doc IEEE 802 11 -09 0796 r 0

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Contention-based Directional MAC Protocols: A Survey Date: 2009 -07 -14 Authors: Submission Slide 1 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Taxonomy of Contention-based Directional MAC Protocols • CSMA/CA based protocols • Data/ACKs are transmitted directionally Submission Slide 2 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Non-Circular Directional MAC Protocols Submission Slide 3 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Omni-directional RTS/ Omni-directional CTS Submission Slide 4 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for mobile ad-hoc networks using directional antennas A. Nasipuri, S. Ye, J. You, R. E. Hiromoto, "A MAC protocol for mobile ad-hoc networks using directional antennas", In Proceedings of IEEE Wireless Communications and Networking Conference(WCNC), Chicago, IL, 2000 • Mulitple Non-circular Directional antennas Assumed • RTS is transmitted omnidirectionally via all antennas (ORTS) Submission Slide 5 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for mobile ad-hoc networks using directional antennas A. Nasipuri, S. Ye, J. You, R. E. Hiromoto, "A MAC protocol for mobile ad-hoc networks using directional antennas", In Proceedings of IEEE Wireless Communications and Networking Conference(WCNC), Chicago, IL, 2000 • If not intended receiver for the RTS, it blocks its antenna(s). • Nodes overhearing RTS blocks its antennas => bad spatial reuse Submission Slide 6 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for mobile ad-hoc networks using directional antennas A. Nasipuri, S. Ye, J. You, R. E. Hiromoto, "A MAC protocol for mobile ad-hoc networks using directional antennas", In Proceedings of IEEE Wireless Communications and Networking Conference(WCNC), Chicago, IL, 2000 • If intended receiver for the RTS, it transmits CTS omnidirectionally via all antennas (OCTS) • If not intended receiver for the CTS, it blocks its antenna(s). • Nodes overhearing CTS blocks its antennas => bad spatial reuse Submission Slide 7 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for mobile ad-hoc networks using directional antennas A. Nasipuri, S. Ye, J. You, R. E. Hiromoto, "A MAC protocol for mobile ad-hoc networks using directional antennas", In Proceedings of IEEE Wireless Communications and Networking Conference(WCNC), Chicago, IL, 2000 • The originators of RTS and CTS block all antennas except the one that is used for DATA/ACK. Submission Slide 8 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for mobile ad-hoc networks using directional antennas • Event-driven simulator (M=# of antennas) Submission Slide 9 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for mobile ad-hoc networks using directional antennas Tx/Rx RTS (Tx) Omni (via M antennas) RTS (Rx) Omni CTS (Tx) Omni (via M antennas) CTS (Rx) Omni Info in RTS/CTS frame Source Address/Destination Address Additional Control Frame None Additional Info stored in a device None Deafness problem Intermediate since ORTS/OCTS can inform neighboring nodes projected communication Hidden node problem Bad since directional DATA can interfere other ongoing communications (Asymmetry in gain) Spatial Reuse Feature Since nodes overhearing RTS or CTS blocks their antennas, the spatial reuse is bad. Submission Slide 10 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Directional RTS/ Omni-directional CTS Submission Slide 11 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Medium access control protocols using directional antennas in ad hoc networks YB Ko, V Shankarkumar, and NH Vaidya, “Medium access control protocols using directional antennas in ad hoc networks, ” INFOCOM 2000, Tel Aviv, Israel, 2000, pp. 13 – 21. • DMAC: Directional MAC (the first “DMAC, ” but its name has been shared by several descendants. ) • Assumptions – Location information is determined by GPS (not in