BWS: Beacon-driven wake-up scheme for train localization using wireless sensor networks

Real-time train localization using wireless sensor networks (WSNs) offers huge benefits in terms of cost reduction and safety enhancement in railway environments. A challenging problem in WSN-based train localization is how to guarantee timely communication between the anchor sensors deployed along the track and the gateway deployed on the train with minimum energy consumption. This paper presents an energy-efficient scheme for timely communication between the gateway and the anchor sensors, in which each anchor sensor runs an asynchronous duty-cycling protocol to conserve energy and wakes up only when it goes into the communication range of the gateway. A beacon-driven wake-up scheme is designed, and we establish the upper bound on the amount of time that an anchor sensor can sleep in one duty cycle to guarantee timely wake-up once a train approaches. We also give a thorough theoretical analysis for the energy efficiency of our scheme and give the optimal amount of time that an anchor sensor should sleep in terms of minimizing the total energy consumption at each anchor sensor. We evaluate the performance of our scheme through simulations, and results show that our scheme can wake up anchor sensors timely at a very low cost on energy consumption.