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Interference-Aware QoS OLSR for Mobile Ad-hoc Network Routing

Interference-Aware QoS OLSR for Mobile Ad-hoc Network Routing. SAWN 2005, May 24 P. Minet & D-Q. Nguyen. Outline. Introduction QoS framework for ad-hoc networks Interference-aware QoS OLSR Performance evaluation Conclusion. 1. Introduction.

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Interference-Aware QoS OLSR for Mobile Ad-hoc Network Routing

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  1. Interference-Aware QoS OLSRfor Mobile Ad-hoc Network Routing SAWN 2005, May 24P. Minet & D-Q. Nguyen

  2. Outline • Introduction • QoS framework for ad-hoc networks • Interference-aware QoS OLSR • Performance evaluation • Conclusion SAWN 2005

  3. 1. Introduction • Transmissions and receptions in ad-hoc networks are subject to radio interference. => Bandwidth resource is affected. SAWN 2005

  4. 1. Introduction • Ad-hoc networks have scarce resources. => QoS management in ad-hoc networks is more difficult than in wired networks. Admission control is needed. SAWN 2005

  5. 2. QoS framework Application (Bandwidth) Class 2 Bandwidth Controland Reservation Path Computation QoS Advertisements MAC layer metrics SAWN 2005

  6. 2. QoS framework Application (Bandwidth) Class 2 Marking Routing on theReserved Path SAWN 2005

  7. 3. Interference-aware QoS OLSR • QoS signalisation • Measure local available bandwidth (LAB) • At each node. • Based on values obtained from MAC layer. • LAB dissemination • Any node broadcasts in Hello message : its LAB and the LAB of each neighbor. • Any MPR (multipoint relay) broadcasts in TC message the LAB of each MPR selector. • MPR selection based on LAB • Any node selects its MPRs so that it can reach any two-hop neighbor by a largest path; i.e. path with maximum bandwidth. SAWN 2005

  8. 3. Interference-aware QoS OLSR • MPR selection example : i N1(i) = {m, n} N2(i) = {x, y, z} m n x y z OLSR native MPR selection MPR selection with bandwidth 5 1 SAWN 2005

  9. 3. Interference-aware QoS OLSR • Interference-aware admission control • Accept a new flow iff: • QoS required by this flow can be met. • QoS of already accepted flows must not be altered. • Perform in 2 steps: • Step 1: Selection of an acceptable pathAny node on the path must provide the amount of bandwidth required by the new flow.Can be checked locally by the source node. • Step 2: Path feasibility with interferencesAny node in the interference zone of a node on the path must have enough bandwidth to support this new flow.A message is sent from source to destination. SAWN 2005

  10. 3. Interference-aware QoS OLSR • Admission control example : S S D This path forthe Yellow flowis not acceptable! D SAWN 2005

  11. 3. Interference-aware QoS OLSR • Interference-aware QoS routing algorithm • The shortest routes tend to minimize network resources required for transmission of each packet from its source to destination in a wireless multihop environment. => Minimize the number of hops as first criterion. • Some flows require bandwidth as QoS parameter.=> Consider local available bandwidth at each node as second criterion. • Route computation is called upon any topology change.=> Complexity must be similar to Dijkstra algorithm. • Network resources is scarce.=> Algorithm is based on partial knowledge of topology. SAWN 2005

  12. 3. Interference-aware QoS OLSR • Interference-aware QoS routing algorithm • Algorithm 1: • Default algorithm used to compute routing table. • Unconstrained, widest-shortest path. • Called upon any change in the one-hop neighborhood, two-hop neighborhood or topology table. • Algorithm 2: • Constrained by a bandwidth request. • Used to compute a route offering the requested bandwidth from a source to a destination if the default route, from algorithm 1, cannot provide that bandwidth. • Called by the admission control for a new flow with bandwidth demand. SAWN 2005

  13. 3. Interference-aware QoS OLSR • Admission control example with routing algorithm 2 : S S D Flow Yellowacceptable! D SAWN 2005

  14. 4. Performance evaluation • Simulation plan • 250 static nodes uniformly located on a 2500x2500m2 square. • 7 CBR flows, each requires 175Kbps at application level. • MAC 802.11b, no RTS/CTS. • Native OLSR and Interference-aware QoS OLSR routing. SAWN 2005

  15. 4. Performance evaluation • Results obtained with native OLSR SAWN 2005

  16. 4. Performance evaluation • Results obtained with Inteference-aware QoS OLSR routing SAWN 2005

  17. 4. Performance evaluation • Loss rate comparison SAWN 2005

  18. 5. Conclusion • Interference-aware routing can accept more flows into the network. • It offers better stability to the accepted flows, better bandwidth guarantee to the applications than native OLSR. • If it cannot find a route meeting the bandwidth requested,then such a route does not exist. • Main drawback: more MPRs selected => more control overhead, broadcasting using MPR becomes less efficient. • Perspective: Reduce control overhead, improve broadcasting. SAWN 2005

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