The wireless Body Sensor Network (BSN) is used to detect and transmit physiological data such as vital signs by using radio wave communication. It offers a large saving potential for future healthcare applications because hospitalization of patients with chronic diseases can be kept at a minimum. The radio wave communication on the human body is impacted by the dielectric properties, the posture, and the movement of the body. Under these conditions a highly dynamic link-state and link quality are observed. In this paper, the authors present a study of the link layer behavior of wireless BSNs operating at 2.45GHz.