s e l i n e r e q u i r e m e n t s
C h e c k s i t e p o s i t i o n
C h e c k i f u p l i n k o r d o w n l i n k p r o b l e m
C h e c k c o v e r a g e p l o t s
C h e c k i f o m n i s i t e
C h e c k a n t e n n a c o n f i g u r a t i o n
C h e c k o u t p u t p o w e r
C a l c u l a t e p o w e r b a l a n c e & l i n kb u d g e t
P e r f o r m d r i v e t e s t s
M a k e s i t e v i s i t
P e r f o r m M T R / C T R r e c o r d i n g s
C h e c k i f i n d o o r p r o b l e m
C o r r e c tp r o b l e m
Limited Internal NPI Training - Retainability 2005-09-3034
TCH Drop – Optimization
Investigate TCH Drop Performance - MOTS:
MOTS_toolMOTS
Limited Internal NPI Training - Retainability 2005-09-3035
AssignmentRequest IL01673 17:04:49
HandoverCommand IL01673 IL04071 17:05:15
HandoverComplete IL04071 17:05:16
HandoverCommand IL04071 IL00053 17:05:27
HandoverComplete IL00053 17:05:27
HandoverCommand IL00053 IL04072 17:05:57
HandoverComplete IL04072 17:05:58
HandoverCommand IL04072 IL02752 17:06:37
HandoverComplete IL02752 17:06:39
ClearRequest IL02752 17:06:49
ClearCommand IL02752 17:06:49
Drop (Clear Request) because wrong decision to HO from IL04072 to IL02752.Solution: Inhibit that HO relation.
: STS pegged drop in IL02752
: Actual drop occured south of IL04072
StartStart
STS-Drop
STS-Drop
Actualdrop-position
Actualdrop-position
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Limited Internal NPI Training - Retainability 2005-09-3036
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
BSIC Confusion• In this example mobiles do not handover to the correct cell but to a cell whose frequency it
measure previously.• In RPMO, this can be seen from the drop table. • For example in the map a mobile traveling south needed to handov er from IL0020.2 to IL1058.0.
IL1058.0 has BCCH 137, and IL0404.3 has BCCH is 137. Mobile meas ured IL0404 previously, and this can be seen from RPMO measurement reports.
• When mobile needed to handover from IL0020.2 to IL1058.0, it act ually makes wrong handover to IL0404.3.
Limited Internal NPI Training - Retainability 2005-09-3037
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Dropped Call due to Bad Quality• All drops due to bad quality UL/DL can be seen easily from RPMO drop and measurement table. • The table below is a example of a short call. Call ID is 59714, and it lasted about 47 seconds. • We can easily see that RXQual DL was bad since the call started.• In this market, RLINK timer set to 32. Therefore, there may be s ome measurement missing ~16
seconds before the clear command. • The table shows several missing report between starting from 17: 43:44 until 17:44:00.
Tie
r
cC
allN
r
Ev
en
tNa
me
Ce
ll
Tid
TA
RQ
UL
RQ
DL
RL
UL
RL
DL
SQ
I
BT
SP
R
MS
PC
NrN
g
Rx
Lev
DL
co
m
p
0 59714 MeasurementReport IL00442 17:43:13 10 2 6 22 28 40 0 5 0 28 0 59714 MeasurementReport IL00442 17:43:16 10 5 7 14 23 49 0 6 0 23 0 59714 MeasurementReport IL00442 17:43:19 10 3 5 19 27 255 0 5 0 27 0 59714 MeasurementReport IL00442 17:43:21 10 0 7 22 22 43 0 6 0 22 0 59714 MeasurementReport IL00442 17:43:24 11 2 7 21 24 255 0 6 0 24 0 59714 MeasurementReport IL00442 17:43:26 10 7 15 10 255 255 0 5 0 255 0 59714 MeasurementReport IL00442 17:43:28 11 4 6 22 26 48 0 5 0 26 0 59714 MeasurementReport IL00442 17:43:31 11 3 7 21 21 255 0 5 0 21 0 59714 MeasurementReport IL00442 17:43:34 11 2 7 21 24 255 0 5 0 24 0 59714 MeasurementReport IL00442 17:43:37 11 4 7 21 24 255 0 5 0 24 0 597 14 MeasurementReport IL00442 17:43:40 11 4 7 21 24 255 0 5 0 24 0 59714 MeasurementReport IL00442 17:43:42 10 6 15 18 255 255 0 5 0 255 0 59714 MeasurementReport IL00442 17:43:44 11 3 7 18 17 255 0 5 0 17 0 59714 MeasurementReport IL00442 17:43:47 11 7 15 6 255 255 0 5 0 255 0 59714 MeasurementReport IL00442 17:43:50 11 7 15 6 255 255 0 5 0 255 0 59714 MeasurementReport IL00442 17:43:53 11 7 15 6 255 255 0 5 0 255 0 59714 MeasurementReport IL00442 17:43:56 11 7 15 11 255 255 0 5 0 255 0 59714 Measure mentReport IL00442 17:43:59 11 7 15 12 255 255 0 5 0 255 0 59714 ClearRequest IL00442 17:44:00 0 59714 ClearCommand IL00442 17:44:00
Limited Internal NPI Training - Retainability 2005-09-3038
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Dropped Call due to Bad SS• We can see the calls dropped due to low signal strength in RPMO.• From measurement reports, we can see when there is a drop due to low signal strength UL/DL, or
both links. • In the table, if we look at the part before the clear request, w e can see that RLDL (RX level DL),
and RLUL (RX level UL) is quite low. In this example this call d ropped due to low SS RX level both links.
