05 GSM BSS Network KPI (TCH Congestion Rate) Optimization Manual.doc.doc

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GSM BSS Network KPI (TCH Congestion Rate) Optimization Manua!"#$

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Product Name Confidentiality Level

G3BSC INTERNAL

Product Version Total 3 !a"es

GS# BSS Net$or% &PI 'TC( Con"estion Rate)

*!timi+ation #anual V,-.

'/or internal use only)

Prepared

by

GS#01#TS Net$or%

Performance Researc2

e!artment

42a

o &an"

Date 5..67.87

.

Reviewed

by

Date

Reviewed

by

Date

Approved

by

Date

(ua$ei Tec2nolo"ies Co-9 Ltd-




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All ri"2ts reserved




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Contents

" einition o t*e TCH Congestion Rate#####################################################################################+

"#" einition########################################################################################################################+

"#, Re-ommen.e. /ormua##################################################################################################+

, Impa-ts o TCH Congestion Rate###############################################################################################0

1 Inuen-ing /a-tors o TCH Congestion Rate############################################################################2

1#" Network Capa-it3 an. Trai- istri4ution####################################################################2

1#, /auts O--urre. uring %5uipment Instaation6 Transmission6 or on Har.ware##########2

1#1 Network Intereren-e####################################################################################################"$

1#7 In-orre-t Parameter Settings#########################################################################################"$

1#8 Cooperation wit* T*ir.9part3 e:i-es#########################################################################""

1#+ Sotware !ersion Pro4em#############################################################################################""

7 &na3sis Pro-e.ure an. Optimization Met*o.#########################################################################""

7#" Network Capa-it3 an. Trai- istri4ution##################################################################",

-,-, Traffic Balancin"#############################################################################################",

-,-5 Traffic istri:ution Environment###################################################################"1

7#, /aut O--urre. uring %5uipment Instaation an. On Har.ware###############################"7

-5-, /eeder Installation and /ault########################################################################"7

-5-5 Board faults#####################################################################################################"+

-5-3 Transmission and Cloc% Pro:lem################################################################"0

7#1 Intereren-e Causes#######################################################################################################"0

-3-, Inter7Net$or% Interference############################################################################"0

-3-5 Im!ro!er /re;uency Plannin"######################################################################"0

7#7 KPI Measurement Pro4ems#########################################################################################";

7#8 Parameter Settings#########################################################################################################";

-<-, C2annel Assi"nment Parameters################################################################"2

-<-5 Call Control Parameters################################################################################,$

-<-3 (andover Parameters###################################################################################,"

-<- Basic Cell Parameters###################################################################################,,

7#+ T*ir.9Part3 e:i-e Pro4ems#######################################################################################,7

-8-, Re!eater Pro:lems########################################################################################,7

-8-5 Com!ati:ility $it2 Non7(ua$ei E;ui!ment################################################,7

-8-3 5G=3G Intero!era:ility###################################################################################,8

7#0 Sotware !ersion Pro4em############################################################################################,+

8 Test Met*o.###############################################################################################################################,0

+ &ppen.i< C*e-k Items on TCH Congestion Rate####################################################################,;




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0 T3pi-a Cases#############################################################################################################################,;

0#" Case "= TCH Congestion Cause. 43 Terrain Reasons##################################################,;

0#, Case ,= Hig* TCH Congestion Rate Cause. 43 /aut o TR> Boar.##########################,2

0#1 Case 1= Stati- TCHH Congestion Cause. 43 Insui-ient TCH/s###############################,2

0#7 Case 7= In-rease o TCH Congestion Rate Cause. 43 Improper Ha9Rate Parameters

ater ?pgra.e rom BSC C"$ to BSC C"1###############################################################################1$

0#8 Case 8= In-rease o TCH Congestion Rate Cause. 43 Mo.ii-ation o eaut !aue

o Han.o:er T*res*o.#############################################################################################################1"

0#+ Case += In-rease o TCH Congestion Rate Cause. 43 Re:erse Conne-tions o

&ntennas####################################################################################################################################1,

0#0 Case 0= Hig* TCH Congestion Rate ue to No Capa-it3 %<pansion o Repeaters ater

BTS Capa-it3 %<pansion rom O, to O7#################################################################################1,

0#; Case ;= Intereren-e Cause. 43 Repeaters####################################################################11

0#2 Case 2= TCP Congestion Cause. 43 %<terna Intereren-e##########################################17




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Revision Record

Date Revision Version Change Description Author

5..67.>75< V,-. raft com!leted 42ao

&an"




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GSM BSS Network KPI (TCH Congestion Rate)

Optii!ation Man"a#

Ke$ words% TC( Con"estion Rate

&'stract% T2is document aims at reducin" t2e con"estion rate and im!rovin" t2e call

connection rate :y analy+in" t2e TC( con"estion rate in t2e traffic measurement of t2e

e?istin" net$or%-

&cron$s and a''reviations

&cron$ and&''reviation

"## Spe##ing




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PreaceT2is document descri:es causes and im!acts of t2e TC( con"estion rate and !rovides

measures ta%en to reduce t2e con"estion rate and o!timi+e t2e &PI-

* +einition o t,e TCH Congestion Rate

,-, efinition

T2e TC( con"estion rate is t2e !ro!ortion of t2e num:er of TC( assi"nment failures to

t2e num:er of TC( sei+ure re;uests- If t2e TC( con"estion rate is 2i"29 t2e net$or%service ;uality deteriorates- In t2is case9 you can e?!and t2e ca!acity to reduce t2e TC(

con"estion rate-

,-5 Recommended /ormula

T2e TC( con"estion rate is o:tained from t2e traffic measurement result- T2e

recommended formula is t2e !ro!ortion of /ailed TC( Sei+ures due to Busy TC( to TC(

Sei+ure Re;uests- T2e formulas defined for t2e BSC35 and t2e BSC8... are as follo$s@

,- efined for t2e BSC35@ TC( Con"estion Rate 'All C2annels Busy) /ailed TC(

Sei+ures due to Busy TC( = TC( Sei+ure Re;uests ? ,..

5- efined for :y BSC8...@ TC( Con"estion Rate 'All C2annels Busy) TC( Sei+ure

Re;uests 'Si"nalin" C2annel) D TC( Sei+ure Re;uests 'Traffic C2annel) D TC(

Sei+ure Re;uests in TC( (andovers 'Traffic C2annel) F 'all t2e TRs in t2e cell)

Successful C2annel Assi"nments 'TC()H = TC( Sei+ure Re;uests 'Si"nalin"

C2annel) D TC( Sei+ure Re;uests 'Traffic C2annel) D TC( Sei+ure Re;uests in

TC( (andovers 'Traffic C2annel)H ? ,..H

Note@ /or t2e BSC8...9 t2e formula of calculatin" t2e con"estion rate on TC( !er BSC

is as follo$s@

Con"estion Rate on TC( !er BSC 'All C2annels Busy) /ailed TC( Sei+ures due to

Busy TC( !er BSC 'Si"nalin" C2annel) D /ailed TC( Sei+ures due to Busy TC( 'Traffic

C2annel) !er BSC D /ailed TC( Sei+ures in TC( (andovers due to Busy TC( !er BSC

'Traffic C2annel)H = TC( Sei+ure Re;uests !er BSC 'Si"nalin" C2annel) D TC( Sei+ure

Re;uests !er BSC 'Traffic C2annel) D TC( Sei+ure Re;uests in TC( (andovers !er BSC

'Traffic C2annel)H ? ,..




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JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

- Ipacts o TCH Congestion Rate

T2e TC( con"estion rate is measured in t2e assi"nment and 2andover !rocedures- T2e

measurement !oints are A9 B9 and C- T2e follo$in" descri:es ne"ative im!acts :rou"2t

:y TC( con"estion in t2e !rocedures-

In t2e TC( assi"nment !rocedure9 t2e #S receives t2e Assi"nment Command messa"e

from t2e BSC at !oint A- If t2e TC( is con"ested9 t2e value of ai#ed TCH Sei!"res d"e

to B"s$ TCH increases :y one- T2en9 Iediate &ssignent S"ccess Rate is

decreased-




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In assi"nment and 2andover !rocedures9 if t2e TC( con"estion leads to t2e TC(

assi"nment failure9 :ot2 t2e immediate assi"nment success rate and 2andover success

rate decrease- T2erefore9 reducin" t2e TC( con"estion rate o!timi+es t2e t$o counters-

Note

At !oint A9 B9 or C in t2e TC( assi"nment !rocedure9 if no TC( is idle9 ai#ed TCH

Sei!"res d"e to B"s$ TCH increases :y one-

At !oint B or C in t2e TC( assi"nment !rocedure9 if no TC( is idle9 :ot2 ai#ed

Incoing Interna# Inter.Ce## Handovers (d"e to '"s$ TCH) and ai#ed Incoing

/0terna# Inter.Ce## Handovers (d"e to '"s$ TCH) increase one-

1 In#"encing actors o TCH Congestion Rate

Accordin" to actual a!!lications and o!timi+ation e?!erience9 influencin" factors of t2e

TC( con"estion rate are as follo$s@

Net$or% ca!acity and traffic distri:ution




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/aults occurred durin" e;ui!ment installation9 transmission9 or on t2e 2ard$are

Net$or% interference

&PI measurement !ro:lems

Incorrect !arameter settin"s

T2ird7!arty device !ro:lems

Soft$are version !ro:lems

3-, Net$or% Ca!acity and Traffic istri:ution

In t2e early !eriod of net$or% de!loyment9 t2e BTS !osition and t2e num:er of TRs are

desi"ned :ased on current #S distri:ution- T2e covera"e ca!a:ility of certain BTSs fails

to meet actual re;uirements due to c2an"es of traffic distri:ution- In t2is case9 it is difficult

to ma%e a call or t2ere are no si"nals-

*!erators and vendors must ta%e measures to reduce t2e TC( con"estion rate-

3-5 /aults *ccurred urin" E;ui!ment Installation9 Transmission9 or on

(ard$are

T2e traffic a:sor!tion is un:alanced in cells of an area :ecause of faults occurred durin"

e;ui!ment installation9 transmission or on t2e 2ard$are or cloc%- As a result9 TC(s in

certain cells are overloaded and in some cells are idle- T2erefore9 resources are $asted-

