# Optimal Energy Consumption Tasks Scheduling Strategy for Multi-Radio WSNs  
[PERSON]  
1 School of Information and Electrical Engineering, Shandong Jianzhu University, Jinan 250101, China; [EMAIL_ADDRESS] (Q.Y.); [EMAIL_ADDRESS] (G.Z.)  
[PERSON]  
(MR-WSNs). Multi-radio technology has successfully aroused many researcher's interest and made them pay more attention to it [8; 9; 10]. Energy consumption which is one of the key research problems in the WSN fields is particularly prominent in the MR-WSN environment, especially when the multi-radio nodes operate by un-chargeable battery. Hence, it is significant to research how to reduce the energy consumption in MR-WSNs for prolonging the network lifetime. The advanced multi-radio task scheduling scheme will directly affect the energy consumption performance, and then further improve the network lifetime. Inspired by the different evolution algorithm, this paper researches the optimal energy consumption task scheduling strategy for the MR-WSN fields in order to reduce the energy consumption and to prolong the network lifetime. In this paper, the energy consumption of the multi radio is firstly converted into a multi-task scheduling problem, and then the analysis of energy consumption under two types of task status is detailed, including transmission state and idle listening state. Based on that analysis, the energy consumption model under those two statuses is built and is further taken as an optimal objective function of the multi-task scheduling problem in MR-WSNs. In order to solve the optimal energy consumption task scheduling problem, the multi-task scheduling strategy is designed based on the Particle Swarm Optimization (PSO) algorithm and its detailed steps are provided. Furthermore, both experimental and simulation results are given. Those results clearly indicate that the proposed strategy outperforms other schemes in terms of energy consumption, network lifetime, etc. Finally, the task extensibility of the proposed scheme is tested in order to obtain the best performance with the optimal number of tasks. The contributions of this paper can be summarized as follows.  
* Analyzes the multi-task (typically the transmission task and idle listening task) scheduling process of multi-radio nodes. In our analysis, the tasks are divided into two sets, i.e., the waiting scheduling task set and the scheduled task set. In detail, the scheduled task set is further distinguished as transmitted packets and un-transmitted packets in order to obtain the accurate energy consumption model from the task scheduling perspective.
* Converts the energy consumption problem into a multi-task scheduling process and builds the accurate energy consumption model of MR-WSNs under the above two types of task status; obtains the optimization objective function and the corresponding constrained conditions of energy consumption for MR-WSNs. Hence, the energy consumption problem finally turns into an optimization problem with constraints.
* Introduces the PSO algorithm to solve the constrained optimization problem and designs the optimal energy consumption task scheduling strategy. Then provides the detailed key steps and pseudo-code of the optimization process. Meanwhile, the performance is also evaluated by experiments and simulations. Furthermore, the task extensibility of the proposed strategy is tested in order to confirm the optimal performance and the best number of tasks.  
The remainder of this paper is organized as follows. Section 2 highlights the related work. In Section 3, detailed analysis of the energy dissipation process is provided and the model of task scheduling energy consumption is given. In Section 4, the constrained optimization objective function of energy consumption is built, and the energy-efficient task scheduling scheme using a PSO algorithm is proposed and the detailed steps are also presented. In Section 5, both experiments and simulations are deployed to evaluate the performance of the proposed task scheduling scheme. Finally, the conclusion is presented.