Enabling High-Bandwidth Vehicular Content Distribution

Enabling High-Bandwidth Vehicular Content Distribution Upendra Shevade, Yi-Chao Chen, Lili Qiu, Yin Zhang, Vinoth Chandar, Mi Kyung Han, Han Hee Song, Yousuk Seung The University of Texas at Austin {upendra,yichao,lili,yzhang,vinothc,hanmi2,hhsong,ysseung}@cs.utexas.edu

Abstract —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ef 8,', $,'" ;%5&6 O ,&'"&&,%= !" #"$2-$1"8 , 1",%;$"1"&' "F3 #"$51"&' ;%5&6 , /,#'-# "^;5##"8 95'7 _"'Z",$ !_*@RKII -& , ."75:/" :-11;&5:,'5&6 95'7 , _"'Z",$ !_*gRRII @A 8"#/-0"8 &",$ '7" $-,8= !" 6-' O=M]4#% ;%5&6 HIJ=KK4+ JJ=J]4#% ;%5&6 HIJ=KK6+ ,&8 RQ=N]4#% ;%5&6 HIJ=KK& ?JFJ ]>]hB -& J=OZeX 2$"^;"&:0+ ,&8 SM=K]4#% ;%5&6 HIJ=KK& -& SZeX= >& :-1#,$5%-&+ *Vi '7$-;67#;' $,&6"% 4"'9""& NMHj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f (MHvII , MHvt ) 2-$ ,// #,5$% -2 '$,D":'-$5"% ?975:7 5% "F#"&%5."B+ 9" -&/0 :-13 #;'" 2-$ '7" '$,D":'-$0 #,5$% '7,' ,$" &",$40= C- ^;5:& ,885'5-&+ 9" ;%" 1;/'5#/" :-&'"&' %"$."$% ,&8 /"."$,6" , :"&'$,/ 85%#,':7"$ '- 85%'$54;'" $"^;"%'% '- ,& ,##$-#$5,'" :-&'"&' %"$."$ 2-$ /-,8 4,/,&:5&6=

4.2

Client Implementation

[,':7 %5X" KKI #,:V 8-"% &-' #$-.58" ,:3 :"%% '- 1,&0 /-9 /"."/ #,$,1"'"$% '- 51#/"1"&' '7" ,%%-3 :5,'5-& -#'515X,'5-&% #$-#-%"8 5& '7" /5'"$,';$"= !5&8-9% ]-45/" #$-.58"% '9- 9,0% '- 5&5'5,'" :-&&":'5-& '- , !53T5 &"'9-$< #$-6$,11,'5:,//0+ "5'7"$ '7$-;67 '7" 95$"/"%% X"$:-&2 6 ?!p)B 5&'"$2,:" -$ 40 %"''5&6 '7" ,##$-#$5,'" _*>V h>*%= C7" ,%%-:5,'5-& '51"% ;%5&6 '7" !p) 5&'"$2,:"% 9"$" ,$-;&8 R=I %":+ 975:7 5% ;&,::"#',4/" 5& '7" ."75:;/,$ &"'3 9-$< :-&'"F'= !" '7"$"2-$" 85%,4/" !p) ,&8 51#/"1"&' _*>V 4,%"8 ,%%-:5,'5-&+ 975:7 05"/8% %56&52 :,&'/0 /-9"$ ,%3 %-:5,'5-& '51"%= !" ,/%- 51#/"1"&' -;$ -9& *e)A :/5"&' ,&8 ;%" '7" *e)A :,:75&6 1":7,&5%1 8"%:$54"8 5& LKIP= h;$ :-&&":'5-& %"';# #$-:"8;$" 5% ,% 2-//-9%= C7" %1,$'3 #7-&" %:,&% 2-$ @A% "."$0 KII 1%= !7"& ,& @A 5% 85%:-.3 "$"8+ '7" %1,$'#7-&" 9,5'% 2-$ R gVV> $",85&6% 6$",'"$ '7,& 3QK8[ 4"2-$" '$05&6 '- ,%%-:5,'"= !" 8- &-' ,%%-:5,'" 511"3 85,'"/0 4":,;%" ,& ,%%-:5,'5-& 2,5/;$" 5% "F#"&%5."= C7" ,%3 %-:5,'5-& #$-:"8;$" 5% $"'$5"8 ;# '- N '51"% 95'7 , %7-$' 8"/,0 -2 SI1% 4"'9""& :-&%":;'5." ,''"1#'%= C7" .,$5-;% '7$"%73 -/8 .,/;"% ;%"8 5& '7" %:7"1" 9"$" :7-%"& "1#5$5:,//0= !" $"#-$' '7" ,%%-:5,'5-& '51" ,&8 2,5/;$"% 5& V":'5-& H=

