Indoor temperature monitoring using wireless sensor networks: A SMAC application in smart cities

Social, Mobile, Analytics and Cloud (SMAC) technologies aim to bridge the cyber, physical and social spaces. The use of wireless sensor networks to monitor indoor temperature is a typical application in smart cities. Rather than splitting the measured temperature and the design of a sensor network, a cyber-physical design approach is proposed by this paper for indoor temperature monitoring using wireless sensor network. The source sensors adopt sleep/wake scheduling, that is, source nodes wake up and sense the temperature periodically. The temperature data is sent to the cloud server via multi-hop relaying sensor nodes in an anycast way. Each sensor decides how to route packets based on its local information and dynamically adjust the sleep/wake duty cycle according to the sensed temperature: if the measured temperature is within normal range, the sensor wakes up infrequently to achieve higher energy efficiency; and vice versa. We first propose an optimal delay algorithm for anycast protocol. The simulation results show that our approach outperforms other heuristic schemes. Furthermore, we implement the proposed algorithm using TelosB sensors with TinyOS. Experiments demonstrate that the designed system can report a temperature anomaly within a small delay and achieve good long-term energy efficiency at the same time.