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Topology Considerations on Contention-based Directional MAC Simulation

Topology Considerations on Contention-based Directional MAC Simulation. Date: 2009-07-14. Authors:. Impact of Topology on Simulation of Contention-based Directional MAC (1/2). Topology and Service Scenario of Directional MAC observes different behaviors in simulation.

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Topology Considerations on Contention-based Directional MAC Simulation

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  1. Topology Considerations on Contention-based Directional MAC Simulation Date: 2009-07-14 Authors: W. Y. Lee et. al

  2. Impact of Topology on Simulation of Contention-based Directional MAC (1/2) Topology and Service Scenario of Directional MACobserves different behaviors in simulation. For example, CRTS and CRCM have been tested under different topology. July 2009 CRTS proposed by T. Korakis, G. Jakllari, and L. Tassiulas, "A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks," Proc. ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), pp.98–107, June 2003. CRCM proposed by G Jakllari, J Broustis, T Korakis,S V. Krishnamurthy, and L Tassiulas, "Handling Asymmetry in Gain in Directional Antenna Equipped Ad Hoc Networks," Proc. IEEE 16th International Symposium on PIMRC, pp.1284-1288, 2005 M Takata, M Bandai and T Watanabe, "MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks," Proc. IEEE Goblecom 2007, pp.620-625, 2007 Randomly distributed 100 Nodesin 1500x1500m 1 2 3 4 <4 nodes in linear topology> <Randomly distributed topology> Slide 2 W. Y. Lee et. al

  3. Impact of Topology on Simulation of Contention-based Directional MAC (1/2) • We observe the throughput performance of the two is reversed with different topology • => Hence, a standardized approach is necessary. July 2009 CRCM CRTS <Randomly distributed topology> <4 node in linear topology> Slide 3 W. Y. Lee et. al

  4. Three Performance Indices need to be analyzed • Deafness problem (e.g., deafness ratio) • Hidden node problem (e.g., failure rate due to hidden nodes) • Spatial reuse W. Y. Lee et. al

  5. Deafness Problem • Definition: deafness occurs if a device does not answer an RTS message addressed to it. • Consequences: originator of the RTS will try more RTSs while increasing contention window, during which messages toward other devices are subject to be blocked. • Two examples

  6. Deafness Example #1 1 1 1 2 2 2 4 4 4 3 3 3 X A B July 2009 • Assume 3 nodes. Slide 6 W. Y. Lee et. al

  7. 1 1 1 2 2 2 4 4 4 3 3 3 X B A Deafness Example #1 • Node A has a data to send B. • A sends DRTS. DRTS W. Y. Lee et. al

  8. Deafness Example #1 1 1 1 2 2 2 4 4 4 3 3 3 B A X July 2009 • Node B responds with DCTS. DCTS Slide 8 W. Y. Lee et. al

  9. Deafness Example #1 1 1 1 2 2 2 4 4 4 3 3 3 B A X July 2009 • Other beams except one in communication are blocked. In Communication Slide 9 W. Y. Lee et. al

  10. Deafness Example #1 1 1 1 2 2 2 Deafness 4 4 4 3 3 3 X A B July 2009 • Now, node X has a data to send A, it will send DRTS to A. (node A is deaf now.) DRTS Slide 10 W. Y. Lee et. al

  11. 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 S A D B Deafness Example #2 • Four nodes. • Now, node S has a data to send D. W. Y. Lee et. al

  12. Deafness Example #2 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 B A S D July 2009 • Four nodes. • Now, node S has a data to send D. DRTS Slide 12 W. Y. Lee et. al

  13. Deafness Example #2 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 B A S D July 2009 • Nodes A and B overhear the DRTS from S. • Nodes A and B block their beams 3 and 4, respectively. DRTS Slide 13 W. Y. Lee et. al

  14. Deafness Example #2 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 B A S D July 2009 • Node D responds with DCTS. • Node B overhears the DCTS and blocks beam 2. DCTS Slide 14 W. Y. Lee et. al

  15. Deafness Example #2 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 B A S D July 2009 • Nodes S and D are in communication. In Communication Slide 15 W. Y. Lee et. al

  16. Deafness Example #2 Deafness 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 S A D B July 2009 • Now, B has a data to A, so it sends DRTS to A. • But, node A’s beam 3 is blocked (Another deafness problem). DRTS DCTS Slide 16 W. Y. Lee et. al

  17. Hidden Terminal W. Y. Lee et. al

  18. Hidden Terminal Problem • Definition: hidden terminal problem occurs if another device interfere on-going communication by causing collision. • Consequences: throughput of on-going communication is degraded. • Two examples

  19. C D A B Hidden Terminal Example #1 • Assume nodes sense carrier omni-directionally. Sensing Range Slide 19 W. Y. Lee et. al

