Abstract-Neighbor discovery is crucial for both wireless sensor networks and mobile computing applications. The crux of the problem is to achieve energy efficiency, which has been demonstrated to be difficult by prior work. In this paper we propose Hello, a generic flexible protocol for neighbor discovery. With an unrestricted parameter, it serves as a generic framework that incorporates existing deterministic protocols. Under the framework, we expose optimal parameters for either symmetric or asymmetric duty cycles, which is the first to our knowledge. As a result, it exhibits great flexibility by adjusting itself to any configuration that best meets application demands. Besides, several techniques are applied to removing redundant discoveries without sacrificing the worst-case latency. We evaluate Hello through extensive simulation and real-world sensor experiments. The results show that Hello is highly energy-efficient under symmetric and asymmetric duty cycles. In particular, it is two times better than the state of the art in terms of the worst-case latency under asymmetric duty cycles.

Many wireless applications urgently demand an efficient neighbor discovery protocol to build up bridges connecting user themselves or to some service providers. However, due to intrinsic constraints of wireless devices, e.g., limited energy and error of clock synchronization, there is still absence of effective and efficient neighbor discovery protocols in the literature. In this work, we propose neighbor discovery protocols for the following two problems. First, we study Asynchronous Symmetry Neighbor Discovery problem, in which potential neighbor devices with asynchronous time clocks but the same duty cycle aim to find each other. Second, we propose an efficient protocol (utilizing Bouncing strategy) named BlindDatewith guaranteed worst-case performance 9 10 ð1 þ dÞ 2 x 2 where d is a small fraction of the length of a time slot unit and 1x is the duty cycle. Third, we extend this strategy to address Asynchronous Asymmetry Neighbor Discovery problem, in which both the time clock and the duty cycles of potential neighbors are considered to be heterogeneous. We conduct extensive experiments and simulations to examine the feasibility and efficiency of the proposed protocols, and results show that BlindDate greatly outperforms existing approaches in average-case. Compared with known protocols, BlindDate also achieves a better worst-case discovery latency bound (e.g., 10 percent performance gain comparing with Searchlight [1]).

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