In vivo wireless communications and networking

In vivo wireless communications and networking of biomedical devices has the potential of being a critical component in advancing health care delivery. Such systems offer the promise of improving the effectiveness of sophisticated cyber-physical biomedical systems. This paper provides an overview of our research on characterizing the in vivo wireless channel and contrasting this channel with the familiar cellular and WLAN channels. Characterization of the in vivo channel is still in its infancy, but the importance of obtaining accurate channel models is essential to the design of efficient communication systems and network protocols to support advanced biomedical applications. We describe our initial research on signal processing matched to the in vivo channel including MIMO in vivo and Cooperative Network Coding [CNC] systems. MIMO in vivo 2×2 systems demonstrate substantial performance improvement relative to SISO arrangements that significantly depends on antenna location. MIMO makes it possible to achieve the target data rate of 100 Mbps, with maximum SAR [Specific Absorption Rate] levels met. Furthermore, it is found that, to satisfy the maximum allowed SAR, a larger bandwidth may, but not necessarily, increase the system capacity. Also, we discuss the ability of Cooperative Network Coding [CNC] to increase the reliability (especially for real-time applications), provide transparent self-healing, and enhance the expected number of correctly received and decoded packets at the WBAN destination, while transmitting at low power. Because of the real-time nature of many of these medical applications and the fact that many sensors can only transmit, error detection and retransmission (i.e., ARQ) is not a preferred option. CNC requires about 3.5 dB less energy per bit than extant WBAN systems that do not use cooperation or network coding.