Neighbor discovery in wireless networks with sectored antennas q R. Murawski a,⇑ , E. Felemban b,1 , E. Ekici a , S. Park c , S. Yoo c , K. Lee c , J. Park c , Z. Hameed Mir c a Department of Electrical and Computer Engineering, The Ohio State University, Columbus, OH 43210, USA b Department of Computer Engineering, Umm Al Qura University (UQU), Makkah, Saudi Arabia c Electronics and Telecommunication Research Institute (ETRI), Daejeon, South Korea article info Article history: Received 8 October 2010 Received in revised form 17 March 2011 Accepted 3 April 2011 Available online 13 April 2011 Keywords: Wireless ad hoc networks Sectored antennas Directional antennas Neighbor discovery abstract Directional antennas offer many potential advantages for wireless networks such as increased network capacity, extended transmission range and reduced energy consump- tion. Exploiting these advantages requires new protocols and mechanisms at various com- munication layers to intelligently control the directional antenna system. With directional antennas, many trivial mechanisms, such as neighbor discovery, become challenging since communicating parties must agree on where and when to point their directional beams to communicate. In this paper, we propose a fully directional neighbor discovery protocol called Sectored- Antenna Neighbor Discovery (SAND) protocol. SAND is designed for sectored-antennas, a low-cost and simple realization of directional antennas, that utilize multiple limited beam- width antennas. Unlike many proposed directional neighbor discovery protocols, SAND depends neither on omnidirectional antennas nor on time synchronization. SAND performs neighbor discovery in a serialized fashion allowing individual nodes to discover all poten- tial neighbors within a predetermined time. SAND guarantees the discovery of the best sec- tor combination at both ends of a link, resulting in more robust and higher quality links between nodes. Finally, SAND reliably gathers the neighborhood information in a central- ized location, if needed, to be used by centralized networking protocols. The effectiveness of SAND has been assessed via simulation studies and real hardware implementation. Ó 2011 Elsevier B.V. All rights reserved. 1. Introduction Performance improvement through directional anten- nas in wireless networks has been discussed extensively in the literature [1–4]. Directional antennas, as opposed to omnidirectional antennas, concentrate the transmission power towards a certain direction with limited beamwidth around this direction. As a result, directional antennas lend many promising features to wireless networks. First, inter- ference between neighboring nodes is greatly reduced which increases the simultaneous transmissions in the neighborhood and network capacity [5]. Second, signal to interference and noise ratio (SINR) is increased due to high- er directional gain allowing transmissions a higher data rates. Finally, for a given transmission power, the commu- nication range is greatly extended. Alternatively, lower transmission power is needed to cover the same transmis- sion range covered by an omnidirectional antenna. One of the simplest realizations of directional antennas is sectored antennas where a fixed number of fixed beamwidth antenna elements are mounted to cover the whole azimuth. One major advantage of sectored antennas compared to other types of directional antennas is its low- cost and implementation simplicity. Switching sectors is done by simply selecting an antenna element as shown in Fig. 1. 1570-8705/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.adhoc.2011.04.001 q A preliminary version of this paper has appeared in the proceedings of IEEE SECON 2010. ⇑ Corresponding author. Tel.: +1 321 947 5188. E-mail addresses: murawskr@ece.osu.edu (R. Murawski), eafelemban@ uqu.edu.sa (E. Felemban), ekici@ece.osu.edu (E. Ekici), sangjoon@etri.re.kr (S. Park), yoos@etri.re.kr (S. Yoo). 1 This work has been done while Emad Felemban was at The Ohio State University. Ad Hoc Networks 10 (2012) 1–18 Contents lists available at ScienceDirect Ad Hoc Networks journal homepage: www.elsevier.com/locate/adhoc