cC
allN
r
cE
ven
tC
ou
nt
Even
t id
Even
tN
am
e
Cell
Tid
TA
RQ
UL
RQ
DL
RL
UL
RL
DL
SQ
I
BT
SP
R
MS
PC
NrN
g
RxL
evD
Lco
mp
9468 141 4 MeasurementReport IL04083 17:15:05 5 5 5 9 12 41 0 5 2 12 9468 142 4 Measure mentReport IL04083 17:15:08 6 5 4 10 15 46 0 5 1 15 9468 143 4 MeasurementReport IL04083 17:15:11 6 6 6 7 13 46 0 5 0 13 9468 144 4 MeasurementReport IL04083 17:15:14 6 4 2 9 14 46 0 5 2 14 9468 145 4 MeasurementReport IL04083 17:15:17 6 5 6 7 8 39 0 5 1 8 9468 146 4 MeasurementReport IL04083 17:15:21 5 7 15 3 255 31 0 5 2 255 9468 147 4 MeasurementReport IL04083 17:15:24 6 7 15 6 255 18 0 5 1 255 9468 148 4 MeasurementReport IL04083 17:15:26 6 7 5 2 2 17 0 5 0 2 9468 149 4 MeasurementReport IL04083 17:15:29 6 7 6 2 2 11 0 5 0 2 9468 150 4 MeasurementReport IL04083 17:15:31 6 7 15 0 255 16 0 5 5 255 9468 151 4 MeasurementReport IL04083 17:15:34 6 7 6 2 6 19 0 5 0 6 9468 152 4 MeasurementReport IL04083 17:15:36 6 6 4 2 6 30 0 5 0 6 9468 153 4 Measu rementReport IL04083 17:15:38 6 6 5 1 8 27 0 5 0 8 9468 154 4 MeasurementReport IL04083 17:15:41 6 7 15 0 255 23 0 5 1 255 9468 155 4 MeasurementReport IL04083 17:15:43 6 7 15 1 255 17 0 5 2 255 9468 156 4 MeasurementReport IL04083 17:15:46 6 5 5 7 7 17 0 5 0 7 9468 157 4 MeasurementReport IL04083 17:15:49 6 7 15 0 255 30 0 5 0 255 9468 158 4 MeasurementReport IL04083 17:15:52 6 7 15 5 255 15 0 5 0 255 9468 159 4 MeasurementReport IL04083 17:15:55 6 7 7 3 3 19 0 5 0 3 9468 160 4 MeasurementReport IL0 4083 17:15:58 6 6 15 5 255 20 0 5 2 255 9468 161 4 MeasurementReport IL04083 17:16:01 6 7 15 2 255 24 0 5 3 255 9468 162 4 MeasurementReport IL04083 17:16:03 6 7 15 6 255 19 0 5 2 255 9468 163 2 ClearRequest IL04083 17:16:03 9468 164 3 ClearC ommand IL04083 17:16:03
Limited Internal NPI Training - Retainability 2005-09-3039
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Dropped Call due to RLINK• In the table we can see drop that happened due to RLINK timer. • In this example the call started on cell IL00231, and ended in t he same cell. The call lasted around
45 seconds. • If we look at the last 16 seconds of the call, we can see severa l missing measurement reports. • If we see 255 or or RXQual=15 we can assume that these values ar e missing• In this example we dropped the call due to low signal strength d ownlink
Tie
r
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allN
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Even
tNa
me
Ce
ll
Tid
TA
RQ
UL
RQ
DL
RL
UL
RL
DL
SQ
I
BT
SP
R
MS
PC
NrN
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RxLe
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Lcom
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1 76137 HandoverComplete IL00231 17:55:41 1 76137 MeasurementReport IL00231 17:55:44 4 3 1 16 17 42 2 5 3 21 1 76137 MeasurementReport IL00231 17:55:46 4 3 5 13 18 49 3 5 3 24 1 76137 MeasurementReport IL00231 17:5 5:49 4 5 6 6 11 41 1 6 3 13 1 76137 MeasurementReport IL00231 17:55:52 4 3 7 15 1 255 0 5 3 1 1 76137 MeasurementReport IL00231 17:55:54 4 1 1 16 14 44 0 5 3 14 1 76137 MeasurementReport IL00231 17:55:56 4 4 2 17 14 47 0 5 3 14 1 76137 MeasurementRepor t IL00231 17:55:59 4 6 1 7 18 38 1 5 3 20 1 76137 MeasurementReport IL00231 17:56:01 4 4 5 9 9 255 0 5 3 9 1 76137 MeasurementReport IL00231 17:56:04 4 7 5 4 7 43 0 5 3 7 1 76137 MeasurementReport IL00231 17:56:07 4 7 15 9 255 24 0 5 3 255 1 76137 Meas urementReport IL00231 17:56:10 4 7 15 0 255 12 0 5 3 255 1 76137 MeasurementReport IL00231 17:56:12 4 7 15 2 255 255 0 5 3 255 1 76137 MeasurementReport IL00231 17:56:15 4 7 15 3 255 14 0 5 3 255 1 76137 MeasurementReport IL00231 17:56:18 4 7 15 4 255 255 0 5 3 255 1 76137 MeasurementReport IL00231 17:56:21 4 4 6 8 4 13 0 5 2 4 1 76137 MeasurementReport IL00231 17:56:23 4 7 15 6 255 255 0 5 3 255 1 76137 MeasurementReport IL00231 17:56:26 4 7 15 5 255 20 0 5 3 255 1 76137 ClearRequest IL00231 17:56:2 6 1 76137 ClearCommand IL00231 17:56:26
Limited Internal NPI Training - Retainability 2005-09-3040