5. MOBILITY PREDICTION ACCURACY

?,B C,F5 /-:,'5-&% ?-& 75679,0%B

?4B C,F5 /-:,'5-&% ?5&%58" :5'0B

Figure 3: Illustration of traces for mobility prediction. Mobility traces: !" -4',5& $",/ ."75:;/,$ 1-45/5'0 '$,:"% 2$-1 ),4%#-''5&6 LKKP ,&8 V",''/" LOKP= C7" 2-$1"$ :-&',5& -."$ KI 15//5-& ZAV /-&65';8" ,&8 /,'5';8" :--$85&,'"% 2-$ ,##$-F51,'"/0 SII ',F5% 5& '7" V,& T$,&:5%:- [,0 @$", -."$ '7" :-;$%" -2 RI 8,0% ?*":"14"$ KR+ JIIH a c,&;,$0 KR+ JIIQB= C7" /,''"$ :-&',5&% %"."$,/ 9""& ,// '7" %:7"1"%+ , ."75:/" 8-9&/-,8% :-&3 '"&' $"1-'"/0 2$-1 '7" >&'"$&"' 97"&"."$ '7" @A 7,% >&'"$&"' :-&&":'5.5'0 ,&8 '7" :-&'"&' 5% &-' ,.,5/,4/" /-:,//0 ,' '7" @A -$ 1"%7 &"'9-$& 4-'7 :,%"%+ 2-$ "."$0 5&'"$.,/+ , ."75:/" $,&8-1/0 %"/":'% , %#":52 "8 &;14"$ -2 2 /"% '- $"^;"%'= >& '7" ;&52-$1 85%'$53 4;'5-&+ , 2 /" 5% ;&52-$1/0 8$,9& 2$-1 '7" #--/ -2 '7" 2 /"% '7,' '7" ."75:/" 7,% &-' $"^;"%'"8 #$".5-;%/0= >& p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d ;&3 8"$ 7567 @A 8"&%5'0 ?T56;$" S?:BB+ ,&8 40 R3KRd 5& /-9 @A 8"&%5'0= C7" 4"&"2 ' -2 1"%7 $"#/5:,'5-& :,& 4" 5&:$",%"8 2;$'7"$ 52 @A% ;%" 7567 6,5& ,&'"&&,% -$ ]>]h= h."$,//+ ,' JJ]4#% !53T5 :,#,:5'0+ ()* ,:75"."% NI a RII j4#% ,.3 "$,6" '7$-;67#;' #"$ ."75:/" 8"#"&85&6 -& '7" @A 8"&%5'0+ 975:7 :,& %;##-$' .58"- %'$",15&6 ,##/5:,'5-&%= Varying fraction of APs with Internet connectivity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

Figure 9: Cross validation: comparing performance in Emulab and simulation '5"%= e-9"."$+ , 2;$'7"$ 5&:$",%" 8"6$,8"% #"$2-$1,&:" 8;" '- 5&:$",%"8 :-&'"&'5-& 2-$ /515'"8 95$"/5&" ,&8 95$"/"%% $"3 %-;$:"%= C75$8+ '7" 4"&"2 ' -2 1"%7 $"#/5:,'5-& 5&:$",%"% 95'7 '7" &;14"$ -2 ."75:/"%= !7"& 9" ;%" ,// '7" ."75:/"% 5& '7" '9-37-;$ '$,:"%+ 9" 2 &8 '7,' '7" 1"%7 $"#/5:,'5-& 7"/#% '5&:$",%" '7$-;67#;' 40 KN3JJd= C75% 5% 4":,;%" 5&:$",%5&6 '7" &;14"$ -2 ."75:/"% 5&:$",%"% ."75:;/,$ $"/,0 -##-$';&53 '5"% ,&8 1,& T56;$" Q?,B+ 9" :-&%58"$ '7,' ,// @A% 7,." >&'"$&"' :-&&":'5.5'0 ,&8 :-1#,$" '7" %51;/,'5-&

