Impact of Receivers Location on the Accuracy of Capsule Endoscope Localization

[EN] In recent years, localization for capsule endoscopy applications using Ultra-Wideband (UWB) technology has become an attractive field of study due to its potential benefits for patients. Performance analysis of RF-based localization techniques are very limited in literature. Most of the available studies rely on software simulations using digital human models. Nonetheless, no realistic studies based on in-vivo measurements has been reported yet. This paper investigates the performance of RSS-based technique for three-dimensional (3D) localization in the UWB frequency band. Impact of receivers selection as well as of the evaluated path loss model on the localization accuracy is investigated. Results obtained through CST-based simulations and from recently conducted in-vivo measurements are presented and compared.This work was supported by the European Union's H2020:MSCA:ITN program for the "Wireless In-body Environment Communication- WiBEC" project under the grant agreement no. 675353. This work was also funded by the Ministerio de Economia y Competitividad, Spain (TEC2014-60258-C2-1-R), by the European FEDER funds.Barbi, M.; Garcia-Pardo, C.; Cardona Marcet, N.; Andrea Nevárez; Vicente Pons Beltrán; Frasson, M. (2018). Impact of Receivers Location on the Accuracy of Capsule Endoscope Localization. IEEE. 340-344. https://doi.org/10.1109/PIMRC.2018.8580862S34034

Analysis of the Localization Error for Capsule Endoscopy Applications at UWB Frequencies

Localization for Wireless Capsule Endoscopy (WCE) in the Ultra-Wideband frequency band is a very active field of investigation due to its potential advantages in future endoscopy applications. Received Signal Strength (RSS) based localization is commonly preferred due to its simplicity. Previous studies on Ultra-Wideband (UWB) RSS-based localization showed that the localization accuracy depends on the average ranging error related to the selected combination of receivers, which not always is the one experiencing the highest level of received power. In this paper the tendency of the localization error is further investigated through supplementary software simulations and previously conducted laboratory measurements. Two-dimensional (2D) and three-dimensional (3D) positioning are performed and the trend of the localization error compared in both cases. Results shows that the distribution of the selected path loss values, corresponding to the receivers used for localization, around the in-body position to estimate also affects the localization accuracy.This work was supported by the H2020:MSCA:ITN program for the “Wireless In-body Environment Communication- WiBEC” project under the grant agreement no. 675353. This work was also supported by the European Union’s H2020:MSCA:ITN program for the ”mmWave Communications in the Built Environments - WaveComBE” project under the grant agreement no. 766231.Barbi, M.; Pérez-Simbor, S.; Garcia-Pardo, C.; Cardona Marcet, N. (2019). Analysis of the Localization Error for Capsule Endoscopy Applications at UWB Frequencies. IEEE. https://doi.org/10.1109/ISMICT.2019.8743813

Spatial In-Body Channel Characterization Using an Accurate UWB Phantom

"(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."Ultra-wideband (UWB) systems have emerged as a possible solution for future wireless in-body communications. However, in-body channel characterization is complex. Animal experimentation is usually restricted. Furthermore, software simulations can be expensive and imply a high computational cost. Synthetic chemical solutions, known as phantoms, can be used to solve this issue. However, achieving a reliable UWB phantom can be challenging since UWB systems use a large bandwidth and the relative permittivity of human tissues are frequency dependent. In this paper, a measurement campaign within 3.1-8.5 GHz using a new UWB phantom is performed. Currently, this phantom achieves the best known approximation to the permittivity of human muscle in the whole UWB band. Measurements were performed in different spatial positions, in order to also investigate the diversity of the in-body channel in the spatial domain. Two experimental in-body to in-body (IB2IB) and in-body to on-body (IB2OB) scenarios are considered. From the measurements, new path loss models are obtained. Besides, the correlation in transmission and reception is computed for both scenarios. Our results show a highly uncorrelated channel in transmission for the IB2IB scenario at all locations. Nevertheless, for the IB2OB scenario, the correlation varies depending on the position of the receiver and transmitter.This work was supported by the Ministerio de Economia y Competitividad, Spain, under Grant TEC2014-60258-C2-1-R and Grant TEC2014-56469-REDT and by the European FEDER Funds.Andreu Estellés, C.; Castelló Palacios, S.; García Pardo, C.; Fornés Leal, A.; Vallés Lluch, A.; Cardona Marcet, N. (2016). Spatial In-Body Channel Characterization Using an Accurate UWB Phantom. IEEE Transactions on Microwave Theory and Techniques. 64(11):3995-4002. doi:10.1109/TMTT.2016.2609409S39954002641

Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis

[EN] An in-body sensor network is that in which at least one of the sensors is located inside the human body. Such wireless in-body sensors are used mainly in medical applications, collecting and monitoring important parameters for health and disease treatment. IEEE Standard 802.15.6-2012 for wireless body area networks (WBANs) considers in-body communications in the Medical Implant Communications Service (MICS) band. Nevertheless, high-data-rate communications are not feasible at the MICS band because of its narrow occupied bandwidth. In this framework, ultrawideband (UWB) systems have emerged as a potential solution for in-body highdata-rate communications because of their miniaturization capabilities and low power consumption.This work was supported by the Programa de Ayudas de Investigación y Desarrollo (PAID-01-16) at the Universitat Politècnica de València, Spain; by the Ministerio de Economía y Competitividad, Spain (TEC2014-60258-C2-1-R); and by the European FEDER funds. It was also funded by the European Union’s H2020:MSCA:ITN program for the Wireless In-Body Environ-ment Communication–WiBEC project under grant 675353.Garcia-Pardo, C.; Andreu-Estellés, C.; Fornés Leal, A.; Castelló-Palacios, S.; Pérez-Simbor, S.; Barbi, M.; Vallés Lluch, A.... (2018). Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis. IEEE Antennas and Propagation Magazine. 60(3):19-33. https://doi.org/10.1109/MAP.2018.2818458S193360

UWB RSS-based Localization for Capsule Endoscopy using a Multilayer Phantom and In Vivo Measurements

[EN] In recent years, the localization for capsule endoscopy applications using ultrawideband (UWB) technology has become an attractive field of investigation due to its potential benefits for patients. The literature concerning performance analysis of radio frequency-based localization techniques for in-body applications at UWB frequencies is very limited. Available studies mainly rely on finite-difference time-domain simulations, using digital human models and on experimental measurements by means of homogeneous phantoms. Nevertheless, no realistic analysis based on multilayer phantom measurements or through in vivo experiment has been reported yet. This paper investigates the performance of the received signal strength-based approach for 2-D and 3-D localizations in the UWB frequency band. For 2-D localization, experimental laboratory measurements using a two-layer phantom-based setup have been conducted. For 3-D localization, data from a recently conducted in vivo experiment have been used. Localization accuracy using path loss models, under ideal and non-ideal channel estimation assumptions, is compared. Results show that, under nonideal channel assumption, the relative localization error slightly increases for the 2-D case but not for the in vivo 3-D case. Impact of receivers selection on the localization accuracy has also been investigated for both 2-D and 3-D cases.This work was supported in part by the European Union's H2020 through the MSCA: ITN Program "Wireless in-Body Environment Communication-WiBEC" under Grant 675353, in part by the Programa de Ayudas de Investigacion y Desarrollo, Universitat Politecnica de Valencia under Grant PAID-01-16, and in part by the Ministerio de Economia y Competitividad, Spain, through the European FEDER Funds under Grant TEC2014-60258-C2-1-R.Barbi, M.; Garcia-Pardo, C.; Nevárez, A.; Pons Beltrán, V.; Cardona Marcet, N. (2019). UWB RSS-based Localization for Capsule Endoscopy using a Multilayer Phantom and In Vivo Measurements. IEEE Transactions on Antennas and Propagation. 67(8):5035-5043. https://doi.org/10.1109/TAP.2019.2916629S5035504367