Progress in medicine has extensive relation with the other fields of science and technology. The thorough effect of the development of various sciences on human life and presenting healthcare services shows this relation. Emersion of Body Area Sensor Networks (BASN) is one of these advances. Wireless body area sensor networks will revolutionize health care services by remote, continuous and non-invasive monitoring. Hence, it's expected that preventing and early detecting of diseases will be added to the current healthcare systems which are mostly based on disease management and not on health management. BASN is one of the important applications of Wireless sensor networks (W) which are one of the most fascinating results of recent advances in multiple branches of technology such as wireless systems, networking, microelectronics, and sensor design. Body area sensor network is a network of biomedical sensor nodes which are placed carefully over the human body or implemented inside of it to provide real time, reliable and long lasting health monitoring. BA should monitor different physiological parameters of a person for a long period of time. Due to finite energy budget of sensor nodes, efficient energy usage is essential in order to provide a long life time for the network. Though, this is one of the most important challenges in BA. In this thesis, after introducing BA and their influence on the modern medicine, the state of the art of this technology is reviewed. Moreover, we investigate the challenge of energy in these networks and propose a method to improve life time of the sensors. This solution includes employing a relay network, in addition to the network of body sensors, to reduce energy consumption of sensor nodes when transmitting data to the sink. The use of the relay network in conjunction with body area sensor networks decreases the depletion rate of energy in the sensor nodes. Hence, the most part of the communication is performed by the relay nodes in a multihop arrangement and the sensor nodes transmit over short ranges with no relaying. The results show significant raise in sensors’ life time compared to either single-hop or multihop transmission. Furthermore, the total energy usage of the network is reduced considerably compared to the single-hop communication case due to substitution of all far field transmissions by near field ones. Based on the original topology of , total energy consumption of plus relay network can be much less than multihop communication. Placemen Key Words Body Sensor Network, Relay Network, Relay Node Placement, Relay Node, Sensor Node.
