In this paper, we study radio frequency (RF) backscatter for high data rate wireless communication with deep medical implants. The radar approach permits remote reading of the implant's information. This means the active transmitter is removed from the implant, that results in significant power saving. We customize our design for wireless capsule endoscopy (WCE) application, which is used for streaming high data rate video signals for improved visualization of the gastrointestinal tract. An efficient antenna system is designed and integrated into the WCE prototype that generates large radar cross section (RCS) using a self-resonant antenna geometry. The antenna is reconfigurable using an active micro-watt switch, which is controlled by the data stream. The switch alters the antenna RCS for an efficient modulation of the incident electromagnetic wave (EM) transmitted from outside the body. The antenna design considers the specific conditions of wave propagation in the biological environments and antenna loading with the lossy tissues. Polarization diversity using bi-static on-body reader antennas is used for communicating with the implant device. The on-body antennas can direct EM energy to the capsule device for improving the backscatter link performance. The feasibility study is demonstrated using numerical computations and experimentally validated in a liquid phantom and in-vivo animal experiments. A reliable backscatter data connectivity of 1 and 5 Mbps is measured for the capsule in the gastrointestinal tract for the depths up to 10 cm using an acceptable level of RF radiations.
An un-coded multi-transmitter query scheme is introduced for wireless backscatter communication systems in which M transmitters and N receivers are used for single-tag connectivity (M × 1 × N). The main idea is to harden the wireless communication channel with a tag device for high data rate readings. The proposed method is designed for multipath fading channels in which the backscatter channel is a multiplicative Rayleigh. A coherent transmit query scheme is used to increase the tag-reflected signals and simultaneously alter the fading statistics in the forward path by implementing a receiver feedback. Full-diversity performance and array gain is achieved using the receiver diversity without requiring any tag antenna diversity. Therefore, the tag device remains simple. Mathematical expressions for the probability density function (PDF) of the backscatter channel are presented using closed-form equations. Bit error rate (BER) simulations for the binary phase shift keying (BPSK) modulation are computed numerically. Diversity gain of 10 dB is obtained by using a 2 × 1 × 1 scheme. The results show that the transmit diversity for single-tag usage performs the same as the tag antenna diversity, at the expense of a moderate transmitter complexity. The tag device remains intact as a requirement for the simplicity and size constraints. Also, the system realization becomes more feasible due to the available space on the transmitter side to accomplish the uncorrelated forward channel conditions. The feasibility study is demonstrated using softwaredefined radio (SDR) implementations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.