practice). – A node shares the location information with its neighbors. N 38 º W 27º N 39 º W 28º Submission Slide 12 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Medium access control protocols using directional antennas in ad hoc networks YB Ko, V Shankarkumar, and NH Vaidya, “Medium access control protocols using directional antennas in ad hoc networks, ” INFOCOM 2000, Tel Aviv, Israel, 2000, pp. 13 – 21. • Since a source knows the destination’s location, it transmits RTS to the destination directionally (DRTS). – If nodes overhear the DRTS, they block their antenna. – Nodes in other direction of the DRTS can exploit spatial reuse. ⅹ Source DRTS Destination ⅹ Submission Slide 13 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Medium access control protocols using directional antennas in ad hoc networks YB Ko, V Shankarkumar, and NH Vaidya, “Medium access control protocols using directional antennas in ad hoc networks, ” INFOCOM 2000, Tel Aviv, Israel, 2000, pp. 13 – 21. • If the intended receiver receives the DRTS successfully, it responds with CTS omni-directionally (OCTS). • Nodes overhearing OCTS block their antennas. ⅹ Source OCTS Destination OCTS ⅹ Submission OCTS Slide 14 ⅹ OCTS W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Medium access control protocols using directional antennas in ad hoc networks • Spatial Reuse Improvement by using DRTS • A B C E D • DRTS (B, C) OCTS (C, B) DATA ACK Submission DRTS(D, E) OCTS (E, D) • Node D cannot transmit anything toward node C due to OCTS(C, B). Since Node D’s RTS is directional to E, node D can initiate DRTS to node E. Spatial reuse is improved by DRTS. DATA ACK Slide 15 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Medium access control protocols using directional antennas in ad hoc networks F A B • Problems DRTS (B) – Since B transmits DRTS directionally to C, node A does not aware of it. (deafness) – This creates significant collisions from A. Submission D C DRTS (A) OCTS(B, C) DATA DRTS (A) Slide 16 ACK W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Simulation (1/3) • • • NS-2 based simulation Mesh topology No mobility Bulk TCP traffic based on several scenarios 2 Mbps links Two adjacent rows and two adjacent columns being separated by 200 meters Traffic model: FTP with infinite backlog at each source node TCP packet size: 1460 bytes Maximum advertised window is 8 packets Submission Slide 17 5 10 15 20 25 4 9 14 19 24 3 8 13 18 23 2 7 12 17 22 1 6 11 16 21 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Simulation (2/3) • Scenario 1 15 9 14 20 19 25 IEEE 802. 11 DMAC 1130. 42 771. 27 No. 2 214. 57 1040. 21 Total throughput 4 10 Connections No. 1 5 1344. 99 1811. 48 24 3 8 13 18 23 2 7 12 17 22 1 6 11 16 2 21 Submission 1 • In 802. 11, communication of connections 1 and 2 cannot occur at the same time unlike in DMAC • Fairness in 802. 11 is not good unlike in DMAC Slide 18 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Simulation (3/3) • Scenario 2 Connections 10 15 20 9 14 19 No. 3 653. 64 1250. 14 No. 4 634. 58 1251. 64 1288. 22 2501. 78 25 4 DMAC Total throughput 5 IEEE 802. 11 24 3 8 2 1 Submission 13 7 3 12 6 11 18 23 17 4 22 16 • Better throughput at the DMAC since it exploits spatial reuse. 21 Slide 19 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Medium access control protocols using directional antennas in ad hoc networks Tx/Rx DMAC RTS (Tx) Directional RTS (Rx) Omni CTS (Tx) Omni CTS (Rx) Omni Info in RTS/CTS frame Source Address/Destination Address Additional Control Frame for sharing location of neighboring nodes Additional Info stored in a device Device’s location information by GPS Deafness problem Directional RTS can cause the Deafness problem behind the RTS originator. Hidden node problem Directional RTS can cause the Hidden node problem behind the RTS originator. Spatial Reuse Feature Intermediate since originator of RTS has its direction of communication Submission Slide 20 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Directional RTS/ Directional CTS Submission Slide 21 W. Y. Lee et. al