T2e cells controlled :y t2e BTS $or% a:normally due to t2e follo$in"s causes@

/eeders are installed reversely or dama"ed-

T2e TR :oard is faulty-

T2e BTS cloc% is faulty-

T2is increases t2e traffic of t2e nei"2:or cells and causes con"estion-

3-3 Net$or% Interference

Inter7net$or% interference or stron" intra7net$or% interference caused :y ti"2t fre;uency

reuse due to limited fre;uency resources affects t2e normal access of t2e #S9 causes

TC( assi"nment failure9 and increases t2e TC( con"estion rate-

T2e follo$in" ty!es of interference may occur@

,- Inter7net$or% interference from scram:lers or !rivately installed antennas

5- Interference from t2e C#A net$or% of C2ina 1nicom

3- Re!eater interference




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- Intermodulation interference from BTSs

<- Intra7net$or% co7c2annel and adKacent7c2annel interference

3- Incorrect Parameter Settin"s

Parameter settin"s on t2e BSC and #SC affect t2e 2andover9 load9 c2annel assi"nment9

and cell con"estion- T2e follo$in" !arameters may cause ne"ative affects@

*2 TCH Traic B"s$ T,res,o#d(3) is incorrectly set-

-2 Tc, Traic B"s$ Over#a$ T,res,o#d and Tc, Traic B"s$ 4nder#a$ T,res,o#d

are incorrectly set-

12 &ssignent Ce## 5oad 6"dge /na'#e 'BSC8...) is invalid-

72 +irected Retr$ 5oad &ccess T,res,o#d is invalid-

82 Ba#ance Traic &##owed is not set-

92 5oad HO &##owed is not set-

:2 5oad HO Step Period is set to a too "reat value-

;2 R&CH Min2&ccess 5eve# is set to a too small value-

<2 Cell reselection !arameters are incorrectly set-

*=2 Ce## +irect Tr$ or'idden T,res,o#d 'BSC8...) is incorrectly set-

**2 +irect Retr$ is set to No2

*-2 S+CCH +$naic &d>"stent is invalid-

*12 /lo$ control !arameters are invalid-

*72 Speec, ?ersion is incorrectly set-

3-< Coo!eration $it2 T2ird7!arty evices

Some !ro:lems 'for e?am!le9 t2e 2andover or access is a:normal) may arise if t2ird7!arty devices are introduced suc2 as9 t2e ado!tion of re!eaters or se"mental net$or%in"

or in t2e :order areas of t2e local net$or%- T2ese !ro:lems cause a:normal &PIs 'for

e?am!le9 2andover success rate) and TC( con"estion-

3-8 Soft$are Version Pro:lem

2en t2e BSC is u!"raded or a ne$ version is used in t2e e?istin" net$or%9 t2e soft$are

of earlier versions may :e incom!ati:le $it2 t2e ne$ !latform 'for e?am!le9 BSC8...) or

soft$are :u"s may increase t2e TC( con"estion rate- T2erefore9 $e s2ould locate and

rectify t2e fault caused :y soft$are !ro:lems :y ta%in" !ro!er measures-




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7 &na#$sis Proced"re and Optii!ation Met,od

Because reducin" t2e TC( con"estion rate involves a relatively lar"e sco!e9 $e canado!t t2e !rinci!le of first solvin" easy !ro:lems and t2en difficult !ro:lems- T2at is9

c2ec% t2e 2ard$are and soft$are to determine $2et2er t2e !ro:lem is common or

s!ecific- T2e !rocess is as follo$s@

C*e-k w*et*er t*ere are *ar.ware or

transmission aut aarms#

C*e-k w*et*er parametersare -orre-t3 set#

C*e-k settings o 4asi- -e parameters#

C*e-k settings o *an.o:er parameters#

C*e-k settings o -e oa. parameters#

C*e-k settings o -*anneassignment parameters#

C*e-k settings o un-tion

parameters#

So:e *ar.ware pro4ems an.-ear aarms#

T*e TCH -ongestion ratein-reases#

C*e-k w*et*er t*e trai- :oumee<-ee.s t*e .esigne. -apa-it3#

@es

Tra-e &4is9intera-e or &9intera-esignaing to o-ate -auses o TCHassignment aiure an. *an.o:er

aiure#

C*e-k w*et*er pro4ems areso:e.#

@es

No

@es

No

C*e-k w*et*er t*ere aresotware :ersion pro4ems#

'o-ate intereren-e -auses#

%<pan. t*e -apa-it3#

C*e-k t*e .istri4ution ointereren-e 4an.s#

@es

C*e-k w*et*er pro4ems o--ur ont*ir.9part3 e5uipment#

Coor.inate wit* t*e t*ir. part3#

@es

%n.

@es

No

&na3ze reate. trai-measurement -ounters#

No

No

No

No




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-, Net$or% Ca!acity and Traffic istri:ution

-,-, Traffic Balancin"

a"#t +escription and Ca"se &na#$sis

,- Common Cell

Radio traffic volume de!ends on t2e num:er of BTSs and cells in t2e net$or%9 t2e

num:er of radio c2annels confi"ured in eac2 cell9 and t2e covera"e of eac2 cell-

Currently9 c2annels are restricted :y desi"ned net$or% ca!acity- T2is is :ecause t2e

radio c2annel confi"uration and t2e covera"e is fi?ed as t2e num:er of BTSs and cells is

determined in t2e early !eriod of t2e net$or%9 2o$ever9 t2e deviation may e?ist :et$een

t2e actual net$or% ca!acity and t2e re;uired ca!acity- T2e TC( con"estion occurs in t2e

cells t2at re;uire "reater ca!acity- it2 city construction and economic develo!ment9

c2an"es of user density determined durin" t2e net$or% construction cause TC(

con"estion-

5- Concentric Cell

Concentric cells are introduced to solve traffic !ro:lems in t2e overlaid su:cell and solve

covera"e !ro:lems in t2e underlaid su:cell- (o$ever9 in actual a!!lications9 un:alanced

traffic distri:ution causes traffic im:alance in overlaid and underlaid su:cells- T2erefore9

t2e TC( con"estion rate in t2e overlaid su:cell is different from t2at in t2e underlaid

su:cell :ecause of t2e difference of t2e desi"n and actual a!!lication-

So#"tion

T2ere are t$o $ays to solve t2ese !ro:lems- T2e first met2od is to solve !ro:lemst2orou"2ly- T2at is9 conduct t2e detailed net$or% evaluation9 determine t2e cells $2ere

t2e TC( con"estion occurs9 and $or% out a detailed net$or% ca!acity e?!ansion solution

:ased on t2e con"estion severity- (o$ever9 $it2 city construction and furt2er economic

develo!ment9 t2e ca!acity e?!ansion is re;uired as t2e TC( con"estion reoccurs- In fact9

o!erators continually o!timi+e net$or%s $it2 t2e increase of su:scri:ers- T2e second

met2od is to o!timi+e net$or%s- T2ere are relatively idle cells in t2e net$or%- Mou can

decrease t2e TC( con"estion rate :y adKustin" TR confi"uration of t2e idle and :usy

cells- In addition9 you can ena:le t2e directed retry9 load 2andover9 and cell traffic

:alancin" functions- /or o!erators9 eac2 TR means ne$ investment- AdKustin" TR

confi"uration in a net$or% ma%es full use of net$or% ca!acity and o!timi+es t2e net$or%-

(o$ever9 t2e second met2od 2as certain limitations- If t2e actual used ca!acity is close

to t2e confi"ured ca!acity in terms of t2e total amount and ca!acity distri:ution9 you must

e?!and t2e net$or% ca!acity-

-,-5 Traffic istri:ution Environment

In actual a!!lications9 it is difficult for t2e #S t2at is located on t2e ed"e of t2e area

covered :y t2e BTS to ma%e a call due to $ea% level on t2e ed"e- T2is results in TC(

sei+ure failure and increases t2e TC( con"estion rate- 'Mou may as%@ oes t2is case

result in t2e increase of t2e TC( con"estion rate) Actually9 fe$er TC(s are sei+ed in t2is




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BTS9 as s2o$n in t2e follo$in" fi"ure-

T2e follo$in" ta:le lists t2e TC( sei+ure counters in t2e traffic measurement result-

BSC 5eve# Ce## 5eve#

BSC #easurement 7O Access

measurement !er BSC 7O

TC( Availa:ility !er BSC

Confi"ured TC(s !er BSC

Availa:le TC(s !er BSC

&PI #easurement 7O

TC( Availa:ility

Availa:le TC(s

Confi"ured TC(s

TC( Con"estion Rate

TC( Traffic Volume

TR #easurement 7O

Num:er of confi"ured TRs in a cell

Num:er of availa:le TRs in a cell

So#"tion

AdKust t2e a+imut2 an"le or tilt of t2e antenna and set t2e static transmit !o$er of t2e

BTS to t2e ma?imum value- T2at is9 increase t2e si"nal stren"t2 in t2is area- In addition9

to decrease t2e TC( con"estion rate9 you can lo$er R&CH B"s$ T,res,o#d to ena:le

t2e #S to sei+e t2e TC( successfully- If t2ese met2ods do not ta%e effect9 de!loy ne$

BTSs near t2e user "rou!-

Case ,

-5 /ault *ccurred urin" E;ui!ment Installation and *n (ard$are

-5-, /eeder Installation and /ault

T2e TC( sei+ure failure may occur durin" t2e installation and confi"uration of feeders of

t2e BTS due to t2e follo$in" causes-

',) C1=SC1 confi"uration

/or e?am!le9 t2e C1DSC1 com:ination confi"uration is ado!ted in t2e cell $it2 four

TRs- T2e TR carryin" t2e BCC( sends si"nals to t2e antennas t2rou"2 t2e C19 and

ot2er TRs com:ine out!ut of si"nals t2rou"2 t2e SC1 and send t2e si"nals t2rou"2 t2e

