IEEE 802.11e Quality of Service Support

1. IEEE 802.11e
Quality of Service
Support
Sanjay Saha Network Performance Analysis
Roll: JN 352 Dr. Md. Abdur Razzaque
MSc. Dept of CSE
University of Dhaka
26th Aprili 2015

2. What & Why
• Provided enhancements over legacy
IEEE 802.11
• To provide quality of service support such as
voice over wireless and streaming multimedia
• DCF is now EDCA
Enhanced Distributed Channel Access
• Two classes of users with different priorities
Network Performance Analysis: Fayez Gebali
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3. Flashback (DCF)
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4. Flashback (DCF)
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5. Protocol Assumptions
• Two priority classes(class 1 & class 2)
(DCF: single class users)
• Two contention windows (w1 & w2)
(DCF: one contention window)
• Probability of a frame to send is ‘a’
• γ < 1 : prob. that a transmitted frame is of
class 1
Network Performance Analysis: Fayez Gebali
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6. Supporting eqns.
Probability that a class 1 user sends data
Population seen by each slot in a contention window
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7. Supporting eqns.
Probability that a ‘k’ class 1 users attempt to transmit
Probability that a ‘k’ class 2 users attempt to transmit
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8. Markov Chain
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9. Markov Chain
Channel stays idle with probability:
Class 1 user transmitting probability:
Class 2 user transmitting probability:
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10. Markov Chain (Dist. Vector)
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11. Performance(1/3)
Throughputs:
Avg. Input Traffic:
Acceptance Probability:
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12. Performance(2.1/3)
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13. Performance(2.2/3)
DCF: Throughput vs. Input Traffic Curve
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14. Performance(3/3)
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15. That’s all !!!
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