measurement study: joint characterizaon of 3g and wifi · 2018-01-04 · aruna balasubramanian...

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

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