C1- In t2is case9 t2e com:ination loss of BCC( "reatly differs from t2at of non7BCC(-T2erefore9 t2e transmit !o$er of BCC( is smaller t2an t2at of non7BCC(- If t2e BSC




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assi"ns TC(s of t2e TR $2ere non7BCC( resides 'es!ecially far a$ay from t2e BTS)

$2en t2e #S ma%es a call9 t2e TC( may fail to :e si+ed :ecause of lo$ transmit !o$er

of t2e TR-

T2ere are t$o met2ods to solve t2is !ro:lem- *ne is to !ut t2e TR carryin" t2e BCC(on t2e c2annel !assin" t2e SC1- In t2is case9 t2e TR 2as smaller transmit !o$er and

TC(s of t2e TR $2ere non7BCC( resides can :e successfully assi"ned- T2e ot2er is to

modify t2e confi"uration- T2at is9 t2e dual C1 confi"uration instead of t2e C1DSC1

com:ination is ado!ted- T2is ensures t2e same !o$er consum!tion of c2annels $2ere

TRs reside and avoids t2e TC( sei+ure failure due to different transmit !o$er of TRs-

T2e second met2od is su!erior to t2e first one in terms of t2e !erformance :ecause t2e

loss of C1 is smaller t2an t2at of t2e SC1- T2is indicates t2at t2e second met2od

features relatively !ro!er covera"e distance- (o$ever9 t2e confi"uration cost is 2i"2er-

'5) Im!ro!er feeder installation

Reverse connections of antennas9 transmit antennas9 and receive antennas cause

serious si"nal im:alance on u!lin% and do$nlin% c2annels- T2at is9 t2e #S to $2ic2 t2e

transmit antenna !oints is :ac% of t2e receive antenna- If t2e #S receives t2e TC(

assi"nment command from t2e BSC durin" t2e call9 t2e TC( fails to :e assi"ned and t2e

TC( con"estion occurs due to !oor level and ;uality of u!lin% si"nals of t2e #S caused

:y small "ain of t2e receive antenna-

To solve t2is !ro:lem9 ma%e drive tests or use a si"nalin" analy+er to analy+e t2e level

and ;uality of u!lin% and do$nlin% si"nals to c2ec% $2et2er si"nal im:alance e?ists- If

yes9 ta%es !ro!er measures to solve t2is !ro:lem-

If t2e a+imut2 and tilt of t2e main antenna are inconsistent $it2 t2ose of t2e diversityantenna or t2e diversity or s!acin" is small $2en sin"le7!olari+ed antennas are used in a

cell9 u!lin% and do$nlin% si"nals are inconsistent and TC(s sei+ure failures tend to occur-

T2e solution to t2ese !ro:lems is t2e same as t2e !recedin" one- T2ese !ro:lems do not

e?ist in cells t2at ado!t dual7!olari+ed antennas-

Case 8

'3) /eeder fault

In t2e follo$in" cases 'suc2 as t2e feeder is dama"ed9 $ater runs into t2e feeder9 or t2e

feeder and t2e connector are not securely connected)9 t2e volta"e standin" $ave ratio

'VSR) increases and :ot2 t2e transmit !o$er and receiver sensitivity of t2e antenna

decrease- T2us9 t2e TC( assi"nment may fail9 causin" TC( con"estion-

To solve t2ese !ro:lems9 c2ec% $2et2er a VSR alarm is "enerated on t2e to$er

mounted am!lifier 'T#A)9 !o$er am!lifier9 com:iner9 and feeders- A rou"2 and sim!le

met2od is to use t2e test #S to test t2e actual transmit si"nals of t2e BTS on t2e foot of

t2e BTS- If si"nal stren"t2 ran"es from 3. dBm to <. dBm9 it indicates si"nals are too

$ea% and t2ere may :e !ro:lems-

If t2e antenna system 2as !ro:lems9 t2e TC( call dro! rate and 2andover failure rate are

2i"2- In addition9 t2e difference :et$een t2e u!lin% ;uality and t2e do$nlin% ;uality is

"reat9 or :ot2 t2e u!lin% ;uality and t2e do$nlin% ;uality are !oor- Mou can c2ec% $2et2er t2e antenna system is faulty :y vie$in" t2e traffic measurement results- T2e follo$in"




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ta:le lists t2e traffic measurement counters related to t2e antenna system-

Ce## 5eve# TR@ 5eve#

Call #easurement 7O &PI #easurement 7O

Radio (andover Success Rate

Call #easurement 7O *ut"oin" Internal

Inter7Cell (andover #easurement !er Cell

7O

*ut"oin" E?ternal Inter7Cell (andover

Re;uests '1!lin% Stren"t2) 7O *ut"oin"

E?ternal Inter7Cell (andover Re;uests

'o$nlin% Stren"t2)

#R #easurement 7O

#easurement of Receive uality

#R #easurement 7O

1!lin%=o$nlin% Balance

Performance #easurement

If !ro:lems !ersist9 verify t2at remote BTSs are o!erational and conduct dialin" tests :y

!erformin" t2e follo$in" ste!s@

,- Perform local maintenance- C2ec% $2et2er alarms are "enerated- If yes9 clear t2ese

alarms immediately-

5- C2ec% $2et2er t2e u!lin% or do$nlin% antenna tri:utary 2as 2ard$are !ro:lems9 for

e?am!le9 t2e connector is loose9 antennas are reversely connected9 semi7ri"id ca:les are

connected incorrectly9 or ca:les are loosely connected to t2e :ac%!lane-

3- 1se t2e test #S to conduct dialin" tests on t2e same location-

Conduct dialin" tests on eac2 c2annel of eac2 TR to c2ec% $2et2er certain

timeslots or :oards cannot :e assi"ned-

C2ec% $2et2er t2e do$nlin% receive level of eac2 TR is similar- /or t2e TR $it2

a:normal level9 re!lace t2e :oard and u!lin% or do$nlin% antenna system to identify

t2e cause-

Note t2at if t2e cell ado!ts fre;uency 2o!!in" '/P)9 c2an"e t2e /( mode of t2e cell

to Non7/( :y usin" !arameters of t2e command line to facilitate dialin" tests-

- Conduct drivin" tests :y usin" t2e net$or% o!timi+ation soft$are ANT7PL*T- T2en9

c2ec% $2et2er t2ere are a:normal 2andover relations2i!s and do$nlin% interference and

find $ays to reduce t2e con"estion rate-

<- 1se a s!ectrum analy+er to furt2er locate t2e interference source-

8- C2ec% $2et2er t2e area covered :y t2e BTS features com!le? terrain-




INT%RN&'

-5-5 Board faults

/aults occurred on t2e TR :oard are t2e most ty!ical ones- T2ere is o:vious difference

:et$een t2e TC( sei+ure failure caused :y t2e :oard fault and t2at caused :y t2e feeder installation or fault- T2e former fault causes !oor c2annel availa:ility and t2e latter does

not affect t2e c2annel availa:ility-

T2e !ro:lem is easy to solve- 1se a si"nalin" analy+er to trace messa"e over t2e A:is

interface in t2e cell $it2 2i"2er TC( con"estion rate- T2en9 use t2e filter of t2e si"nalin"

analy+er to list t2e Assi"nment /ailure messa"e- In t2is messa"e9 t2e cause value is t2e

e;ui!ment failure- 1se t2e call trace function to list t2e entire messa"e !rocedure- /ind

t2e Assi"nment Command messa"e- T2en9 o!en t2e messa"e and o:tain t2e TR

num:er of t2e faulty TR :oard or #AI* 'of t2e /( c2annel)- T2erefore9 t2e fault is

concerned $it2 t2e TR- Mou can re!lace t2e TR or un:loc% t2e TR tem!orarily-

Case 5

-5-3 Transmission and Cloc% Pro:lem

Generally9 t2e u!!er7level cloc% is loc%ed :y t2e BTS- (o$ever9 due to o:Kective reasons

or malo!erations9 transmission !ro:lems suc2 as PC# out7of7sync2roni+ation of t2e A

interface9 intermittent LAP lin%s9 free oscillation and cloc% !ro:lems may occur- At t2is

time9 t2e TC( fails to :e sei+ed :y t2e #S9 causin" 2i"2er TC( con"estion rate-

To solve t2is !ro:lem9 c2ec% t2e alarm information and t2e status of t2e BTS cloc%

dis!layed on t2e L#T and determine $2et2er t2e transmission or t2e cloc% is faulty-T2en9 correctly set t2e status of t2e cloc% or contact related de!artment to rectify t2e

transmission fault-

-3 Interference Causes

-3-, Inter7Net$or% Interference

In t2e on7site de!loyment9 invalid inter7net$or% fre;uencies "enerate interference on our

net$or%- T2e interference affects t2e TC( sei+ure success rate9 call dro! rate9 and

2andover success rate- If t2e BSC assi"ns a TC( affected :y interference for a call9 t2e

assi"nment may fail and t2e TC( con"estion occurs-

/or inter7net$or% interference9 t2e traffic measurement s2o$s t2at t2e TC( con"estion

rate is 2i"2er in interference :ands four and five- T2e u!lin% interference is only for

reference- Eliminatin" t2e interference re;uires t2e coordination $it2 t2e local

"overnment- isa:le t2e affected fre;uencies- 1se t2e s!ectrum analy+er and 2i"27"ain

directional antenna to locate t2e interference source- T2en disa:le t2e interference

source- T2e inter7net$or% interference is difficult to analy+e- It is not descri:ed in detail

2ere-

Case Q




INT%RN&'

-3-5 Im!ro!er /re;uency Plannin"

