Smart antennas can help overcome problems in ad-hoc networks by increasing efficiency. Using a two-lobe antenna pattern addresses hidden terminal problems from nodes not receiving RTS/CTS frames by keeping them silent. It also uses an additional antenna lobe to cover potential interference in opposite directions. For asymmetry in gain issues, increasing antenna gain ensures nodes in forbidden zones can receive RTS/CTS frames. The paper concludes smart antennas can enhance ad-hoc network performance by providing a greater combined gain than individual techniques.

1. SMART ANTENNAS IN AD-HOC
NETWORKS

2. Abstract
 Build up channel limit.
 Critical effect on the effective utilization of the range.
 The minimization of the expense of building new remote
systems.
 enhancement of administration quality.

3. Table of Contents
 Problem Statement.
 Proposed Solution.
 Performance Analysis.
 Conclusion.
 References.

4. Problem Statement
 Quality of service may not be consistent for
every user.
 Hidden terminal problems occurs due to
unheard RTS/CTS or due to asymmetry in
gain.

5. Proposed Solution
 Adding smart antennas to ad-hoc networks
increases the efficiency the networks.
 Two lobe antenna pattern can be used to
overcome hidden terminal problem due to
unheard RTS/CTS.

6. Two Lobe Antenna Pattern
(for unheard RTS/CTS frames)
 To avoid hidden terminal problems nodes in
forbidden zone are kept silent if they don’t
receive RTS/CTS frames.
 A two-lobe antenna pattern for the
transmission of DATA frames.
 Additional lobe covers all
potential interferences in
opposite directions.
Figure : Two-lobe antenna
pattern

7. Increasing antenna gain
(asymmetry in gain)
 If hidden terminal is due to asymmetry in gain
then increasing the gain of antenna to extent
that nodes in forbidden zone can receive
RTS/CTS frames solves the problem.

8. Performance Analysis
Degradation of theoretical throughput

9. Conclusion
 Use of smart antenna in ad-hoc networks
enhances their performance, providing a gain
greater than the sum of gains of each
technique.

10. References
 [1] Jack H. Winters, “Smart antenna technologies and their application to
wireless ad-hoc networks.”
 [2] Wen-Tsuen Chen, “An MAC Protocol for Wireless Ad-hoc Networks
Using Smart Antennas.”
 [3] R.S. Kawitkar, “Design of Smart Antenna Testbed Prototype.”
 [4] Angeliki Alexiou, Bell Laboratories, Lucent Technologies Martin Haardt,
Ilmenau University of Technology, “Smart Antenna Technologies for Future
Wireless Systems: Trends and Challenges.”
 [5] M. Takai, J. Martin, A. Ren and R. Bagrodia, “Directional Virtual Carrier
Sensing for Directional Antennas in Mobile Ad Hoc Networks,” ACM
MobiHoc, June 2002.
 [6] T. Korakis, G. Jakllari and L. Tassiulas, “A MAC Protocol for Full
Exploitation of Directional Antennas in Ad-hoc Wireless Networks,” ACM
MobiHoc, June 2003.
 [7] S. Roy, D. Saha, S. Bandyopadhyay, T. Ueda and S. Tanaka, “A
Network-Aware MAC and Routing Protocol for Effective Load Balancing in
Ad Hoc Wireless Networks with Directional Antenna,” ACM MobiHoc, June
2003.
 [8] A. Acharya, A. Misra and S. Bansal, “High-Performance Architectures