July 2009 doc. : IEEE 802. 11 -09/0796 r 0 MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks 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 • DMAC/DA protocol – Each device maintains a neighbor table by communication history. – Device’s neighbor table maps each neighboring node’s ID with that device’s beam number. – Deafness duration: the time of Deafness (initiated by WTS), e. g. , C notifies that C will be busy for Tc. – Link Activity: Latest transmission time from backlogged nodes (e. g. , D and E). => WTS is necessary Submission Slide 22 E (5) (6) C (4) A (1) B (3) (2) D W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks 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 – (1) DRTS – (2) DCTS – WTS is transmitted circularly to avoid deafness and hidden node problem • (3) WTS (Wait-to-Send) A->E and B->G • (4) WTS A->D – (5) DATA – (6) ACK Submission Slide 23 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks – WTS (Wait To Send) message Submission Slide 24 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks • Simulation – – Event Driven Node: 100 (randomly distributed) 1500 x 1500 m Transmission range • Omni: 250 m • Directional: 500 m – Data rate: 11 Mbps Submission Slide 25 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks • Simulation Result Submission NPN: Next Packet Notification (to increase throughput) PCS: Physical Carrier Sensing MDA: MAC protocol for Directional Antenna [12] Slide 26 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks Tx/Rx DMCA/DA with NPN RTS (Tx) Directional RTS (Rx) Omni CTS (Tx) Directional CTS (Rx) Omni Info in RTS/CTS frame Source Address/Destination Address , # of WTSs (which will synchronizes the transmission time of DATA) Additional Control Frame WTS Additional Info stored in a device Neighbor Table (Beam index, Deafness duration, and Link Activity) Deafness problem Intermediate since WTS can effectively avoid deafness problem (But not enough since WTS is selectively transmitted to subset of beams) Hidden node problem Intermediate since WTS can effectively avoid hidden node problem (But not enough since WTS is selectively transmitted to subset of beams) Spatial Reuse Feature Good since neighbor table is maintained Submission Slide 27 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Circular Directional MAC Protocols Submission Slide 28 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Circular Directional RTS/ Directional CTS Submission Slide 29 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks 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 (Mobi. Hoc), pp. 98– 107, June 2003. • CRTS protocol maintains location table – Through Circular RTS, each node records location table. Rx beam 4 Circular RTS (B B with Tx beam 2) Submission Tx beam 2 A Me My beam Neighbor’s beam A Slide 30 Neighbor B 4 2 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks 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 (Mobi. Hoc), pp. 98– 107, June 2003. • CRTS protocol – Source node transmits RTS circularly. – Destination node transmits CTS directionally toward RTS originator. – Nodes behind the destination does not aware of it. – Node receiving either RTS or CTS blocks its corresponding antenna. Circular DRTS DCTS Submission Slide 31 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks 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 (Mobi. Hoc), pp. 98– 107, June 2003. • Problem of CRTS protocol – Since DCTS does not inform nodes behind the destination node, collision may occur (hidden node problem) Circular DRTS Collision DCTS Submission Slide 32 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks • Simulation – – – Event driven simulation Physical channel is error free Propagation delay is zero Packet length is constant and equal to 1024 bytes The packet arrival at each station is a Poisson process with the same mean – Each simulation runs for 200 seconds with a warm up period of 50 seconds. Submission Slide 33 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks • Simulation – Scenario 1 33. 