In actual net$or%s9 fre;uency resources are limited- T2erefore9 fre;uencies must :e

reused to meet re;uirements of t2e net$or% ca!acity- /rom t2is !oint of vie$9 net$or%ca!acity is al$ays incom!ati:le $it2 net$or% !erformance- If t2e fre;uencies are

im!ro!erly !lanned9 t2e re;uirement for t2e carrier7to7interference ratios 'CIRs) fails to

meet and co7c2annel interference or adKacent7c2annel interference is "enerated- T2e co7

c2annel interference or adKacent7c2annel interference !roduces t2e same effect as t2e

inter7net$or% interference- T2at is9 t2e TC( assi"nment may fail and t2e TC( con"estion

occurs-

It is easier to analy+e and eliminate t2e interference caused :y im!ro!erly !lanned

fre;uencies- 1!lin% and do$nlin% fre;uencies are !aired- T2erefore9 $e can c2ec% t2e

information a:out interference :ands in t2e traffic measurement results- /irst9 find out t2e

cells $it2 2i"2 mean num:er of SCC(s in interference :ands four and five- T2en9 c2ec%

t2e fre;uency !lannin" and t2e to!olo"y of t2e BTS- /ind intra7fre;uency or inter7

fre;uency nei"2:or cells in o!!osite directions9 readKust t2e fre;uency !lannin"9 and

eliminate t2e interference- In addition9 if t2e antenna is installed reversely t2ou"2 t2e

fre;uency !lannin" is !ro!erly formulated9 interference is also "enerated- In t2is case9

you cannot solve t2is !ro:lem :y referrin" to t2e fre;uency !lannin" and net$or%

to!olo"y- T2erefore9 !erform a lar"e ;uantity of drive tests in t2e cells $it2 2i"2 mean

num:er of SCC(s in interference :ands four and five- C2ec% t2e actual distri:ution of

si"nals to determine $2et2er t2e interference e?ists- T2en9 modify t2e antenna !lannin"

or fre;uency !lannin"-

- &PI #easurement Pro:lems

T2ere are differences :et$een traffic measurement counters :ecause eac2 vendor

calculates t2ese counters :y usin" self7defined counters- It is difficult to find traffic

measurement !ro:lems causin" 2i"2 TC( con"estion rate- /or t2e BSC of earlier

versions9 t2e TC( sei+ure failure inde? 'numerator of t2e formula for calculatin" t2e TC(

con"estion rate) increases :y one if t2e Assi"nment Com!lete messa"e 'rat2er t2an t2e

Assi"nment /ailure messa"e) is not received after t2e BSC delivers t2e Assi"nment

Command messa"e- T2en9 a statistical error is "enerated9 and t2e calculated TC(

con"estion rate is 2i"2er t2an t2e actual rate-

T2is !ro:lem is com!le? :ecause a net$or% involves multi!le cells and TC( con"estion

occurs in many cells due to various causes@ suc2 as 2i"2 traffic or radio lin% failure 'due

to t2e !recedin" causes)9 includin" statistical errors- T2e ty!ical situation is t2at t2e call is

released once t2e #S initiates t2e call- T2e cause may :e t2at after re!ortin" t2e

isconnect messa"e9 t2e #S receives t2e Assi"nment Command messa"e from t2e

BSC9 and t2en re!orts t2e Status messa"e carryin" t2e cause value indicatin" messa"e

ty!e mismatc2- After receivin" t2e Status messa"e9 t2e #SC releases t2is call-

T2erefore9 neit2er t2e Assi"nment Com!lete messa"e nor t2e Assi"nment /ailure

messa"e e?ists in t2e messa"e !rocedure- /or t2e BSC of earlier versions9 t2e TC(




INT%RN&'

sei+ure failure counter increases :y one- T2ere are many cases in a lar"e GS# net$or%-

T2erefore9 t2e calculated TC( con"estion rate is 2i"2er t2an t2e actual rate- Currently9

t2e met2od of measurin" t2e TC( sei+ure failure is c2an"ed- T2e counter increases :y

one $2en t2e Assi"nment /ailure messa"e is received-/or t2e formula definition and recommended formula9 refer to t2e GSM BSS Network KPI

(TCH Call Drop Rate) Baseline-

-< Parameter Settin"s

Parameter settin"s may lead to t2e TC( con"estion due to various causes- Generally9

t2e !arameter settin"s may affect t2e TC( con"estion rate in all t2e cells in t2e entire

net$or% or certain cells- In t2e case of t2e former situation9 c2ec% $2et2er im!ortant

!arameters and t2en less im!ortant !arameters are correctly set :ecause of multi!le

cells involvin" t2e TC( con"estion and "reat on7site !ressure-

-<-, C2annel Assi"nment Parameters

TC( Traffic Busy T2res2old')H

/or (ua$ei c2annel assi"nment al"orit2m II9 $2en t2e TC( assi"nment rate reac2es or

e?ceeds t2e t2res2old9 t2e BSC assi"ns TC((s for t2e dual7rate call- *t2er$ise9 TC(/s

are assi"ned- *:viously9 t2is !arameter determines $2et2er TC((s or TC(/s are

assi"ned- T2erefore9 if t2e TC( con"estion rate is 2i"2er9 set t2e !arameter to a small

value to assi"n TC((s- T2is increases t2e c2annels usa"e ratio- (o$ever9 t2e s!eec2

;uality de"rades9 for e?am!le9 #*S tests may :e affected-

Tc2 Traffic Busy *verlay '1nderlay) T2res2oldH

T2e BSC assi"ns c2annels in t2e overlaid su:cell to t2e #S in a concentric cell- If t2e

c2annel sei+ure ratio of t2e overlaid su:cell is "reater t2an t2e value of t2is !arameter9

TC((s are assi"ned- *t2er$ise9 TC(/s are assi"ned- T2e im!acts of t2is !arameter are

t2e same as t2ose :rou"2t :y TCH Traic B"s$ T,res,o#d(3)9 t2at is9 c2annels are

utili+ed fully9 :ut t2e s!eec2 ;uality de"rades-

/i? A:is Prior C2oose A:is Load T2res2old')H

T2is !arameter s!ecifies t2e static A:is resource load t2res2old- 2en t2e static A:is

resource load is lo$er t2an t2e value of i0 &'is Prior C,oose &'is 5oad T,red(3)9

t2e TC(/ is !referentially assi"ned- *t2er$ise9 t2e TC(/ or TC(( is !referred

accordin" to t2e dynamic A:is resource load-

/le? A:is Prior C2oose A:is Load T2res2old')H

2en t2e static A:is resource load is 2i"2er t2an t2e value of i0 &'is Prior C,oose

&'is 5oad T,res,o#d(3) and t2e dynamic A:is resource load is 2i"2er t2an t2e value of

#e0 &'is Prior C,oose &'is 5oad T,res,o#d(3)9 t2e TC(( is !referred- *t2er$ise9

t2e TC(/ is !referred-




INT%RN&'

Balance Traffic Allo$edH

If t2is !arameter is set to A/S9 t2e start of t2e c2annel traverse is selected randomly- If

t2is !arameter is set to NO9 t2e ne?t c2annel of t2e assi"ned c2annel is selected as t2estart of t2e c2annel traverse-

Generally9 t2is !arameter is set to A/S to ensure t2at t2e start !oint of t2e c2annel

traversal is selected randomly and ensure t2e c2annel load s2arin"-

Case 3

-<-5 Call Control Parameters

Assi"nment Cell Load ud"e Ena:le 'BSC8...)H

2en &ssignent Ce## 5oad 6"dge /na'#ed is set to Aes9 t2e directed try !rocedure is

started if t2e follo$in" t$o conditions are met@ T2e cell su!!orts directed try- T2e load of

t2e cell is "reater t2an or e;ual to t2e value of Ce## +irect Tr$ or'idden T,res,o#d-

irected Retry Load Access T2res2old 'BSC8...)H

T2is !arameter is used to adKust candidate tar"et cells for directed retry-

urin" directed retry9 only t2e cells $2ose loads are smaller t2an or e;ual to t2e value of

+irected Retr$ 5oad &ccess T,res,o#d are selected as candidate tar"et cells-

If t2e !arameter value is too 2i"29 t2e cells $it2 2eavy loads are selected as candidate

tar"et cells so t2at t2e 2andover does not ma%e sense- If t2e value of t2e !arameter is

too lo$9 it is difficult to select candidate tar"et cells-

TC( Immediate Assi"nmentH

If t2e !arameter is set to Aes9 t2e BSC assi"ns TC(s immediately if no SCC(s are

availa:le durin" t2e !rocessin" of access re;uest- If t2e !arameter is set to No9 t2e BSC

can only assi"n SCC(s- T2is !arameter is used to relieve con"estion and increase t2e

c2annel assi"nment success rate-

Load (* Allo$edH

T2is !arameter s!ecifies $2et2er a traffic load7s2arin" 2andover is ena:led-Load s2arin" 2el!s to reduce cell con"estion9 increase success rate of c2annel

assi"nment and :alance t2e traffic load amon" cells9 t2us im!rovin" net$or%

!erformance- T2e load 2andover functions :et$een t2e TC(s $it2in one BSC or t2e

TC(s in t2e cells of t2e same layer-

T2e load 2andover is used as an emer"ency measure instead of a !rimary measure to adKust

a:normal traffic !ea% in certain areas- If load 2andovers occur fre;uently in a local net$or%9

you must adKust t2e TR confi"uration of t2e BTS and t2e net$or% layout-

Load (* Ste! Period and Load (* Ste! LevelH

2en t2e load of t2e cell is e;ual to or "reater t2an t2e value of 5oad HO T,res,o#d9 all




INT%RN&'

t2e calls served :y t2e cell may send 2andover re;uests simultaneously9 and t2e load on

t2e CP1 increases ra!idly as a conse;uence- In some cases9 call dro!s may occur due

to traffic con"estion in t2e cell- T2erefore9 t2e BSC ado!ts t2e 2ierarc2ical load 2andover

al"orit2m to control t2e num:er of calls to :e 2anded over at eac2 level-T2is !arameter s!ecifies t2e !eriod re;uired for !erformin" t2e load 2andover at a level-

In t2e 2ierarc2ical load 2andover9 t2e load 2andover stri! increases :y one 5oad HO