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Dropped Call due Handover Timer – T3103B1• This timer expires ~11 to 14 seconds after handover command sent . • When the timer expire, we can assume that handover command that was sent was not heard
either by the cell, or by mobile. • The table shows an example of a drop happened due to this reason . If we look the time stamp
17:05:23, we can see that we request channel from IL04271, and h andover was initiated the very same second.
• However, about 12 seconds after handover command, we can see tha t call drop. As we know, this can not be a RLINK timer drop because it is set to 32 (~16 secon ds).
cC
allN
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Ev
en
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Ce
ll
Ce
llr
Tid
Ca
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es
sa
ge
su
bc
ell
ty
pe
Ch
an
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l
Ty
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227 ChannelBusy IL02523 17:04:12 1 TCH (FR) 227 HandoverCommand IL30071 IL02523 17:04:12 227 HandoverComplete IL02523 17:04:13 1 227 ChannelBusy IL30071 17:04:19 0 TCH (FR) 227 Handover Command IL02523 IL30071 17:04:19 227 HandoverComplete IL30071 17:04:19 0 227 ChannelBusy IL02523 17:04:35 1 TCH (FR) 227 HandoverCommand IL30071 IL02523 17:04:35 227 HandoverComplete IL02523 17:04:36 1 227 ChannelBusy IL30071 17:05:11 0 TCH (FR) 227 HandoverCommand IL02523 IL30071 17:05:11 227 HandoverComplete IL30071 17:05:11 0 227 ChannelBusy IL02523 17:05:18 0 TCH (FR) 227 HandoverCommand IL30071 IL02523 17:05:18 227 HandoverComplete IL02523 17:05:19 0 227 Channel Busy IL04271 17:05:23 1 TCH (FR) 227 HandoverCommand IL02523 IL04271 17:05:23
227 ClearRequest IL02523 17:05:35
RADIO INTERFERENCE MESSAGE FAILURE TCH (FR)
227 ClearCommand IL02523 17:05:35
RADIO INTERFERENCE MESSAGE FAILURE TCH (FR)
Limited Internal NPI Training - Retainability 2005-09-3041
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Handover Timer – T3103B1
Limited Internal NPI Training - Retainability 2005-09-3042
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Dropped Call due Handover Timer – T3103B2• This timer usually expires ~ 8 to ~10 seconds after hand over co mmand request. • When this timer expires, we can assume that the MS, or target ce ll heard HO command but we do
not have any respond from them.• In the table we can see that at 17:19:46 we have handover comman d from IL04271 to IL01831.• We have clear request coming in 17:19:54 – 8 seconds after handover command
cC
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Cell
Cellr
Tid
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su
bc
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Ch
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733 ChannelBusy IL02813 17:04:04 1 SDCCH 733 HandoverCommand IL04293 IL00423 17:04:23
733 ChannelBusy IL01831 17:19:46 1 733 HandoverCommand IL04271 IL01831 17:19:46
733 ClearRequest IL04271 17:19:54
RADIO INTERFERENCE MESSAGE FAILURE TCH (FR)
733 ClearCommand IL04271 17:19:54
RADIO INTERFERENCE MESSAGE FAILURE TCH (FR)
Limited Internal NPI Training - Retainability 2005-09-3043
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
Handover Timer – T3103B2
Limited Internal NPI Training - Retainability 2005-09-3044
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
17:31:50 17:33:00:00 :10 :20 :30 :40 :50
Ce
ll 9
73
Ce
ll 2
43
1
FR
FR
FR FR
FR HR
HR FR FR
Call set -up17:31:54Call set -up17:31:54
Major mistake17:32:39Major mistake17:32:39
Actual drop moment17:32:53Actual drop moment17:32:53
Call dropped17:32:59Call dropped17:32:59
OLUL
Limited Internal NPI Training - Retainability 2005-09-3045
TCH Drop – OptimizationInvestigate TCH Drop Performance - RPMO:
17:31:50 17:33:00:00 :10 :20 :30 :40 :50
Ce
ll 9
73
Ce
ll 2
43
1
FR
FR
FR FR
FR HR
HR FR FR
HOVERCNTHOVERSUC
HOVERCNTHOVERSUC
HOVERCNTHORTTOCH
HOVERCNTHOVERSUC
HOATFRHRAMR HOSUCFRHRAMR
HOAATOLHOSUCOL
HOATHRFRAMR
THNDROPSUB
TFCASSALLTFMSESTB
TFMSESTB+SUB
TFMSESTBTFMSESTB
TFCALLSTFV3CALLSTASSALLTCASSALL
TFCALLSTFV3CALLSTFCALLSTFV3CALLS
TFCALLS + SUBTFV3CALLS+SUB(TFV2CALLS+SUBTFV1CALLS+SUBTFCONGSHO+SUB?)