34 40. 21 15. 57 39. 89 Total throughput Submission CRTS Node C (2) Now, C is trying to send RTS to B DMAC (DRTS/OCTS) Node A (1) A and B are communicating Throughput (%) In high load 48. 91 80. 1 • DMAC: Since either DRTS from A or OCTS from B does not reach to C, C can continuously transmit RTS to B (Hidden node problem) • CRTS: Since A’s CRTS inform C of communication with B, C suppress its RTS. Slide 34 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 A MAC protocol for full exploitation of directional antennas in ad-hoc wireless networks Tx/Rx CRTS (Tx) Circular (one round and waits until CTS) RTS (Rx) Omni CTS (Tx) Directional to the RTS beam CTS (Rx) Omni Info in RTS/CTS frame Source Address/Destination Address , Source Beam Index/ Destination Beam Index Additional Control Frame None Additional Info stored in a device Location Table Deafness problem Bad since CTS is transmitted directionally Hidden node problem Bad since CTS is transmitted directionally Spatial Reuse Feature Good since location table is maintained Submission Slide 35 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Circular Directional RTS/ Circular Directional CTS Submission Slide 36 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Handling Asymmetry in Gain in Directional Antenna Equipped Ad Hoc Networks 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 16 th International Symposium on PIMRC, pp. 1284 -1288, 2005 • CRCM (Circular RTS and CTS MAC) protocol – Source transmits RTS circularly – Destination sends CTS circularly – Circular CTS is partially transmitted to non-overlapping region of CRTS to reduce overhead. – Node receiving either RTS or CTS blocks its corresponding antenna. – Circular RTS/CTS reduces Deafness and hidden node problems. Submission Slide 37 Circular RTS Circular CTS Location of RTS originator is determined by location table W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Handling Asymmetry in Gain in Directional Antenna Equipped Ad Hoc Networks • Location tracking and maintenance – Using location table, relative location of nodes can be figured out. – Under the following scenario, node C needs to block beams 2 and 4. 4 4 Submission Slide 38 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Handling Asymmetry in Gain in Directional Antenna Equipped Ad Hoc Networks • Simulation – Opnet ver. 10. 0 – 4 nodes in the line 1 RTS 2 3 4 Scenario: Node 2 initiates communication to node 3. Now, node 4 tries to send RTS to node 3 in CRTS protocol. Throughput of CRCM is better than CRTS. Submission Slide 39 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Handling Asymmetry in Gain in Directional Antenna Equipped Ad Hoc Networks Tx/Rx CRCM RTS (Tx) Circular (one round and waits until CTS) RTS (Rx) Omni CTS (Tx) Circular CTS (Rx) Omni Info in RTS/CTS frame Source Address/Destination Address , Source Beam Index/ Destination Beam Index Additional Control Frame None Additional Info stored in a device Location Table Deafness problem Intermediate since circular RTS and circular CTS Hidden node problem Intermediate since circular RTS and circular CTS Spatial Reuse Feature Good since location table is maintained Submission Slide 40 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 Comparison of Directional MAC Protocols 　 　 Non-Circular DMAC DRTS/OCTS ORTS/OCTS Circular DMAC CRTS/DCTS CRTS/CCTS DRTS/DCTS 　 DMAC Nasipuri et al CW-MAC DMAC Tone. DMAC MMAC DMAC/DA UDAAN CRTS DMAC-PDX CRCM 　 [Infocom 00] [WCNC 00] [COMSWARE 07] [Infocom 00] [Tech report] [Mobicom 02, [Globecom 07] [JSAC 05] [Mobihoc 03, [Globecom 07] [PIMRC 05] 　 (Scheme 1) 　 , TMC 06] 　 　 TMC 08] 　 　 (Scheme 2) 　 　 　 RTS Tx/ RTS Rx 　 　 