Assisted Slotless Neighbor Discovery Based on Additional Scan Windows

Neighbor discovery is a prerequisite to establish self-organizing IoT networks. IoT devices are mostly energy-limited, so neighbor discovery is usually implemented in a duty-cycled manner. A fundamental problem of optimizing energy efficiency of duty-cycled neighbor discovery is to minimize neighbor discovery latency for given duty cycle. We investigate purely interval (PI)-based neighbor discovery that adopts pseudo-random delay to avoid blocking problem, which is also adopted by pseudo-random delay advertising mode of Bluetooth low energy (BLE). In this article, we proposed an additional scan windows-based assisted protocol, which achieves early discovery with the help of assistance mechanism. Based on the assistance mechanism, we model and optimize the neighbor discovery latency of the PI-based protocol. Moreover, to analyze the impact of assistance failure caused by contention problem in a clique scenario, we proposed a mutual exclusive drawer model. Simulation results show that the proposed protocol using the derived near-optimal parameters achieves 26% lower average latency in sparse networks.