21954499 gsm-kpi-improvement-process-and-guidelines

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


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


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



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



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)



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


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


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



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.



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



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



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


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


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


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).


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


SDCCH Drops – OverviewConnection Release, Abnormal Disconnection

MSC BSC BTS

Clear Command

Channel Release

Clear CompleteDeactivate SACCH

DISC


RF Channel Release


SCCP Rel.

SCCP Rel. Ack.

Clear Request Step drop call counter, CNDROP


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



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



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



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


TCH Drop – Overview

MSC BSC BTS MS

Clear Command

Channel ReleaseClear Complete

Deactivate SACCH

DISC


RF Channel Release


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


TCH Drop – OverviewConnection Release, Abnormal Disconnection

MSC BSC BTS

Clear Command

Channel Release

Clear Complete

Deactivate SACCH

DISC


RF Channel Release


SCCP Rel .

SCCP Rel . Ack .

Clear Request Step drop call counter,TFNDROP


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


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


TCH Drop parameters

RLINKT

STS Workshop43

Radio Link Time -out


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


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



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



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


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



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



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



Investigate TCH Drop Performance - MOTS:

MOTS_toolMOTS


AssignmentRequest IL01673 17:04:49

HandoverCommand IL01673 IL04071 17:05:15

HandoverComplete IL04071 17:05:16







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:



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.



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.

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Tid

TA

RQ

UL

RQ

DL

RL

UL

RL

DL

SQ

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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



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.

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t id

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Cell

Tid

TA

RQ

UL

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RL

UL

RL

DL

SQ

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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



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

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UL

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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



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).

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Ce

ll

Ce

llr

Tid

Ca

us

eM

es

sa

ge

su

bc

ell

ty

pe

Ch

an

ne

l

Ty

pe

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




Handover Timer – T3103B1



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

allN

r

Ev

en

tNa

me

Cell

Cellr

Tid

Cau

se

Mes

sag

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ell ty

pe

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


733 ClearCommand IL04271 17:19:54




Handover Timer – T3103B2



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



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



Investigate TCH Drop Performance - DIP

DIP


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


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


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



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



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



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



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




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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list


•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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







Locating – Ordering the candidate list

Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list





Indication Description1 Assignment Request Arrived2 AW state3 Excessive TA urgency

detected4 Bad Quality urgency detected5 OL/UL subcell change or ICHO

requested


Handover – Locating OverviewLocating – List preparation

Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list



Penalty list

Measurementresults

Organizing the list

Urgency condition


evaluations

Allocation reply

Basic ranking

Filtering

Initiations

Sending the list







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.



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



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 .


Handover – Neighbor Cells

Neighbor cells (NCELLS) impacts the following radio network areas:

Handover Performance TCH Drops Coverage Interference Frequency plan



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



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



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.



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.


Handover – Neighbor CellsNeighboring Cell Support (NCS)



Adding Neighbor cells using NCS




Overview report used to decide which cells to investigate


Handover – Neighbor CellsAdding Neighbor cells using NCS



Missing relationship




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




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


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



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



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


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



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


Handover – OptimizationHandovers - Congestion

Hop

BCCH

Correct Behavior

Hop

BCCH

Congestion 1

Hop

BCCH

Congestion 2

Hop

BCCH

Congestion 3 No HO!

= Congestion = Drop


Handover – OptimizationHandover – Co BCCH & BSIC NCELLS 01761 & 01783 – Co-Channel, Co-BSIC (694-26)


Handover – OptimizationHandover – BSIC Confusion

BCCH: 588 BSIC: 34

BCCH: 588 BSIC: 47

BCCH: 580 BSIC: 30

BCCH: 586 BSIC: 13

BCCH: 586 BSIC: 21



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



Handover – BSIC ConfusionOutgoing HO failures increased on the 30th


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

21954499 gsm-kpi-improvement-process-and-guidelines

Data & Analytics

sdcch assignments

sdcch available

note sdcch congestion

overview sdcch drops

lapd congestion

tch connection

bts accessibility

ms bsc mscvlr trc bts