Step 5eve# for every 5oad HO Step Period9 startin" from t2e value of /dge HO +5

R@5/? T,res,o#d- T2e 2andovers are !erformed as suc2 until all t2e calls $2ose

receive levels are $it2in t2e ran"e of 'Ed"e (* L RJLEV T2res2old9 Ed"e (* L

RJLEV T2res2old D Load (* :and$idt2) are 2anded off t2e current servin" cell-

T2e value of 5oad HO Step 5eve# must :e smaller t2an t2at of 5oad HO Bandwidt,-

.83 corres!onds to ,,. dBm to > dBm-

irect Retry and Cell irect Try /or:idden T2res2old 'BSC8...)H

If &ssignent Ce## 5oad 6"dge /na'#e is set to Aes9 t2e directed try !rocedure is

started to assi"n c2annels for t2e #S if t2e follo$in" t$o conditions are met@ T2e cell

su!!orts t2e directed try !rocedure- T2e load of t2e cell is "reater t2an or e;ual to t2e

value of Ce## +irect Tr$ or'idden T,res,o#d- T2is !arameter decreases TC(

accesses of t2e source cell and reduces TC( con"estion t2rou"2 increases t2e call dro!

rate-

A#R TC(=( Prior Allo$edH

T2is !arameter s!ecifies $2et2er TC((s are !referentially assi"ned on t2e :asis of t2ec2annel ty!e and current service c2annel sei+ure ratio t2at are allo$ed :y t2e #SC-

urin" TC( assi"nment9 TC(/s or TC((s are re;uired and TC((s are !referentially in

t2e follo$in" conditions@ TC((s and TC(/s are allo$ed to :e assi"ned :y t2e #SC9

&MR TCHH Prior &##owed is set to Aes9 and t2e !ercenta"e of sei+ed TC(s in t2e cell

is "reater t2an t2e value of &MR TCHH Prior Ce## 5oad T,res,o#d- In ot2er cases9

TC(/s or TC((s are re;uired and TC(/s are !referentially-

-<-3 (andover Parameters

PBGT (* T2res2oldH

2en t2e 2andover is !erformed :et$een nei"2:or cells9 im!ro!er !arameter settin"s

cause out"oin" inter7cell 2andover or incomin" inter7cell 2andover to fail- T2is leads to

un:alanced traffic distri:ution and con"estion-

Parameters related to ed"e 2andoverH

2en t2e receive level dro!s "reatly9 an ed"e 2andover cannot :e !erformed in time in

any of t2e follo$in" conditions@ T2e !arameter /dge HO 45 R@5/? T,res,o#d or

/dge HO +5 R@5/? T,res,o#d is set to a small value t2e !arameter Inter.ce## HO

H$steresis is set to a "reat value t2e !arameters /dge HO Datc, Tie and /dge HO




INT%RN&'

?a#id Tie are set to "reat values- As a result9 con"estion occurs- To reduce t2e TC(

con"estion rate9 you can a!!ro!riately set t2ese !arameters so t2at ed"e 2andovers can

:e !erformed in time-

Parameters related to B 2andoverH

2en t2e si"nal ;uality deteriorates9 a B 2andover cannot :e !erformed in time in any

of t2e follo$in" conditions@ T2e !arameters 45 E"a#it$ 5iit or /ergenc$ Handover

(&MR&MRR&MRHR) and +5 E"a#it$ 5iit or /ergenc$ Handover

(&MR&MRR&MRHR) are set to "reat values t2e !arameter BE HO Margin is set to a

small value t2e !arameter Inter.ce## HO H$steresis is set to a "reat value- As a result9

call dro!s occur- To reduce t2e TC( con"estion rate9 you can a!!ro!riately set t2ese

!arameters so t2at B 2andovers can :e !erformed in time-

Parameters related to interference 2andoverH

If t2e !arameters R@E4&5* to R@E4&5*- are set to "reat values or if t2e R@5/?O

!arameter is set to a "reat value9 interference 2andovers cannot :e !erformed in time

$2en stron" interference occurs- As a result9 t2e con"estion occurs- To reduce t2e TC(

con"estion rate9 you can a!!ro!riately set t2ese !arameters so t2at interference

2andovers can :e !erformed in time to !revent con"estion- If t2e !arameters R@E4&5*

to R@E4&5*- are set to small values9 t2e num:er of 2andovers due to ot2er causes

increases "reatly9 t2us affectin" t2e 2andover success rate-

T3,.3 and T3,.>HT3,.3 and T3,.> are timers for t2e 2andover and assi"nment res!ectively- If eit2er timer

is set to a "reat value9 t2e time for $aitin" t2e 2andover=assi"nment com!lete messa"e

is too lon" after t2e 2andover=assi"nment command is delivered9 causin" con"estion-

/5( (* t2= (5/ (* t2H

2en an A#R call occu!ies a TC((9 an intra7cell TC(( to TC(/ 2andover is tri""ered if

t2e radio ;uality indication 'RI) remains lo$er t2an t2e confi"ured (5/ (* T2res2old

for a !redefined !eriod- T2is !arameter is used $it2 Intrace## .H HO Stat Tie (s) and

Intrace## .H HO 5ast Tie (s)-

Parameters related to concentric cell 2andoverH

A call at t2e ed"e of t2e overlaid su:cell cannot :e 2anded over to t2e underlaid su:cell

in any of t2e follo$in" conditions@ /or a normal concentric cell9 t2e !arameters R@5/?

T,res,o#d and R@5/? H$steresis are set to "reat values for an en2anced concentric

cell9 t2e !arameter Oto4 HO Received 5eve# T,res,o#d is set to a "reat value- As a

result9 TC( con"estion occurs- If t2e TC( con"estion rate in t2e overlaid su:cell is 2i"29

you can a!!ro!riately set t2ese !arameters so t2at calls at t2e ed"e of t2e overlaid

su:cell can :e 2anded over to t2e underlaid su:cell in time-

If R@E4&5 or 4O HO &##owed is set to Aes and R@E4&5 T,res,o#d is set to a"reat value9 a call in t2e case of interference cannot :e 2anded over from t2e underlaid




INT%RN&'

su:cell to t2e overlaid su:cell- T2us9 TC( con"estion occurs- If t2e TC( con"estion rate

in t2e underlaid su:cell is 2i"29 you can set t2ese !arameters !ro!erly so t2at t2e

interfered calls can :e 2anded over to t2e overlaid su:cell in time-

Case <

-<- Basic Cell Parameters

RLEVJACCESSJ#INH

T2is !arameter s!ecifies t2e minimum receive level of an #S to access t2e BSS- If t2is

!arameter is set to a too small value9 some #Ss $it2 lo$ receive levels may access t2e

net$or% and TC( con"estion is li%ely to occur- Mou can set t2is !arameter to a "reat

value to reduce t2e TC( con"estion rate- T2e counters suc2 as call setu! success rate

and t2e counters related to traffic volume9 2o$ever9 are accordin"ly affected-

SACC( #ulti7/rames and Radio Lin% TimeoutH

If t2e traffic volume is very 2eavy 'in cities)9 it is recommended t2at t2e value of S&CCH

M"#ti.raes ran"es from 5. to 35- In t2e areas $2ere t2e traffic volume is very 2eavy

'"enerally covered :y micro cells)9 it is recommended t2at t2is !arameter value ran"es

from to ,8- In t2e cells $2ere some areas are not covered or call dro!s occur fre;uently9

t2is !arameter must :e set to a lar"er value so t2at conversations can resume- T2erefore9 if

t2e !arameter is im!ro!erly set durin" 2eavy traffic volume9 t2e TC( con"estion is li%ely to

occur-

RAC( #in Access LevelH

T2is !arameter s!ecifies t2e level t2res2old for t2e #S access- If t2is !arameter is set to

a too small value9 some #Ss $it2 lo$ si"nal levels may access t2e net$or% and TC(

con"estion is li%ely to occur- Mou can set t2is !arameter to a "reat value to reduce t2e

TC( con"estion rate- T2e counters suc2 as call setu! success rate and !a"in" success

rate9 2o$ever9 are affected-

Parameters related to cell reselection

Im!ro!er settin"s of cell reselection !arameters affect t2e selection of t2e net$or% on$2ic2 t2e #S cam!s durin" cell reselection9 for e?am!le9 im!ro!er !arameter settin"s

durin" t2e dual7net$or% covera"e affect net$or% selection and cause TC( con"estion-

SCC( ynamic AdKustmentH

2en t2ere is a su:stantial user increase in a cell9 some users may not :e a:le to

access t2e net$or% :ecause t2ey cannot o:tain SCC(s- In t2is case9 you need to

convert some TC(s to SCC(s to ensure t2at all t2e users can access t2e net$or%-

2en t2e traffic volume decreases9 t2e TC(s used as SCC(s are converted :ac% to

TC(s- T2e dynamic conversion of SCC(s can increase t2e system ca!acity and lo$er

t2e re;uirement for t2e accurate num:er of re;uired si"nalin" c2annels-




INT%RN&'

/lo$ ControlH

T2ere are multi!le flo$ control !arameters- To relieve TC( con"estion9 t2e system starts

t2e flo$ control- (o$ever9 t2is affects TC( access and cause messa"e loss-

S!eec2 VersionH

T2is !arameter can :e set to one of t2e follo$in" values@ 2alf7rate version 39 2alf7rate

version 59 2alf7rate version ,9 full7rate version 39 full7rate version 59 and full7rate version ,-

If t2is !arameter does not su!!ort 2alf7rate versions9 t2e BSC assi"ns TC(/s instead of

TC((s- As a result9 TC( con"estion occurs-

-8 T2ird7Party evice Pro:lems

-8-, Re!eater Pro:lems

Currently9 re!eaters '/( re!eaters or o!tical re!eaters) are ado!ted to solve t2e !ro:lem

of insufficient indoor covera"e- It is difficult for /( re!eaters to o:tain si"nal resources-

