VoLTE RAN Case Study

(1)

(2)



V

VoL

oLTE

TE Ser

Service

vices

s



V

Various

arious T

Tools

ools used

used for

for optimizat

optimization

ion



VoLTE RAN Case Studies



T

Take A

ake Away

way

VoLTE SERVICES

Services

•

• _{VoLTE RAN ptimization}_{VoLTE RAN ptimization}

•

• _{VoLTE !order ptimization}_{VoLTE !order ptimization}

•

• _{VoLTE "arameter and Con#$uration}_{VoLTE "arameter and Con#$uration}

Audit

•

• _{VoLTE E%E Analysis}_{VoLTE E%E Analysis}

Analysis (

Analysis ( RANRAN & & EPCEPC ) )

•

• _{&rive lo$s}_{&rive lo$s}

• • _{'ETR ( )%*}_{'ETR ( )%*}_S+*RR_S+*RR_C,_C, • • _{-S scores}_{-S scores} • • _S++_S++ • • _{R. / 0.}_{R. / 0.} • • _S0i_S0i •

• _{SI" si$nalin$}_{SI" si$nalin$}

•

• _{E"C traces}_{E"C traces}

Tools:

•

• _{TE-S &iscovery}_{TE-S &iscovery}

•

• _IT1_IT1

•

• _{!usiness 23ect}_{!usiness 23ect}

•

• _ERTT_ERTT

•

• _{VoLTE E%E Analyzer / NE}_{VoLTE E%E Analyzer / NE}

• • _4IRES5AR1_4IRES5AR1 • • _EC_EC Accomplishments: Accomplishments: •

• _{ptimized 67778 sites}_{ptimized 67778 sites}_{for AT}_{for AT}_{/T and}_{/T and}

+9778 sites for Sin$Tel

•

• _SRVCC_SRVCC_!order_!order_optimization_optimization

•

• _{-T RRC re:esta2lis;ment}_{-T RRC re:esta2lis;ment}_<eatur_<eatur_e_e

workaround

•

• _{&L ICIC feature testin$ performed}_{&L ICIC feature testin$ performed}

•

• _{4inin$ &<4 1"I improvement}_{4inin$ &<4 1"I improvement}

c;allen$e

•

(4)

TE-S &iscovery

••

Analyze layer =

messa$es

••

Analyze

poor

-S

••

Analyze

VoLTE

setup failures /

drop calls

&rive data ( =

&rive data ( =rdrd_{"arty tool,}_{"arty tool,}

••

Identify

"R

-S calls>clips

••

<etc; 5IT info

••

<etc;

NC->Scanner

data

••

<etc; Network

type info

EC>ERA

••

'sed

for

automatic

tilt

automatic

tilt

analysis

>

analysis

>

recommendatio

ns usin$ drive

data

R<

data

R<

conditions

as

conditions

as

input

••

"CI confusion

••

"arameter

Audit

T

ools used

ERTT

••

<etc;

SS

parameters

••

"erform Audit

VoLTE End:%:End

Analyzer> 4ires;ark

••

Analyze

'ETRs

/

Cell traces

••

Analyze E"C traces

••

Analyze I-S traces

IT1 > !

••

'sed

to

fetc;

counter

2ased

counter

2ased

statistics for analysis

and

provide

and

provide

supportin$ stats for

(5)

VoLTE RAN CASE ST'&IES

List of case stuies

+?

V

oL

TE &r

op wi

t;ou

t RR

C dro

p

%?

RR

C dro

p wit;

out V

oL

TE dr

op

=?

@CI + "r

o#le no

t de#ne

d res

ultin$ i

n V

oL

TE setup f

ailur

e

?

-T RR

C 4

ork around to

reduce V

oL

TE>L

TE &rop

B?

Incor

rect

-CS ass

i$nme

nt Causi

n$ V

oL

TE &r

op

?

Impr

oveme

nt in R

etaina2

ility wi

t; &L ICI

C featur

e activati

on / -T RR

C

4ork around

9?

Impr

oveme

nt in R

etaina2

ility and S

R

VCC SR wi

t; c;an$e i

n parame

ter

D2%t;res;old%rscp'traosetF?

(6)

+?VoLTE &R" wit;out RRC drop

+>=+>=

! ! " " # # $ $ " " _$_$ +?

+?'E 'E sets up sets up RRC RRC connection connection (mt:access,?(mt:access,?

%?

%?VoLTE 2earer is esta2lis;ed?VoLTE 2earer is esta2lis;ed?