TFCALLS + SUBTFV3CALLS+SUBTFMESTAB (dep)?
THMSESTB
THV3CALLSTHCALLS are not stepped
THMSESTB
THV3CALLSTHCALLS are not stepped
THMESTAB+SUBTHCALLS + SUBTHV3CALLS+SUB
TFCALLS + SUBTFV3CALLS+SUB(TFV2CALLS+SUBTFV1CALLS+SUBTFCONGSHO+SUB?)
TFCALLSTFV3CALLSTFCALLSTFV3CALLS
Limited Internal NPI Training - Retainability 2005-09-3046
TCH Drop – Optimization
Investigate TCH Drop Performance - DIP
DIP
Limited Internal NPI Training - Retainability 2005-09-3047
Handover - Overview
The fundamental concept of mobile communications is the mobility, where the person using the phone moves around being handed over between cells
HANDOVER is the process that ensures that the user is placed on the best server and that the following requirements for mobile communications are fulfilled:
– Coverage: to provide a connection with sufficient signal strength– Speech Quality: to avoid disturbances– Capacity: to even out the traffic load
LOCATING Is the software algorithm that determines Handover Decisions
Limited Internal NPI Training - Retainability 2005-09-3048
Handover - Overview
BCCHSACCH
BSIC, SS Measure Report1FACCH FACCH
HOAccess HOCommand2
HO
Det
e ct
FACCH
HOComplete
3
If all signaling goes well, call is established on target cell and old channel is released.
FACCHHOCommand3
Mobile has moved too far away from serving siteFACCH can’t reach (C/I-wise)Drop!
Or
Limited Internal NPI Training - Retainability 2005-09-3049
Handover – Locating Overview
Locating Basic Handover
Candidate list
9702661
Signalstrength aboveSUFFICIENT
level?
Moreneighbors?
Penalty evaluation
Signalstrength aboveSUFFICIENTlevel including
TROFFSET andTRHYST?
Wait untilranking of
neighbor cellis done
L-cells
K-cells
Rank n according toL-criterion including
LOFFSET and LHYST
L-cells
K-cells
Minimum levelcriterion fulfilled?
Rank n according to K-criterion including
KOFFSET and KHYST
Discard nNo
Yes
Yes No
For serving cell s
For all reported neighbor cells n
Yes
No
No
YesServing cell
is L-cell
Serving cellis K-cell
Best neighborused for serving
cell sufficientcondition
Limited Internal NPI Training - Retainability 2005-09-3050
Handover – Locating Overview
Locating Types of cell
borders
9702590
L-L border
transition border (K-L border)
equal L
equal K
effective sufficient levelfrom A to B
transition border (K-L border)
AB
effective sufficient levelfrom B to A
K-K border
Limited Internal NPI Training - Retainability 2005-09-3051
Handover – Locating Overview
Locating – Basic Ranking: Ericsson 3
The first three stages of the algorithm are performed in exactly the same way as Ericsson 1, but Ericsson 3 takes only the signal strength in account:
1. Correction of the BTS output power for downlink measurements
2. Evaluation of the Minimum Signal Strength condition3. Subtraction of the signal strength penalties4. Signal Strength Evaluation5. Combination into a basic ranking list sorted by a
descending order of SS
Limited Internal NPI Training - Retainability 2005-09-3052
Handover – Locating Overview
Locating – Basic Ranking: Ericsson 3
9 7 0 2 3 6 7
R A N Ks = S S _ D O W NsR A N Kn = p _ S S _ D O W Nn - O F F S E Ts ,n - H Y S Ts ,n
w h e re
H Y S T = H IH Y S T if rx le vn ≥ H Y S T S E PH Y S T = L O H Y S T if rx le vn < H Y S T S E P
Limited Internal NPI Training - Retainability 2005-09-3053
Handover – Locating Overview
Locating – Auxiliary Radio Network functions evaluation
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
• Assignment to another cell• Hierarchical cell structures• Overlaid and underlaid subcells• Intra-cell handover• Extended range• Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3054
Handover – Locating Overview
Locating – Auxiliary Radio Network functions evaluation
Limited Internal NPI Training - Retainability 2005-09-3055
Handover – Locating Overview
Locating – Auxiliary Radio Network functions evaluation
Categorization 1: The candidates in the ranking list are divided into categories. The signal strength is used to set the categories for the neighboring cells. The existing categories are:
– Better cell: Cell with a higher ranking value than serving cell in the candidate list.
