Beacon Scheduling in Receiver-initiated MAC Protocols for Low-delay and Energy-efficient WSNs

Wireless Sensor Networks (WSNs) should collect sensing data quickly without increasing the energy consumption in order to deal with various applications, particularly delaysensitive applications. This paper proposes a method to schedule beacon transmissions for receiver-initiated MAC protocols, which are promising energy efficient protocols, to improve data collection delay. The key idea of the proposed method is scheduling beacon timings in the sequence of distance from leaf node to the root (i. e., sink) node so that data frames are forwarded to the sink node with small duration staying at each node. Each sensor node selects a time slot to send beacon in distributed manner based on their distances (i. e. hop counts) from the sink node. In addition, each node autonomously adjusts its beacon timing to avoid frame collisions. Computer simulations show that the proposed method can collect data in a shorter time with less energy consumption than conventional beacon scheduling methods for receiver-initiated MAC protocols.