Air Force hosts computer scientist at anniversary celebration|
by Dr. Robert White
Air Force Office of Scientific Research
2/6/2012 - ARLINGTON, Va. -- On Jan. 30, the Air Force Office of Scientific Research in Arlington, Va., hosted a presentation by computer scientist Dr. Dina Katabi from the Massachusetts Institute of Technology.
Dr. Katabi's presentation was part of a continuing series of events planned throughout the coming year as part of AFOSR's 60th anniversary celebration.
Dr. Katabi informed and entertained an audience consisting of attendees from a wide variety of science and technology organizations, to include a representative from the White House Office of Science and Technology Policy. Dr Katabi's presentation focused on the challenge of improving the throughput and reliability of wireless systems--a topic which touches all institutions and every individual in this age of ever-increasing digital speed, mobile devices, and consumer demand for increased performance.
Dr. Katabi's approach in improving wireless networks is centered on cutting through the layers of the "network stack" that comprises the wireless system. The existing architecture of both the hard-wired and wireless network stack is based on layer separation where the physical--read hardware--layers ideally deliver the correct packets of digital information. But errors in the physical layer are orders of magnitude higher in wireless networks. To address this shortfall, Professor Katabi offers a "Cross-Layer Design" that exploits the interaction at the physical layer, basically decoding packet collisions (the transmission errors) to reassemble correct packets, improving the performance of the network and subsequent higher (wireless) layers.
To attack this problem, Katabi's team designed a wireless test bed system with 80 percent of the transmitting terminals in a perfect sensing mode, while ten percent were partially hidden, and the remaining ten percent completely hidden. The goal was to find a way to decode the two packets that resulted from an initial unsuccessful transmission and the subsequent retransmission. This was accomplished by exploiting the interference free bits of one packet and comparing it to the distorted section of the retransmission. Via a sophisticated decoding, re-modulation and discovery process, the data loss rate from the hidden terminals was reduced from a high of 72 percent to 0.7 percent.
Dr. Katabi also addressed data loss rate in mobile video applications using the same cross-layered design, where again, data packet collisions can be decoded followed by the exploitation of those collisions to increase signal throughput using analog network coding which results in a more robust mobile video that does not glitch or stall.
Dr. Katabi is a professor in the Department of Electrical and Computer Science at MIT, a member of the Computer Science Artificial Intelligence Laboratory, and leads the NETMIT networking group at MIT. The primary goal of her research is to build new protocols and architectures that improve the robustness and performance of computer networks. AFOSR has funded this MIT effort since 2008.
AFOSR continues to expand the horizon of scientific knowledge through its leadership and management of the Air Force's basic research program. As a vital component of the Air Force Research Laboratory, AFOSR's mission is to discover, shape, and champion basic science that profoundly impacts the future Air Force.
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