– Worse cell: Cell with a lower ranking value than serving cell in the candidate list.
– Serving cell: The cell serving the connection.
These categories are later used in evaluations and selection of cause values
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3056
Handover – Locating Overview
Locating – Cell Load Sharing Evaluation
The cell load sharing evaluation is performed after the normal ranking procedure. The evaluation is only performed if
– cell load sharing is active for the cell – if no urgency conditions apply and – if the channel is a TCH where the channel mode
is "speech/data”
A channel in a multislot configuration is not evaluated. Further, no evaluation is performed at request of a candidate list for assignment.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3057
Handover – Locating Overview
Locating – Cell Load Sharing Evaluation
Only candidates that fulfill the following conditions are involved in the evaluation:
– The candidate is ranked Worse– The candidate is Internal– It exists in the same cell layer as serving cell– It accepts 'handover due to cell load sharing'
The evaluation is then performed as a new ranking with reduced hysteresis areas between serving cell and the neighboring cells.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3058
Handover – Locating Overview
Locating – Overlaid/Underlaid Evaluation
The evaluation is only performed if the serving cell has an overlaid and underlaid subcell structure.
An evaluation is performed to determine if a subcell change (overlaid to underlaid or underlaid to overlaid) is desired.
The criterion is based on the downlink signal strength, timing advance measurements from the serving cell and the traffic load in the cell.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3059
Handover – Locating Overview
Locating – Overlaid/Underlaid Evaluation
If the serving cell is co-sited with a neighboring cell that has a subcell structure, then locating evaluates if the handover shall be proposed to the overlaid or underlaid neighboring subcell.
If the MS is located in the overlaid subcell and a bad quality urgency occurs, Locating proposes a subcell change from overlaid to underlaid subcell to prevent the MS from remaining on connections with bad quality.
A timer is used to prevent an immediate return back to the overlaid subcell.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3060
Handover – Locating Overview
Locating – Intracell Handover Evaluation
The Intracell Handover evaluation is not performed at assignment and otherwise only performed if intracell handover is allowed for the current subcell.
The criterion for determining if an intracell handover is desired is based on uplink and downlink quality and signal strength measurements from the serving cell.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3061
Handover – Locating Overview
Locating – Intracell Handover Evaluation
The criterion is fulfilled when the quality is worse than could be expected from the signal strength level. There are parameters to prevent too many consecutive intracell handovers in a sequence during a connection.
If the MS is located in the overlaid subcell and the number of allowed consecutive intracell handovers have been executed then Locating proposes a subcell change from overlaid to underlaid subcell to prevent the MS from remaining on connections with bad quality.
A timer is used to prevent an immediate return back to the overlaid subcell.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3062
Handover – Locating Overview
Locating – Assignment to Other Cell
The normal Locating is used in order to find the most suitable cell at the call setup
If a better cell than the serving cell is found during the call setup signaling, that cell will be the first one in the Locating candidate list. This is called Assignment to a better cell.
Also worse cells can be found, and at congestion in the serving cell or in the better cell, the call can be setup in a worse cell. This is called Assignment to a worse cell.
However, cells at a large distance from the nominal cell are not allowed to remain as candidates. This is controlled by the parameter AWOFFSET.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3063
Handover – Locating Overview
Locating – Hierarchical Cell Structures The HCS feature provides the possibility to give priority
to cells that are not the strongest but provide sufficient signal strength levels
The appropriate level of the sufficient signal strength levels mainly depends on the co- and adjacent interference from the surrounding cells
With low interference it is the noise level with a safety margin that set the sufficient signal strength levels
Each cell should be associated with a LAYER The Layer could be defined by the traffic that the cell
captures with just a basic ranking, how much traffic the cell are dimensioned for and how much the cell interfere with the rest of the network
The lower the layer the higher the priority
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3064
Handover – Locating Overview
Locating – Removal of candidates
The reasons for removal of candidates from the list are:
The candidate belongs to a system type not supported by the mobile.
Evaluation of BSC parameters and timers controlling handover, i.e. if it is allowed to make handover on SDCCH etc. The evaluated parameters are IBHOSICH, SCHO, ASSOC, IBHOASS, TALLOC and TURGEN.
