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Huawei Confidential
Security Level:10/08/15
Cell update & FACH Transfer
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Content
* UE Working Modes and States
* Cell Update and FHHO Scenarios
* Main Reason for CDR Increase in FACH
* Proble and Sol!tions
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U !or"in# $odes and %tates
Idle Mode
Connected Mode
C'(CH
C'FACH
C')CH U*A')CH
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+dle $ode
The UE has no relation to UTRAN, only to CN. Any data
transfer, a sinallin connection should have to !e
esta!lished.
UE ca"#s on a cell
+t ena,les the U to recei-e sstem information from the )$
U can monitor )+CH of a cell for pa#in#
The idle "ode tas$s can !e divided into three #rocesses:
)$ selection and reselection
Cell selection and reselection
ocation re#istration
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Connected $ode
%hen UE is in connected "ode The U position can ,e "nown on dierent le-els
Cell le-el 2C'(CH/C'FACH/C')CH3
UT*A *e#istration Area 2U*A3 le-el 2U*A')CH3
The U can use dierent tpes of channels in connected mode
(edicated transport channels 2C'(CH3
Common transport channels 2C'FACH3
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Connected $ode
Cell&'C( +n acti-e state
Communicatin# -ia its dedicated channels
UT*A "nows which cell U stas in
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Connected $ode
Cell&)AC(
+n acti-e state
Few data to ,e transmitted ,oth in uplin" and in downlin". There is
no need to allocate dedicated channel for this U
(ownlin" uses FACH and uplin" uses *ACH
U needs to monitor the FACH for its information
UT*A "nows which cell the U stas in
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Connected $ode
Cell&*C(
o data to ,e transmitted or recei-ed
$onitor )+CH4 to recei-e its pa#in#
UT*A "nows which cell the U stas in
UT*A has to u#date cell infor"ation of UE when U roams to
another cell ower the power consumption of U
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Connected $ode
URA&*C( o data to ,e transmitted or recei-ed
$onitor )+CH4 to recei-e its pa#in#
UT*A onl "nows which U*A 2which consists of multiple cells3
that U stas
UT*A updates U information onl after U has roamed to otherU*A
A ,etter wa to reduce the resource occupanc and si#nalin#
transmission
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U !or"in# $odes and %tates
C'(CH C'FACH
C')CHU*A')CH
+(
(A( %can networ"s 2)$3 Camp on a cell
$onitor pa#in# channel Cell reselection
(edicated channel Common ser-ice4
such as -oice
*educe acti-it4 (*64
and sa-e power**C Connection
Common channel )% ser-ice with few
data to transmit
*educe acti-it further
A-oid unnecessarsi#nalin#
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FHH7 : Forward Hard Hando-er
)((+ used to "onitor the RRC connection state onco""on channel, hich #rocess the "o!ility of UE
on Co""on Channel
)((+ also contains the RRC connection re!uilt in
'C(. )((+ includin Cell U*'ATE and URA U*'ATE-only
occurs in URA*C(/
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FHH7 Function( C'(CH)
RLC Un&recovery Error: recover the RL hen UE cannotnor"al co""unicate ith UTRAN e0ualed RLC layer
usin AM "ode
RL failure: usin in RRC connection re!uilt, hen all
the RLs loss of synchroni1ation, UE try to re!uilt the
RRC connection ith UTRAN
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*elation ,etween FHH7 and **C %tate
RRC Conne$tion "tate Reali,a!le F. Fun$tion(
update $au"e)
C/LLC Cell 2pdate RLC /RR 、 RL F%L
C/LLF%C Cell 2pdate )eriodical Cell update4 Cell
reselection4 *eenter %er-in# Cell4 RLC /RR
C/LLPC Cell 2pdate )eriodical Cell update4 Cell
reselection4 *eenter %er-in# Cell4 )a#in#
*esponse4 U (ata Transmit3
2R%PC Cell 2pdate )a#in# *esponse4 U (ata
Transmit34 2R% 2pdate )eriodical U*A update4
U*A reselection3
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Cell Update Function *eriodical Cell u#date: UE "ovin ithin one cell "a2ority
ay to "onitor RRC connection
Cell reselection: UE "o!ility state cross di3erent cells, "a2or
ay of UE $ee# RRC connection ith UTRAN servin in
Co""on Channel.
