sdcch_prb

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MEMO 1 (4)

TNP/APACThomas Quick 13.7.2000

"SDCCH drop" problem solved in Nokia Area

1. INTRODUCTION

Sinc i! "as a#$% "i!h A&S !ha! !h S'CC %$o $a! "i** + $o$!% as a ,P& (k- $o$mancin%ica!o$) i#u$ i! has +n $co#ni% !ha! !his a*u is $a!h$ hi#h coma$% !o o!h$ su*i$s!-ica**- a! a $#iona* ** o ca. 101.

Nokia has $o$m% a s$is o !s!s !o ins!i#a! !h $o+*m. On in%in# "as !ha! !h a*u "as$- hi#h in sa!**i! A+is connc!ions "ha! "as 5*aina+* %u !o !h sa!**i! A+is s!!in#s.

Ano!h$ ins!i#a!ion sho"% !ha! !his $o+*m !-ica**- occu$s in $oa% co$a# si!s "h$ !hma6o$i!- o !h %$os a$ caus% +- ai*% *oca!ion u%a! ca**s.

cn! !$ia*s ha no" $a*% !h #n$a* na!u$ o !h $o+*m. This mmo 5*ains !his an%#is som su##s!ions o$ i!s so*u!ion.

2. CALL STU! !ROCDUR IN S#

To un%$s!an% !h $o+*m 5*ana!ion i! is n%% !o $i" !h ini!ia* ca** s!u $oc%u$ (*a-$ 3$o!oco*) in 8SM. &! is sk!ch% in 9i#u$ 1.

Figure 1: Initial call setup phase in GSM

Th ca** s!u s!a$!s "i!h !h CANNE:;EQ<EST mssa# "hich is sn! +- !h mo+i* s!a!ion(MS) on !h $an%om accss chann* (AC). This is !h cas +o!h o$ a mo+i* o$i#ina!in# ca** an% in$sons !o a a#in# mssa#. Th $=us! is $ci% as CANNE:;EQ<&E' mssa# in !h>SC "hich in !u$n ac!ia!s !h S'CC $sou$c in !h >TS (!h$ou#h !h CANNE:;ACT&?AT&ONcomman% "hich is ackno"*%#% +- !h >TS).From this point onwards, the SDDCH channel is occupied by the base station system (whether

it will be used or not).To !** !h MS !o !un !o !h $*a!% S'CC !h >SC sn%s !h &MME'&ATE;ASS&8NMENTcomman% on !h accss #$an! chann* (A8C) !o !h MS "hich ina**- s!a+*ishs !h si#na**in#connc!ion +- $!u$nin# !h $ason o$ !h s!a+*ishmn! on !h S'CC (in !h i#u$ a+o !his issho"n o$ a ca** s!u@ ano!h$ $ason mi#h! + ans"$ !o a#in# o$ *oca!ion u%a!). This is %on +-

CANNE:;EQ<EST

CANNE:;EQ<&E'

CANNE:;ACT&?AT&ON

CANNE:;ACT&?AT&ON;AC,

&MME'&ATE;ASS&8NMENT;COMMAN'

&MME'&ATE;ASS&8NMENT

SA>M CA:: SET<P

ESTA>:&S;&N'&CAT&ON

T3101

MS >TS >SC

8/13/2019 sdcch_prb


MEMO 2 (4)


mans o a SA>M (s! as-nch$onous +a*anc mo%) mssa# as a$! o !h :AP' $o!oco*. Hence,this is the very first time the reserved SDCCH will be used.

As can + sn u$!h$ !h >SC moni!o$s !h $o!oco* +- s!a$!in# a !im$ (ca**% T3101 in 8SM) uonsn%in# !h &MME'&ATE;ASS&8NMENT comman%. T3101 chcks !h 5c!% ans"$ $om !h MS"hich is o$"a$%% +- !h >TS as ESTA>:&S;&N'&CAT&ON mssa#.

$. !R%OR#ANC #ASUR#NT O% TH SDCCH DRO! RAT

& !h !$aic masu$mn! is ac!ia!% in >SC an% NMS/2000 !h co$$c! unc!ionin# o !h :AP'$o!oco* (!his is !h *a-$ 2 $o!oco*) "hi* usin# an S'CC is "a!ch% +- a $o$mancmasu$mn! coun!$ ca**% sdcch_abis_fail_call "hich coun!s !h ai*u$s in !h $o!oco* in

cas i! *% !o an S'CC %$o. &! is us% in !h a#$% ,P& o$mu*a o$ !h S'CC %$o $a! B1. Thiscoun!$ has +n sn !o + $sonsi+* o !h ma6o$i!- o !h 5$inc% S'CC %$os.