T2e im!lementation !rinci!le of t2e /( re!eaters is t2at t2e /( re!eater am!lifies si"nals

received :y t2e main antenna of t2e o!tical re!eater and transmits t2ese am!lified

si"nals to t2e areas $it2 !oor covera"e- In ot2er $ords9 t2e covera"e of t2e cell is

e?!anded- T2erefore9 t2e traffic volume increases- If t2e traffic volume e?ceeds t2e

system ca!acity9 t2e TC( con"estion rate increases-

C2ec% $2et2er t2e !arameter +irect#$ Magniier Site #ag is set to Aes in t2e data

confi"uration on t2e L#T- If t2is !arameter is set to Aes9 you can infer t2at t2e cell is

confi"ured $it2 re!eaters- If t2is !arameter is set to No9 c2ec% $2et2er ot2er o!erators

re!eaters are installed near t2e cell-

If re!eaters are installed9 c2ec% $2et2er t2ey are $ide7fre;uency re!eaters- If yes9 c2ec%

$2et2er t2e u!lin%=do$nlin% am!lification coefficient is too "reat- Ensure t2at t2e

am!lification coefficient is !ro!erly set- If a re!eater 2as a "reat im!act on t2e call dro!

rate9 s$itc2 off t2e re!eater-

If re!eater !ro:lems e?ist in a cell9 t2e TA distri:ution varies "reatly in t2e traffic

measurement results- T2e follo$in" ta:le lists t2e traffic measurement counters related to

re!eaters-


None #R #easurement 7O

Num:er of #Rs Based on TA

Case >




INT%RN&'

-8-5 Com!ati:ility $it2 Non7(ua$ei E;ui!ment

In t2e e?istin" net$or%9 t2ere are certain overla!!ed areas9 for e?am!le9 :oundary

:et$een t$o !rovinces and rural7ur:an frin"e +one covered :y e;ui!ment of differentvendors :ut t2e same o!erator- Coo!eration of e;ui!ment from different vendors re;uires

t2e inter7#SN 2andover- ifferent !olicies or !arameter settin"s may cause t2e traffic to

increase :ut fail to :e 2anded over immediately- As a result9 t2e TC( con"estion rate

increases-

If t2e !ro:lem occurs9 c2ec% t2e success rate of out"oin" BSC 2andovers and

distri:ution of out"oin" 2andover failure causes to identify t2e main causes- T2e follo$in"

ta:le s2o$s related traffic measurement counters-


None Call #easurement 7O

*ut"oin" E?ternal Inter7Cell (andover

#easurement !er Cell

-8-3 5G=3G Intero!era:ility

it2 t2e develo!ment of 3G net$or%s9 certain 2i"27end #Ss ado!ts t2e dual transfer mode- T2erefore9 t2e #Ss can :e reselected from 5G net$or%s to 3G net$or%s and

5G=3G Intero!era:ility e?ists- it2 t2e increase of suc2 #Ss9 t2e con"estion may occur

in t2e 5G and 3G systems if !arameters are incorrectly set-

/or e?am!le9 normally9 an #S in t2e 5G net$or% is reselected to t2e 3G net$or%-

(o$ever9 nei"2:or cells in t2e Q..#7net$or% and 3G net$or% are set to unidirectional

adKacent cells- T2erefore9 t2e #S is reselected to t2e 5G net$or% rat2er t2an t2e 3G

net$or%9 causin" con"estion in t2e 5G net$or%-

5G=3G Intero!era:ility !ro:lems increase $it2 t2e develo!ment of 3G net$or%s- T2e

3GPP !rotocols s!ecify 5G=3G 2andovers of RQQ and later versions rat2er t2an

2andovers of earlier versions- T2erefore9 if !ro:lems occur9 c2ec% $2et2er t2e 2andover

is limited :y t2e version9 and t2en c2ec% t2e 2andover9 reselection9 confi"uration of

nei"2:or cells9 and !arameter settin"s to locate t2e !ro:lem-

/or !arameter settin"s9 refer to t2ose related to reselection9 2andover9 and 3G e?ternal

cells-

Note@ Currently9 t2e BSC8... su!!orts 5G7to73G inter7RAT 2andovers suc2 as TA emer"ency 2andover9

B emer"ency 2andover9 ra!id level dro! 2andover9 interference 2andover9 and ed"e 2andover-

Currently9 t2e BSC8... does not su!!ort t2e GS#7to7T7SC#A al"orit2m for t2e inter7RAT load7




INT%RN&'

:ased 2andovers and service7:ased 2andovers- (o$ever9 inter7RAT 2andovers :ased on certain

conditions can :e reali+ed in later versions-



GS# BSS Net$or% &PI 'TC( Con"estion Rate) *!timi+ation#anual V,-.

Confidentiality Level

-> Soft$are Version Pro:lem

Recently9 (ua$ei re;uires to im!lement multi!le mi"ration and u!"rade !roKects in t2e

5G net$or%- urin" t2e mi"ration9 early !roducts of (ua$ei re;uirin" to :e re!laced suc2

as BTSs of earlier version de!loyed on t2e BSC35 may :e incom!ati:le $it2 t2e

BSC8...- As a result t2e TC( con"estion rate increases or ot2er suc2 !ro:lems occur-

Solution

,- Mou re;uire to devote more ener"ies to analy+e suc2 !ro:lems- It is recommended

to c2ec% t2e !recaution9 find !ossi:le !ro:lems :efore t2e u!"rade9 and analy+e

cases to o:tain t2e solution and !rocessin" mec2anism ado!ted in t2e old version-

5- *n t2e remote L#T9 c2ec% $2et2er soft$are of eac2 :oard of t2e BTS is com!ati:le

and !erform version u!"rade accordin" to t2e version notice on t2e

2tt!@==su!!ort-2ua$ei-com site- *n t2e remote L#T9 :loc% TC(s of t2e TR :oard in

turn in t2e cell $it2 2i"2 con"estion rate- T2en9 c2ec% $2et2er t2e con"estion rate is

relevant to t2e TR :oard of t2e cell and t2en ado!t t2e follo$in" !rinci!les-

If yes9 it indicates t2at t2e con"estion rate is concerned $it2 t2e TR :oard-

C2ec% $2et2er co7c2annel interference e?ists9 and t2en c2ec% t2e !erformance

of u!lin% and do$nlin% 2ard$are and t2e TR :oard-

If not9 t2e interference e?ists in t2e entire cell or t2e con"estion rate is su:Kect to

t2e terrain-

3- Si"nalin" tracin" and analysis

1se a si"nalin" analy+er to trace messa"es over t2e A:is interface in t2e cell $it2 2i"2

con"estion rate- T2en9 com!are tracin" results $it2 measurement items in t2e call

!rocedure and measurement counters relatin" to t2e TC( assi"nment failure- T2e

follo$in" fi"ure dis!lays t2e messa"e tracin" results :y usin" t2e #A,. si"nalin"

analy+er-

C2ec%in" t2e &ssignent CM+ command delivered on t2e SCC(9 you can see t2at

T/I determines t2e TR :oard $2ere t2e SCC( resides9 and &RCN s!ecifies t2e

TR :oard $2ere t2e TC( resides- C2ec% $2et2er t2e assi"nment failure occurs on a

certain TR :oard- T2en9 locate s!ecific causes :ased on t2e TA value of t2e #S9

u!lin%=do$nlin% level9 and u!lin%=do$nlin% si"nal ;uality included in t2e measurement

re!ort and ma%e dialin" test locally-

5.,87<73. (ua$ei !ro!rietary Pa"e 56 of 38

http://support.huawei.com/







T2e assi"nment failure occurred on a TR :oard may :e caused :y one of t2e follo$in"

reasons@

',) T2e TR :oard is faulty or t2e !erformance is unsta:le-

'5) 1!lin% and do$nlin% levels are not :alanced or u!lin% or do$nlin% antenna tri:utary

2as 2ard$are !ro:lems-

'3) 1!lin% and do$nlin% si"nals are of !oor ;uality- C2ec% t2e c2annel on $2ic2 t2e

interference e?ists :y considerin" t2e TA value-

If assi"nment failures randomly distri:ute on TR :oards in t2e entire cell9 t2e failures

may :e caused :y one of t2e follo$in"s t2rou"2 t2e measurement re!ort analysis@

',) T2e areas covered :y t2e BTS feature t2e com!le? terrain-

'5) T2e fre;uency interference e?ists in t2e entire cell9 for e?am!le9 interference from

re!eaters-

8 Test Met,od

T2e TC( con"estion rate is one of t2e &PIs to evaluate net$or% access !erformance9

$2ic2 can :e o:tained t2rou"2 t2e re"istration or re!ortin" of t2e related &PIs- At

!resent9 vendors and mo:ile o!erators use different formulas to calculate t2e TC(

con"estion rate9 t2us leadin" to different values of t2is counter- In actual measurement9

5.,87<73. (ua$ei !ro!rietary Pa"e 5Q of 38





you s2ould re"ister t2e s!ecific counters and use an a!!ro!riate formula to calculate t2e

value of t2e counter-

9 &ppendi0 C,eck Ites on TCH Congestion Rate

C2ec% Item Remar%s Pur!ose

Version

information

Version information a:out

t2e BSC9 PC19 and BTS

To c2ec% t2e version matc2in" relations2i!-

/re;uency

multi!le?in"

mode

,6..#9 Q..# To c2ec% t2e fre;uency confi"uration-

ata

confi"uration

ta:le

U-dat file To c2ec% t2e settin"s of t2e net$or%

o!timi+ation !arameters9 nei"2:or cell

relations9 and !o$er confi"uration

Alarm

information

(ard$are9 cloc%9 and

transmission alarms 'self7

c2ec%)

To c2ec% $2et2er t2ese alarms are

"enerated in t2e cell- (andle t2e alarms if

t2ey are "enerated-

Traffic

measuremen

t

&PI #easurement !er Cell To com!are t2e num:er of S=TC(

re;uests9 S=TC( sei+ure success rate9

and traffic volume to c2ec% $2et2er t2e

coo!eration $it2 t2e nei"2:or BTS is

normal-

Intra7cell (andover

#easurement !er Cell

To com!are t2e num:er of incomin" inter7

cell 2andovers and t2e num:er of out"oin"

inter7cell 2andovers res!ectively :efore and

after net$or% re!lacement to c2ec% $2et2er

t2e coo!eration $it2 t2e nei"2:or BTS is

normal-

Incomin"=*ut"oin"

Internal=E?ternal Inter7Cell

(andover #easurement

!er Cell

rivin" test

data

U-lo" 'U-cell site) or U-ant

file

To identify t2e covera"e !ro:lem :y

com!arin" t2e covera"e :efore and after net$or% re!lacement-

*t2ers En"ineerin" !arameter

ta:le and electronic ma!

