Asymptotic Power Limits for Ad-Hoc Networks Reconsider the Smart Antenna Cases

Abstract — Smart antennas can be useful in significantly increasing the capacity of wireless ad hoc networks. A number of media access and routing protocols have been recently proposed for the use with such antennas, and have shown significant performance improvements over the omnidirectional case. However, none of these works explores if and how different directional and smart antenna designs affect the asymptotic capacity bounds, derived by Kumar and Gupta[12]. These bounds are inherent to specific ad-hoc network characteristics, like the shared wireless media and multi-hop connectivity, and pose major scalability limitations for such networks. In this work, we present how smart antennas can affect the asymptotic behavior of an ad-hoc network’s capacity. Specifically, we perform a capacity analysis for an ideal flat-topped antenna, a linear phased-array antenna, and an adaptive array antenna model. Finally, we explain how an ad-hoc network designer can manipulate different antenna parameters to improve the scalability of an ad-hoc network. Keywords-capacity; ad-hoc; directional antennas; smart antennas; I