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.