To c2ec% t2e "eo"ra!2ical information

t2rou"2 t2e NASTAR soft$are-

: T$pica# Cases

>-,Case ,@ TC( Con"estion Caused :y Terrain Reasons

+escription

5.,87<73. (ua$ei !ro!rietary Pa"e 3. of 38





T2e TC( con"estion rate of a certain omnidirectional cell is 3,.-

Tro"'#es,ooting

Analy+in" A:is7interface si"nalin"9 you can find t2at t2e con"estion reason is t2at t2e

level is too lo$ and t2e :it error rate increases- In addition9 t2e TA value of t2e #S t2e

distance :et$een t2e #S and t2e BTS is 5<-8 %m to 3,-, %m- *:vious9 t2e TC(

assi"nment fails :ecause t2e #S is far a$ay from t2e BTS- #a%e on7site drivin" tests9

and t2en you $ill find t2at an isolated BTS is de!loyed 2ere and t2e area features

com!le? terrain- T2erefore9 t2e con"estion of t2e BTS cannot :e solved tem!orarily due

to environment limitations

Hand#ing Proposa#

To solve t2e cell con"estion !ro:lem caused :y lar"e covera"e and com!le? terrain9

o!erators are advised to do t2e follo$in"s@ Add BTSs to im!lement continuous covera"e-

C2an"e t2e omnidirectional BTS to t2e directional BTS9 adKust t2e a+imut2 and tilt of t2e

antenna9 and en2ance transmit level- In addition9 !revent cross7area covera"e-

>-5 Case 5@ (i"2 TC( Con"estion Rate Caused :y /ault of TR Board

+escription

T2e BTS ado!ts t2e S8==5 confi"uration- *ne day9 t2e traffic measurements su""est

t2at t2e TC( overflo$ rate is 2i"2 in cell , $it2 si? TRs and t2e TC( con"estion rate

reac2es 5.- T2e traffic on TC( in t2e cell is lo$9 "enerally9 .-6Erl durin" :usy 2ours- In

addition9 t2e TC( sei+ure failure due to :usy TC( is .- C2annels on all t2e BTs in cell ,are in t2e idle state- T2e :ase:and attri:ute and RC attri:ute are normal- T2ere is no

a:normality on t2e L#T-

Tro"'#es,ooting

,- *n t2e L#T9 ;uery t2e status of c2annels on BTs :y usin" t2e !recedin" met2od- Mou

can conclude !reliminarily t2at t2e TC( fails to :e sei+ed on BT and BT< in cell ,-

5- If you :loc% BT9 BT<9 RC9 and RC<9 t2ere is no TC( con"estion all day- T2en9 you

can inter t2at RC and RC< are faulty-

3- If you un:loc% BT9 BT<9 RC9 and RC< and reset RC 'TR) and RC< 'TR<)9 2i"2

con"estion rate !ersists-

- Insert and remove TR and TR< on t2e field- After ma%in" dialin" tests 'on TR

and TR<) after fre;uency loc%9 t2e TC( still fails to :e sei+ed- E?c2an"e slots of TR

and TR< and ma%e dialin" tests 'on TR and TR<) after fre;uency loc%- In t2is case9

t2e TC( still fails to :e sei+ed-

<- #a%e dialin" tests 'on TR and TR<) after fre;uency loc% after re!lacin" TR and

TR<- T2en9 t2e TC( is successfully sei+ed and t2e TC( con"estion is released-

>-3 Case 3@ Static TC(( Con"estion Caused :y Insufficient TC(/s

+escription

Previously9 several BTSs ado!tin" t2e static 2alf7rate function $ere added to t2e BSC

5.,87<73. (ua$ei !ro!rietary Pa"e 3, of 38





'G3BSC35V3..R..5C,.)- In su:se;uent days9 2o$ever9 t2e con"estion rate of t2e

several BTSs in :usy 2ours in t2e evenin" is 2i"2 'over ,.)- Instead9 t2e traffic volume

is not very 2i"2- *:vious9 t2e a:normality occurs-

Ca"se &na#$sis

,- C2ec%in" !arameter settin"s9 you $ill find t2at TCH Rate &d>"st &##owed of eac2 cell

is disa:led and static TC((s are confi"ured in t2ese cells- *nly one or no TC( is

confi"ured in t2ese cells-

5- C2ec%in" t2e TC( !erformance measurement9 you $ill find t2at only one or t$o TRs

are confi"ured in t2e con"ested cell-

3- Recordin" t2e !erformance counters in cell !erformance measurement 59 you $ill find

t2at C/55 &55OC &I5 TIM/S R is muc2 "reater t2an &55OC &I5 TIM/S R-

Ma0i" N"'er o B"s$ TCHs is "reater t2an t2e num:er of confi"ured TC(/s-

Ma0i" N"'er o B"s$ TCHHs is smaller t2an t2e confi"ured num:er- C2ec%in"t2e status of TC(s in :usy 2ours9 you $ill find t2at all t2e TC(/s of t2ese cells are

occu!ied and some TC((s are in t2e idle state-

- T2ese cells are located in rural areas or su:ur:s and multi!le #Ss can only use

TC(/s :ecause TC((s are not su!!orted- In addition9 insufficient TC(/s result in

TC(( con"estion-

Tro"'#es,ooting

,- Increase t$o or t2ree TC(/s for eac2 cell accordin" to Traic ?o#"e on TCH and

Traic ?o#"e on TCHH and t2e num:er of TC((s confi"ured in ERLANG B-

5- *:serve t2e traffic measurement result after modifyin" t2ese !arameters- T2en9 youcan find t2at t2e TC( con"estion rate of eac2 cell is "reatly reduced9 nearly +ero-

Hand#ing Proposa#

Si"nificant modifications are made in t2e 2alf7rate al"orit2m ado!ted in C,3 and later

version- If TC((s must :e su!!orted9 it is recommended t2at t2e al"orit2m version is

u!"raded to C,3 or later- In C,3 version9 after t2e TC( rate adKustment is ena:led9 you

can set t2e traffic :usy t2res2old to control t2e ty!e of !referred TC(s- T2en9 t2e

!recedin" !ro:lems are solved-

/or t2e con"estion of t2e cell in $2ic2 2alf7rate service is ena:led9 c2ec% $2et2er

dynamic TC(( adKustment is allo$ed- T2en9 locate t2e main cause and ta%e !ro!er measures accordin"ly-

>- Case @ Increase of TC( Con"estion Rate Caused :y Im!ro!er (alf7Rate

Parameters after 1!"rade from BSC C,. to BSC C,3

+escription

In an area9 t2e TC( con"estion rate increases after BSC C,. is u!"raded to BSC C,3

and t2e 2alf7rate traffic a:sor!tion decreases-

Ca"se &na#$sis






BSC C,. does not su!!ort real7time conversion of TC((s- T2erefore9 :efore u!"rade9

TC((s are confi"ured in t2e net$or% and TCH Rate &d>"st &##ow is disa:led9 t2at is9

dynamic adKustment of TC( rate is unallo$ed- In BSC C,.9 if t2e assi"nment re;uest of

t2e #SC is TC(/ !referred or TC(( !referred9 t2e BSC c2ec%s $2et2er t2e num:er of

idle TC(/s is "reater t2an t2e value of Preerred TCH Id#e T,res,o#d and assi"ns

a!!ro!riate c2annels- T2e c2annel confi"uration remains unc2an"ed after u!"rade and

TC(( !arameters use default values in C,3 version- (o$ever9 t2e 2alf7rate al"orit2m

ado!ted :y BSC C,3 "reatly differs from t2at of BSC C,.- In BSC C,.9 TCH Rate

&d>"st &##ow is disa:led- T2erefore9 TC(/s fail to :e coverted to TC((s and t2e TC(

con"estion rate increases-

Tro"'#es,ooting

Set t2e TC( ty!e to TCH "## Rate and TCH Rate &d>"st &##ow to Aes- After t2e

dynamic adKustment of t2e TC( rate is allo$ed9 t2e con"estion rate decreases and 2alf7rate traffic a:sor!tion increases- T2en9 !ro:lems are solved-

Hand#ing Proposa#

BSC C,3 o!timi+es t2e 2alf7rate al"orit2m and reali+es t2e real7time dynamic adKustment

of t2e TC( rate- /ocus on t2e im!act im!osed on t2e traffic a:sor!tion and t2e TCP

con"estion rate :y t2e modification of t2e 2alf7rate al"orit2m after and :efore t2e u!"rade

of t2e BSC version-

>-< Case <@ Increase of TC( Con"estion Rate Caused :y #odification of efault Value of (andover T2res2old

+escription

In a site9 if BSC8... is u!"raded from VQR,C.,B.68 to VQR,C.3B,.9 t2e traffic

measurement result reveals t2at t2e num:er of TC( con"estion is muc2 "reater t2an t2at

'nearly +ero) :efore t2e u!"rade- In addition9 t2e 2i"2er traffic volume in t2e cell9 t2e

more serious t2e con"estion is- T2e traffic volume9 2o$ever9 does not increase s2ar!ly-

