In this paper we are concerned with the problem of data forwarding from a wireless body area network (WBAN) to a gateway when body shadowing affects the ability of WBAN nodes to communicate with the gateway. To solve this problem we present a new WBAN architecture that uses two communication technologies. One network is formed between on-body nodes, and is realized with capacitive body-coupled communication (BCC), while an IEEE 802.15.4 radio frequency (RF) network is used for forwarding data to the gateway. WBAN nodes that have blocked RF links due to body shadowing forward their data through the BCC link to a node that acts as a relay and has an active RF connection. For this architecture we design a network layer protocol that manages the two communication technologies and is responsible for relay selection and data forwarding. Next, we develop analytical performance models of the medium access control (MAC) protocols of the two independent communication links in order to be used for driving the decisions of the previous algorithms. Finally, the analytical models are used for further optimizing energy and delay efficiency. We test our system under different configurations first by performing simulations and next by using real RF traces.
Wireless sensor network (WSN) technologies have been extended to the bio-medical area, and it is called body sensor networks (BSN). BSN systems sense and transmit the vital signs of human, such as electrocardiogram (ECG) and electromyogram (EMG), in unobtrusive and efficient way. Those vital signs are critical to human's life and behavior, so the data should be reliable and transmitted in real-time. In this paper, we propose a BSN platform that is using two-level communications (TLC) to increase the reliability of the system. Also, we develop a hardware and software platform to support the TLC and increase the reliability and energy efficiency.