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Chen Xinyu and Michael R. Lyu The Chinese Univ. of Hong Kong 2004-03-08 Big Sky, MT

2004 IEEE Aerospace Conference. Queueing Analysis for Access Points with Failures and Handoffs of Mobile Stations in Wireless Networks. Chen Xinyu and Michael R. Lyu The Chinese Univ. of Hong Kong 2004-03-08 Big Sky, MT. Outline. Wireless network architecture System model and assumptions

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Chen Xinyu and Michael R. Lyu The Chinese Univ. of Hong Kong 2004-03-08 Big Sky, MT

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  1. 2004 IEEE Aerospace Conference Queueing Analysis for Access Points with Failures and Handoffs of Mobile Stations in Wireless Networks Chen Xinyu and Michael R. Lyu The Chinese Univ. of Hong Kong 2004-03-08 Big Sky, MT

  2. Outline • Wireless network architecture • System model and assumptions • Five dispatch strategies • Analytical results and comparisons • Conclusions CUHK

  3. Handoff: a mechanism for a Mobile Station to seamlessly change a connection from one Access Point to another Mobile Station Static Host Access Point Wired Link Cell Radio Link Wireless Network Architecture CUHK

  4.    • R: Recovery time • H: Handoff time State Transition Diagram • Three states for a mobile station • State 0 – Normal, State 1 – Recovery, State 2 – Handoff 0 2 1 CUHK

  5. Stationary State Probability CUHK

  6. System Model and Assumptions • Communications among all three components are by message-passing • The message arrival process for each Mobile Station is with a constant rate  • The message dispatch requirementDis an exponentially distributed random variable with rate  • The Access Point itself does not undergo failures CUHK

  7. Undispatchable Message • Undispatchable message • a message reaches the dispatch facility, however, its target mobile station is not in the normal state, i.e., in the recovery or handoff state CUHK

  8. Expected Sojourn Time • Sojourn time • the time period between that a message enters an Access Point and that the message leaves it • Objective • Derive the expected message sojourn time in an Access Point with different dispatch strategies in the presence of failures and handoffs of Mobile Stations. CUHK

  9. Dispatch Model (1) • Basic Dispatch Model n  q0 CUHK

  10. Message Sojourn Time (1) • Conditioned message dispatch time • Expected message sojourn time CUHK

  11. q1 q2 qn /n /n /n Dispatch Model (2) • Static Processor-Sharing Dispatch Model    CUHK

  12. Message Sojourn Time (2) • Conditioned message dispatch time • Expected message sojourn time CUHK

  13. /K /K /K Dispatch Model (3) • Dynamic Processor-Sharing Dispatch Model    q1 q2 qn K CUHK

  14. K Dispatchable Messages • When a message enters the dispatch facility CUHK

  15. Message Sojourn Time (3) • Conditioned message dispatch time • Expected message sojourn time CUHK

  16.   Dispatch Model (4) • Round-Robin Dispatch Model    q1 q2 qn    • No swap time CUHK

  17. Message Sojourn Time (4) • Conditioned message dispatch time CUHK

  18. Dispatch Model (5) • Feedback Dispatch Model n  q0 CUHK

  19. Possion Arrivals See Time Averages • Possion Arrivals See Time Averages (PASTA) • The probability of having M messages in the system at a random epoch is equal to the steady state probability of having M messages in the system at any random time CUHK

  20. Message Sojourn Time (5) CUHK

  21. Analytical Results and Comparisons (1) • Number of mobile stations CUHK

  22. Analytical Results and Comparisons (2) • Failure rate CUHK

  23. Analytical Results and Comparisons (3) • Message arrival rate CUHK

  24. Analytical Results and Comparisons (4) • Expected message dispatch requirement CUHK

  25. Conclusions • Analyze the message sojourn time within an Access Point in the presence of failures and handoffs of mobile stations in wireless networks • Consider five dispatch strategies • Obtain analytical results and comparisons CUHK

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