A Scheduling Method Solving Successive Contentions
of Heterogeneous Periodic Flows Based
on Mathematical Formulation in Multi-hop WSNs
Recently, the number of wireless sensor networks is increasing. In these networks, the sensors usually collect data every period. This leads to the increase in the number periodic flows and the interference among them. Most of the related researches focus only on single kind of periodic flow systems, which are not suitable for practical applications. The others are based on TDMA which requires global synchronization and thus cannot be scalable. In this paper, we propose and prove a formula that determines the interference between heterogeneous periodic flows. By using this formula, we propose a scheduling method to improve the performance of the heterogeneous periodic multi-hop sensors network. Our proposed method uses the naive and popular DCF for the MAC layer, which is low cost and is highly feasible because of the wide diffusion of IEEE 802.11, and does not require global synchronization. Furthermore, because all the calculations are done by the sink, the hardware requirement of the sensor nodes is reduced. Therefore, it is scalable and easy to implement. We demonstrate the performance of the proposed method by extensive simulations. The results show that the final proposal reduces the packet loss rate by 91% and 95% in comparison with the related works, Delta Shifting Method and Binary Division Method, respectively.