Social sensing-based duty cycle management for monitoring rare events in wireless sensor networks This paper introduces a social sensing-based dynamic duty cycle management scheme, namely probabilistic duty cycle in sensor medium access control (PDC-SMAC) protocol, for wireless sensornetworks (WSNs). The objective of PDC-SMAC is to minimise energy consumption in monitoring `rare events’ by reducing the period of `ineffective sensing’. Ineffective sensing is defined as event monitoring or sensing, even if there is no event to monitor or sense. Existing schemes suffer from unnecessary energy consumption because of ineffective sensing. For example, the period and frequency of occurrence of an event in military applications is unpredictable, and sometimes the delay between two consecutive occurrences is very large. We exploit the social sensing behaviour of socialnetworks for avoiding ineffective sensing by managing the duty cycle of a node in a sensor network. PDC-SMAC minimises the energy consumption of a WSN as the event monitoring overhead is accounted for by the social network. Simulation results show that PDC-SMAC consumes 37% less energy in an ideal environment and 15% less energy on overall performances as compared with the benchmark considered for comparison. It minimises message delivery latency by 27 – 60% for different packet generation intervals and by 47% for different event occurrence rates, compared with the benchmark.