Optical Antennas and Nano-apertures
Future data storage systems as well as optical microscopy
require the ability to address or image spots of the order of 20 nm in
diameter. We are collaborating with researchers in the Data Storage Systems
Center to design and fabricate optical nano-structures
that deliver sufficient heat to a 20 nm spot to enable magnetic writing on high
anisotropy media. Such media are needed for ultra-high density storage. This
technique is referred to as Heat Assisted Magnetic Recording, or HAMR.
Wireless Position Location in Amusement Parks and Athletics
Precise position location using wireless technologies in
indoor/outdoor environments is very challenging. However, in situations such as
amusement parks and athletic courts/fields, enhanced accuracy may be possible
by taking advantage of the well-controlled environments that exist in these
locations. We are exploring such technologies and applications for amusement
parks and football fields, as well as improvements in RFID technologies for
these applications and environements.
Micro-Inertial Navigation Systems
Foot navigation is a challenge when GPS satellites are not
available, e.g., in buildings, caves, or on the moon. In this case
micro-inertial navigation systems can be used. However, accelerometer drifts
quickly accumulate unacceptable error. One way to minimize the error is to set
biases to zero if one has independent knowledge that the velocity is zero at
certain times. We are collaborating with researchers in MEMS, RF ICs, and
Inertial Navigation to develop an instrumented boot that would be capable of
such navigation. We have constructed a miniature radar
that fits into the heel of a boot and can identify instances when the boot is
stationary with respect to the ground. Ongoing work includes wireless
techniques for ranging between boots.
Cognitive Radio and Spectrum Sensing
Although the easily accessible portions of the radio
spectrum are completely allocated, there is a continuing demand for new
high-bandwidth radio applications. New paradigms for using the spectrum are
being made possible by technologies such as cognitive radio and smart antennas.
A paradigm of particular interest is dynamic spectrum access. Under this
scheme, an agile radio searches for unused spectrum, then reconfigures rapidly
to use the spectrum, negotiating with the primary user if necessary. When the
spectrum is needed by the primary user, the secondary user must immediately
cease transmissions and find a new available frequency without causing
interference to the primary user. A student team from ARC recently designed and
constructed a dynamic spectrum access wireless network in which spectrum information
from multiple separated sensing nodes was aggregated to enable detection of
available frequencies. The system was designed and constructed as an entry to
the Software Defined Forum’s Smart Radio Challenge. The project won
awards for Best Design, Best in Problem Category, and overall Grand Prize. More
information on this project can be found at http://www.radiochallenge.org/08Challenge.html.
Remote Educational Antenna Laboratory
The Remote Educational Antenna Laboratory (REAL) is a
collaborative project between Carnegie Mellon University and San Diego State
University, and was established to encourage the use of antenna construction
projects in undergraduate education. Goals of the Project are to 1) establish
an antenna test facility that can be operated remotely via the internet, 2) develop
an easy-to-use, inexpensive "Antenna Construction Starter Kit"
containing basic supplies and procedures enabling students to construct their
own test antennas, and 3) evaluate the educational effectiveness of the remote
laboratory experience using rigorous assessment procedures. Goal #1 is being
implemented at the Carnegie Mellon University (CMU), while goal #2 is being
completed at the San Diego State University. Goal #3 is ongoing and we solicit
collaboration with faculty interested in using the REAL facility in their
courses to help assess the effectiveness of the concept. More information on
this project can be obtained at http://www.preal.ece.cmu.edu.
Wireless Network Emulator
Wireless network simulators provide a repeatable environment
for exploring network behavior, but are often suspect owing to over simplistic
modeling of the physical channel. In contrast, actual experimental wireless
networks offer real physical layers, but generally do not offer a repeatable
environment owing to lack of control over the wireless environment. We are
exploring an interesting middle ground where actual hardware and real-time
applications are used down to the RF connector. From the RF connector, signals
are down-converted, digitized, and propagated in real time through a mobile
channel using an FPGA DSP engine. The signals are then converted back to analog
and up-converted for reception by the receiving node. The system is flexible
and available to remote users over the web. More info on this collaborative
project can be obtained at http://www.cs.cmu.edu/~emulator.
