Neighbor discovery is a crucial first step in configuring and managing a wireless network. Most existing studies on neighbor discovery are based on broadcast algorithms, where nodes send 1-way messages without getting response from their neighbors. However, when directional antennas are used, the ability to coordinate with a neighbor is crucial for later communication between nodes, which requires handshake-based (at least 2-way) protocols. In this paper, we provide a detailed analysis of neighbor discovery protocols with 2-way communication when using directional antennas.
Based on this analysis, we present the design of a randomized 2-way neighbor discovery algorithm that uses a selective feedback. Our result shows that a node needs Θ(n2/k) time to discover its n neighbors with k antenna sectors, which yields a significant performance improvement over pure randomized algorithms. We also extend our schemes to practical cases, where the number of neighbors is unknown, and show a factor of no more than 4/3 slowdown in performance.