Tro"'#es,ooting

/irst9 t2e main cause is not t2e traffic volume :ecause t2e traffic measurement s2o$s no

o:vious c2an"es of traffic volume :efore and after con"estion-

Second9 t2e traffic measurement su""ests t2at t2e interference :and is normal-

T2erefore9 you can infer t2at t2ere is no u!lin% interference-

T2ird9 t2e con"estion occurs suddenly in a "reat num:er of cells and t2e TR sei+ure is

normal in t2e cell $it2 serious con"estion- T2erefore9 you can infer t2at t2ere are no

im!licit faults of t2e :oard-

/ourt29 t2ere are no !arameter modifications recently- T2en9 t2e con"estion cause

cannot :e t2e manual !arameter modification-

T2en9 you can determine t2at t2e con"estion is caused :y u!"rade- Accordin" to






tec2nical su!!ort en"ineers and R0 !ersonnel9 t2e P=N !arameter of t2e PBGT

2andover does not :rin" any im!act :efore u!"rade $2et2er t2is !arameter is set to any

value 'By default9 P 3 and N 3)- After u!"rade9 t2e P=N !arameter settin" 'P 3 and

N 5) ta%es effect- T2e num:er of 2andover re;uests is multi!lied several times due to

t2e decrease of t2e 2andover t2res2old-

Hand#ing Proposa#

T2is case !rovides ne$ t2ou"2ts for net$or% o!timi+ation@ To reduce t2e TC( con"estion

rate9 you can increase t2e 2andover t2res2old and reduce t2e num:er of 2andovers in

t2e com!le? do$nto$n area $it2 dense si"nals- If t2is met2od is a!!lied to t2e rural area

$it2 !oor si"nals9 some ris%s may e?ist9 suc2 as call dro! occurs and t2e s!eec2 ;uality

deteriorates 't2e 2andover cannot :e !erformed till t2e covera"e level is in !oor ;uality)-

>-8 Case 8@ Increase of TC( Con"estion Rate Caused :y ReverseConnections of Antennas

+escription

T2e customer com!lains t2at t2e covera"e of a BTS decreases and call setu! is difficult

2o$ever9 no alarm is found on t2e L#T-

Tro"'#es,ooting

Reverse connections of antennas9 transmit antennas9 and receive antennas cause

un:alanced si"nals on u!lin% c2annels and do$nlin% c2annels- T2at is9 t2e user to $2ic2

t2e transmit antenna !oints is :ac% of t2e receive antenna- If t2e #S receives t2e TC(assi"nment command from t2e BSC durin" t2e call9 t2e TC( fails to :e assi"ned and t2e

TC( con"estion occurs due to !oor level and ;uality of u!lin% si"nals of t2e #S caused

:y small "ain of t2e receive antenna-

Hand#ing Proposa#

To solve t2is !ro:lem9 ma%e drivin" tests or use a si"nalin" analy+er to analy+e t2e level

and ;uality of u!lin% and do$nlin% si"nals to c2ec% $2et2er si"nal im:alance e?ists- If

yes9 ta%es !ro!er measures to solve t2is !ro:lem-

If t2e a+imut2 and tilt of t2e main antenna is inconsistent $it2 t2ose of t2e diversity

antenna or t2e diversity or s!acin" is small $2en sin"le7!olari+ation antennas are used in

a cell9 u!lin% and do$nlin% si"nals are inconsistent and TC(s sei+ure failures tend to

occur- T2ere are no suc2 !ro:lems in cells t2at ado!t dual !olari+ation antennas-

>-> Case >@ (i"2 TC( Con"estion Rate ue to No Ca!acity E?!ansion of

Re!eaters after BTS Ca!acity E?!ansion from *5 to *

+escription

After t2e ca!acity of a BTS is e?!anded from *5 to *9 t2e con"estion rate increases9

reac2in" u! to .-Tro"'#es,ooting






,- If t2e latter t$o TRs are :loc%ed on t2e remote L#T9 t2e TC( con"estion rate is

dramatically reduced to t2e normal level- T2en9 you can infer t2at t2e main cause is t2e

t$o TRs-

5- Tracin" and analy+in" A:is7interface si"nalin"9 you can find t2at t2e assi"nment failure

occurs on t2e t$o ne$ TRs- 2en t2e assi"nment failure occurs9 t2e measure re!ort of

SCC(s su""ests t2at t2e level on t2e SCC( is normal and t2e TA value is relatively

"reater- T2en9 you can determine t2at t2e failure occurs on a remote area- (o$ever9

t2ere are no SACC( 'TC() measurement re!orts- It is estimated t2at u!lin% or do$nlin%

tri:utaries of t2e t$o TRs may :e faulty- In some cases9 t2e TC( assi"nment is

successful on t2e t$o TRs- T2en9 t2e t$o TRs cannot :e faulty-

3- T2ere are no faults occurred on antenna and feeder 2ard$are :ecause t2is cell ado!ts

t2e four7in7one com:iners and one7to7four dividers- In addition9 t2ere are no 2ard$are

!ro:lems on t2e semi7ri"id ca:les connectin" TR :oards to com:iners and dividers-

- Accordin" to t2e maintenance en"ineers9 t2is cell is installed $it2 a re!eater- Before

ca!acity e?!ansion9 t$o TRs are confi"ured in t2is cell and t$o fre;uencies are loc%ed

:y t2e re!eater- After ca!acity e?!ansion9 no fre;uencies are loc%ed for t2e t$o TRs-

T2erefore9 to solve t2e !ro:lem of 2i"2 TCP con"estion rate9 you must solve t2e

fre;uency !ro:lem of t2e re!eater-

Ca"se &na#$sis

T2e covera"e of t2e latter t$o TRs differs from t2at of former t$o TRs due to t2e

de!loyment of re!eaters- T2is causes TC( assi"nment failure-

>-6 Case 6@ Interference Caused :y Re!eaters

+escription

In cell 3 of a BTS9 t2e call dro! rate reac2es ,. traffic volume is lo$ t2e TC(

con"estion rate is 2i"2- In cell , and cell 59 2o$ever9 t2e call dro! rate and TC(

con"estion rate are normal-

Tro"'#es,ooting

,- T2e TC( con"estion rate remains 2i"2 no matter 2o$ to :loc% TC(s of t2e TR in t2e

cell- It is estimated t2at interference e?ists or t2e area covered :y t2e cell features

com!le? terrain-

5- Accordin" to t2e traffic measurement data9 idle TC(s fall in interference :and or < in

cell 3 in daytime and in interference :and , or 5 from 53@.. in t2e ni"2t to >@.. in t2e

mornin"- T2ere is re"ularity :et$een t2e TC( con"estion rate and call dro! rate and t2e

interference :and-

3- C2ec% $2et2er co7c2annel interference e?ists- C2an"e t2e fre;uency of cell 3 so t2at

t2e s!acin" :et$een t2e fre;uency and t2e ori"inal one is at least , meter- T2e

interference9 2o$ever9 !ersists- T2erefore9 t2e !ro:a:ility of co7c2annel interference and

adKacent7c2annel interference is eliminated-

- C2ec% $2et2er t2e e;ui!ment is faulty- E?c2an"e antenna feeders of cell 3 and cell ,-T2e interference9 2o$ever9 still e?ists in cell 3- T2erefore9 you can infer t2at t2e

5.,87<73. (ua$ei !ro!rietary Pa"e 3< of 38





e;ui!ment is in t2e normal state- T2en9 c2ec% $2et2er e?ternal interference e?ists-

<- 1se a s!ectrum analy+er to ma%e fre;uency s$ee! tests on t2e divider !ort- T2en9 you

$ill find t2at a si"nal similar to t2e si"nal from an analo" s!ectrum 't2e central fre;uency

is Q.-, #(+ and t2e s!ectrum :and$idt2 is 3.. %(+) e?ists continuously- T2e stren"t2

of t2e si"nal at t2e divider !ort of cell 39 cell 59 and cell , is 5> dBm9 . dBm9 and 8.

dBm res!ectively9 and t2e si"nal stren"t2 is consistent $it2 t2e interference level-

T2rou"2 t2e s!acin" :et$een t2e fre;uency and t2e ori"inal one is ,. meters9 t2e

fre;uency out!uts continuous si"nals- In t2is case9 collision and intermodulation $it2

ot2er si"nals tend to occur- Some intersected si"nals may fall in t2e receivin" :and9

causin" interference- T2e traffic volume in daytime is 2i"2er t2an t2at in t2e ni"2t-

T2erefore9 intersected si"nals are more and t2e interference is more serious- (ua$ei

reac2es an a"reement $it2 o!erators t2at t2ere is no Q.-, #(+ interference source-

Put t2e s!ectrum analy+er in t2e car to ma%e drivin" tests- At t2is time9 2o$ever9 no Q.

#(+ interference source is found- T2en9 ma%e drivin" tests on t2e roof- At last9 t2e fault

is considered to :e concerned $it2 t2e unim!ortant little antenna- Su:se;uent si"nal

interru!tion tests !rove t2is 2y!ot2esis- After t2e antenna is !o$ered off9 t2e interference

is eliminated and measurement counters of BTS A :ecome normal-

>-Q Case Q@ TCP Con"estion Caused :y E?ternal Interference

+escription

A cell encounters TC( con"estion caused :y e?ternal interference-

Tro"'#es,ooting

T2ree radars are de!loyed in t2e BTS a:out one %ilometer a$ay from t2e do$nto$n

area- /or t2e 5> radar $2ose o!eratin" fre;uency :and is similar to GS# fre;uency

:and9 t2e o!eratin" fre;uency :and is Q..QQQ#(+ and t2e transmit !o$er is <6.&-

T2e stand:y time is lon"- Lon"7time tests and analysis s2o$ t2at t2e radar cause serious

interference- T2e receiver of t2e BTS features 2i"2 receive :ac%"round noise t2at

reac2es a ma?imum of 6.dBm- T2en9 u!lin% si"nals transmitted from t2e #S $it2 lo$

!o$er may :e over$2elmed :y noise si"nals- At t2is time9 it is difficult for su:scri:ers to

ma%e a call- In addition9 t2ere is no !rom!t sound- As a result9 t2e TC( con"estion

occurs- Mou can reduce t2e interference :y decreasin" t2e antenna tilt-

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05 GSM BSS Network KPI (TCH Congestion Rate) Optimization Manual.doc.doc