Network switching strategy for energy conservation in heterogeneous networks.

Yujae Song,Seungjae Baek,Wooyeol Choi

doi:10.1371/journal.pone.0172318

Abstract

In heterogeneous networks (HetNets), the large-scale deployment of small base stations (BSs) together with traditional macro BSs is an economical and efficient solution that is employed to address the exponential growth in mobile data traffic. In dense HetNets, network switching, i.e., handovers, plays a critical role in connecting a mobile terminal (MT) to the best of all accessible networks. In the existing literature, a handover decision is made using various handover metrics such as the signal-to-noise ratio, data rate, and movement speed. However, there are few studies on handovers that focus on energy efficiency in HetNets. In this paper, we propose a handover strategy that helps to minimize energy consumption at BSs in HetNets without compromising the quality of service (QoS) of each MT. The proposed handover strategy aims to capture the effect of the stochastic behavior of handover parameters and the expected energy consumption due to handover execution when making a handover decision. To identify the validity of the proposed handover strategy, we formulate a handover problem as a constrained Markov decision process (CMDP), by which the effects of the stochastic behaviors of handover parameters and consequential handover energy consumption can be accurately reflected when making a handover decision. In the CMDP, the aim is to minimize the energy consumption to service an MT over the lifetime of its connection, and the constraint is to guarantee the QoS requirements of the MT given in terms of the transmission delay and call-dropping probability. We find an optimal policy for the CMDP using a combination of the Lagrangian method and value iteration. Simulation results verify the validity of the proposed handover strategy.

Highlights

There has been an exponential growth in mobile traffic globally [1]
We propose a handover strategy that helps to enhance the energy efficiency of base stations (BSs) in Heterogeneous networks (HetNets)
In the constrained Markov decision process (CMDP), the objective is to minimize the energy consumption generated at BSs during the service time of a traffic flow, and the constraint is to meet the quality of service (QoS) requirements of an mobile terminal (MT) given in terms of the transmission delay and call-dropping probability

Summary

Introduction

There has been an exponential growth in mobile traffic globally [1]. To cope with the rapid increase in the traffic, various issues and solutions have been discussed in the field of wireless communication. Our objective is to minimize the energy consumption of BSs while serving a traffic flow, while guaranteeing two MT QoS requirements, namely the transmission delay and call-dropping probability. In the CMDP, the objective is to minimize the energy consumption generated at BSs during the service time of a traffic flow, and the constraint is to meet the QoS requirements of an MT given in terms of the transmission delay and call-dropping probability. Given policy π and the number of frames in a traffic flow K + 1, the expected total energy consumption when serving the MT over the lifetime of its connection from initial state s can be expressed as:.

3: If k Gpμþ1ðsÞ À

Findings

Conclusion