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Quality of Service Aware MAC Based on IEEE 802.11 for Multihop Ad-Hoc Networks

Quality of Service Aware MAC Based on IEEE 802.11 for Multihop Ad-Hoc Networks. S. Sivavakeesar, G. Pavlou IEEE WCNC 2004. Outline. INTRODUCTION PREVIOUS WORK AND OUR MOTIVATION PROPOSED APPROACH EVALUATION THROUGH SIMULATION CONCLUSIONS AND FUTURE WORK. INTRODUCTION. ad hoc network

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Quality of Service Aware MAC Based on IEEE 802.11 for Multihop Ad-Hoc Networks

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  1. Quality of Service Aware MAC Based on IEEE 802.11 for Multihop Ad-Hoc Networks S. Sivavakeesar, G. Pavlou IEEE WCNC 2004

  2. Outline • INTRODUCTION • PREVIOUS WORK AND OUR MOTIVATION • PROPOSED APPROACH • EVALUATION THROUGH SIMULATION • CONCLUSIONS AND FUTURE WORK

  3. INTRODUCTION • ad hoc network • real-time application • lack fixed infrastructure • medium access technology • network-level QoS mechanisms cannot work in MANETs • main focus • PCF • WLAN • AP • combination • random (contention-based) • regulated (contention-free) access

  4. PREVIOUS WORK AND OUR MOTIVATION(1) • based on IEEE 802.11 • main focus – PCF mode

  5. PREVIOUS WORK AND OUR MOTIVATION(2) • Time Division Multiple Access (TDMA) • Service-differentiation • no explicit guarantee of service differentiation • Fairness • drawbacks of the above • does not have the capability to provide MAC level QoS

  6. PROPOSED APPROACH (1) • to support both asynchronous and time-sensitive multimedia traffic • to adopt hierarchical approach

  7. PROPOSED APPROACH (2) • simultaneous transmission • multiple parallel media (channels) • receiver-based spread-spectrum technology • full duplex radio • medium model • common medium • each node has its unique code (medium) • channel management • each node has to maintain constant CP and CFP

  8. PROPOSED APPROACH (3) • channel management (cont.) • common code • only pureDCF • disseminate and acquire routing related information • to perform dynamic code assignment • unique code • pure DCF and combined (DCF + PCF) mode • switches between two mode depending on traffic type

  9. PROPOSED APPROACH (4) • traffic type • best-effort traffic (low priority) • time-sensitive multimedia traffic (high priority) • “Association Request” (AReq) frame (to the forwarder) • Association Response (ARes) frame • polling-list • virtual PC (VPC) • POLLING_TIME_OUT, • three components • admission control • QoS-mapping • resource reservation

  10. PROPOSED APPROACH (5)

  11. PROPOSED APPROACH (6) • details • superframe • CFP – high-priority traffic • CP – AReq, ARes, and best-effort data • provisioning of network resources • resource reservation in PCF mode • prioritization in the DCF mode • prioritization • service-differentiation • allowing faster access to the medium • SIFS < PIFS < RIFS < DIFS

  12. PROPOSED APPROACH (7) • details (cont.) • prioritization (cont.) • fairness • admission control • Tcp: duration of CP • Tovhd : overhead involved for beacon and CF_END transmissions • Tv : time to send a voice packet • the VPC can poll to a maximum of Np number of times (or nodes)

  13. PROPOSED APPROACH (8) • QoS-mapping module • calculates the number of times it has to be polled by any VPC • AReq frame • ASSO_PROC_THERESHOLD_TIME_OUT • look for another appropriate forwarding node • Exception • cannot rely on PCF-based operation • depending on relative velocities • MOBIC model

  14. PROPOSED APPROACH (9) • MOBIC model • negative value • moving away • Mx : low value • relatively less mobile • Mthreshold: higher => rely on common medium

  15. EVALUATION THROUGH SIMULATION(1) • GloMoSim • 500m X 500m • 20 nodes • 300 seconds of simulation time • transmission range of 100m • full duplex operation • data packet size is 512 bytes

  16. EVALUATION THROUGH SIMULATION(2)

  17. EVALUATION THROUGH SIMULATION(3)

  18. EVALUATION THROUGH SIMULATION(4)

  19. CONCLUSIONS AND FUTURE WORK • a QoS-aware MAC protocol • based on the IEEE 802.11 standard • To be easily integrated into existing systems • Extension • 802.11e standard • support multiple traffic classes

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