目前來說，無線 ad hoc網路都是使用全方向性的天線，全方向性天線本身有許多實質上的限制，而使用方向性天線提供了許多的優勢，可以降低co-channel的干擾問題，提升空間的利用率，增加整體的throughput，節省傳送所需的Power，所以許多運用方向性天線在ad hoc網路的研究逐漸地被提出，然而這些已經提出的通訊協定，絕大部分都是針對IEEE 802.11通訊協定來做改進，在改進整體效能上仍然有限，因這些通訊協定並沒有設計出讓ad hoc上節點有同時傳送或是接收多個方向的能力。
在這篇論文中我們提出一個新的MAC通訊協定，我們採用了Adaptive Beam-forming System來降低干擾的問題，Adaptive Beam-forming System 可以讓Signal-to-interference-plus-noise-ratio (SINR)降到最低，而本篇論文所提出的MAC通訊協定將使ad hoc網路中的節點擁有同時傳送與同時接收的能力，我們提出MAC通訊協定的Handshake機制是採用如MACA/BI這樣以接收者為起始的Handshake機制，我們把機制中的代表Ready-to-Receive(RTR)詢問(Poll)的control packet改成一個代表Ready-to-Receive-and-Transmit(RTRT)兩用的control packet，來讓傳送者和接收者之間能夠同步，在模擬分析後，可以發現我們所提出的新MAC通訊協定能夠大幅的減緩Ad hoc中出現因Bottleneck節點降低整體網路效能的問題。

Typically, MAC protocols for mobile ad hoc networks assume omnidirectional antennas, and use of directional antennas offers many advantages, such as range extension, reduced co-channel interference, increased the degree of spatial reuse, improved the throughput of networks, and reduced the transmission power. There are many wireless ad hoc MAC protocol have been proposed. However, these protocols do not provide significant improvement of network performance because they can’t let nodes to support multiple simultaneous transmissions or receptions ability.
In this paper, we proposed a newly designed MAC protocols, we used adaptive beam-forming system to reduce the co-channel interference problem, and our proposed MAC protocol will enable nodes with multiple simultaneous transmissions and receptions ability. The handshake mechanism of proposed MAC protocol is that used receiver initialize handshake mechanism such as MACA/BI. We changed the Ready-to-Receive (RTR) control packet, which was used to poll neighbor nodes to be a dual-used control packet, Ready-to-Receive-Transmission (RTRT). Our simulation results will show that our proposed MAC protocol do exploit the advantage of space division multiple access that significantly reduced the problem of poor networks throughput which caused by bottleneck nodes in wireless ad hoc networks.

I. 導論 1
1.1研究動機 1
1.2研究想法 4
1.3 論文架構 5
II. 方向性天線與SDMA 6
2.1 天線系統 6
2.1.1 Sector Antennas 6
2.1.2 Diversity Antennas System 7
2.1.3 Antennas Array System 7
A. Switched Beam Antenna Systems: 9
B. Adaptive Beam-forming Antenna Systems: 10
2.2 ADAPTIVE BEAM-FORMING 原理 11
2.3 SPATIAL DIVISION MULTIPLE ACCESS (SDMA) 15
III. 相關的MAC PROTOCOL研究與分析設計 16
3.1 THE MAC LAYER PROTOCOL 16
3.2 全方向性的MAC 16
3.2.1 CSMA 16
3.2.2 CSMA/CA 17
3.2.3 MACA 18
3.2.4 DBTMA 18
3.2.5 MACA/BI 19
3.2.6 PDMA 20
3.3 WIRELESS CHARACTERISTICS 21
3.4 DIRECTIONAL ANTENNA (ANTENNA ARRAY) MAC 22
3.4.1 DBTMA/DA 22
3.4.2 Power Consumption 23
3.4.3 Throughput Enhancement 24
3.4.4 Smart Antenna on Ad hoc 24
3.4.5 ABF-CSMA/CA 24
3.4.6 Directional RTS/CTS 25
3.4.7 Novel MAC for Ad hoc with SDMA support 26
3.5 如何設計一個新的MAC支援SDMA 29
IV. THE PROPOSED SCHEME 31
4.1 PROPOSED MAC PROTOCOL 31
4.2 PROPOSED HANDSHAKE MECHANISM 31
4.3 PROPOSED PROTOCOL FINITE STATE MACHINE 36
4.4 NULL ANGLE TABLE 39
4.5 CONTROL PACKET FORMAT 39
V. 模擬分析 41
5.1 SIMULATION MODEL 41
5.2 SIMULATION RESULT 42
5.2.1 Data forward by bottleneck node 42
5.2.2 Complete Session Number 46
VI. 結論 48

