Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin...
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![Page 1: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/1.jpg)
Wireless “ESP”: Using Sensors to Develop Better Network Protocols
Lenin RavindranathCalvin Newport, Hari Balakrishnan, Sam Madden
Massachusetts Institute of Technology
![Page 2: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/2.jpg)
Big Changes in Access Devices
• 172M smartphones sold worldwide in 2009– 25% of US phone market; 50% in two years
• Smartphones and tablets will exceed PC sales by 2011
• Mobile Internet growing at a tremendous pace
![Page 3: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/3.jpg)
Big Changes in Access Devices
Dominant mode of data access in the future
![Page 4: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/4.jpg)
“Truly Mobile” Devices• Often switch between static and mobile• Exhibit a variety of mobility modes• Move through different environments
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• Protocols need to adapt to different settings – Mobility mode impacts wireless performance
The Problem
• Most protocols optimized for static settings– They perform poorly during mobility
• Protocols that compensate for mobility are not optimal in static settings
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Static vs. Mobile• Channel constantly changing
– Channel assessments quickly outdated– Protocols should not maintain long
histories
• Channel relatively stable– Protocols can average estimates– Ignore short-term variations
![Page 7: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/7.jpg)
• Topology is hardly changing– Probe for links less frequently– Compute routes over long time scales
• Topology changing rapidly– Probe for links more often– Compute routes over shorter time scales
Static vs. Mobile
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Current Wireless Protocols
• Do not differentiate between mobility modes • Attempt to adapt to both settings implicitly
using measurements of packet loss, SNR, BER• Leading to suboptimal performance
• Lack of explicit knowledge about prevalent mobility mode
• Can we do better?
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Proximity Sensor Camera
Ambient Light Sensor Microphone
Accelerometer
GPS
Compass
Gyro
![Page 10: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/10.jpg)
Accelerometer
Proximity Sensor Camera
Ambient Light Sensor Microphone
GPS
Compass
Gyro
Many, many, applications…
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Accelerometer
Proximity Sensor Camera
Ambient Light Sensor Microphone
GPS
Compass
Gyro
Ignored by Protocols!
![Page 12: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/12.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
Accelerometer
Proximity Sensor Camera
Ambient Light Sensor Microphone
GPS
Compass
Gyro
Ignored by Protocols!
![Page 13: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/13.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
Accelerometer
GPS
Compass
Gyro
![Page 14: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/14.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
Gyro
Hints
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
Gyro
Hints
• Movement• Direction• Speed
Use hints to adapt to different mobility
modes differently
Hints Protocol
Adapt to hints from neighbors
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Vehicular Routing
Walking
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Disassociation
Packet Scheduling
Power SavingPreamble
Network Monitoring
Speed
Walking
Location Vehicular Routing
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Walking
Vehicular Routing
![Page 19: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/19.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
![Page 20: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/20.jpg)
Accl
Movement
Reliably detect movement within 100ms
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
![Page 22: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/22.jpg)
Rate Adaptation in Wireless Networks
6 Mbps9 Mbps12 Mbps18 Mbps24 Mbps36 Mbps48 Mbps54 Mbps
802.11a/g bit rates
Packet encoded at a particular bit rate
Rate Adaptation:Finding the best bit rate to transmit a packet
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Static vs. Mobile Performance• Static and walking traces
– Cycle through bit rates
• 4 different environments– 80 traces, 20 seconds long
• Trace-driven simulation– TCP throughput
Static Sample Rate 85 – 99%
RRAA 80 – 97%
RBAR 70 – 80%CHARM
MovingSample Rate 33 – 59%
RRAA 45 – 63%
RBAR 60 – 75%CHARM
Compare to optimal throughput
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Static vs. Mobile Loss PatternsProbability that packet i+k is lost given packet i is lost
10 ms
Losses are more bursty when a node is mobilethan when a node is static
k
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6 Mbps9 Mbps12 Mbps18 Mbps24 Mbps36 Mbps48 Mbps54 Mbps
6 Mbps9 Mbps12 Mbps18 Mbps24 Mbps36 Mbps48 Mbps54 Mbps
RapidSample
6 Mbps9 Mbps12 Mbps18 Mbps24 Mbps36 Mbps48 Mbps54 Mbps
1. After a single loss Reduce rate
2. History - 10 ms Don’t retry a failed rate Or any higher rate
3. Channel not degrading, probably improving After few successes, sample
higher rate not failed If wrong, come back to the
original rate
[failed – within last 10ms]
[failed – within last 10ms]
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RapidSample, when device is moving