150 100 50 0

0

20

40

60 80 100 120 Wireless capacity (Mbps)

140

100

Average download (Kbps/taxi)

200

700

No replicate VCD wireline alone VCD vehicular relay alone VCD wireline + vehicular relay VCD

120

80 60 40 20 0

160

0

20

40


140

500 400 300 200 100 0

160

160


600


140


250



300

0

20

40


140

120 100 80 60 40 20 0

160


140

0

20

40


?,B V,& T$,&:5%:-+ :-22"" %7-#%+ ?4B V,& T$,&:5%:-+ gas station+ ?:B V,& T$,&:5%:-+ :-22"" %7-#%+ ?8B Seattle+ $,&6"qKII1 $,&6"qKII1 range=200m $,&6"qKII1

:-22""

140

160

%7-#%+

Figure 5: Average throughput of 50 vehicles under varying wireless capacity and Zipf-like trafc demands. The difference from the base conguration is in bold.

100 80 60 40 20 0 1000

160


140 120 100 80 60 40 20 0

1500

2000 2500 3000 Number of files

3500

?,B U&52-$1G .,$0 r 2 /"%

4000

0

2

4 6 8 10 12 14 16 Number of files each user interested

18

20

?4B U&52-$1G .,$0 r 2 /"% #"$ ;%"$

140 120

160



120

160



140



160

100 80 60 40 20 0 1000


140 120 100 80 60 40 20 0

1500

2000 2500 3000 Number of files

3500

?:B p5#23/5& '75% :,%"+ %5&:" 1-%' @A% ,$" &-' :-&&":'"8 ''7" >&'"$&"' ,&8 '7"$" 5% &- 1"%7 :-&&":'5.5'0+ 1-%' :-&'"&' 5% $"#/5:,'"8 .5, ."75:/"%= T56;$" Q ?4B %7-9% '7,' '7" %513 ;/,'5-& $"%;/'% 1,':7 9"// 95'7 E1;/,4 $"%;/'%G 95'75& KId 8522"$"&:" 2-$ 4-'7 ."75:;/,$ $"#/5:,'5-& ,&8 ()*= Micro-benchmarks: C7" 2-//-95&6 15:$-34"&:71,$< $"3 %;/'% %7-9 '7,' -;$ 51#/"1"&','5-& 5% "22 :5"&' ,&8 /567'3 9"567' "."& 97"& -#"$,'5&6 ,' %:,/"= !" "1;/,'" '7" KJI 1-%' 5&'"$,:'5." @A% ,&8 RKN ."75:/"% 2$-1 '7" '$,:"= C,4/" J %7-9% '7" #"$35&'"$.,/ :-&'$-/ 1"%%,6" -."$7",8= !" -4%"$." '7,' :-&'$-/ 1"%%,6"% :-&%'5';'" -&/0 I=ISOd -2 '7" '-',/ 95$"/5&" '$,22 : "F:7,&6"8 ,1-&6%' @A% ,&8 4"3 '9""& @A% ,&8 '7" :-&'$-//"$+ ,&8 :-&%'5';'" -&/0 K=Md -2 '7" '-',/ 95$"/"%% '$,22 : 4"'9""& @A% ,&8 ."75:/"%= _"F' 9" ".,/;,'" '7" "22 :5"&:0 -2 '7" :-&'$-//"$= h& , J=KRRZeX `"-& 1,:75&" 95'7 RZ[ g@]+ ,."$,6" )AU ,&8 1"1-$0 ;'5/5X,'5-& -2 '7" :-&'$-//"$ 5% Jd ,&8 RH ][ $"3 %#":'5."/0= C7" ,."$,6" /,'"&:0 ,' '7" :-&'$-//"$ 5% N=H%+ 975:7 5% , %1,// 2$,:'5-& -2 '7" R315&;'" 5&'"$.,/= h;' -2 N=H%+ '7" iA :-1#;','5-& ',& 4-'7 '"%'4"8%+ '7" @A% 7,." K]4#% 95$"/5&" ,:3 :"%% /5&< :-&&":'5&6 '- '7" 4,:& 4-'7 '"%'4"8%+ 1"%7 :-11;&5:,'5-& ',& -;$ HIJ=KK& -;'8--$ '"%'4"8+ ,%%-:5,'5-& %;::"%% $,'" 9,% HQ=SHd -;' -2 OH ,''"1#'%= C7" 15&51;1+ 1"85,& ,&8 1,F51;1 ,%%-:5,'5-& '51"% 9"$" OH 1%+ KMJ 1%+ ,&8 OIHM 1%+ $"%#":'5."/0= HId -2 '7" ,%%-:5,'5-&% 2 &5%7 95'75& JOM 1% ,&8 '7" 1"85,& $"'$0 :-;&' 9,% K= C7" 4"''"$ $"%;/'% 2-$ HIJ=KK& '"%'4"8 9"$" 4":,;%" ?5B 9" ;%"8 /,#'-#% ,% :/5"&'%+ ?55B @A% 9"$" #/,:"8 -;'8--$ :/-%"$ '- ."75:/"%+ ,&8 ?555B ]>]h 5& HIJ=KK& 51#$-."% $":"5."8 %56&,/ %'$"&6'7= Wireline and mesh replication: !" 51#/"1"&'"8 , .58"%'$",15&6 ,##/5:,'5-& '7,' :,& #/,0 e=JMO .58"-% ?8-9&3 /-,8"8 2$-1 @A%B "&:-8"8 ,' MOj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