Vehicle-to-Vehicle Channel Characterization and Modeling
Vehicle-to-vehicle communication is of interest because of active safety
application such as collision or congestion avoidance, as well as
entertainment. The FCC has allocated 75 MHz of spectrum near 5.9 GHz for
Intelligent Transportation System applications, including V2V networking.
Research topics related to these applications in ARC include field measurements of
the V2V channel in various on-road environments, developing models based on the
measurements, evaluating the performance of various modulation types, and
developing robust physical layers for this channel. This activity is part of
the GM-CMU Collaborative Research Laborator. More
info on this collaborative project can be obtained at http://gm.web.cmu.edu.
Characterization of the Enclosed Space Radio Channel
Consider a wireless communications system operating in an environment such as
the inside of an aircraft wing, an UAV fuselage, a small submarine hull or an
automobile engine compartment. Such a system could be part of a sensor network,
performing instrumentation functions inside the environment, and
instrumentation systems which both currently use wireline
communications and those which would otherwise be enabled by a wireless
connectivity could be enhanced by such a development. Referring to the previous
environments generally as enclosed space environments, the development of
wireless communications in these spaces requires knowledge of the properties of
the enclosed space radio channel. This project seeks to characterize the
enclosed space radio channel, so that an insight into and a description of this
novel channel can be given to the architects of wireless instrumentation
systems deployed in enclosed spaces. Project deliverables include the
characterization of received power, dispersion properties and diversity gains
given simple descriptions of enclosed spaces with highly nonuniform
geometries. Analytical modeling of these characteristics supported with
empirical measurements and numerical simulations illustrate the properties of
the enclosed space radio channel.
RF Distribution in Buildings using HVAC Ducts
An alternative method of distributing RF in buildings is to use the heating and
ventilation ducts as waveguides. Because of the relatively low waveguide loss,
this method may lead to more efficient RF distribution than possible with
radiation through walls or the use of leaky coax. Further, the use of existing
infrastructure could lead to a lower-cost system. Experimental demonstrations
include channel delay-spread measurements and WaveLAN
data transmissions between three floors in Roberts Hall on the CMU campus using
duct-assisted propagation.
Super-Resolution Focusing Using Time-Reversal Techniques in Multipath
Environments
Electromagnetic waves propagating in both indoor and outdoor environments
reflect and scatter from many objects, resulting in the creation of multiple
paths from the transmitter to the receiver. Recent research has focused on
using these multiple propagation paths to enhance the radio channel. In our
work, the term "super-resolution" is used to refer to an improved
spatial focusing of power from an antenna array beyond what is predicted by the
Rayleigh criterion (i.e. cross-range focusing). An increase in scatterers in the environment should allow an increase in
the effective numerical aperture of the antenna array. By using time-reversal
techniques, this project strives to provide focusing of electromagnetic power
at desired locations.
High-speed Wireless Disk Drive
A wireless disk-drive interface can dramatically
increase the convenience of Digital Video, PDA Access and similar applications.
It can also be used for disk array interconnects. The goal of this project is
to develop an extremely high speed (600 Mb/s) wireless communication system
suitable for hard drives for limited range (radius less than 5m) and extremely
low transmitted power spectral density that will not interfere with any existing
wireless technologies.
The Tunnel-Radio Project (www.tunnelradio.net)
This is a community service project to provide FM and
AM radio in the Squirrel Hill and Ft. Pitt tunnels in Pittsburgh. For more information,
check out the website.
Wireless physical layer models for the ns network simulator
The ns network simulator has a very detailed
description of protocols like IP and TCP. Recently, mobility extensions have
been added to allow the simulation of mobile hosts and wireless networks. We
have been working on realistic physical layer models that can be incorporated
into ns to provide a better simulation of wireless links.
Intelligent protocols advised by real-time propagation and communication
models
A common feature of all wireless mobile data networks
is the dynamic nature of the propagation environment. A new level of
intelligence can be introduced into wireless networks by creating a real-time
prediction model that runs independently on each mobile node. Such a prediction
can assist the routing protocol in making hand-offs or in choosing the best
route to a destination, taking into account future RF propagation conditions.
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