Measuring Effective Capacity of IEEE 802.15.4 Beaconless Mode

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Measuring Effective Capacity of IEEE 802.15.4
Beaconless Mode

• Tony Sun, Ling-Jyh Chen, Chih-Chieh Han, Guang
  Yang, Mario Gerla

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Outline

• Motivation
• Background
• IEEE 802.15.4
• Hardware/Software Configuration
• On Measuring Effective Capacity
• Theoretical Effective Capacity
• SenProbe
• Testbed Experiment Results
• Conclusion

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Motivation

• IEEE 802.15.4 WPAN standard features low-rate,
  low-cost, and low power consumption.
• Applicable to field of home/industrial
  automation, and etc
• Mobile computing platforms may interact with
  ambient IEEE 802.15.4 sensor environment
  establishing opportunistic wireless networks
• Evaluation and measurement of wireless path
  capacity in sensor network is of realistic
  interest
• (i.e. Capacity planning, protocol design,
  performance analysis, system deployment, assess
  applicability of deployment)

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Outline

• Motivation
• Background
• IEEE 802.15.4
• Hardware/Software Configuration
• On Measuring Effective Capacity
• Theoretical Effective Capacity
• SenProbe
• Testbed Experiment Results
• Conclusion

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Background IEEE 802.15.4

• Defined Two Device Types
• Full Function Devices (FFD)
• Reduce Function Devices (RFD)

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Background Configuration

• Hardware
• MICAz, IEEE 802.15.4 compliant radio chip
• MIB510 Interface board
• Software
• Sensor Operating Software (SOS) with IEEE
  802.15.4 driver support.
• With optional ACK frame disabled, to test the
  maximum achievable rate.

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Outline

• Motivation
• Background
• IEEE 802.15.4
• Hardware/Software Configuration
• On Measuring Effective Capacity
• Theoretical Effective Capacity
• SenProbe
• Testbed Experiment Results
• Conclusion

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Theoretical Effective Capacity

• The effective end-to-end rate is defined as the
  maximum achievable data rate in the absence of
  any cross traffic connection.
• Varies with MAC protocol and link scheduling,
  Link interference, S/N ratio, Tx power,
  Encoding/modulation scheme, Number of antennas
  (e.g. MIMO), Antenna directionality, and etc
• It is smaller than the raw data rate at the
  physical layer due to
• Packet Overhead
• Interference between multiple packets in the
  pipeline

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Neighborhood Example

• If DrDi , nodes 3,4,5 are within the same
  n-hood, CC/3
• If Dr Di /2, nodes 2,3,4,5,6 are in n-hood,
  CC/4

Dr effective receive range from node 4
(solid-line circle) Di interference range
caused by node 4 (dotted-line circle)
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Effective Capacity of IEEE 802.15.4 Beaconless
mode (1)

• The effective capacity of a one-hop link can be
  calculated as

Twait the minimum time the radio has to wait
before sending another packet. Including CCA,
Radio Turnaround time, and etc
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Effective Capacity of IEEE 802.15.4 Beaconless
mode (2)

• For the CSMA environment in our study (with
  disabled ACK)

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SenProbe

• Path capacity estimation tool specially designed
  for the multi-hop CSMA based wireless networks.
• One-way estimation technique, based on CapProbe
  concepts
• Aimed to simplify the path capacity estimation
  process
• A back-to-back packet train technique designed to
  overcome the hidden terminal effects in CSMA
  environment
• SenProbe measures end-to-end effective capacity
  in wireless ad hoc networks.
• SenProbe is simple, fast and less intrusive to
  comparative techniques.

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SenProbe Algorithm(1)

• Instead of using back-to-back packet pairs,
  SenProbe relies on back-to-back packet train to
  overcome the effect of hidden terminal in CSMA-CA
  
• The length of this back-to-back packet train
  depends on the interference range and the
  transmission range of the specific radio
  technology under question

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SenProbe Algorithm(2)

• The receiver measures the OWD of every packet in
  kth packet train received as the difference
  between time received and time sent
• the minimum OWDSUM is kept for the kth packet
  train. The good dispersion sample r (i.e.
  samples encountering no cross traffic) is the
  sample with the minimum OWD sum
• Dispersion of the good sample calculated, and
  used to estimation capacity

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Outline

• Motivation
• Background
• IEEE 802.15.4
• Hardware/Software Configuration
• On Measuring Effective Capacity
• Theoretical Effective Capacity
• SenProbe
• Testbed Experiment Results
• Conclusion

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Experiment Results (1)

• Path capacity of adhoc multi-hop forwarding chain
  in IEEE 802.15.4 beaconless mode

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Simulation Results (2)

• End-to-end capacity estimation of multi-hop IEEE
  802.15.4 beaconless mode connections within the
  same collision domain

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Experiment Results (3)

• Path Capacity measured via FTP connection and
  Packet-Pair technique (one way CapProbe)

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Conclusion

• In-depth evaluation of effective data capacity of
  IEEE 802.15.4 beaconless mode.
• Used SenProbe to estimate e2e path capacity in
  IEEE 802.15.4 beaconless enabled wireless sensor
  network.
• SenProbe uses back-to-back packet trains, and
  relies on packet dispersion between the packet
  trains to measure the path capacities in a
  one-way fashion.
• Illustrated and verify the simplicity and
  accuracy of SenProbe in measuring effective path
  capacity

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Thanks!
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Previous Work (Morris et al)

• Dr250m, Di500m
• Use UDP flows to probe the maximum achievable
  throughput (brute force method)

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SenProbe-Visualization
1)
2)
3)
4)
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CapProbe Concept

• Key insight a packet pair that gets through with
  zero queueing delay yields the exact estimate

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Issues Compression and Expansion

• Queueing delay on the first packet gt
  compression
• Queueing delay on the second packet gt expansion