Progresses in on-body channel models for wireless body area networks

On-body communication channels are a physical basis for the establishment of an effective and reliable wireless link between on-body nodes in wireless body area networks (WBANs).Due to normally strict limitations in transmit power and power consumptions of on-body nodes as well as the human-centered characteristics of WBANs,on-body channels are prone to be affected by the electromagnetic properties of human tissues,human movements,application environments and transceiver antennas,which increase greatly the complexity of the research on channel models.The paper discusses the developments,mathematical expressions and application characteristics of five types of on-body channel models,such as the simple path loss model,the hybrid path loss model,the small-scale fading model,the scenario-based model and the ultra-wideband model,and reviews the current progress on the modeling on-body channels. Key words: Wireless body area network;  On-body channel;  Path loss;  Fading