Body network gains speed
By Eric Smalley, Technology
The human body
is capable of many things, including acting as an information conduit --
Researchers from NTT Docomo Multimedia Labs and NTT Microsystem
Integration Labs in Japan have demonstrated a 10-megabits-per-second indoor
network that uses human bodies as portable ethernet cables.
The network, dubbed ElectAura-Net, is wireless, but instead of using
radio waves, infrared light, or microwaves to transmit information it uses
a combination of the electric field that emanates from humans and a similar
field emanating from special floor tiles.
The network is faster than commercially available personal area
networks like the 1-megabit-per-second Bluetooth radio wave system, and
tops the 4-megabits-per-second infrared standard set by the Infrared Data
The system could eventually provide high-speed wireless communications
among portable electronic devices whose positions constantly change. "The
main aim of the system is to provide [a] new indoor communication infrastructure
for [the] coming wearable and ubiquitous [computing] era," said Masaaki
Fukumoto, a researcher at NTT Docomo Multimedia Labs.
The researchers' prototype network consists of a series of transceivers
that can be placed every square meter under a tile or carpet floor, and
a transceiver worn on the body or attached to a handheld device. "The user
who holds [a] PDA or wearable device can connect to the Internet by just
standing or walking on the floor," said Fukumoto.
A network that taps the human body's electric field was first developed
by Massachusetts Institute of Technology researchers in 1996. To date, prototype
electric field networks have been relatively slow, however, operating at
speeds comparable to dial-up Internet connections, or about 180 times slower
than the ElectAura-Net prototype.
The researchers' transceiver transmits data by oscillating the electric
field surrounding the device. When the electric field that naturally emanates
from a person intersects the electric field of the nearest tile transceiver,
oscillations in one field are transmitted to the other.
The transceiver senses the oscillations with a sensor originally
designed for testing circuit boards that bounces a laser beam off of a crystal
and measures the reflected beam. Oscillations in an electric field surrounding
the crystal alter the crystal, which changes the reflected light's polarization.
The polarization measurements are translated into electric signals, which
are forwarded over an ethernet network in the floor tiles to the portable
device carried by the human.
In a world of ubiquitous networked communications, cellular data
networks and GPS systems can be used outdoors to transmit data and determine
locations. The researchers' system can provide the indoor equivalents, according
to Fukumoto. "We're developing [a] large-scale floor communications system
with automatic map generation and automatic routing," he said.
Using the transceivers contained in every square meter of a networked
floor, the network can potentially track the positions of people or portable
devices and generate maps showing their locations. Automatic routing determines
the best path for transmitting communications between devices in the network.
The researchers are working to miniaturize the system components
and to scale up the network so it can be used across larger spaces.
The researchers intrabody communication system is several orders
of magnitude faster than anybody else's, said Kurt Partridge, a researcher
at the University of Washington. They have shown that, as far as data rates
are concerned, intrabody communication can compete with radio frequency
technologies like Bluetooth, he said.
The challenge is reducing the device's power consumption, said Partridge.
"With the prototype running at 2.7 watts, there's a lot to do before it's
usable as a portable device," he said.
It's too soon to tell whether and when the prototype can be developed
into a practical network, said Fukumoto.
Fukumoto's research colleagues were Katsuyuki Ochiai, and Mitsuru
Shinagawa of NTT Microsystem Integration Labs in Japan and Toshiaki Sugimura
of NTT Docomo. The researchers presented the work at the Association of
Computing Machinery (ACM) Special Interest Group Graphics (Siggraph) 2003
conference in San Diego, July 27 to 31. The research was funded by NTT Docomo
TRN Categories: Networking; Wireless Communications
Story Type: News
Related Elements: Technical paper, "ElectAura-Net," presented
at the Association of Computing Machinery (ACM) Special Interest Group Graphics
(Siggraph) 2003 conference in San Diego, July 27-31; Technical paper, "A
Broadband Intrabody Communication System With the Electro-Optic Probe,"
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