Energy Efficient MAC Protocols

This paper presents a survey of energy efficiency of Medium Access Control (MAC) protocols for Wireless Body Area Sensor Networks (WBASNs). We highlight the features of MAC protocols along with their advantages and limitations in context of WBASNs. Comparison of Low Power Listening (LPL), Scheduled Contention and Time Division Multiple Access (TDMA) is also elaborated. MAC protocols with respect to different approaches and techniques which are used for energy minimization, traffic control mechanisms for collision avoidance are discussed. We also present a survey of path loss models for In-body, On-body and Off-body communications in WBASNs and analytically discuss that path loss is maximum in In-body communication because of low energy levels to take care of tissues and organs located inside the body. Survey of Power model for WBANs of CSMA/CA and beacon mode is also presented.

I. Introduction

EVOLUTION of wireless, medical and computer networking technology has merged into an emerging horizon of science and technology called Wireless Body Area Networks (WBANs). However, applications of WBANs are not limited to medical field only. Miniaturization and connectivity are notable parameters of this field. WBANs consist of three levels; first level is low power sensors or nodes which are battery powered and need to be operated for a long time without repairing and maintenance. These nodes may be placed on the body, around the body or implanted in the body. Second level is called master node, gateway or coordinator which controls its child nodes; its power requirements may be less strengthened than nodes due to its applications and flexibility. Third level is the local or metropolitan or internet network that serves for monitoring purposes.