[Systems][Enabling Technologies][Fundamental Knowledge]

UWB RFID for Low Power Wireless Signal Transmission in BBCI

Applications

Pragnesh V Patel1, Rutul Patel1, Dr. Santosh Nagaraj1, Dr. MahaSweta Sarkar1

1 Electrical and Computer Engineering, San Diego State University

Introduction• To design any wireless communication system, the position of

Transmitter and Receiver and the channel through which the

signal propagates are important parameters.

• For in body communications human tissues are channel model.

This is because human body is a complex system consisting of

many different kinds of tissues.

• These tissues are constructed in a layered way where the

thickness is different for each tissue and differ for each human.

Therefore the tissues present in human torso have to be taken

into account for in body communication applications.

• The dielectric properties of human tissues is not only complex

but also frequency dependent. Moreover human tissues have

non zero conductivity. [1-2]

Results• After studying the MRI scans of Human Brain of different age

people we found out the size of different medium through

which the signal will propagate.

• The absorption loss for all kind of thickness was investigated

and we found out that cerebellum and blood are major

contributor to absorption losses.

Table 1 Comparison of Attenuation for different size

Discussion• From the results obtained we can show that as the frequency of

the signal increases the attenuation also increases irrespective

of size of medium.

• The attenuation due to variations in thickness of Cerebellum

causes big attenuation differences for all frequency bands.

• From the results it is investigated that the absorption losses are

not that frequency dependent as is expected and mentioned in

literature.

• For better energy efficiency and less power consumption the

Ultra Wideband Transmitter and Receiver can be modified

based on these results.

• Type of Antenna used and its directivity pattern along with

VSWR will have different effects on the results that are

obtained considering ideal conditions.

Conclusion• In this research the radio propagation inside a human body has

been analyzed by investigating the physical characteristics of a

new developed multilayer model.

• In future work the influence of oblique incidence on the power

attenuations and reflections have to be investigated as well as

other effects as multipath and diffraction.

References[1] Pahlavan, Kaveh, Yunxing Ye, Ruijun Fu, and Umair Khan.

"Challenges in channel measurement and modeling for RF

localization inside the human body." International Journal of

Embedded and Real-Time Communication Systems (IJERTCS) 3,

no. 3 (2012): 18-37.

[2] Gabriel, Camelia. Compilation of the Dielectric Properties of

Body Tissues at RF and Microwave Frequencies. KING'S COLL

LONDON (UNITED KINGDOM) DEPT OF PHYSICS, 1996.

[3] Pozar, MicroWave Engineering. Wiley, 2012

Method• After studying the human brain we found out that Cerebellum

is best place to fit the electrodes to pick up the signal of neurons

and feed to transmitter.

• The transmitter sitting on cerebellum will transmit the signal to

receiver sitting outside the human head.

Figure 1 The Channel in Human Brain

• The losses that signal undergoes while propagating depend not

only on dielectric properties of human tissues but it also depend

on the size of the medium too. The medium through which the

signal propagates is shown in above figure. [3-4]

Tissue Thickness (mm)

Min Max Average

Cerebellum 30 50 40

Blood 8 10 9

Grey Matter 4 6 5

Bone 10 12 11

Scalp Fat 10 12 11

Skin 1 1.5 1.25

Total 63 91.5 77.25