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3065
Handover – Locating Overview
Locating – Removal of candidates
The reasons for removal of candidates from the list are:
Evaluation of co-sited neighbors. Three checks are performed:
– If average timing advance exceeds the MAXTA value for the co-sited cell.
– If average timing advance is less than the TALIM value for serving cell and greater than or equal to the TALIM value for the co-sited cell.
– If the cell is worse and in the same cell layer as serving cell and the average timing advance exceeds the TALIM value for the co-sited cell.
Evaluation and removal of candidates if the MS is classified as a fast moving mobile (if this feature is used).
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3066
Handover – Locating Overview
Locating – Categorization 2
The cells in the candidate list are then organized in the following three categories:
– Above S: Neighboring cell above serving cell in the candidate list
– Below S: Neighboring cell below serving cell in the candidate list
– S: Serving cell
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3067
Handover – Locating Overview
Locating – Ordering the candidate list
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Indication Description1 Assignment Request Arrived2 AW state3 Excessive TA urgency
detected4 Bad Quality urgency detected5 OL/UL subcell change or ICHO
requested
Limited Internal NPI Training - Retainability 2005-09-3068
Handover – Locating OverviewLocating – List preparation
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Penalty list
Measurementresults
Organizing the list
Urgency condition
Auxiliary radionetwork functions
evaluations
Allocation reply
Basic ranking
Filtering
Initiations
Sending the list
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Six auxiliary radio network functions areincorporated in the locating software:
•Assignment to another cell•Hierarchical cell structures•Overlaid and underlaid subcells•Intra -cell handover•Extended range•Cell load sharing
Limited Internal NPI Training - Retainability 2005-09-3069
Handover – Locating Overview
Locating – Sending the list
9702607
Pena lty lis t
M easu rem en tresu lts
O rga niz ing the list
U rge ncy co nd ition
Auxilia ry rad ione tw ork functions
eva lua tions
Alloca tion rep ly
B asic ranking
F ilte rin g
In itia tions
S end ing the lis t
• If the candidate list is em pty (i.e . serv ing ce ll isthe best) the cand idate list is no t sent to thecentra l processor.
• The first ce ll in the candidate lis t is the “best”candidate . A t congestion the next ce ll in thecandidate list is tried.
Limited Internal NPI Training - Retainability 2005-09-3070
Handover – Locating Overview
Locating – Allocation reply
9 7 0 2 6 0 8
• A t s u c c e s s a p e n a lty lis t is tra n s fe rre d fro m th elo c a tin g in d iv id u a l to th e n e w o n e . I f th e h a n d o v e rre a s o n w a s d u e to u rg e n c y a p e n a lty fo r th ea b a n d o n e d c e ll m u s t b e in c lu d e d . T h e o ldlo c a t in g in d iv id u a l is th e n d e le te d .
• A t in te r-B S C h a n d o v e r it is n o t p o s s ib le to s e n dth e p e n a lty lis t. H o w e v e r it is p o s s ib le in d ic a te ifth e c a u s e o f th e h a n d o v e r w a s d u e to b a d q u a lityo r e x c e s s iv e t im in g a d v a n c e . T h e p e n a lt ie s o f th en e w c e ll w ill th e n b e u s e d . (E X T P E N = O N )
P e n a lty lis t
M e a s u re m e n tre s u lts
O rg a n iz in g th e lis t
U rg e n c y co n d itio n
A u x ilia ry ra d ion e tw o rk fu n c tio n s
e va lu a tio n s
A llo ca t io n re p ly
B a s ic ra n k in g
F i lte rin g
In itia tio n s
S e n d in g th e lis t
Limited Internal NPI Training - Retainability 2005-09-3071
Handover – Locating Overview
Locating – Allocation reply
9 7 0 2 6 0 8
• A t s u c c e s s a p e n a l t y l i s t i s t r a n s f e r r e d f r o m t h el o c a t i n g i n d i v i d u a l t o t h e n e w o n e . I f t h e h a n d o v e rr e a s o n w a s d u e t o u r g e n c y a p e n a l t y f o r t h ea b a n d o n e d c e l l m u s t b e i n c l u d e d . T h e o l dl o c a t i n g i n d i v i d u a l i s t h e n d e l e t e d .
• A t i n t e r - B S C h a n d o v e r i t i s n o t p o s s i b l e t o s e n dt h e p e n a l t y l i s t . H o w e v e r i t i s p o s s i b l e i n d i c a t e i ft h e c a u s e o f t h e h a n d o v e r w a s d u e t o b a d q u a l i t yo r e x c e s s i v e t i m i n g a d v a n c e . T h e p e n a l t i e s o f t h en e w c e l l w i l l t h e n b e u s e d . (E X T P E N = O N )
P e n a l t y l i s t
M e a s u r e m e n tr e s u l t s
O r g a n i z i n g t h e l i s t
U r g e n c y c o n d i t i o n
A u x i l i a r y r a d i on e t w o r k f u n c t i o n s
e v a l u a t i o n s
A l l o c a t i o n r e p l y
B a s i c r a n k i n g
F i l t e r i n g
I n i t i a t i o n s
S e n d i n g t h e l i s t
9 7 0 2 6 0 9
•A t c o n g e s t io n i n a l l t h e c a n d id a t e s i n t h e l i s t a n e w a t t e m p tw i l l b e m a d e a f t e r a c e r t a in t im e s p e c i f i e d b y t h e t im e r sT A L L O C o r T U R G E N.