[1]M. Cooper and M. Goldburg, “Intelligent Antennas: Spatial Division Multiple Access,” Annual Review of Communication, pp. 999–1002, 1996.
[2]A. N. Barreto, M. Mecking, and G. Fettweis, “A Flexible Air interface for Integrated Broadband Mobile Systems,” Proceedings of IEEE Vehicular Tech. Conference 2000, pp. 1899–1903, May 2000.
[3]J. Razavilar, F. Rashid-Farrokhi, and K.J.R. Liu, “Software radio architecture with smart antennas: a tutorial on algorithms and complexity,” IEEE Journal on Selected Areas in Communications, pages 662--76, Apr. 1999.
[4]T.Gebauer and H.Gockler, “Channel-individual adaptive beamforming for Mobile satellite communications,” IEEE J.Select. Areas Commun., pp. 439-448, Feb. 1995.
[5]J. Li, C. Blake, et al., “Capacity of Ad Hoc Wireless Networks,” Proceedings of ACM/IEEE International Conference on Mobile Computing and Networking, pp. 61–69, 2001.
[6]Y.-B. Ko, V. Shankarkumar, and N. H. Vaidya., “Medium Access Control Protocols Using Directional Antennas in Ad Hoc Networks.” Proceedings of IEEE INFOCOM’2000, March 2000.
[7]GPS Primer, downloadable from the world-wide-web. Site at http://www.aero.org/publications/GPSPRIMER.
[8]P. Karn, “MACA - a new channel access method for packet radio,” AARUCRRL Amateur Radio 9th Computer Networking Conference, pages 13440, 1990.
[9]A. F. Naguib, A. Paulraj, et al., “Capacity Improvement with Base-Station Antenna Arrays in Cellular CDMA,” IEEE Transactions on Vehicular Tech, vol. 43, pp. 691–698, 1994.
[10]J. H. Winters, “Smart Antennas for Wireless Systems,” IEEE Personal Communications, vol. 1, pp. 23–27, 1998.
[11]Dhananjay Lal, Rahul Gupta, Dharma P. Agrawal, “Throughput Enhancement in Wireless Ad Hoc Networks with Spatial Channels- A MAC Layer Perspective”, Proceedings of the Seventh IEEE Symposium on Computers and Communications, Taormina, Italy, July 2002.
[12]“A Busy-Tone Based Directional MAC Protocol for Ad hoc Networks,” IEEE MILCOM, Anaheim, California, October 2002.
[13]Asis Nasipuri, Kai Li, and Uma Reddy Sappidi, “Power Consumption and Throughput in Mobile Ad Hoc Networks using Directional Antennas”, Proceedings of the IEEE International Conference on Computer Communication and Networks (ICCCN2002), October 2002.
[14]Lal, D. Toshniwal, R. Radhakrishnan, R. Agrawal, and D.P. Caffery, “A novel MAC layer protocol for space division multiple access in wireless ad hoc networks,” J. Computer Communications and Networks, pp. 614 –619. 2002.
[15]F. Talucci and M. Gerla, “MACA-BI (MACA By Invitation) A Wireless MAC Protocol for High Speed ad hoc Networking,” IEEE ICUPC, 1997.
[16]A. Spyropoulos and C.S. Raghavendra, “Capacity Bound for Ad-Hoc Network Using Directional Antennas,” IEEE International Conference on Communications , Volume: 1 , 2003.
[17]A. Tzamaloukas and J.J. Garcia-Luna-Aceves, “Poll-Before-DATA Multiple Access,” Communications, 1999. ICC '99. 1999 IEEE International Conference on, Volume: 2 , 6-10 June 1999, pp. 1207 -1211 vol.2
[18]Jiandong Li and Min Sheng, ”MAC protocol for mobile ad hoc networks with smart antenna Jun Yang,” Electronics Letters , Volume: 39 Issue: 6 , pps: 555 –557, 20 March 2003.
[20]Yu Wang and J.J. Garcia-Luna-Aceves, “Spatial reuse and collision avoidance in ad hoc networks with directional antennas” GLOBECOM '02. IEEE , Volume: 1, pp. 112 –116, Nov. 2002.
[21]P. Gupta and P.R. Kumar, “The capacity of wireless networks,” IEEE Transactions on Information Theory, Volume: 46 Issue: 2, pp. 388 –404, March 2000.
[22]J. Zander, ”Slotted ALOHA multihop packet radio networks with directional antennas,” Electronics Letters, vol. 26, 1990.
[23]R. Radhakrishnan, Lai Dhananjay, J.Jr. Caffery, and D.P. Agrawal, “Performance Comparison of Smart Antenna Techniques for Spatial Multiplexing in Wireless Ad Hoc Networks,” The 5th International Symposium on Wireless Personal Multimedia Communications, 2002, Volume: 1, pp. 168 -171, Oct. 2002.
[24]Wireless LAN medium access control (MAC) and physical layer (PHY) specifications, IEEE standard 802.11
[25]J. Deng and Z.J. Haas, “Dual busy tone multiple access (DBTMA): a new medium access control for packet radio networks,” ICUPC '98, pp. 973 -977 vol.2, 1998
[26]R. A. Meyer and R. Bagrodia, PARSEC Simulation Language User Manual. UCLA Parallel Computing Laboratory. http://pcl.cs.ucla.edu/