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DARP: Distance-Aware Relay Placement in WiMAX Mesh Networks

DARP: Distance-Aware Relay Placement in WiMAX Mesh Networks. Weiyi Zhang * , Shi Bai * , Guoliang Xue § , Jian Tang † , Chonggang Wang ‡ * Department of Computer Science, North Dakota State University, Fargo § Department of Computer Science and Engineering, Arizona State University, Tempe

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DARP: Distance-Aware Relay Placement in WiMAX Mesh Networks

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  1. DARP: Distance-Aware Relay Placement in WiMAX Mesh Networks Weiyi Zhang*, Shi Bai*, Guoliang Xue§, Jian Tang†, Chonggang Wang‡ * Department of Computer Science, North Dakota State University, Fargo § Department of Computer Science and Engineering, Arizona State University, Tempe † Department of Electrical Engineering and Computer Science, Syracuse University, Syracuse ‡ NEC Laboratories America, Princeton, USA IEEE INFOCOM 2011

  2. Outline • Introduction • Motivation & Problem • Observation & Goals • System Model • Solution for DARP: Distance-Aware Relay station Placement • LORC-MIS // lower tier • LORC-HS // lower tier • MUST // upper tier • Simulation • Conclusion

  3. Introduction • The emerging WiMAX technology is the 4G standard for • high-speed (up to 75Mbps) • long-range communications SS SS BS SS

  4. Introduction • IEEE 802.16j enhances IEEE 802.16e by the concept of mesh networks • Base Station (BS) • Relay Station (RS) • Subscriber Station (SS) RS SS RS SS BS SS

  5. Introduction • WiMAX 802.16j Relay Station • eliminate coverage hole • Range extension Coverage Extension Internet SS RS SS Building Penetration RS BS RS RS Mobile Access Coverage Hole

  6. Motivation • n Subscriber Stations (SS) • different user data rate requests • Problem: • finding where to place a minimum number of relay nodes • to satisfy the certain performance requests BS SS SS SS SS SS

  7. Observation – distance aware • Signal to noise ratio (SNR) at receiver • SNRr=Pr/N0 • Pr : power level at the receiver • N0 : noise power is normally a constant user data rate requests: 35 Mbps SS

  8. Observation – distance aware • Two-ray ground path loss model • Pr = Pt Gt Gr Ht2 Hr2 d - • Pt : Transmission power (constant) • Gt /Gr : gains of transmitter/receiver antenna (constant) • Ht/Hr : heights of transmitter/receiver antenna (constant) • d : Euclidean distance between transmitter and receiver •  : attenuation factor (constant : 2~4) SS SS higherdata rate request lower data rate request

  9. Goals • Given a WiMAX mesh network • One BS • A set of SSs, S = {s1, s2, …, Sn} • Aset of distance requirements for the SSs, D = {d1, d2, …, dn} BS SS SS

  10. Goals • Solve the distance-aware relay placement (DARP) problem by a minimum number of RSs • Providing feasible coverage for each SS • covered by at least one RS or BS • Each placed RS has enough data rate to relay traffic for each SS or another RS BS  25 Mbps SS 25 Mbps SS RS

  11. System Model • A WiMAX mesh network • n SSs, S = {s1, s2, …, Sn} • Distance requirementsD = {d1, d2, …, dn} • No routing and traffic relay capabilities • BS, is aware of the locationand distance requirement of each SS BS SS SS

  12. Solution for DARP problem • Two-tiered relay model BS upper tier MUST RS SS LORC-MIS LORC-HS SS lower tier

  13. LORC-MIS • LORC-MIS • LOwer-tier Relay Coverage – Maximal Independent Set based approximation solution SS lower tier SS

  14. LORC-MIS • First consider the SS with the smallest distance requirement • Highest user data rate requirement C1 C2 d1 1 d2 2 C5 4 d4 3 5 d5 C4 d3 C3

  15. LORC-MIS • Construct a regular hexagon with 7 possible positions S2 d2 d

  16. LORC-MIS • Choose the point which covers most SSs S1 S2 S5 S4 S3

  17. LORC-HS • LORC-HS • LOwer-tier Relay Coverage – Hitting Set based approximation solution SS lower tier SS

  18. LORC-HS • Find the Minimum hitting set • to cover all SSs // {p0, p2} • admits PTAS [18] S0={p0, p1} S1={p0, p1 , p2 , p3 , p4 , p5 , p7} S2={p2, p3 , p4 , p5 , p6} S3={p2, p4 , p5 , p6 , p7} s3 p7 p6 p0 s0 s1 s2 p2 p4 p5 p1 p3 [18] N. Mustafa and S. Ray, PTAS for geometric hitting set problems via local search, SCG’09, pp. 17-22.

  19. MUST • Minimum Upper-tier Steiner Tree BS RS upper tier

  20. MUST • The “MUST” ensures data rate for each individual SS or RS 15 BS RS3 18 15 18 RS2 16 15 C RS1 B A

  21. MUST • Construct a complete graph • Assign edge weight w • Number of RSs BS 20 21 w=3 w=4 10 5 w=3 RS1 RS2 16 d2=5 d1=10

  22. MUST • Minimum spanning tree BS 20 w=3 w=3 RS1 RS2 16 d2=5 d1=5

  23. MUST • Place RSs on edges BS 5 5 w=3 20 5 w=3 5 RS1 4 4 4 4 RS2 d2=5 d1=5 16

  24. SimulationSetup • SSs are uniformly distributed in a square playing ground • 20002000 • 30003000 • Distance requirements randomly distributed in [100,150] • BS is deployed at the center of the field • All figures illustrate the average of 10 test runs for various scenarios

  25. Simulation

  26. Simulation– lower-tier relay coverage

  27. Simulation – upper-tier relay connectivity

  28. Simulation

  29. Simulation

  30. Conclusion • This paper studies the Distance-Aware Relay Placement (DARP) problem • Multi-hop relay placement • Relay coverage • Relay connectivity T h e E N D Thanks for your attention !

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