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ABSTRACT

The capacity of ad hoc wireless networks is constrained by the interference between concurrent transmissions from neighboring nodes. Gupta and Kumar have shown that the capacity of an ad hoc network does not scale well with the increasing number of nodes in the system when using omnidirectional antennas [6]. We investigate the capacity of ad hoc wireless networks using directional antennas. In this work, we consider arbitrary networks and random networks where nodes are assumed to be static.In arbitrary networks, due to the reduction of the interference area, the capacity gain is proven to be √2π/α when using directional transmission and omni reception. Because of the reduced probability of two neighbors pointing to each other, the capacity gain is √2π/β when omni transmission and directional reception are used. Although these two expressions look similar, the proof technique is different. By taking advantage of the above two approaches, the capacity gain is 2π/√αβ when both transmission and reception are directional.For random networks, interfering neighbors are reduced due to the decrease of interference area when directional antennas are used for transmission and/or reception. The throughput improvement factor is 2π/α, 2π/β and 4π²/αβ for directional transmission/omni reception, omni transmission/direc-tional reception, and directional transmission/directional reception, respectively.We have also analyzed hybrid beamform patterns that are a mix of omnidirectional/directional and a better model of real directional antennas.

REFERENCES

• 1: Lichun Bao , J.J. Garcia-Luna-Aceves, Transmission scheduling in ad hoc networks with directional antennas, Proceedings of the 8th annual international conference on Mobile computing and networking, September 23-28, 2002, Atlanta, Georgia, USA [doi>10.1145/570645.570652]
• 2: J. J. Carr. Directional or Omnidirectional Antenna? Http://www.dxing.com/tnotes/tnote01.pdf.
• 3: Romit Roy Choudhury , Xue Yang , Nitin H. Vaidya , Ram Ramanathan, Using directional antennas for medium access control in ad hoc networks, Proceedings of the 8th annual international conference on Mobile computing and networking, September 23-28, 2002, Atlanta, Georgia, USA [doi>10.1145/570645.570653]
• 4: M. Gastpar and M. Vetterli. On the capacity of wireless networks: The relay case. In IEEE INFOCOM'02, June 2002.
• 5: M. Grossglauser and D. Tse. Mobility increases the capacity of ad hoc wireless networks. In IEEE INFOCOM'01, April 2001.
• 6: P. Gupta and P. R. Kumar. The capacity of wireless networks. IEEE Transactions on Information Theory, IT-46(2):388--404, March 2000.
• 7: Y. Ko, V. Shankarkumar, and N. H. Vaidya. Medium access control protocols using directional antennas in ad hoc networks. In IEEE INFOCOM'2000, March 2000.
• 8: J. D. Kraus and R. J. Marhefka. Antennas: for All Applications, 3rd Ed. McGraw-Hill, New York, 2002.
• 9: Jinyang Li , Charles Blake , Douglas S.J. De Couto , Hu Imm Lee , Robert Morris, Capacity of Ad Hoc wireless networks, Proceedings of the 7th annual international conference on Mobile computing and networking, p.61-69, July 2001, Rome, Italy [doi>10.1145/381677.381684]
• 10: B. Liu, Z. Liu, and D. Towsley. On the capacity of hybrid wireless networks. In IEEE INFOCOM'03, March 2003.
• 11: A. Nasipuri, S. Ye, and R. E. Hiromoto. A mac protocol for mobile ad hoc networks using directional antennas. In Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC 2000), September 2000.
• 12: Ram Ramanathan, On the performance of ad hoc networks with beamforming antennas, Proceedings of the 2nd ACM international symposium on Mobile ad hoc networking & computing, October 04-05, 2001, Long Beach, CA, USA [doi>10.1145/501426.501430]
• 13: Theodore S. Rappaport, Wireless Communications: Principles and Practice, IEEE Press, Piscataway, NJ, 1996

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS

General Terms:
Theory

Keywords:
ad hoc networks, capacity, directional antenna