High data rate MIMO wireless communication for ingestible capsule endoscope system : antenna design and propagation

Abstract

Wireless capsule endoscope system has been widely used for gastrointestinal monitoring, since it can provide biological statistics in real time without causing any pain or discomfort. Current commercial capsule endoscope system suffers from low transmission data rate which cannot meet the requirement for high-resolution images. MIMO systems can provide high data rate without the need for additional spectrum and transmitting power. However, the design of MIMO antennas for capsule endoscope system is a challenging task due to the capsule size as well as the hostile human body environment. Cross-polarized nearly omni-directional MIMO antennas in the ISM band 433 MHz for capsule endoscope system are proposed in this thesis. The proposed MIMO antennas consist of a small magnetic loop antenna with horizontal polarization and a conformal meandered dipole antenna with vertically polarization. By using polarization diversity, the antennas still maintain good isolation even within the limited available space in the capsule. Simulation and measurement results are in good agreement. Multipath fading characteristics of human body channel is studied through discrete-time baseband equivalent impulse response and can be best described by normal distribution. MIMO system model is studied with consideration of antenna correlation and mutual coupling. The capacity gain for the proposed MIMO system is evaluated through simulation and it is shown capacity can be nearly doubled for a 2 × 2 MIMO capsule system. Finally, external multiple-port beam switchable base station antennas for receiving small signals transmitted from the implanted biomedical devices are introduced.

Date of Award	2012
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology