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Angular MAC: a framework for directional antennas in wireless mesh networks

Angular MAC: a framework for directional antennas in wireless mesh networks. Erdem Ulukan and Özgür Gürbüz Faculty of Engineering and Natural Sciences, Sabanci University, Turkey ACM Journal of Wireless Networks vol. 14 no.2 (April 2008) (SCI 2008=0.741). Outline. Introduction

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Angular MAC: a framework for directional antennas in wireless mesh networks

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  1. Angular MAC: a framework for directional antennas in wireless mesh networks Erdem Ulukan and ÖzgürGürbüz Faculty of Engineering and Natural Sciences, Sabanci University, Turkey ACM Journal of Wireless Networks vol. 14 no.2 (April 2008) (SCI 2008=0.741)

  2. Outline • Introduction • Proposed Mechanism – Angular MAC • Evaluation • Analysis – Throughput Enhancement • Conclusion

  3. Introduction • Capacity of wireless mesh networks can be enhanced through the use of smart directional antennas. • High quality links • Throughput enhancement by spatial reuse • Lots of previous works suffer from • Hidden terminal problem • Deafness problem • Head-of-line blocking problem

  4. a Introduction – Antenna Model • Each node is equipped with a multi-beam antenna. • The multi-beam antenna either transmit or receive data packets at a time, but not both. 2 3 a 1 0

  5. Directional RTS Directional CTS Directional RTS Data (cd) Directional CTS Introduction – Related Work • D-CSMA • All nodes are 1-hop neighbor. 2 3 b 1 0 Data (ab) 2 3 c 1 0 2 3 a 2 3 1 0 d 1 0 Nasipuri, A., Ye, S., You, J., & Hiromoto, R. E. A MAC protocol for mobile ad hoc networks using directional antennas. IEEE WCNC, 2000.

  6. Directional RTS Data (cd) Introduction – Related Work • D-CSMA • Deafness problem 2 3 b 1 0 Deafness in node c 2 3 c 1 0 2 3 a 2 3 1 0 d 1 0 Nasipuri, A., Ye, S., You, J., & Hiromoto, R. E. “A MAC protocol for mobile ad hoc networks using directional antennas.” IEEE WCNC, 2000.

  7. Data (cd) Introduction – Related Work • Head-of-line blocking problem • Result from transmission queue (FIFO) • Optimal scheduling is ab, ac 2 3 b 1 0 2 3 c Queue(2) 1 0 Queue(1) 2 3 a 2 3 1 0 d 1 0 Kolar, V., Tilak, S., & Abu-Ghazaleh, N. B. “Avoiding head of line blocking in directional antenna.” IEEE LCN, 2004.

  8. Goal • Proposed Angular MAC (ANMAC) • Hidden terminal problem is alleviated • Deafness problem is prevented • Head-of-line blocking problem is alleviated

  9. [b,a,2,1,3] [b,a,3,1,3] [3,a,b] [b,a,1,1,3] Data (ab) [b,a,0,1,3] AN-CTS [2,a,b] AN-RTS [3,a,b] [1,a,b] [0,a,b] Proposed Mechanism • Angular MAC (ANMAC) • All nodes are single hop. 2 3 b 1 0 2 3 c 1 0 2 3 a 2 3 1 0 d 1 0

  10. Data (dc) SIFS SIFS SIFS SIFS SIFS SIFS DIFS DIFS DIFS Proposed Mechanism 2 3 • Angular MAC (ANMAC) • Tdefer=SIFS+TACK b 1 0 2 3 c 1 0 2 3 a 2 3 1 0 d 1 0 a to b ANRTS ANCTS DATA ACK Tdefer time d to c ANRTS ANCTS DATA ACK CW CW

  11. Data (cd) SIFS SIFS SIFS SIFS SIFS SIFS SIFS a to b ANRTS ANCTS DATA ACK NAN Tdefer DIFS DIFS DIFS time c to d ANRTS ANCTS DATA ACK CW CW Proposed Mechanism 2 3 • Angular MAC (ANMAC) • Network Allocation Notification (NAN) b 1 0 2 3 c 1 0 NAN 2 3 a 2 3 1 0 d 1 0

  12. Evaluation

  13. Cross-like Topology

  14. Cross-like Topology

  15. Random Topology

  16. From: IEEE Std 802.11 Figure. 51 Analysis – Throughput Enhancement (Contention Window) • According to success ratio (Nc/Ns) for tuning optimal contention window to maximize the throughput. • Nc – the number of collided packets • Ns – the number of successful packets • Define • τ– the probability that a node transmits in a randomly chosen slot • p – the probability that a transmitted packet encounters a collision • Ps – the probability of successful transmission

  17. i,wi-2 i,wi-1 Figrue. Markov Chain model for the backoff window size Analysis i as backoff stage k as backoff time counter W as CWmin Wi as 2iW, i∈(0,m), so CWmax=2mW

  18. Analysis

  19. Evaluation for Contention channel enhancements Omni 802.11b Directional ANMAC-LS Optimal CWmin is for 802.11b.

  20. Conclusion • ANMAC’s contributions are • self configuring nature with neighbor discovery • immunity to deafness • optimal selection and dynamic adaptationof contention window to maximize the network throughput

  21. Thank you~

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