Energy-aware exploitation of white spaces in the time domain for wireless sensor networks

Low power communications of sensor nodes operating in unlicensed bands are easily corrupted by transmissions of collocated wireless terminals whose interference can induce packet losses and consequently increase energy consumption of sensor devices. Dynamic spectrum access mechanisms can mitigate these problems however the energy aware design of these access schemes is a challenging task. In this paper we consider an energy constrained system comprising two sensor nodes that avoid interference by exploiting spectrum opportunities in the time domain. Using the distributions of idle period duration obtained during a measurement campaign we show how it is possible to design the access scheme deployed by sensors in an energy efficient manner. We compare different spectrum sensing strategies, showing that per-packet sensing results in significant energy overhead. We further provide a way for dimensioning the size of transmitted packets. Simulation results show that our approach outperforms other access strategies and allows to reduce energy consumption of 20 to 90 percent depending on channel conditions.