T A L L O C ( a t n o r m a l h a n d o v e r s ) i n h ib i t s r a n k in g u n le s s a nu r g e n c y c o n d i t i o n s f o u n d .
T U R G E N ( a t u r g e n c y h a n d o v e r s ) i n h ib i t s s e n d in g a c a n d id a t el i s t u n le s s a b e t t e r c e l l i s f o u n d .
Limited Internal NPI Training - Retainability 2005-09-3072
Handover – Neighbor Cells
Neighbor cells (NCELLS) impacts the following radio network areas:
Handover Performance TCH Drops Coverage Interference Frequency plan
Limited Internal NPI Training - Retainability 2005-09-3073
Handover – Neighbor Cells
Optimization of NCELLS mainly consists of the following activities:
Find and Add missing NCELLS Find and Remove unnecessary or wrong NCELLS Optimize Neighbor cell BCCH frequencies and BSICs
Limited Internal NPI Training - Retainability 2005-09-3074
Handover – Neighbor Cells
Optimization of NCELLS are done using the following information:
Map information – Site location and terrain Predicted coverage STS Handover statistics MRR - Signal strength and Timing Advance (TA) NCS and NOX from RNO
Limited Internal NPI Training - Retainability 2005-09-3075
Handover – Neighbor Cells
Neighboring Cell Support (NCS)
NCS is part of the RNO (Radio Network Optimization) tool NCS helps to maintain a well working neighboring cell list NCS data is collected through Measurement reports NCS is operated through OSS NCS is used to detect missing neighboring cell relations n. NCS is used to constantly evaluate the existing neighboring
cell relations.
Limited Internal NPI Training - Retainability 2005-09-3076
Handover – Neighbor Cells
Neighboring Cell Support (NCS)
NCS initiates the Active BA-list Recording (BAR) in BSC The BAR modify the selected cell BA-list, to include test
frequencies. MS measures the defined frequencies in its neighbor list +
test frequencies Result are recorded in NCS and presented in several report
formats.
Limited Internal NPI Training - Retainability 2005-09-3077
Handover – Neighbor CellsNeighboring Cell Support (NCS)
Limited Internal NPI Training - Retainability 2005-09-3078
Handover – Neighbor CellsNeighboring Cell Support (NCS)
Limited Internal NPI Training - Retainability 2005-09-3079
Handover – Neighbor Cells
Adding Neighbor cells using NCS
Limited Internal NPI Training - Retainability 2005-09-3080
Handover – Neighbor Cells
Adding Neighbor cells using NCS
Overview report used to decide which cells to investigate
Limited Internal NPI Training - Retainability 2005-09-3081
Handover – Neighbor CellsAdding Neighbor cells using NCS
Limited Internal NPI Training - Retainability 2005-09-3082
Handover – Neighbor CellsAdding Neighbor cells using NCS
Limited Internal NPI Training - Retainability 2005-09-3083
Handover – Neighbor CellsAdding Neighbor cells using NCS
Limited Internal NPI Training - Retainability 2005-09-3084
Handover – Neighbor CellsAdding Neighbor cells using NCS
Missing relationship
Limited Internal NPI Training - Retainability 2005-09-3085
Handover – Neighbor Cells
Adding Neighbor cells using NCS
STS used to evaluate result of NCELL add
OUTINCELL DATE PERIOD PERLEN EXCHID HOVERCNT H_SUC
LZ0105B-LZ0113B 020114 1000-1900 540 1BSC4 439.00 98.18
LZ0113B-LZ0105B 020114 1000-1900 540 1BSC4 409.00 99.02
Limited Internal NPI Training - Retainability 2005-09-3086
Handover – Neighbor Cells
Adding Neighbor cells using NCS
NCCPERM parameter NCCPERM defines the allowed NCCs (Network Color
Code) on the BCCH carriers for which the MS is permitted to send measurement reports. To capture interactions with other cells (such as with NCS, ICDM etc.), all 0&&7 should be used
Limited Internal NPI Training - Retainability 2005-09-3087
Handover – Optimization
Analyze the following issues that could be possible reasons for poor Handover Performance:
– Coverage– Interference – Incorrect parameter settings – Unnecessary or Missing NCELL relations– Hardware or Link/Transmission Faults– Missing Frequencies in the Measurement list– Poor Inter MSC/BSC handover performance– TCH Congestion
Limited Internal NPI Training - Retainability 2005-09-3088
Handover – Optimization
U n s u c c e s s f u l H a n d o v e r s
C h e c k c o n g e s t i o np e r f o r m a n c e
T C Hc o n g e s t i o n ?