=?

=?Event A is tri$$ered indicatin$ 5 for I<L!* followed 2yEvent A is tri$$ered indicatin$ 5 for I<L!* followed 2y

;andover?

?

?'E 'E performs performs 5 5 (R< (R< 5 5 successful,successful,

B?

B?%7 sec after 5 %7 sec after 5 RRC connection is released due to 'serRRC connection is released due to 'ser

%

(7)

! ! # # 3 3 2 2 'E 'E 2 2 22 ! ! !! !! # # Cell G did

Cell G did not ;ave RLC : '- feature for not ;ave RLC : '- feature for VVoLoLTE 2earer ( @CI +, TE 2earer ( @CI +, activatedactivated

'E

was

served

2y

cell !

("CI

B6,?

Event

A

is

tri$$ered for I<L! 5?

+?

+?Source cell ! sends D5 ReHuest D to tar$et cell

Source cell ! sends D5 ReHuest D to tar$et cell

G

%?

%? T

T

ar$e

t cell G

accepts

two default

2earers( Internet /

I-S, / does

not admit

V

oL

TE

2earer?

+?VoLTE &R" wit;out RRC drop

(8)

T

ypical causes for V

oL

TE &rop wit;out R

RC

drop

••

_{RLC mode mismatc; in source / tar$et cell}

••

_{"&C" SN len$t; for @CI + mismatc;}

_{"&C" SN len$t; for @CI + mismatc; in source / tar$et cell}

_{in source / tar$et cell}

••

_{RLC SN len$t; for @CI + mismatc; in}

_{RLC SN len$t; for @CI + mismatc; in source / tar$et cell}

_{source / tar$et cell}

••

_R

_{Ro5C feature must 2e}

_{o5C feature must 2e activated on 2ot;}

_{activated on 2ot; source / tar$et cell}

_{source / tar$et cell}

+?VoLTE &R" wit;out RRC drop

=>==>=

I-"RTANT

›

_{In some cases it was o2served t;at RLC mode >"&C" > RLC SN len$t;}

mismatc; was

mismatc; was o2served

o2served in c

in con#$ured

on#$ured value

value

/ value

/ value found

found in l

in layer =

ayer =

messa$es

SL'TN:

J

(9)

%?RRC drop wit;out VoLTE &R"

+>=+>=

+/% &edicated VoLTE 2earer is setup wit;

E"S 2earer Id9 / @CI+

= 'E performs successful 5

T;ere is

T;ere is time oset of 5rs 2>t drive lo$s / 'ETRtime oset of 5rs 2>t drive lo$s / 'ETR

! ! " " ! ! " " $ $ $ $ " " ! !

(10)

%?RRC drop wit;out VoLTE &R"

%>=%>=

?

? &ue to poor R< conditions* RRC ReCon#$ ms$ sent 2y&ue to poor R< conditions* RRC ReCon#$ ms$ sent 2y

EN! is missed out?

B?

B? !efore t;e old EN! can detect t;e RL<* 'E esta2lis;es!efore t;e old EN! can detect t;e RL<* 'E esta2lis;es

new RR

new RRC C connection connection wit; %++%wit; %++%%?%?

?

? 'E reHuests for all = 2earers? 4;en --E receives'E reHuests for all = 2earers? 4;en --E receives

initial conte.t reHuest * it realizes t;at 'E is no lon$er

connected to %+7K+6? It transfers all t;e t;ree 2earers

to new EN!?

9?

9? --E commands old EN! to release all t;e 2earers (as--E commands old EN! to release all t;e 2earers (as

'E is now connected to new cell,

V

VolTE call olTE call continues continues as t;e as t;e 'E $ets 'E $ets 2ack all 2ack all t;e t;rt;e t;r

# # % % # #   l l Cel Cel ll Ne Ne * * Cel Cel ll + +  

(11)

E<<ECT of R

adioadio

L

inkink

<

ailureailure

on VLTE call

•

• _{RL< can}

_{RL< can}

_{2e 'E}

_detected

_{or EN!}

_detected

•

• _{If t;e RL< is 'E detected / if 'E performs a successful RRC}

_{If t;e RL< is 'E detected / if 'E performs a successful RRC}

connection 2efore --E releases t;e 'E conte.t t;en VLTE

call will continue

•

• _{If t;e RL< is EN! detected t;en EN! will reHuest --E to}

_{If t;e RL< is EN! detected t;en EN! will reHuest --E to}

release t;e 2earers resultin$ in VoLTE drop?