@AK @AJ

_- $"#/5:,'5-& ),$ K ),$ J I I I I

!5$"/"%% $"#/5:,'5-& ),$ K ),$ J U#/-,8 NHI #& :-1#,$5%-&+ ()* "F#/-5'% '7" ."75:;/,$ $"#/5:,'5-& -#3 #-$';&5'0= !7"& :,$ K 1""'% APK+ ()* 2 &8% '7,' 2 /"% K3JI 7,." 7567"%' ;'5/5'0 4":,;%" 5' #$"85:'% :,$ J 95// .5%5' APK %--& ,&8 &""8 '7"%" 2 /"%= V- APK 5&%'$;:'% '7" :,$ '- ;#/-,8 '7"1 2 $%'= V515/,$/0+ :,$ J ;#/-,8% 2 /" JK3OI ,' APJ= !7"& :,$ K $",:7"% APJ 5' :,& 8-9&/-,8 '7"%" 2 /"%= V515/,$/0+ :,$ J :,& 8-9&/-,8 2 /"% K3JI 2$-1 APK+ /",85&6 '- 1;:7 7567"$ '7$-;67#;'= C,4/" S %7-9% '7,' 4-'7 :,$% 8-9&/-,8 '7"5$ 5&3 '"$"%'"8 2 /"% 5& '7" ,:';,/ $-,8 "F#"$51"&'%=

9. RELATED WORK !" :/,%%520 $"/,'"8 9-$&'"$,:'5." !5T5 :-&&":'5.5'0 2-$ 1-.5&6 ."75:/"%= >& Proc. of SIGCOMM+ JIIH= LHP _= [,&"$D""+ ]= )-$&"$+ *= C-9%/"0+ ,&8 [= i".5&"= g"/,0%+ 4,%" %','5-&%+ ,&8 1"%7"%G E&7,&:5&6 1-45/" &"'9-$& Proc. of MobiCom+ V"#'= JIIH= LKRP ),$J),$ :-11;&5:,'5-& :-&%-$'5;1= 7''#G\\999=:,$3'-3:,$=-$6= LKOP ),$'"/= 7''#G\\:,$'"/=:%,5/=15'="8;\8-& Proc. of MobiSys+ JIIN= LJMP C= e-+ ]= ]"8,$8+ c= V75+ ]= E$-%+ ,&8 *= g= j,$6"$= h& $,&8-15X"8 &"'9-$< :-85&6+ h:'= IM JIIR= LJNP A= c;,&6+ e= h& Proc. of MobiCom+ V"#'= JIIH= LRNP (= _= A,81,&,47,& ,&8 c= )= ]-6;/= U%5&6 #$"85:'5." #$"2"':75&6 '- 51#$-." 9-$/8 958" 9"4 /,'"&:0= SIGCOMM Comput. Commun. Rev.+ JM?RB+ KQQM= LRHP A= _= A,'75$,&,+ @= (= V,.