Modeling Channel Conflict Probabilities between IEEE 802.15 based WPANs

1
Modeling Channel Conflict Probabilities between
IEEE 802.15 based WPANs

• Ling-Jyh Chen1, Tony Sun2, and Mario Gerla2
• 1Institute of Information Science, Academia
  Sinica
• 2Dept. of Computer Science, University of
  California at Los Angeles

2
Outline

• Introduction
• Overview of WPAN standards
• Coexistence issues
• Analysis
• Conclusion

3
Introduction

• With the increasingly deployed WPAN devices,
  channel conflict has become very frequent and
  severe.
• Previous studies focus on modeling packet/frame
  error rates and/or measuring data throughput when
  channel conflicts are present.
• In this paper, we study the prob of channel
  conflicts when multiple WPAN devices coexist.

4
Channel allocation of IEEE 802.15 standards

• IEEE 802.15.1 (Bluetooth)
• IEEE 802.15.4

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Channel allocation of IEEE 802.15 standards

• IEEE 802.15.3

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Channel allocation of IEEE 802.11/15 standards
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Frequency Hopping in Bluetooth

• Each time, the FH kernel selects a segment of 64
  adjacent channels, and then hops to 32 of them
  without repetition in a random order
• Next, a different 32-hop sequence is chosen from
  another segment of 64 adjacent channels

8
Coexistence issues

• coexistence The ability of one system to perform
  a task in a given shared environment where other
  systems have an ability to perform their tasks
  and may or may not be using the same set of
  rules.
• IEEE 802.15.2Coexistence of Wireless Personal
  Area Networks with Other Wireless Devices
  Operating in Unlicensed Frequency Bands

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Analysis

• 4 cases
• One 802.15.1 multiple 802.15.3
• One 802.15.1 multiple 802.15.4
• One 802.15.3 multiple 802.15.4
• One 802.15.4 multiple 802.15.3

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Analysis 1 one 15.1 multiple 15.3

• PRr the prob that there are r conflicting
  channels in the selected segment of 64 adjacent
  channels
• PKkRr the prob that, given r conflicted
  channels in the 64 adjacent channels, k out of
  the selected 32 hop sequence are conflicted
• S1 the selected channel (out of the 32 hop
  sequence) is conflicted

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Analysis 1 one 15.1 multiple 15.3

• Case 1 n1

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Analysis 1 one 15.1 multiple 15.3

• Case 2 n2

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Analysis 1 one 15.1 multiple 15.3

• Case 3 n3

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Analysis 2 one 15.1 multiple 15.4

• Case 1 n1
• Case 2 ngt1
• Use Monte Carlo simulation method

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Analysis 2 one 15.1 multiple 15.4
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Analysis 3 one 15.3 multiple 15.4

• Pigeonhole Principle
• one 15.3 can coexist with at most 12 15.4
  networks (i.e., 0ltnlt12)

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Analysis 3 one 15.3 multiple 15.4
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Analysis 4 one 15.4 multiple 15.3

• Case 1 15.4 operates on one of the four
  non-overlapped channels (i.e., P_good 1)
• Case 2 15.4 operates on one of the overlapped
  channels (i.e., P_good (3-n)/3)

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Analysis 4 one 15.4 multiple 15.3
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Conclusion

• IEEE 802.15.1 coexists well with 15.3 and 15.4
  networks (i.e., due to FHSS)
• IEEE 802.15.3 and 802.15.4 have coexistence
  problem.
• The analytical results need to consider SNR and
  other issues in order to obtain packet/frame/bit
  error rate.