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Department of Information Engineering University of Padova, ITALY
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Department of Information Engineering University of Padova, ITALY

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  1. Department of Information EngineeringUniversity of Padova, ITALY Special Interest Group on NEtworking & Telecommunications On Providing Soft-QoS in Wireless Ad-Hoc Networks Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Paolo Raimondi {andrea.zanella, daniele.miorandi, silvano.pupolin}@dei.unipd.it WPMC 2003, 21-22 October 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003

  2. Outline of the contents • Motivations & Purposes • Soft-QoS & Call Admission Control • Path creation & maintenance • Results • Conclusions Yokosuka, Kanagawa (Japan) 21-22 October 2003

  3. What & Why… Motivations & Purposes Yokosuka, Kanagawa (Japan) 21-22 October 2003

  4. Motivations • Ad-hoc networks are a valuable solution to • Extend in a multi-hop fashion the radio access to wired networks • Interconnect wireless nodes without any fixed network structure • In these contexts, providing QoS is a key issue • audio/video streaming • interactive games • multimedia • Classic QoS support methods involve • QoS-routing • Call-Admission-Control (CAC) mechanisms • MAC-layer Resource Reservation (MRR) strategies Yokosuka, Kanagawa (Japan) 21-22 October 2003

  5. Aim of the study • Providing basic Soft-QoS support over low-profile ad-hoc wireless networks • No hard QoS guarantees  Soft QoS • Simple QoS routing algorithm  modified AODV • Simple CAC mechanism  distributed statistical CAC • No static MRR  statistical MRR Yokosuka, Kanagawa (Japan) 21-22 October 2003

  6. Introduction to QoS issues Soft QoS & CAC Yokosuka, Kanagawa (Japan) 21-22 October 2003

  7. Widely used in wired networks Integrated Services: flow based (RSVP) Differentiated Services: class based Suitable for wireless networks Applications may work even if, for short periods of time, QoS requirements are not satisfied Deal with limited bandwidth and radio channel Hard & Soft QoS Hard-QoS Soft-QoS Yokosuka, Kanagawa (Japan) 21-22 October 2003

  8. Soft-QoS parameters • QoS parameters required per link • Minimum peak band: Br • End-to-End Delay: Dr • Soft QoS parameter: Target Satisfaction index • r = percentage of pcks expected to satisfy QoS constrains • r = 1  hard QoS • r = 0  pure best-effort • Path Service Levels P = (p1,…, pN) • Path Peak Bandwidth • Path Delay Yokosuka, Kanagawa (Japan) 21-22 October 2003

  9. Call-Admission Control • Path is feasible if • Bandwidth constrained requests • Delay constrained requests • Using Gaussian approx, Bandwidth and Delay statistic is determined by mean and standard deviation • Bandwidth constrained requests • Delay constrained requests Yokosuka, Kanagawa (Japan) 21-22 October 2003

  10. Bandwidth-constrained Delay-constrained Extra-delay margin given to each link along the path is inversely proportional to the mean link delay Statistical Resource Reservation • Resource bounds • Minimal residual resources that should be guaranteed to preserve QoS levels of accepted connections Resource bounds Actual Satisfaction Yokosuka, Kanagawa (Japan) 21-22 October 2003

  11. Path creation & maintenance • Soft-QoS routing is largely inspired to AODV • Each Route Request (RREQ) packet gathers statistical information on the minimum bandwidth and maximum delay along that portion of the path • RREQ is propagated only whether bandwidth request is satisfied • The destination node back propagates a Route Reply (RREP) packet along the selected path • RREP acquaints intermediate nodes with new resource bounds and updates maximum sustainable traffic rate • Source node is required to respect the maximum sustainable traffic rate limit or to refuse the connection Yokosuka, Kanagawa (Japan) 21-22 October 2003

  12. Simulation Results Simulation of Soft-QoS routing algorithm Yokosuka, Kanagawa (Japan) 21-22 October 2003

  13. Bluetooth Scatternet Round Robin Polling Gateways spend 50 slots in each piconet Poisson packets arrival process Mixed packet formats with average length of 1500 bits Delay-constrained requests Simulation Scenario Yokosuka, Kanagawa (Japan) 21-22 October 2003

  14. Local slave-to-slave connections in each piconet Data rate=9.6 Kbit/s Gaussian Approximation • 1 hop • 6 hops • Gaussian approx is fairly close to empirical delay CDF • Gap increases for long-distance and high traffic connection Yokosuka, Kanagawa (Japan) 21-22 October 2003

  15. Simulation setup • Target connection c1 • Dr = 50 ms • r = 0.2 • r = 20 kbit/s • Target connection c2 • Dr = 200 ms • r = 0.9 • r = 30 kbit/s • Target connection c3 • Dr = 200 ms • r = 0.9 • r = 20 kbit/s • Target connection c4 • Dr = 50 ms • r = 0.2 • r = 60 kbit/s • Transversal connections • Starting after 20 s, last for 10 s • On average 1 request/s • Random source, destination & QoS requests • Rate: 520 kbit/s Yokosuka, Kanagawa (Japan) 21-22 October 2003

  16. Satisfaction & Delay dynamics • Satisfaction • Delay Yokosuka, Kanagawa (Japan) 21-22 October 2003

  17. Conclusions • We have proposed a basic Soft QoS routing algorithm for low-profile ad hoc networks • Provides Soft-QoS guarantees • Requires • basic nodes’ functionalities • statistical link state monitoring (mean and standard deviation) • Does not require • service differentiation • static resource reservation • Drawbacks • Lower resource utilization • Higher rate of connection request rejection Yokosuka, Kanagawa (Japan) 21-22 October 2003

  18. Department of Information EngineeringUniversity of Padova, ITALY Special Interest Group on NEtworking & Telecommunications On Providing Soft-QoS in Wireless Ad-Hoc Networks Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Paolo Raimondi {andrea.zanella, daniele.miorandi, silvano.pupolin}@dei.unipd.it WPMC 2003, 21-22 October 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003