measurement study: joint characterizaon of 3g and wifi · 2018-01-04 · aruna balasubramanian...
TRANSCRIPT
Wifflerprotocol
Deploymentresults
Whybother?
FutureworkTrace‐drivensimula=onresults
Comple'on'me %dataoffloadedtoWiFi
Predic'on‐basedoffloading 45seconds 30%
Measurementsummary
Availability
WiFicanoffload3Gdataatmost11%of'me
Performance
WiFilossratepoorercomparedto3G:Mayeffectloss‐sensi'veapplica'ons
DeployedWifflerinthe20‐nodeAmhersttestbed.
Augmen'ng3GwithWifFcanreducepressureoncellularspectrum
Challenges:LowavailabilityandpoorperformanceofWiFi
Wiffler:Predic'on‐basedoffloadingandfastswitchingtotacklethesechallenges
Wifflerimplementa=on
Measurementstudy:Jointcharacteriza=onof3GandWiFi
Goal:Augment3Gusing“cheaper”WiFiaccess
ArunaBalasubramanianUMassAmherst
RatulMahajanMicrosoOResearch
ArunVenkataramaniUMassAmherst
Userrequest
3Gcelltowershavelimitedspectrum
Butuserdemandcon'nuestogrow
NY=mesar=cleonuserfrustra=onduetopoor3Gperformance
Setup
Vehicularnodeswith3G/WiFiradios
WiFiconnec'vitythroughopenAPs;3Gconnec'vitythroughcelltowers
Measurementin3ci=es:Amherst,SeaTle,SFO
3GversusWiFiavailability
3GversusWiFiUDPthroughput
3GversusWiFilossrate
Spa=aldistribu=onof3G/WiFiovera150sq.mileareainAmherst
%'mevoicequalitygood
%dataoffloadedtoWiFi
Fastswitching 68% 34%
WiFiwhenavailable 42% 40%
Filetransferapplica=on:Filesize=5Mb.Delaythreshold=60seconds
VoiceOverIPapplica=on:Load=20bytepacketsevery20ms
Wifflerproxy
Fordelaytolerantapplica=ons (E.g.,Email,Filetransfer)
Wifflerwaitsun'ladelay‐tolerancethresholdtooffloaddatatoWiFi
Wiffler’spredic=on‐basedoffloading:
LetWbethepredictedtransfersize;LetSbefilesize
1. If(WiFiavailable),senddataonWiFi
2. Else,if(W<Sand3Gisavailable),senddataon3G
Forloss‐sensi=veapplica=ons(E.g.,VoIP,videostreaming)
Wifflerfast‐switchesto3GwhenWiFiperformanceispoor
Wiffler’sfastswitching:
1.IfnoWiFilink‐layeracknowledgmentwithina50msthreshold
a. Senddataon3G
2.Else,con'nuesendingonWiFiSimplehistorybasedpredic=onofWiFitransfersizes.Predic=onerrorislowbothinAmherstandSeaTle
Trace‐drivensimula=onsyieldsresultscomparabletodeployment
Summary
ReduceenergycostofsearchingforWiFi
Prefetchdatabypredic'ngfutureuserrequests
Predic=on‐basedoffloading Fast‐switchingOracle:BasedonperfectknowledgeofWiFiperformanceOnly3G:Alwaysuse3GNoswitching:UseWiFiwhenavailableWiffler
% ti
me
voice
qu
ality
goo
d
PaFent:WaitunFlthedelaythresholdOracle:UseperfectpredicFonBreadcrumbs:UselocaFon+mobilitypredicFonImpaFent:UseWiFiwhenavailableWiffler
% d
ata
offlo
aded
to
WiF
i
Com
plet
ion
tim
e (s
ec)