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| 2. |
- Chandra, Rohit, et al.
(författare)
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A Link Loss Model for the On-body Propagation Channel for Binaural Hearing Aids
- 2013
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Ingår i: IEEE Transactions on Antennas and Propagation. - 0018-926X. ; 61:12, s. 6180-6190
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Tidskriftsartikel (refereegranskat)abstract
- Binaural hearing aids communicate with each other through a wireless link for synchronization. A propagation model is needed to estimate the ear-to-ear link loss for such binaural hearing aids. The link loss is a critical parameter in a link budget to decide the sensitivity of the transceiver. In this paper, we have presented a model for the deterministic component of the ear-to-ear link loss. The model takes into account the dominant paths having most of the power of the creeping wave from the transceiver in one ear to the transceiver in other ear and the effect of the protruding part of the outer ear called pinna. Simulations are done to validate the model using in-the-ear (ITE) placement of antennas at 2.45 GHz on two heterogeneous phantoms of different age-group and body size. The model agrees with the simulations. The ear-to-ear link loss between the antennas for the binaural hearing aids in the homogeneous SAM phantom is compared with a heterogeneous phantom. It is found that the absence of the pinna and the lossless shell in the SAM phantom underestimate the link loss. This is verified by the measurements on a phantom where we have included the pinnas fabricated by 3D-printing.
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| 3. |
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| 4. |
- Chandra, Rohit, et al.
(författare)
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An Analytical Link Loss Model for On-Body Propagation Around the Body Based on Elliptical Approximation of the Torso with Arms' Influence Included
- 2013
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 12, s. 528-531
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Tidskriftsartikel (refereegranskat)abstract
- An analytical model for estimating the link loss for the on-body wave propagation around the torso is presented. The model is based on the attenuation of the creeping waves over an elliptical approximation of the human torso and includes the influence of the arms. The importance of including the arms’ effect for a proper estimation of the link loss is discussed. The model is validated by the full-wave electromagnetic simulations on a numerical phantom.
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| 5. |
- Chandra, Rohit, et al.
(författare)
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An Approach to Analyze the Movements of the Arms while Walking using Wearable Wireless Devices
- 2013
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Ingår i: [Host publication title missing]. - 1557-170X. ; , s. 3435-3438
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Konferensbidrag (refereegranskat)abstract
- Abstract—Rhythmic movement of the arms while walking is an important feature of human gait. In this paper, we present an approach to analyze the movements of the arms while walking by using three wearable wireless devices placed around the torso. One of the devices is transmitter placed at the back and the other two are symmetrically placed receivers that record the power variation due to movements of the arms while walking. We show that the power received by the receivers will have symmetrical variation if the arms’ swing is symmetrical. An analytical model has been used to calculate the position of the receivers. Full wave simulations on a walking phantom are done to confirm the results.
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| 6. |
- Chandra, Rohit, et al.
(författare)
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An elliptical analytic link loss model for wireless propagation around the human torso
- 2012
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Ingår i: 6th European Conference on Antennas and Propagation (EUCAP), 2012. - 9781457709180 ; , s. 3121-3124
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Konferensbidrag (refereegranskat)abstract
- A simple analytical model for the link loss between two very low profile wireless body area network transceivers located at the same level on the human torso is presented. The model is based on the attenuation of the creeping waves on an elliptical approximation of the human torso. A good agreement between the model and the FDTD simulations on realistic heterogeneous phantoms of different age and body-size is obtained.
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| 7. |
- Chandra, Rohit, et al.
(författare)
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Analytical On-Body Propagation Models for the Channel around the Body based on Attenuation of Creeping Waves over an Elliptical Surface
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Wireless wearable medical devices located on the opposite side of the body communicate through creeping waves. The creeping waves undergo exponential attenuation with distance. Hence, an analytical propagation model is useful to estimate the link loss for a reliable link. In this document, we have presented analytical link loss models for the wireless propagation channel between the devices located around the body such as: (a) around the torso and (b) in the ears for hearing aids. Initially, a model is developed based on attenuation of creeping waves over an elliptical approximation of the body. This model is then extended for the ear-to-ear propagation and around the torso propagation cases. The presented models are validated through full wave electromagnetic simulations done with numerical phantoms. A good agreement between the analytical models and the simulations is obtained showing the applicability of the models to estimate the link loss for around the torso and ear-to-ear propagation.
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| 9. |
- Chandra, Rohit, et al.
(författare)
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Antennas and Propagation for In-Mouth Tongue Controlled Devices in Wireless Body Area Networks
- 2015
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Ingår i: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 14, s. 1518-1521
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Tidskriftsartikel (refereegranskat)abstract
- Tetraplegic patients have to depend upon someone else for moving the wheelchair or typing on a computer. One of the ways to make them independent is by using tongue-controlled in-mouth wireless devices. This letter presents antennas and propagation for such devices in 2.45 GHz ISM band. A monopole and a loop antenna suitable in size and performance is presented for such devices. The propagation link between the in-mouth antenna and an external antenna is measured by mimicking the use-case scenarios of such devices by placing an external antenna on a laptop, and on a chair. The link loss is found to be in the range of 55-75 dB depending upon the antenna type and the scenario. Using these values of the link loss, a reliable link can be established between the in-mouth device and the external device either mounted on a wheelchair or a computer.
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| 10. |
- Chandra, Rohit, et al.
(författare)
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Antennas and Propagation for the Ear-to-Ear Propagation Channel for Binaural Hearing Aids
- 2011
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have investigated the possibility of using the 2.45 GHz ISM band for communication between binaural hearing aids. The preliminary investigations were done by FDTD simulations on a modified SAM phantom head, where we have included a simple model of the ear canal. Two different types of hearing aid placements have been investigated: in the outer ear and in the ear canal. Antennas which have been miniaturized by applying disc loads and high permittivity materials were used for estimating the ear-to-ear link loss. The outer ear placement gives a total link loss of 48 dB and the placement in the ear canal gives a total link loss of 92 dB. Since the preliminary investigation indicated that the loss in the outer ear placement is low enough to support low power communication at 2.45 GHz, this configuration was chosen for further investigation on realistic heterogeneous human phantoms with proper electrical properties of all the tissues in the head. It was found that the antenna detunes differently for the different realistic phantoms and different ears within the same phantom. It was also found that the ear-to-ear link loss was 30 dB higher in a realistic heterogeneous phantom (named Duke of a 34 year old male) than in the SAM phantom. This was mainly due to the presence of an outer lossy layer (skin) and outer ears (pinna) in the Duke phantom. Other factors which may affect the ear-to-ear propagation channel like shoulders, metallic glass frame and size of the head have also been investigated.
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