Up to 75% better throughput than SampleRate25% better than other protocols
• Trace driven (ns3)• 30 traces• 20 seconds long• TCP throughput
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But when static…
Up to 30% lower throughput than other schemes
• Trace driven (ns3)• 30 traces• 20 seconds long• TCP throughput
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Application
Transport
Network
Rate Adaptation
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
Gyro Movement
• RapidSample when movement
• SampleRate when static
Movement
Hint-Aware Rate Adaptation
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Hint-Aware Rate Adaptation
40-50% better than other schemes
• Trace driven (ns3)• 10 traces• 20 seconds long• Static + Moving• TCP throughput
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Walking
Vehicular Routing
![Page 31: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/31.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
Gyro
HeadingAP Association
Walking
![Page 32: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/32.jpg)
AP Association
Scan Scan ScanInfrequent scans
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AP Association
Suboptimal Association
Static
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Movement-Aware Association
1. Static – Stop Scanning
2. Moving – Scan Periodically
3. Moving to Static – Scan once
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Movement-Aware Association
On median, 40% more throughput
• Android implementation• 30 traces• Static + Moving• Throughput
![Page 36: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/36.jpg)
Heading-Aware Association
Minimize Handoff
Training based approachHeading
![Page 37: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/37.jpg)
Heading-Aware Association
40% median reduction in handoffs
• Android implementation• Training (30 traces)• 30 traces• # Handoffs
![Page 38: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/38.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Walking
Vehicular Routing
![Page 39: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/39.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
Gyro
Heading
Speed
Vehicular Routing
![Page 40: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/40.jpg)
Routing in Vehicular Mesh Networks
“V2V”
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Routing in Vehicular Mesh Networks
• Longevity of links useful – avoids expensive repairs
• Link between nodes heading in the same direction tend to last longer
Connection Time Estimate (CTE)• Use heading, speed and
position to predict connection duration
![Page 42: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/42.jpg)
Routing in Vehicular Mesh Networks
Heading [0, 9) [10, 19) [20, 29) [30, 180] All Links
Link Duration (s) 66 32 15 9 16
• Empirical evaluation on taxi traces• 15 networks, 100 vehicles each
Links with similar heading lasted 4 to 5 times longer than the median duration over all links
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Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Walking
Vehicular Routing
![Page 44: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/44.jpg)
Application
Transport
Network
MAC
PHY
Wireless Radio
Wireless Protocol Stack
GPS
Compass
Accl
GyroRate AdaptationMovement
HeadingAP Association
Speed
Disassociation
Packet Scheduling
Power SavingPreamble
Network Monitoring
Speed
Walking
Location Vehicular Routing
![Page 45: Wireless “ESP”: Using Sensors to Develop Better Network Protocols Lenin Ravindranath Calvin Newport, Hari Balakrishnan, Sam Madden Massachusetts Institute.](https://reader030.fdocuments.net/reader030/viewer/2022032705/56649d8d5503460f94a76546/html5/thumbnails/45.jpg)
Related Work
• Wireless power saving– WakeOnWireless, Cell2Notify, Blue-Fi
• Vehicular networking – use GPS– AP association
• Mobisteer, Breadcrumbs
– Rate adaptation• CARS: Adapt rate based on speed and heading
• Very recent work– Accelerometer-assisted rate adaptation
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Take-Away Message
• Truly mobile devices will soon be dominant– Variety of mobility modes poses problems for
wireless protocols• Sensors on these devices give us a new
opportunity to develop network protocols• Protocol architecture using sensor hints can
significantly improve MAC, link, network layers
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Backup
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Probing
How frequently should nodes probe?
Delivery Probability• ETX, ETT
Probes
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Infrequent Probing
Inaccurate link estimation leads to poor throughput
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Frequent Probing
Probing wastes bandwidth
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Delivery Probability
Mobility causes delivery probability tofluctuate with bigger jumps
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Static vs. Mobile
Mobile case requires 20x more probesto maintain acceptable estimation error
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Adaptive Probing Protocol
• Adapt probing based on movement hints• When a node is static
– Probe infrequently (1 probe every 2 seconds)• When a node is mobile
– Probe frequently (10 probes per second)
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Adaptive Probing
Tracks the link accurately with fewer probes
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Pruning association