Real-Time Demonstration of Antenna Effects on Emulated Wireless Capsule Endoscope Links

A real-time over-the-air video transfer platform is developed for a wireless capsule endoscope scenario. With this platform, we aim at providing an intuitive and instant understanding of antenna effects on both quantitative and qualitative radio link performance, e.g., on video image quality, on bit error rate (BER) and on constellation diagrams of digital modulation. The platform consists of a host computer and a universal software-defined peripheral, complemented with an endoscope capsule mockup including an antenna, a liquid body phantom for creating a realistic inbody-to-onbody radio link scenario and an on-body antenna. The antennas operate at 433 MHz, while the liquid mimics the complex permittivity of colon tissue at that frequency range. Uncoded orthogonal frequency division multiplexing with 2.3 MHz bandwidth is adopted as a physical layer. Footage of the real-time demonstration is available from the link in [1] and shows the clear effects on radio link performance when 1) the distance of the capsule antenna from the wall of the liquid phantom is increased, and 2) when capsule antenna is moved out of the liquid phantom. In both cases, disruption of the video images is observed, due to an increased BER. The BER plots are reproduced in this paper as evidence. The demonstration has been used for post-graduate education to deepen students' understanding of the importance of antenna design, while the same benefit may be expected when showing the video to clinical experts who operate capsule endoscopes.