Panacea: A low-latency, energy-efficient neighbor discovery protocol for wireless sensor networks

Neighbor discovery is essential to construct wireless sensor networks. Most existing studies on neighbor discovery are designed on the assumption that either all nodes are within the radio range of each other, or only two nodes compose the network. However, networks are partially-connected in reality: some nodes are within the radio range of each other, while others are not. Low latency and energy efficiency are two common goals, which become even more challenging to achieve at the same time in partially-connected networks. We find the collision caused by simultaneous transmissions is the main obstruction of achieving the two goals. In this paper, by alleviating collisions, we present Panacea, the first low-latency, energy-efficient protocol for a partially-connected network. To begin with, we design Panacea-WCD for nodes that have collision detection mechanisms and Panacea-NCD for nodes that do not have. Then, we prove the discovery latency of Panacea is bounded by a low latency O(n·ln n), where each node has n neighbors on average. Finally, we implement Panacea for evaluations in complicated partially-connected networks. The evaluated results corroborate our analyses: compared with two notable protocols, i.e. PND and Coupon, Panacea achieves up to 5.14 times lower latency with the same energy consumption; and saves 30% energy for similar latency with Coupon.