Sleeping Schedule-Aware Local Broadcast in Wireless Sensor Networks

Broadcast is widely used in applications in wireless sensor networks (WSNs). In the last decade, the broadcast problem in WSNs has been well studied. However, few of existing broadcasting strategies have considered the scenarios with sleeping schedules, which have been emerging as a prevalent energy-saving method for WSNs. In WSNs with sleeping schedule, each node switches on and off periodically, rendering the broadcast problem more difficult. To handle the periodical sleep issue, we focus on designing effective sleeping schedule-aware broadcast algorithms. We practically propose SALB, a sleeping schedule-aware local broadcast algorithm. In SALB, a typical local algorithm for constructing connected dominating set is employed to form the broadcast backbone. To guarantee proper transmission of broadcast messages, a sleep-aware forwarding mechanism is implemented. Moreover, heuristic strategies are used to decrease the number of transmissions and the broadcast latency. Theoretical analysis shows that the number of transmissions for SALB is within 4(min( , ) ( is constant) is constant) times of the optimal value. And the broadcast latency of SALB is within 4 times of the optimal value ( is the maximum degree in the network, is the scheduling period length). The performance of SALB is evaluated via simulations. 1. Introduction Energy is regarded as scarce resource in wireless sensor networks (WSNs). It is shown that most energy is wasted in sensor node’s idle listening. To handle this issue, sleeping schedule has been proposed to preserve energy in WSNs. With sleeping schedule, each node is switched on and off periodically. Nodes turn on to detect object and receive and forward data and then turn to sleep to save energy. As a simple yet efficient method, sleeping scheduling has been widely used in WSN applications like environment monitoring and object tracking applications [1]. Broadcast is a fundamental operation in WSNs for routing discovery, information dissemination, and so on [2]. Naive broadcast methods such as flooding always lead to massive redundancy and intolerable latency, wasting the energy dramatically [2]. In order to design energy-efficient broadcast algorithms, a lot of effort has been devoted to reduce data transmission and broadcast latency. For instance, many MCDS-based approaches are proposed to minimize transmission redundancy [3–7]. And lots of coloring-based collision-avoiding approaches are used to reduce latency [8–10]. In this paper, we focus on the sleeping schedule-ware broadcast problem in WSNs, which is quite different from