Transport Protocols for Sensor Networks

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Transport Protocols for Sensor Networks

• Nischal M. Piratla
• Sangeetha L. Bangolae
• Tarun Banka
• Computer Networking Research Laboratory
• Colorado State University

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Motivation

• What is expected out of a transport protocol for
  sensor networks ?
• Reliability, congestion control, mux/demux,
• Why cant we use the existing protocols ?
• Resource constraints power, storage,
  computation complexity, data rates,
• Are these constraints common for all sensor
  networks ?
• No, they are application specific.

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Motivation ..contd.

• Any application can have a union of the
  constraints that we know or yet to figure out?
• Spectra for known constraints

Low data Rate High
data Rate
Power limited Not Power limited
Storage limited Not Storage limited
Bursty samples Periodic samples
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Motivation ..contd.

• General notion for sensor networks

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Motivation ..contd.

• Radar application
• Range of Transport protocols is yet to be
  explored
• ESRT, PSFQ, CODA .!!!!..TRABOL

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Event-to-Sink Reliable Transport (ESRT) for
Wireless Sensor Networks

• Salient Features
• Event-to-sink reliability
• Self-configuration
• Energy awareness low power consumption
  requirement!
• Congestion Control
• Variation in complexity at source and sink.
  computation complexity

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ESRTs Definition of Reliability

• Reliability is measured in terms of the number of
  packets received. Or reporting frequency i.e.,
  number of packets/decision interval.
• Observed reliability number of received data
  packets in decision interval at the sink.
• Desired reliability number of packets required
  for reliable event detection.
• Normalized reliability observed/desired.

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ESRT operation
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Algorithm for ESRT

• If congestion and low reliability decrease
  reporting frequency aggressively. (exponential
  decrease)
• If congestion and high reliability decrease
  reporting to relieve congestion. No compromise on
  reliability (multiplicative increase)
• If no congestion and low reliability increase
  reporting frequency aggressively (multiplicative
  increase)
• If no congestion and high reliability decrease
  reporting slowing (half the slope)

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Components of ESRT

• In sink
• Normalized reliability computation
• A congestion detection mechanism
• In source
• Listen to sink broadcast
• Overhead free local congestion detection
  mechanism
• E.g., buffer level monitoring, CN Congestion
  Notification

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Analytical Results

• Analytical results (intuitive yet useful) .. We
  will skip this slide
• Starting from no congestion, high reliability and
  with linear reliability behavior when the network
  is not congested, the network state remains
  unchanged until ESRT converges
• Starting from no congestion, high reliability,
  and with linear reliability behavior when the
  network is congested, ESRT converges to optimum
  operating range in tlog2((?-1)/?)
• With linear reliability behavior when the network
  is not congested, the network state transition
  from congestion, high reliability to no
  congestion, low reliability.

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Performance Results (based on simulations)
please refer to the paper for graphs .. They may
not be legible here

• Starting with no congestion and low reliability

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Performance Results contd (based on
simulations)

• Starting with no congestion and high reliability

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Performance Results contd (based on
simulations) please refer to the paper for
graphs

• Starting with congestion and high reliability

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Performance Results contd (based on
simulations) please refer to the paper for
graphs

• Starting with congestion and low reliability

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Performance Results contd (based on
simulations) please refer to the paper for
graphs

• Average power consumption while starting with no
  congestion and high reliability

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Challenges with ESRT

• Multiple concurrent events.
• Congestion may be due to all sensor nodes. Can
  there be a better way to slow down the nodes
  causing the congestion ?
• Buffer occupancy and congestion.
• We will now move to TRABOL.

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Gigabit Networking Digitized Radar Data Transfer
and BeyondSangeetha L.Bangolae, Anura P.
Jayasumana, V. Chandrasekar

• Sangeetha L. Bangolae
• (Sang)
• Computer Networking Research Lab
• Colorado State University

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Motivation

• Present a new class of high-bandwidth (64 384
  Mbps) application VCHILL radar
• Discuss the transport protocols to satisfy
  real-time radar data transfer over high-speed
  links
• Congestion Control to be TCP-friendly

VCHILL Virtual CHILL
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Gigabit Networking Applications

• Digital Earth
• Bio-medical Tele Immersion
• NASA
• Virtual MechanoSynthesis
• Digital Sky
• VCHILL

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VCHILL Radar Application

• AIM
• Transfer and Display of Digitized Radar Signals
  in real-time over the NGI (Next Generation
  Internet)
• Remote Control of the radar

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VCHILL Radar Application

• CHARACTERISTICS
• High-bandwidth requirement for best operation A
  high responsiveness to available bandwidth.
• Satisfactory operation with a minimum bandwidth
  threshold possible Yet increase in bandwidth
  provides a better display image.
• Tolerance to losses and end-to-end delay high,
  compared to audio and video streaming media.
• Smoothness (delay jitter) not critical for proper
  functioning.

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CSU-CHILL Doppler Radar
11 cm wavelength Dual-polarization Radar
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Current Status
Display PPI/RHI (Plan Position
Indicator/Range Height Indicator) End stations
Sun Solaris based Signal Processing DSP
Software based
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Radar Data Format
One Ray of DRS Data
1st Sample
2nd Sample
3rd Sample
4st Sample
Each Sample size 16000 bytes
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Radar Parameter Display Image
UDP-based (RDP) DRS Transfer with no losses
RDP Radar Data transfer Protocol
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Radar Parameter Display Image
UDP-based (RDP) DRS Transfer with 90 losses
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Transport protocols and Congestion Control

• VCHILL Application
• TCP too conservative, not suitable for
  real-time
• UDP Suitable for real-time, but No congestion
  control, flow control
• Require a transport protocol for real-time data
  transfer - With Congestion control!

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VCHILL UDP-based DRS Transfer Architecture
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TRABOL TCP-friendly Rate Adaptation Based On Loss

• Source-based Rate Control based on AIMD
• If (Congestion)
• Decrease sending rate to MIN_RATE
• If (No Congestion)
• Increase sending rate towards TARGET_RATE in
  steps
• Congestion policies based on feedback from
  receiver

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Feedback Mechanism
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Performance Evaluation
Sending rate (Mbps) and Loss rate () for Radar
Application without rate control
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Performance Evaluation (contd)
Sending rate (Mbps) and Loss rate () for Radar
Application with memory-based TRABOL
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Summary

• VCHILL as a NGI application
• Current Status of the Project
• Transport protocols for the application
• UDP-based Radar data transfer protocol
• Need for congestion Control
• TRABOL and Performance Evaluation

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Thank youQuestions!