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Interference-aware QoS Routing ( IQRouting ) for Ad-Hoc Networks

Interference-aware QoS Routing ( IQRouting ) for Ad-Hoc Networks. Rajarshi Gupta, Zhanfeng Jia, Teresa Tung, and Jean Walrand Dept of EECS, UC Berkeley Globecom 2005 St. Louis, Missouri. Battalion of Tanks. Support flows with QoS Video streaming Voice calls Urgent messages

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Interference-aware QoS Routing ( IQRouting ) for Ad-Hoc Networks

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  1. Interference-aware QoS Routing (IQRouting) for Ad-Hoc Networks Rajarshi Gupta, Zhanfeng Jia, Teresa Tung, and Jean Walrand Dept of EECS, UC Berkeley Globecom 2005 St. Louis, Missouri

  2. Battalion of Tanks • Support flows with QoS • Video streaming • Voice calls • Urgent messages • DARPA sponsored SmartNets Project November 2005

  3. Interference • Wired networks • Independent links • Ad-hoc networks • Neighbor links interfere • Interference range > Transmission range • For simulations • Tx range = 500 m • Ix range = 1 km November 2005

  4. Link Conflict Node Interference Model Link November 2005

  5. Maximal Cliques: ABC, BCEF, CDF Cliques • Cliques • Clique= Complete Subgraph • Maximal Clique is not a subset of any other clique • Cliques in Conflict Graph • Set of links that all interfere with each other • Closely related to capacity • Clique Constraints • Only one link in a clique may be active at once • Flows on all links in a clique must sum  1 November 2005

  6. Available Bandwidth • Available bandwidth on a link (avlbw) • Each link part of many maximal cliques • Consider slack on each clique constraint • Take the minimum • Available bandwidth in network/path • Minimum of avlbw of all links in network/path • Key difference between wired and ad-hoc • In wired, width of path determined by bottleneck link • In ad-hoc, width determined by bottleneck clique November 2005

  7. Bellman’s Principle of Optimality • Principle states: If optimal path from S to D goes through A, then it follows optimal path from A to D (Bellman) • Distributed routing algorithms hinge on this principle November 2005

  8. Principle of Optimality in Ad-Hoc ? • Widest path from node 1 to 3 is link A (FA 1) • Consider widest path from node 1 to 5 • Path A-D-E: • FA+FD+FE  1 • so capacity  1/3 • Path B-C-D-E: • FB+FC  1, FC+FD  1, FD+FE  1, • so capacity  1/2 • Does not conform with Bellman’s Principle of Optimality • Hence, work with distributed heuristic algorithms November 2005

  9. IQRouting at Source • Link state protocol distributes available bandwidth information • Choose five candidate paths by source routing • Widest Shortest Path (WSP) • WSP compliment • Shortest Feasible Path (SFP) • OSPF-like weighted path cost ( + used capacity) • Shortest Widest Path (SWP) • Use ad-hoc versions of well-known QoS routing algorithms • Account for interference among neighboring links • Clique constraints determine avlbw November 2005

  10. Distributed IQRouting • Candidate paths are compared using probe packets • Distributed comparison across network • Nodes in path use local and current clique information • Probe rejected if lack of resources • QoS metric accumulated along path • Best candidate chosen at destination November 2005

  11. Comparison of Path Metric • Probe packets • Evaluate clique capacities along path • Check if clique constraints are met • Accumulate path metric (e.g. minimum of avlbw on path) • Look for bottleneck clique 4 C D 6 E 3 5 G B 7 2 H 8 A 1 FB+FC+FD+Fothers 1 FD+FE+FG+Fothers 1 November 2005

  12. Simulations • Topology • Random 100 nodes • 3 km X 3 km field • Transmission 500 m • Interference 1 km • Flows between 5 src & 5 dest nodes • Note • Random flow arrivals, durations • By changing mean of flow arrival and duration, we alter the “load” on the network November 2005

  13. Competing algorithms Shortest Path OSPF ILP-based SFP Ad-Hoc SFP 2 flavors IQR-Width IQR-Cost Results IQR performs better Comparing Admission Ratios November 2005

  14. Grid • 10X10 Grid • Choose node pairs 7 hops apart • Compare adm ratios and path length • At higher load, IQR finds longer paths with greater capacity November 2005

  15. 0 kbps 500 kbps 1000 kbps 0 33 18 27 4 10 14 3 11 46 17 48 100% 0.5 43 15 20 37 38 23 6 1 39 41 47 21 40 50% 5 22 44 36 16 29 9 49 1.5 28 7 1 26 12 42 13 34 0% 45 2 35 50 25 31 8 2 24 19 30 32 2.5 0 0.5 1 1.5 2 2.5 Choose Destination Routing… Click on bar to choose flow rate Choose Source Y position in km X position in km November 2005

  16. 0 kbps 500 kbps 1000 kbps Choose Next Source Choose Destination Click on bar to choose flow rate Routing… November 2005

  17. November 2005

  18. 0 kbps 500 kbps 1000 kbps Choose Next Source Choose Destination Click on bar to choose flow rate Flow Rejected. Insufficient Resources November 2005

  19. Conclusions • Multi-hop services have a long way to go • Actual capacity far lower than advertised • Shortest path methods are inadequate • Heuristic schemes most promising • IQRouting proposes one simple, distributed algorithm for ad-hoc networks • Performance results show significant improvement November 2005

  20. Questions  http://www.eecs.berkeley.edu/~guptar guptar@eecs.berkeley.edu

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