&n cas i !h T3101 coun!$ 5i$s manin# !ha! !h >SC sn%s an &MME'&ATE;ASS&8NMENTmssa# +u! !h MS %osnD! $*- "i!h a s!a+*ish in%ica!ion !his is a*so consi%$% as a ai*u$coun!% +- sdcch_abis_fail_call !hou#h !h S'CC hasnD! +n us% a! a** in !his a$!icu*a$

cas. Sinc >SS S $sion S7 a n" coun!$ is aai*a+* as a$! o !h s$ic ** masu$mn!"hich coun!s !h T3101 5i$is 5!$a. Th nam o !his coun!$ is t3101_expired.

A $cn! ins!i#a!ion $a*% !ha! !h coun!s o t3101_expired is $- c*os !o !h ons o

sdcch_abis_fail_call manin# !ha! mos! o !h %$os a$ comin# $om T3101 5i$is. As an

5am* 9i#u$ 2 sho"s !h ,P& %a!a o$ !h $cn! %a-s o$ !h com*! s!$n $#ion "h$as9i#u$ 3 #is !h si!ua!ion "i!h !h t3101_expired coun!$ minus% $om !h num+$ o S'CC

%$os in !h ,P& o$mu*a. Th $su*!s sho" c*a$*- !ha! !h %sc$i+% $o+*m cas is %ominan! in !h

"ho* s!$n $#ion. i!h !h mo%iica!ion in !h ,P& o$mu*a !h S'CC %$o $a! (S') is *o"$!han !h TC %$o $a! (ca** %$o $a! C'). Ts!s in !h No$!h$n an% Sou!h$n $#ion $a*% !hsam in%in#s.

Figure 2: KPI measurements based on the agreed KPI formulas

0

2

4

F

G

10

12

2 F . 0 F . 2 0

0 0

2 7 . 0 F . 2 0

0 0

2 G . 0 F . 2 0

0 0

2 H . 0 F . 2 0

0 0

3 0 . 0 F . 2 0

0 0

0 1 . 0 7 . 2 0

0 0

0 2 . 0 7 . 2 0

0 0

0 3 . 0 7 . 2 0

0 0

0 4 . 0 7 . 2 0

0 0

0 . 0 7 . 2 0

0 0

C '

7 /

S ' 7 /

( O 9 7 B 4

0

10

1

20

2

30

3

40

4

0

E $ * a

n # m i n u ! s ) $ % $ o )

Erlmin/drop

CDR

SDR

HOFR

8/13/2019 sdcch_prb


MEMO 3 (4)


Figure 3: KPI measurements with modified KPI formula for S!!" drop rate

&. !RO'L# (!LANATION

Th$ a$ !h$ ma6o$ causs "hich *a% !o T3101 5i$is

1. "ando#er $%!" bursts in n!"o$ks "i!h $- !i#h! $=unc- $Ius i! can han !ha! !h >TSacci%n!a**- $cis AC +u$s!s "hich ha +n sn% +- !h MS !o ano!h$ !a$#! >TS %u$in#a han%o$ $oc%u$. Th- a$ in!$$!% as CANNE:;EQ<EST mssa#s o$ a ca** s!u.This can + aoi%% !h$ou#h ca$u* >S&C *annin#. An-"a- in ou$ cas !his caus can +

5c*u%% as !h $o+*m aa$s in $u$a* a$as as "**.

2. &Ghost& accesses inc$as% nois in an >TS $ci$ u*ink in!$$nc !c. can + in!$$!%+- !h >TS as CANNE:;EQ<EST mssa# i a c$!ain +i! a!!$n is $co#ni%. Th Nokia>SC is caa+* !o %is!in#uish +i! a!!$ns "hich in%ica! ina*i% s!a+*ishmn! causs an%suo$!s a coun!$ "hich $#is!$s !his n!s as #hos! accsss. This caus can a*so +5c*u%% as !h coun!% #hos!s a$ in #n$a* n#*i#i+* coma$% !o !h T3101 5i$- coun!s.