%?RRC drop wit;out VoLTE &R"

=>==>=

It is important to note t;at RRC drop alone do

not conclude t;at t;e VoLTE call ;as dropped?

<urt;er analysis on 2earer level needs to 2e

performed

(12)

+?

+? &efault &efault 2earers 2earers (Internet (Internet and and I-S, I-S, are are setupsetup

%?

%? --E ReHuests EN! to setup @CI+ 2earer ( VoLTE 2earer,--E ReHuests EN! to setup @CI+ 2earer ( VoLTE 2earer,

=?

=? EN! fails to EN! fails to setup @CI + setup @CI + / responds wit; Dnot:supported:@CI:/ responds wit; Dnot:supported:@CI:VValueFalueF

=?@CI:+ pro#le not de#ned

! ! " " $ $

CA'SE @CI:+ "ro#le was not activated in t;e site? CA'SE @CI:+ "ro#le was not activated in t;e site?

! ! ! ! !! " " $ $

(13)

?-ulti tar$et RRC connection Re:esta2lis;ment

54 -'LTI TAR0ET RRC CNNECTIN RE:ESTA!LIS5-ENT 4R1S

+?

+? 'E detects radio link failure'E detects radio link failure

%?

%? 'E selects a new cell ( on same or dierent freHuency, and attempts RRC CNNECTIN RE:'E selects a new cell ( on same or dierent freHuency, and attempts RRC CNNECTIN RE:

ESTA!LIS5-ENT

=?

=? 'E s'E sends ends "CI* C:RNT"CI* C:RNTI* s;I* s;ort -ort -AC:I AC:I of of t;e t;e last last servin$ servin$ cell cell in rin re:esta2lis;ment messa$e?e:esta2lis;ment messa$e?

S;ort -AC:I

S;ort -AC:I is used to verify is used to verify t;e credi2ility of t;e Rt;e credi2ility of t;e Re:esta2lis;ment messa$e?e:esta2lis;ment messa$e?

?

? New New cell attempts cell attempts to fetc; to fetc; 'E 'E conte.t conte.t from from cells ;avin$ cells ;avin$ t;e t;e same "CI same "CI t;rou$; t;rou$; )% interface)% interface

B?

B? If t;e conte.t If t;e conte.t fetc; is successful* fetc; is successful* RRC conRRC connection re:esta2lis;ment procednection re:esta2lis;ment procedure is completedure is completed

<or multi tar

<or multi tar$et RR$et RRC connection re:esta2lis;ment to C connection re:esta2lis;ment to 2e successful 2e successful nei$;2or relations must nei$;2or relations must 2e2e

de#ned fr

(14)

?Conte.

?Conte.t fetc; timeout

t fetc; timeout ( I<5 N!R not de#ned,

( I<5 N!R not de#ned,

+?

+? 'E is served 2y cell #rst carrier (2and +9, cell ("CI:'E is served 2y cell #rst carrier (2and +9, cell ("CI:

=9,

=9, and and attempts attempts 5 5 to to "CI "CI 9+ 9+ w;ic; w;ic; fails? fails? RRCRRC

connection

connection Re:esta2lis;ment Re:esta2lis;ment complete complete messa$emessa$e

does not reac; EN!? (not seen in 'ETR,

%?

%? 'E lat'E latc;es on c;es on to a to a new cell new cell on second on second carrier (!ancarrier (!andd

,?

'E dr

'E dropped opped on on #rst car#rst carrier / rier / latc;ed on latc;ed on to to secondsecond carrier cell

carrier cell =?

=? 'E attempts 'E attempts RRC CNNECRRC CNNECTIN RE:ESTTIN RE:ESTA!LIS5-ENTA!LIS5-ENT

(multi tar$et,

?

? Conte.t fetc; result s;ows cause as D%F ? %Conte.t fetc; result s;ows cause as D%F ? %

represent

represents s conte.t conte.t fetc; tfetc; timeout?imeout?

perator ;as +C / %C on !and +9 /  respectively?

4;en t;e new cells tries to fetc; conte.t from

old cell* t;e old cell is now aware t;at 'E is no

lon$er

lon$er connected connected to to it* it* ;ence ;ence it it releases releases t;et;e

'E

'E conte.t conte.t (MB,(MB,

T;is will always result

T;is will always result in VLin VLTE &R"TE &R"

! !

"

$

"EN&IN0

# #

!

%

#

(15)

?

