Click here to load reader

Stochastic Forecasts Achieve High Throughput and Low · PDF fileVerizon LTE uplink throughput 0 500 1000 1500 ... Verizon 3G/LTE, AT&T LTE, T-Mobile 3G uplink and ... Stochastic Forecasts

  • View
    225

  • Download
    4

Embed Size (px)

Text of Stochastic Forecasts Achieve High Throughput and Low · PDF fileVerizon LTE uplink throughput...

  • Stochastic Forecasts Achieve High Throughputand Low Delay over Cellular Networks

    Keith Winstein

    MIT Computer Science and Artificial Intelligence Laboratory

    http://alfalfa.mit.edu

    March 6, 2014

    Joint work with Anirudh Sivaraman and Hari Balakrishnan.

  • Sprout: a transport protocol designed for variability

    Observation:Videoconferences perform poorly over cellular networks.

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Verizon LTE uplink throughput

    0

    500

    1000

    1500

    2000

    0:00 0:30 1:00 1:30

    thro

    ugh

    pu

    t(k

    bp

    s)

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Verizon LTE ping delay during one TCP download

    0.2

    0.3

    2

    3

    0.1

    1

    10

    0 50 100 150 200 250

    Ro

    un

    d-t

    rip

    tim

    e(s

    )

    Time (s)

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Interactive apps work poorly

    I We measured cellular networks while driving:

    I Verizon LTEI Verizon 3G (1xEV-DO)I AT&T LTEI T-Mobile 3G (UMTS)

    I Then ran apps across replayed network trace:

    I Skype (Windows 7)I Google Hangouts (Chrome on Windows 7)I Apple Facetime (OS X)

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Skypes performance

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Performance summary

    0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    100200300500100020005000

    Th

    rou

    gh

    pu

    t(k

    bp

    s)

    Self-inflicted delay (ms)

    Verizon LTE Downlink

    SkypeFacetime

    Google Hangout

    Bette

    r

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Whats wrong?

    I Existing schemes react to congestion signals.

    I Packet loss.I Increase in round-trip time.

    I Feedback comes too late.

    I The killer: self-inflicted queueing delay.

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Sprouts mission

    I Most throughput

    I Bounded risk of delay > 100 ms

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Bounded risk of delay

    I Model variation in link speed

    I Infer current link speed

    I Predict future link speed

    I Dont wait for congestion

    I Control: Send as much as possible, but require:

    I 95% chance all packets arrive within 100 ms

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Model: packet deliveries looks like flicker noise

    0.0001

    0.001

    0.01

    0.1

    1

    10

    100

    (< 0.5)

    39041 10 100 1000

    Per

    cen

    tin

    tera

    rriv

    als

    interarrival time (ms)

    t3.27

    (Verizon LTE, phone stationary.)

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Model: average rate looks like random walk

    0

    500

    1000

    1500

    2000

    0:00 0:30 1:00 1:30

    thro

    ugh

    pu

    t(k

    bp

    s)

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Sprouts model

    Sender Queue Receiver

    Poisson process

    Rate controls

    Brownian motion

    z

    If in an outage,

    drains queue

    Poisson process

    of t varies z is escape rate.

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Sprouts model parameters

    Volatility : fixed @ 200 pkts/ss

    Expected outage time 1/z : 1 sTick length (): 20 msForecast length: 160 msDelay target: 100 msRisk tolerance: 5%

    All source code was frozen before data collection began.

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Infer: current link speed

    I Observe packets received every

    I Update P()

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Predict: future link speed

    I Evolve model forward

    I Forecast 5th percentile cumulative packets

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    100 ms

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    Send

    50

    pkts

    100 ms

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    Send

    50

    pkts

    100 ms100 ms

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    Send

    50

    pkts Se

    nd 5

    100 ms100 ms

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    Send

    50

    pkts Se

    nd 5

    100 ms100 ms

    100 ms

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Control: fill up 100 ms forecast window

    0

    10

    20

    30

    40

    50

    60

    70

    0 20 40 60 80 100 120 140 160

    Cum

    ulat

    ive

    pack

    ets

    sent

    time (ms)

    Send

    50

    pkts Se

    nd 5

    Send

    3 100 ms100 ms

    100 ms

    Cautiou

    s forec

    ast

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • Sprouts results

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • 0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    100200300500100020005000

    Th

    rou

    gh

    pu

    t(k

    bp

    s)

    Self-inflicted delay (ms)

    Verizon LTE Downlink

    SkypeFacetime

    Google Hangout

    Bette

    r

    Keith Winstein (with Anirudh Sivaraman and Hari Balakrishnan)

    Stochastic Forecasts Achieve High Throughput and Low Delay over Cellular Networks

  • 0

    1000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    100200300500100020005000

    Th

    rou

    gh

    pu

    t(k

    bp

    s)

    Self-inflicted