  20. C D A B Hidden Terminal Example #1 • Now, node B has a data to A Slide 20 W. Y. Lee et. al

  21. C D A B Hidden Terminal Example #1 • Node B has a data to A DRTS Slide 21 W. Y. Lee et. al

  22. C D A B Hidden Terminal Example #1 • Node B changes it receiving antenna mode to directional one. Slide 22 W. Y. Lee et. al

  23. C D A B Hidden Terminal Example #1 • Node A sends back to B with DCTS. DCTS Slide 23 W. Y. Lee et. al

  24. C D A B Hidden Terminal Example #1 • Node A turns its receiving antenna mode to directional one, and communication is going on. In Communication Slide 24 W. Y. Lee et. al

  25. C D A B Collision Hidden Terminal Example #1 • Now, node D has a data to send C. • But, D’s RTS accidentally reaches to node A’s receiving range due to some channel conditions. In Communication Slide 25 W. Y. Lee et. al

  26. Hidden Terminal Example #2 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 D B A July 2009 • 4 nodes • Node A has a data to B. Slide 26 W. Y. Lee et. al

  27. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 B A D Hidden Terminal Example #2 • Node A sends DRTS to B. DRTS W. Y. Lee et. al

  28. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 B A D July 2009 Hidden Terminal Example #2 • Node B responds with DCTS. DCTS Slide 28 W. Y. Lee et. al

  29. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 B A D July 2009 Hidden Terminal Example #2 • Nodes A and B are in communication. In Communication Slide 29 W. Y. Lee et. al

  30. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 A D B July 2009 Hidden Terminal Example #2 • Now, node S has a data to send D, so it sends DRTS to D. DRTS In Communication Slide 30 W. Y. Lee et. al

  31. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 A D B July 2009 Hidden Terminal Example #2 • Node D responds with DCTS. DCTS In Communication Slide 31 W. Y. Lee et. al

  32. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 A D B July 2009 Hidden Terminal Example #2 • Nodes S and D are in communication. In Communication In Communication Slide 32 W. Y. Lee et. al

  33. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 A D B July 2009 Hidden Terminal Example #2 • Further, nodes A and B complete their communication. In Communication Communication completed Slide 33 W. Y. Lee et. al

  34. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 A D B July 2009 Hidden Terminal Example #2 • Again, node A has a data to D. In Communication Now, A has a data to D Slide 34 W. Y. Lee et. al

  35. 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 A D B July 2009 Hidden Terminal Example #2 • Node A sends DRTS to D since A did not hear previous DRTS from S nor DCTS from D. In Communication DRTS Slide 35 W. Y. Lee et. al

  36. Collision 2 1 1 1 2 2 2 3 S 1 4 4 4 4 3 3 3 D A B July 2009 Hidden Terminal Example #2 • Collision due to unheard RTS/CTS. In Communication DRTS Slide 36 W. Y. Lee et. al

  37. Spatial Reuse • Benefit from directivity of directional antennas. • Two examples

  38. 1 1 1 1 1 1 2 2 2 2 2 2 4 4 4 4 4 4 3 3 3 3 3 3 D C A F B E Spatial Reuse W. Y. Lee et. al

  39. 1 1 1 1 2 2 2 2 4 4 4 4 3 3 3 3 S D A B Spatial Reuse W. Y. Lee et. al

  40. An Example of Topology in Simulation W. Y. Lee et. al

  41. Scenarios (Conference Room) Deafness Example#1 W. Y. Lee et. al

  42. Scenarios (Conference Room) Antenna blocked Deafness Example #2 W. Y. Lee et. al

  43. Scenarios (Conference Room) Hidden Terminal Problem Example#1 W. Y. Lee et. al

  44. Scenarios (Conference Room) Communication Completed Hidden terminal example #2 W. Y. Lee et. al

  45. Scenarios (Conference Room) Spatial reuse W. Y. Lee et. al

  46. Scenarios (Conference Room) W. Y. Lee et. al

  47. References July 2009 [1] R. R. Choudhury, X. Yang, R. Ramanathan and NH Vaidya, “On designing MAC protocols for wireless networks using directional antennas,” IEEE Trans. Mobile Computing, Volume 5, Issue 5, May 2006, pp.477 – 491 [2] R.R. Choudhury, X. Yang, N.H. Vaidya, and R. Ramanathan, “Using Directional Antennas for Medium Access Control in Ad Hoc Networks,” Proc. ACM MobiCom, June 2002 [3] M. Takata, M. Bandai and T. Watanabe, "MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks," Proc. IEEE GLOBECOM, pp.620-625, 2007 [4] G. Jakllari, J. Broustis, T. Korakis,S V. Krishnamurthy, and L. Tassiulas, "Handling Asymmetry in Gain in Directional Antenna Equipped Ad Hoc Networks," Proc. IEEE 16th International Symposium on PIMRC, pp.1284-1288 [5] T. Korakis, G. Jakllari, and L. Tassiulas, "A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks," Proc. ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc), pp.98–107, June 2003. Slide 47 W. Y. Lee et. al

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