? -T RRC RE:ESTA!LIS5-ENT 4orkaround

-T RRC RE:ESTA!LIS5-ENT 4orkaround

"urpose

T

To o improve improve t;e t;e performance performance of of -ulti -ulti TTar$et ar$et RRC RRC Connection Connection re:esta2lis;ment re:esta2lis;ment feature feature //

improve LTE / VoLTE retaina2ility?

›

› _{-T RRC feature does not work if cell relation is missin$ and result in VoLTE as well as LTE}_{-T RRC feature does not work if cell relation is missin$ and result in VoLTE as well as LTE}

&rop?

›

› _{In t;is case as per perator strate$y 5andover is not allowed from +}_{In t;is case as per perator strate$y 5andover is not allowed from +} stst_{carrier to second}_{carrier to second}

carrier ;ence t;ere was no freHuency relation de#ned eit;er? So * followin$ solutions were

implemented to reduce t;e limitation

›

› _{Add %C <r}_{Add %C <r}_{eHuency in +C}_{eHuency in +C}_cells_cells

›

› _{Rela. t;e I< ANR parameters}_{Rela. t;e I< ANR parameters}

›

› _{Increase t;e nei$;2or removal time}_{Increase t;e nei$;2or removal time}

›

› _{!lock t;e nei$;2or so ANR can not delete it}_{!lock t;e nei$;2or so ANR can not delete it}

›

› _{&o not allow I<5 from +C to %C}_{&o not allow I<5 from +C to %C}

"arameters Ad3usted "arameters Ad3ustedPPaarraammeetteer r VVaalluuee connecte,oe,o-ilityPrio connecte,oe,o-ilityPrio -1-1 voicePrio voicePrio -1-1

a5Threshold1Rsrp (cell level)

a5Threshold1Rsrp (cell level) -112-112

a5Threshold2Rsrp (cell level)

a5Threshold2Rsrp (cell level) -112-112

a5Threshold1RsrpA

a5Threshold1RsrpAnrDelta (cell nrDelta (cell level)level) 1010

a5Threshold2RsrpA

a5Threshold2RsrpAnrDelta (cell nrDelta (cell level)level) 11

IsRemove Allowed

(16)

B?Incorrect -CS

B?Incorrect -CS leadin

leadin$ to

$ to VL

VLTE &R"

TE &R"

+>%+>%

! ! ! ! ! ! +?

+? 'E r'E reports eports -R -R for for 55

%?

%? Source EN! Source EN! responds responds RRC RRC connection recon#$uration? connection recon#$uration? RSR"  RSR"  :+76?% > :+76?% > SINR SINR  :7?=  :7?= d!d!

=?

=? 'E 'E misses misses t;e t;e RRC RRC connection connection recon#$uration recon#$uration messa$e? messa$e? 'E 'E assumes assumes t;at t;at 5 5 is is notnot

initiated / sends multiple -R for 5?

?

? T.%R T.%Relocoverall timer e.pires ( B sec, elocoverall timer e.pires ( B sec, / 'E conte.t is released?/ 'E conte.t is released?

Since

Since t;e 'E conte.t is released* t;is will always result in Vt;e 'E conte.t is released* t;is will always result in VoLoLTE drop?TE drop?

SINR was

SINR was poor 2ut poor 2ut not t;e kind not t;e kind of SINR of SINR t;at 'E would not;at 'E would not 2e a2le t 2e a2le decode t;e L= decode t;e L= messa$e?messa$e?

<u

<urt;er investi$ation was rt;er investi$ation was performed on suc; 2e;aviorperformed on suc; 2e;avior

" " " "

$

$ $

#

(17)

B?Incorrect -CS

B?Incorrect -CS leadin

leadin$ to

$ to VL

VLTE &R"

TE &R"

%>%

›

› _{<urt;er investi$ation revealed t;at}_{<urt;er investi$ation revealed t;at}

tar$et EN! sent t;e RRC connection

recon#$uration wit; a dierent -CS

(modulation codin$ sc;eme,

›

› _T;e_T;e_'EOs_'EOs_used_used_for_for_drive_drive_test_test_was_was_Rel:_Rel:

6* -CS codin$ assi$ned to 'E was in

accordance wit; Rel:+7

›

› _Rel:+7_Rel:+7 _'EOs_'EOs _can_can _decode_decode _messa$es_messa$es

wit; relative ;i$;er -CS w;en

compared to Rel:6 device for a

speci#c SINR

›

› _{5ence* ;i$;er -CS was assi$ned}_{5ence* ;i$;er -CS was assi$ned}

RRC recon#$uration messa$e w;ic;

t;e Rel:6 'E could not decode?

t;e Rel:6 'E could not decode? Solution

Solution EN! soft

EN! software ware was up$radwas up$raded to L+=! ed to L+=! E"+E"+ w;ic; #.ed t;is issue

w;ic; #.ed t;is issue

0reen CL

drive stopped?

