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.