An Analytical Study of Reliable and Energy-efficient Data Collection in Sparse Sensor Networks with Mobile Relays

Sparse wireless sensor networks (WSNs) are emerging as an effective solution for a wide range of applications, especially for environmental monitoring. In this context, special mobile elements - i.e. mobile relays (MRs) - can be used to get data sampled by sensor nodes. In this paper we present an analytical evaluation of the data collection performance in sparse WSNs with MRs. Our main contribution is the definition of a flexible model which can derive the total energy consumption for each message correctly transferred by sensors to the MR. The results show that a low duty cycle is convenient and allows a significant amount of correctly received messages, especially when the MR moves with a low speed. When the MR moves fast, depending on its mobility pattern, a low duty cycle may not always be the most energy efficient option.