Re&enter Service Area: another ay to $ee# RRC connection
hen "ove, T456 e7#ired RLC Un&recovery Error: recover the RL hen UE cannot
nor"al co""unicate ith UTRAN e0ualed RLC layer usin AM
"ode
*ain Res#onse res#onse to #ain ty#e 8 fro" UTRAN
hen RRC connection e7ist UL 'ata Trans"it UE infor" UTRAN needin data trans"it
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U*A Update Function
*eriodical URA u#date: URA I' contained in Cell syste" infoith UE "o!ility
URA reselection: URA I' not in the syste" info hen UE "ove
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Cell Update %i#nalin# Flow
Page &"
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Main reasons for the C'R increaseon )AC(
*S call dro# after () R; Recono crossed!y )( R; Recon
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*eason and %olutions
Reason
No #oer control on )AC(
No Soft(+ on )AC(
The state not consistent !eteen UE and RAN
Solutions
'ecrease Users on the )AC( state !y decrease ()
volu"e threshold
Con
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*T+ *adio etwor" Temporar+denti9er )ive ty#es of RNTI e7ist
%er-in# *C *T+ 2%*T+3
(rift *C *T+ 2(*T+3
Cell *T+ 2C*T+3
UT*A *T+ 2U*T+3 H%(%CH *T+ 2H*T+3
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Cell update :ow( );F)
U **$ ** F$* %+<
(CCCHCell update con9rm
Appl radio resource
UCCCHCell update re=uest
+f $ACC/$AC( in dierent ,oard, ,uilt AA> connection
?uilt $ACC and $AC( lo#ical channel
U(CCH)hsical channal recon9#uration
complete
Cell update and U stateindicate
*C restore
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Cell update with relocation( )%)
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Cell update with relocation( )%)
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UEDR"C
So!rce
DR"C
#arget SRNC
R"SAP R"SAP'6 Coon Tran"p6 C7annel Re"our$e" Relea"e
R"SAPR"SAP
&6 2plin) +ignalling Tran"8er
ndi$ation
R"SAP
36 Coon Tran"p6 C7annel Re"our$e"
nitiali,ation Re9ue"tR"SAP
RRC16 CCC: Cell 2pdate
RRC$rela%
RRC
6 CC: Cell 2pdate Con8ir
RRC
RRC;6 CC: RNT Relo$ation Coplete
RRC
R"SAPR"SAP
46 Coon Tran"p6 C7annel Re"our$e"initiali,ation Re"pon"e
56 %LC%P ur !earer "etup
FHH7( Cell Update crossin# +U*)
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UE#arget
R"C
56CCC: 2R% 2pdate Con8ir
So!rce
R"C
&62plin) +ignalling Tran"8er ndi$ation
Ser&ing
R"C
[ new C-RNTI,D-RNTI, UL message]
16CCC: 2R% 2pdate
[U-RNTI, URA update cause]
RRC-rela#RRC
36 e$i"ion Not to
per8or +RN+
relo$ation
RRC RRC-rela#
RN+%P
RN+%P
46 o
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FHH7 Flow-. R/S
Cell -pa0e
Cell -pa0e Con1ir"
-. R/S
Cell -pa0e
Cell -pa0e Con1ir"
-*RA/ 2o3ili0( &n1o Con1ir"
-. R/S
Cell -pa0e
Cell -pa0e Con1ir"
RB Release Co"ple0e
Cell +pa0e pro!e+re 4i05 raio 3earer release
Cell +pa0e pro!e+re 4i05 +pa0e o1 -*RA/ "o3ili0( in1or"a0ion
Cell +pa0e pro!e+re 4i05 raio 3earer release
-. R/S
Cell -pa0e
Cell -pa0e Con1ir"
RB re!16 !o"ple0e
Cell +pa0e pro!e+re 4i05 raio 3earer re!on1i6+ra0ion
-. R/S
-RA -pa0e
-AR -pa0e Con1ir"
-RA +pa0e pro!e+re7 3asi! 1lo4
-. R/S
-RA -pa0e
-AR -pa0e Con1ir"
-*RA/ 2o3ili0( &n1o Con1ir"
-RA +pa0e pro!e+re 4i05 +pa0e o1 -*RA/ "o3ili0( in1or"a0ion