L+=! E" + Software rollout

(18)

?

? &L ICIC feature activation

&L ICIC feature activation

+>=

"urpose

&L ICIC is used to randomize "R! allocation to reduce t;e inter:cell interference?

›

› _{4it; t;e current 2aseline* t;e sc;eduler on t;e &L assi$ns t;e "R!s from t;e lower to ;i$;er}_{4it; t;e current 2aseline* t;e sc;eduler on t;e &L assi$ns t;e "R!s from t;e lower to ;i$;er}

freHuency

freHuency t;at is frt;at is from left om left to ri$;t? to ri$;t? &ue to &ue to t;is* sites wit; t;is* sites wit; covera$e overlap covera$e overlap will causewill cause

interference? In typical scenarios wit;out &L ICIC feature* t;e resource allocation for all t;e cells

wit; start from "R! 7?

›

› _{4;en t;e PInter:Cell Interference Coordination (ICIC, : autonomous resource allocationP feature}_{4;en t;e PInter:Cell Interference Coordination (ICIC, : autonomous resource allocationP feature}

is activated in downlink* a random selection is made as to w;ere t;e allocation starts? 4it; a

randomized allocation* t;e e.pectation is t;at t;e overall interference will 2e reduced?

•

• _{Sites wit; ;i$; "R! utilization will not 2ene#t from &L ICIC since most of t;e "R!s are}_{Sites wit; ;i$; "R! utilization will not 2ene#t from &L ICIC since most of t;e "R!s are}

allocated?

•

• _{Sites wit; lower "R! utilization* can 2ene#t since t;e allocation is spread across t;e availa2le}_{Sites wit; lower "R! utilization* can 2ene#t since t;e allocation is spread across t;e availa2le}

"R!s?

•

• _{Note t;at t;e sc;eduler will try to allocate all t;e "R!s for a data user wit;in t;e same TTI for}_{Note t;at t;e sc;eduler will try to allocate all t;e "R!s for a data user wit;in t;e same TTI for}

lar$e data users?

lar$e data users? T;is can reducT;is can reduce t;e 2ene#t of &L ICIC since t;e "R!s ae t;e 2ene#t of &L ICIC since t;e "R!s are 2ein$ fully utilized?re 2ein$ fully utilized?

Since VoLTE packets are small* t;e "R!s would not 2e fully utilized so &L ICIC can 2e

2ene#cial

??

"arameters Ad3usted

›

› _{E'tranCell<&& dlInterference-ana$ementActivetrue}_{E'tranCell<&& dlInterference-ana$ementActivetrue}

›

(19)

?

? 1"I TREN& after &L ICIC / -T RRC 4ork around

1"I TREN& after &L ICIC / -T RRC 4ork around

%>=

LTE Retaina2ility

pm data

LTE Re:

esta2lis;ment

pm data

VoLTE

Retaina2ility pm

data

LTE T;rou$;put

pm data

2servation 2servation

Improvement in LTE retaina2ilityQ7?7% * VoLTEQ+? No? of radio link failures reduced si$ni#cantly* No Improvement in LTE retaina2ilityQ7?7% * VoLTEQ+? No? of radio link failures reduced si$ni#cantly* No si$ni#cant de$radation in

si$ni#cant de$radation in t;rou$;t;rou$;put?put?

-AR1ET

TREN&

(20)

-AR1ET TREN& J &RIVE

&ATA

?

? &rive

&rive 1"I TREN& after &L ICIC / -T RRC 4ork

1"I TREN& after &L ICIC / -T RRC 4ork

around

(21)

9?

9? Retaina2ility / SRVCC SR improvement

Retaina2ility / SRVCC SR improvement

+>%

!%T;res;old%Rscp'traset c;an$e

›

› _{!%T;res;old%Rscp'tra}_{!%T;res;old%Rscp'tra} _"arameter_"arameter

de#nes

de#nes t;e t;e t;res;old t;res;old w;ic; w;ic; '-TS'-TS

cell must meet 2y ;ysteresis for a

period of timetotri$$er in order to

2ein$ reported 2y t;e 'E provided

LTE Cell is worse t;an

!%T;res;old+Rsrp85ysteresis for a

period of t

period of timetotri$$erimetotri$$er??