CTS Tx/ Omni/ Omni 　 　 Omni/ CTS Rx Omni 　 　 DATA Tx/ DATA Rx 　 　 ACK Tx/ ACK Rx 　 　 　 Directional/ Directional 　 　 None Additional Control Frame 　 Deafness 　 　 Hidden Node 　 　 Spatial Reuse 　 　 Omni/ Directional/ Directional/ Circular/ Omni　 　Omni Omni 　 　 　 　 Directional/ Omni/ Directional/ Directional/ Circular/ Omni, 　Directional Omni Omni Directional 　 　 　 　 　 　 　 　 Directional/ Directional/ Directional/ Directional/ Directional/ Directional Directional Directional Directional Directional 　 　 　 　 　 Tone WTS None Multihop RTS None Test frame None (out-of-band) Wait to Send 　 　 Intermediate 　 　 　 Good 　 　 　 　 Bad 　 　 　 　 Intermediate 　 　 　 　 Bad 　 　 　 Intermediate Bad Good Bad Intermediate 　 　 　 　 　 Bad Intermediate Good Intermediate Good 　 　 　 Submission Slide 41 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 References [1] A. Nasipuri, S. Ye, J. You, R. E. Hiromoto, "A MAC protocol for mobile ad-hoc networks using directional antennas", In Proceedings of IEEE Wireless Communications and Networking Conference(WCNC), Chicago, I L, 2000 [2] YB Ko, V Shankarkumar, and NH Vaidya, “Medium access control protocols using directional antennas in ad hoc networks, ” INFOCOM 2000, Tel Aviv, Israel, 2000, pp. 13 – 21. [3] R. R. Choudhury and NH Vaidya, “Deafness: a mac problem in ad hoc networks when using directional antennas, ” ICNP 2004, pp. 283 – 292. [4] 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 [5] R. R. Choudhury, X. Yang, N. H. Vaidya, and R. Ramanathan, “Using Directional Antennas for Medium Access Control in Ad Hoc Networks, ” Proc. ACM Mobi. Com, June 2002 [6] M. Takata, M. Bandai and T. Watanabe, "MAC Protocol with Directional Antennas for Deafness Avoidance in Ad Hoc Networks, " Proc. IEEE GLOBECOM, pp. 620625, 2007 [7] R. Ramanathan, "Ad Hoc Networking With Directional Antennas: A Complete System Solution, " IEEE JSAC 2005, vol. 23, no. 3 , pp. 496 -506, Mar 2005 [8] 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 16 th International Symposium on PIMRC, pp. 1284 -1288 Submission Slide 42 W. Y. Lee et. al

doc. : IEEE 802. 11 -09/0796 r 0 July 2009 [9] F. Yildirim and H. Liu, "Directional MAC for 60 GHz using Polarization Diversity Extension (DMAC-PDX), " Proc. IEEE GLOBECOM, pp. 4697 -4701, 2007 [10] G. Li, L. L. Yang, "On Utilizing Directional Antenna in 802. 11 Networks: Deafness Study, " Proc. IEEE COMSWARE 2007, pp. 1 -6, Jan 2007 [11] A P Subramanian and S R. Das, "Addressing Deafness and Hidden Terminal Problem in Directional Antenna based Wireless Multi-Hop Networks, " Proc. IEEE COMSWARE, pp. 1 -6, Jan. 2007 [12] H. Gossain, C. Cordeiro and D. P. Agrawal, “MDA: An Efficient Directional MAC scheme for Wireless Ad Hoc Networks, ” Proc. IEEE GLOBECOM, Nov. 2005. [13] T. Korakis, G. Jakllari, and L. Tassiulas, "A A MAC protocol for full exploitation of Directional Antennas in Ad-hoc Wireless Networks", Proc. ACM Mobi. Hoc 2003, 2003 [14] T. Korakis, G. Jakllari, and L. Tassiulas, "CDR-MAC: A Protocol for Full Exploitation of Directional Antennas in Ad Hoc Wireless Networks, " IEEE Transactions on Mobile Computing, Vol. 7, No. 2, Feb 2008. [15] M. Taksata, M. Bandai, and T. Watanabe, "A Directional MAC Protocol with Deafness Avoidance in Ad Hoc Networks, " IEICE Trans. Commun, Vol. E 90 -B, No. 4, APR 2007 [16] M. Takata, M. Bandai, and T. Watanabe, “Performance analysis of a directional MAC protocol for location information staleness in MANETs, ” IPSJ J. , vol. 46, no. 11, pp. 2623– 2632, Nov. 2005. [17] J. Wang, Y. Fang, and D. Wu, “SYN-DMAC: A directional MAC protocol for ad hoc networks with synchronization, ” Proc. IEEE Military Communications Conference (MILCOM), pp. 2258– 2263, Oct. 2005. [18] M. Takata, K. Nagashima, and T. Watanabe, “A dual access mode MAC protocol for ad hoc networks using smart antennas, ” Proc. IEEE International Conference on Communications (ICC), pp. 4182– 4186, June 2004. Submission Slide 43 W. Y. Lee et. al