3. Multiple $%!" sent b' MS in cas !h MS %osnD! $ci an &MME'&ATE;ASS&8NMENTcomman% "i!hin a c$!ain $io% a!$ sn%in# !h CANNE:;EQ<EST mssa# i! sn%su$!h$ ACs (%n%in# on !h n!"o$k s!!in#s@ !h $*a!% a$am!$ con!$o*s !h ma5imumnum+$ o AC $!$ansmissions MAJ;ETANS). Th >SC mi#h! com*! !h $o!oco* o$

on o !h sn! AC +u! ano!h$ on mi#h! + in!$$!% as ano!h$ ca** s!u "h$ !h MS"i** n$ ans"$ !h &MME'&ATE;ASS&8NMENT mssa#. This is the case which serves asa eneral SDCCH problem e!planation for the "#S networ$ .

&n #n$a* !h T3101 5i$is can no! + coun!% as S'CC %$os as !h S'CC has no! n -!+n s!a+*ish%. Th unsui!a+* $co#ni% ACs cou*% ho"$ *a% !o S'CC +*ockin#.

). !RO!OSD SOLUTION

As !h %sc$i+% $o+*m is no! in con6unc!ion "i!h $a* S'CC %$os i! is $=ui$% !o mak !hmn!ion% mo%iica!ion in !h S'CC %$o o$mu*a. Th mo%ii% sc$i! is a*$a%- aai*a+* an% can+ $*ac%.

Th a%%i!iona* occui% S'CC a$ no! causin# an- ha$m !o !h s-s!m un*ss !h- a$ *a%in# !oS'CC +*ockin#. Thus !h S'CC +*ockin# "i** + moni!o$% as a$! o !h o!imia!ion $ocss.

0

2

4

F

G

10

12

2 F

. 0 F . 2 0

0 0

2 7

. 0 F . 2 0

0 0

2 G

. 0 F . 2 0

0 0

2 H

. 0 F . 2 0

0 0

3 0

. 0 F . 2 0

0 0

0 1

. 0 7 . 2 0

0 0

0 2

. 0 7 . 2 0

0 0

0 3

. 0 7 . 2 0

0 0

0 4

. 0 7 . 2 0

0 0

0

. 0 7 . 2 0

0 0

C ' 7 /

S ' 7 /

( O 9 7 B 4

0

10

1

20

2

30

3

40

4

0

E $ * a n # m i n u ! s ) $ % $ o )

Erlmin/drop

CDR

SDR

HOFR

8/13/2019 sdcch_prb


MEMO 4 (4)


8n$a**- a sui!a+* "a- !o aoi% S'CC +*ockin# is usin# NokiaDs %-namica**- S'CC a!u$"hich coni#u$s a%%i!iona* S'CC !ims*o!s au!oma!ica**- i $=ui$%. This a!u$ is aai*a+* in a**

$#ions.

Ano!h$ o!ion is mo%ii-in# !h con!$o* chann* (CCC) a$am!$s. &n Nokia !h %au*! s!!in# o!h MAJ;ETANS a$am!$ mn!ion% a+o is s! !o 4 so i! mi#h! + $%uc% !o a*us %o"n !o2 o$ n 1. 9u$!h$ a$am!$s mi#h! + consi%$% o$ mo%iica!ion as "**.

As !h mu*!i* AC $o+*m occu$s !-ica**- un%$ "ak $a%io con%i!ions i! is *ik*- !ha! amo%iica!ion o !h MAJ;ETANS a$am!$ *a%s !o an 5c*usion o c** $in# su+sc$i+$s !hou#hin a mo$ #n!* "a- !han coma$% !o a mo%iica!ion o !h J;:E?;ACCESS;M&N a*u "hich+*ocks su+sc$i+$s in accssin# !h n!"o$k +- $=ui$in# a minimum $ci% si#na* s!$n#!h.

&n i!h$ "a- !h num+$ o ca**s shou*% + ca$u**- moni!o$% +o$ an% a!$ im*mn!a!ion o

!h chan# an% on !h ac!ua* $su*! i! can + %ci%% !o acc! im$omn!s in =ua*i!- "i!hcom$omiss in su+sc$i+$ num+$s o$ $$!in# +ack !o !h o*% s!!in#s an% acc!in# !h +*ockin#un*ss !his can + ca!$% +- masu$s *ik sc!o$ia!ion o$ a%%i!iona* si!s.

*. R%RNCS

B1 !ustomi(ed )etwor* doctor script +,,-Nokia %ocumn! (Thomas Quick ?$sion 1.3)

B2 )o*ia )MS.2///: atabase description for 0S! measurementsNokia %ocumn! NTC TAN 0422/3 n

B3 )etwor* doctor: sers guideNokia %ocumn! NTC TAN 0H3/2.1 n

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