›

› _&efault_&efault _value_value _for_for

!%T;res;old%Rscp'tra is set to :++B

d!m resultin$ in cells ;avin$ poor

'-TS covera$e 2ein$ selected for

SRVCC and eventually droppin$ t;e

call? C;an$in$ t;is parameter will

aect LTE as well ?

›

› _{!%T;res;old%Rscp'traoset is @CI}_{!%T;res;old%Rscp'traoset is @CI}

speci#c

speci#c oset oset site site level level parameter parameter **

so c;an$es were made to @CI+?

›

› _{!%T;res;old%Rscp'traoset}_{!%T;res;old%Rscp'traoset} _was_was

c;an$ed from 7 to +7 eectively

reducin$ !%T;res;old%Rscp'tra to

(22)

2servation Counter !ased 2servation Counter !ased

!%T;res;old%Rscp'traoset w

!%T;res;old%Rscp'traoset was c;an$ed as c;an$ed from 7 to from 7 to +7 eectively r+7 eectively reducin$ educin$ !%T;res;old%Rscp'tra !%T;res;old%Rscp'tra to :+7Bd!m?to :+7Bd!m?

Retaina2

Retaina2ility s;ows sli$;t improvement after t;e ility s;ows sli$;t improvement after t;e c;an$es ? SRVCC attempt reduced as e.pected andc;an$es ? SRVCC attempt reduced as e.pected and SR

SRVCC success rate VCC success rate improved w;en compared to same improved w;en compared to same amount of attempts 2efore?amount of attempts 2efore?

9?

9? Retaina2ility / SRVCC SR improvement

Retaina2ility / SRVCC SR improvement

%>%

!%T;res;old%Rscp'traset c;an$e

(23)

+?

+? NormNormal RRal RRC connecC connection retion release neelease need not necd not necessarily essarily mean not enmean not end to Vd to VoLoLTE call?TE call?

-ismatc; in t;e 2elow paramet

-ismatc; in t;e 2elow parameters will lead to 2earer drop?ers will lead to 2earer drop?

  rlc-oderlc-ode   rlcSnLen$t;rlcSnLen$t;   pdcpSnLen$t;pdcpSnLen$t;   ro;cEna2ledro;cEna2led %?

%? It is imporIt is important to nottant to note t;at RRe t;at RRC droC drop alone dp alone do not conco not conclude t;alude t;at t;e Vt t;e VoLoLTE call ;asTE call ;as

dropped? <urt;er analysis on 2earer level needs to 2e performed to ascertain if VoLTE

call dropped?

=?

=? @CI + pr@CI + pro#lo#le must 2e must 2e de#ne de#ned to ened to ena2le Va2le VoLoLTE seTE servicrvices?es?

?

? -ulti T-ulti Tar$ar$et RRet RRC ConneC Connection rction re:estae:esta2lis;me2lis;ment will nnt will not 2e sot 2e successuccessful (L+ful (L+=!, if=!, if

nei$;2ors are not de#ned in 2ot; t;e directions? T;e pro2lem could 2e more severe

w;en layerin$ strate$y does not allow ;andover from one carrier to ot;er(I<5,? A

work around is possi2le to reduce t;e impact of t;e lim

work around is possi2le to reduce t;e impact of t;e limitation?itation?

B?

B? IncorIncorrect -CS arect -CS assi$nessi$ned 2y EN! to Rd 2y EN! to Rel 6 'E was causinel 6 'E was causin$ t;e V$ t;e VoLoLTE droTE drops in poor SIps in poor SINRs*NRs*

t;is was a eN! software 2u$ and was recti#ed 2y E"+ rollout? A si$ni#cant

improvement in retaina2ility was o2served?

?

? &L ICIC fe&L ICIC featurature s;ows $e s;ows $ood improod improvement in ovement in VVoLoLTE RTE Retaina2etaina2ilityility??

9

9?? @@CCI I + + ssppeeccii##c c DD2%T;res;old%Rscp'traset2%T;res;old%Rscp'trasetF F ;elps to ;elps to improve Vimprove VoLoLTE TE retainaretaina2ili2ility ty asas

well as SRVCC performance? set value

well as SRVCC performance? set value of +7d! s;owed $ood results?of +7d! s;owed $ood results?

VoLTE RAN Case Study - Ericsson