Divisible Load Theory Based Active-Sleep Workload Assignment Schemes for Wireless Sensor Networks

Ngaiming Kwok,Shengyong Chen,Wanliang Wang,Haiyan Shi

doi:10.1155/2014/929416

Abstract

Wireless sensor networks (WSNs) have been widely applied in many monitoring and surveillance processes. Due to the limited onboard energy resources, the operation of a WSN is severely hindered by its shortened lifespan arising from energy depletion. In order to alleviate this problem, and with the possibility of partitioning sensing workloads, the divisible load theory (DLT) can be adopted to derive a proper workload assignment scheme. However, special considerations have to be paid for its generic applicability in feasible workload assignment for WSNs. In this paper, an examination of DLT based WSN operations including the effect of assignment, measurement, and report times is presented, and the problem of negative workloads inherently generated in some schemes is revealed. Furthermore, by making use of the negativity phenomenon, an active-sleep scheme is proposed for the WSN such that sensor energy consumptions can be reduced and consequently extend the WSN operation lifespan. Specifically, sensors with smaller amount of residual energies are put into the sleep mode when the assigned workloads are negative. On the other hand, positive workloads are normalized and reassigned to sensors with larger amount of onboard energies. Simulation studies are carried out to demonstrate the negative workload phenomenon, and satisfactory performances of the proposed active-sleep scheme are verified.

Highlights

Monitoring and surveillance of the environment have become common practices in contemporary societies
It has been well recognized that the limitation in onboard energy is a major concern for the extended lifespan operation of Wireless sensor networks (WSNs)
We focus on using the cooperative sensing approach where sensors are assigned part of the sensing workload using the divisible load theory

Summary

Introduction

Monitoring and surveillance of the environment have become common practices in contemporary societies. It has been well recognized that the limitation in onboard energy is a major concern for the extended lifespan operation of WSNs. While it is possible to preserve sensor energy by carefully manage its data reporting routes, it is feasible to arrange their sensing activities. It was observed that some schemes may result in negative workloads derived from DLT [18], which are practically infeasible This special feature, can be made use of in putting sensors into the sleep mode to preserve the battery energy. While satisfying coverage requirements and radio reception strength constraints, methods are being developed to reduce energy consumptions These include grouping sensors into clusters to route the sensed data, to cooperatively complete the sensing task by sharing the workload, and to enter into sleep or inactive states to preserve energy and extend their operation durations.

Divisible Load Theory in Generic Wireless Sensor Network Operations

Instantaneous Measurement and Dependent Reporting

Active-Sleep Scheme for Wireless Sensor Networks

Experiments

Conclusion