16 Capacity Engineering

LTE Capacity Engineering

14 Sep 2015

Factors Impacting Capacity in LTE       

Multiple Access Techniques – OFDMA an S! FDMA "nter#erence management Multiple Antenna Techniques S$S Semi $ersistent Scheuling %#or &o"$ '( reucing control channel loa) Short Su' #rame Duration an *o+ ,A-. -oun Trip Time A/ance -ecei/ers – lie *MMSE %*inear Minimum Mean Square Error) +ith "-! % "nter#erence -eection !om'ining) -eucing *a(er 1 an *a(er 2 O/erheas

Interference Management in LTE *TE s(stem pro/ies orthogonal resources allocation in the #requenc( omain +hich ena'les #requenc( omain multi user i/ersit( gain *TE supports /arious techniques to mitigate inter cell inter#erence 3 DOW LI!   

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!-S – !ell Speci4c -e#erence Signals ha/e #requenc( shi#t applie as per $!" Do+n *in !ontrol !hannels – a cell speci4c #requenc( #requenc( oset is applie to $!F"!, an $,"!, 6 #or $DS!, interlea/ing pro/ies #requenc( i/ersit( "!"! "nter !ell "nter#erence !o3orination Techniques '( utili7ing -8T$ -elati/e 8arro+ 'an Transmit $o+er messages o/er 92 inter#ace

"#LI!    

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Fractional $o+er !ontrol -esources Allocation – higher -:s at !ell center an *o+er -:s at !ell Ege $;!, – cell speci4c s(m'ol le/el c(clic shi#t hopping is applie < Each $;!!, -: is mappe to 'oth eges o# the s(stem 'an+ith to achie/e a chie/e #requenc( #requenc( i/ersit( "nepenent inter#erence management techniques lie po+er control can 'e applie to control an ata channels

e &c ng ayer O'er(ea%s 

an

ayer

An( part o# the time #requenc( transmission resources not irectl( use #or ata transmission constitutes an o/erhea  -equire to minimi7e these o/erheas +hile achie/ing high s(stem per#ormance an >e?i'ilit(  O/erheas are @uar 'ans6 the OFDM !$6 -S an !ontrol !hannels   The percentage o/erhea increases +ith num'er o# transmit antennas ue to higher -S o/erhea   Thus the @ain #rom M"8O has to oset this increase o/erhea

E)amp*e of O'er(ea%s + FDD   

E?ample o# $ercentage O/erhea o# *TE FDD calculate o/er 10 ms raio #rame #or 10 M,7 :an+ith -E in 10 ms raio #rame #or 10 M,7  B= C 2C10C50  B=000 !-S per -:  = -E #or antenna 1 an 2 an 2 -E #or antenna  an =

,&ar% -an%

OFDM Sym.o*s an% C# Lengt(s

e pec c e erence one ntenna

gna s or

CELL S#ECIFIC $EFE$ECE SI,LS FO$ FO"$ TE -S require#O$TS #or •

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channel estimation #or coherent etection $ort 0 an 1 ha/e #our -S per -: $ort 2 an  ha/e t+o -S per -: to reuce o/erheas E/er( si? su'carriers ha/e one -: Ghen one antenna raiate -S6 other eep quiet so that ;E can measure one -S at an( time !ell Speci4c Frequenc( Shi#t is applie up to si? cells to reuce inter

Contro* C(anne*s

#DCC Each $D!!, carries a message no+n as D!" Do+n *in !ontrol "n#ormation +hich contains resource assignments an other control in#ormation #or a ;E or a group o# ;Es  Each $D!!, is transmitte using one o# more !!Es !ontrol !hannel Elements +hich each !!E correspons to nine -E@s – Four .$SH s(m'ols are mappe to each -E@  Four $D!!, Formats are supporte as uner   The num'er o# !!Es are aggregate as per !hannel !onitions – one !!E ma( 'e suIcient in goo -F conitions +hile eight !!Es ma( 'e require at !ell Ege 

DCI Formats 

Dierent D!" Formats are use as per s(stem eplo(ment to transmit onl( rele/ant in#ormation – #or e?ample i# M"MO is not use6 there is no nee to signal parameters neee onl( #or M"MO transmission

an Signa*s

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ync ron 3a on

#-C

E)amp*e of O'er(ea%s + TDD 

E?ample o# $ercentage O/erhea #or *TE TDD uplin o/er a 10 ms raio #rame #or a 10 M,7 s(stem 'an+ith

"p Lin $eference Signa*s De Moulation -S %DM -S) associate +ith $;S!, an J or $;!!, – use #or channel estimation #or coherent etection  Souning -S S-S – not associate +ith uplin ata or control an primaril( use #or channel qualit( etermination to ena'le #requenc( selecti/e scheuling on the uplin   The DM-S occup( the same -: as $;S!, J $;!!,   The S-S are transmitte on the last S! FDMA s(m'ol in the con4gure su' #rame   The S-S an DM -S are locate in ierent S! FDMA s(m'ols  $;S!, ata transmission is not permitte on the S! FDMA s(m'ol esignate #or S-S   The e8: ma( either request an ini/iual S-S transmission #rom a ;E or con4gure a ;E to transmit S-S perioicall(  "# perioic S-S transmission are con4gure #or a ;E6 the perioicit( ma( 'e 2656106206=06B0610 or 20 ms 

emo & a on $eference Signa*s   The DM-S are pro/ie #or channel estimation

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 The DM-S occupies the #ourth S! FDMA s(m'ol #or normal !$

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 The DM-S occupies the thir S! FDMA s(m'ol in case o# e?tene !$

S$S So&n%ing $eference Signa*s

#"CC

$C

$C

S$S -an%i%t( 6for 40+70 $-s8

Capacity Dimensioning 

E?ample to con/ert cell throughput /alues into ma?imum num'er o# 'roa'an su'scri'ers

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 TraIc &olume :ase Approach 3 estimates the ma?imum traIc /olume in @iga :(tes that can 'e carrie '( *TE 20 M,7 +ith gi/en spectral eIcienc( an 2?2 M"MO

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Data -ate :ase Approach – the :us( ,our *oaing is assume to carr( 15K o# the ail( traIc an :us( ,our A/erage *oaing is 50K<

S&.scri.ers #er Site

 BC102=

5 M'psC50K J %1J20)C L5 M'psJB12C00C50K

pec a & rame Con/g&rations

+

T-S :s MCS :s $-s

Transport -*oc Si3e 6T-S8 !F" -: num -E num per ms -E num per secon  T: Si7e in :its $er ms  B= OFDM S(m'ols ? 2  1B S(m'ols !-S  = per -: per Antenna $ort +hich means B per Antenna $ort per Time Slot or 1 per ms !ontrol S(m'ols  12 containing #our -S positions Data OFDM S(m'ols  1B313%123=)

M!S  2B %T:S 2) 1 2  100 100 100 1== 12 120 1200 1==00 1200 0 5 5 5 

M!S  2 %T:S 25) 1 2  100 100 100 1== 12 120 1==0 120 1200 0 0 0      

!F"2 !ontrol OFDM S(m'ols  2= Data OFDM S(m'ols  1B313%2=3=)  12

M!S  2 %T:S 2=) 1 2  100 100 100 1== 12 120 1==0 120 1200 0 0 0 1 1 1 = = =

!F" !ontrol OFDM S(m'ols   Data OFDM S(m'ols  1B313%3=)  120

!oe -ate % T: Si7e ) J %Total TT" :its)

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!oe -ate is e4ne as the num'er o# o+nlin in#ormation 'its incluing !-! 'its i/ie '( the num'er o# $h(sical !hannel :its on the $DS!,

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