C h e c k S A E s e t t i n g
N O
S Wc o n g e s t i o n ?
C h e c k L o c a t i n g p a r a m e t e r s
C h e c k N e i g h b o u r i n g c e l l d e f i n i t i o n s
W r o n g c e l l sd e f i n e d ?
M i s s i n gn e i g h b o u r s ?
T o o m a n yn e i g h b o u r s ?
T o o m a n ym e a s u r e m e n t
c h a n n e l s ?
S t r a n g e o r c o r r u p tp a r a m e t e r s e t t i n g ?
N O
N O
N O
N O
N O
A d d T C Hc a p a c i t y
Y E S
I n c r e a s e S A EY E S
R e m o v e i n c o r r e c td e f i n i t i o n s
Y E S
A d d m i s s i n gr e l a t i o n
Y E S
R e m o v e u n n e c e s s a r yr e l a t i o n s
Y E S
R e v i e w a n d c o r r e c t t h ed e f i n e d M B C C H N O
Y E S
C
N O
C o r r e c t p a r a m e t e r sY E S
Limited Internal NPI Training - Retainability 2005-09-3089
Handover – Optimization
C h e c k u s e o f r a d i of e a t u r e s
C
N O
A r e a l l r a d i of e a t u r e s u s e d ?
Y E S
C h e c k c o v e r a g e
N O
L o w S S o n c e l lb o r d e r ?
P e r f o r m d r i v e t e s t
Y E S I m p r o v e c o v e r a g e
C h e c k i n t e r f e r e n c e
Y E S
B a dq u a l i t y ?
R e d u c e i n t e r f e r e n c e f o rp o t e n t i a l c a n d i d a t e
Y E S
D e l a y e d h a n d o v e r
d e c i s i o n ?
C h e c k h a n d o v e rp a r a m e t e r s
Y E S
I n t r o d u c e u n u s e df e a t u r e s
∙ T i m e r E x p i r y A f t e rM S i s L o s t
N O
D
N O
Limited Internal NPI Training - Retainability 2005-09-3090
Handover – Optimization
D
C h e c k B T S E r r o r L o g
H Wf a u l t ?
C h e c k l i n k q u a l i t y
T r a n s m i s s i o nf a u l t ?
S w a p & r e p a i r H WY ES
N O
I m p r o v et r a n s m i s s i o n
Y ES
P e r f o r m s i t e v i s i t
N O
C h e c k a n t e n n ai n s t a l l a t i o n
A n t e n n a c o n n e c t e d t ow r o n g f e e d e r ?
I n c o r r e c td o w n t i l t ?
H i d e da n t e n n a ?
B a d a n t e n n ai n s t a l l a t i o n ?
N O
N O
N O
C h a n g e f e e d e rY ES
C o r r e c t t i l t i n gY ES
C h a n g e a n t e n n ap o s i t i o n
Y ES
C o r r e c t i n s t a l l a t i o nY ES
E N D
N O
I s t h e c e l l a t i n t e r - M S Cb o r d e r ?
Y ES
C h e c k i n t e r - M S C H O
p e r f o r m a n c e
N O
Limited Internal NPI Training - Retainability 2005-09-3091
Handover – OptimizationHandovers - Congestion
Hop
BCCH
Correct Behavior
Hop
BCCH
Congestion 1
Hop
BCCH
Congestion 2
Hop
BCCH
Congestion 3 No HO!
= Congestion = Drop
Limited Internal NPI Training - Retainability 2005-09-3092
Handover – OptimizationHandover – Co BCCH & BSIC NCELLS 01761 & 01783 – Co-Channel, Co-BSIC (694-26)
Limited Internal NPI Training - Retainability 2005-09-3093
Handover – OptimizationHandover – BSIC Confusion
BCCH: 588 BSIC: 34
BCCH: 588 BSIC: 47
BCCH: 580 BSIC: 30
BCCH: 586 BSIC: 13
BCCH: 586 BSIC: 21
Limited Internal NPI Training - Retainability 2005-09-3094
Handover – Optimization
Handover – BSIC Confusion
The BCCH should be planned so that BSIC-decoding is possible
Avoid BSIC-confusion – Mobiles only have to decode BSIC every 10 seconds
With tight BCCH re-use (12 channels) the focus of the BCCH planning should be on handover performance
Limited Internal NPI Training - Retainability 2005-09-3095
Handover – Optimization
Handover – BSIC ConfusionOutgoing HO failures increased on the 30th
Limited Internal NPI Training - Retainability 2005-09-3096
Co Channel
Handover Failure BetweenNJ5112A and NJ5029C.
Handover – OptimizationHandover – BSIC Confusion
NJ5112A and NJ5421B are Co-BCCH causing BSIC Confusion for the mobiles coming from NJ5029C to NJ5112A causing a high percentage of HO lost
Limited Internal NPI Training - Retainability 2005-09-3097