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Best paper award

The team received a best paper award at the 2009 ReConFig conference for “Enhancing the Productivity of Radio Designers with RapidRadio.”

Custom radio on demand

Adolfo Recio (Photograph by John McCormick)

Adolfo Recio and the RapidRadio framework

Researchers in ECE’s Configurable Computing Laboratory have developed a RapidRadio framework that helps a user configure a radio receiver on the fly, based on a set of signal characteristics. The framework has potential for applications that must classify transmitters with unknown modulation types, such as cognitive radios trying to avoid interference, or signal intelligence users attempting to become silent third-party “listeners.”

RapidRadio divides the radio creation into two phases: the analysis phase and the synthesis phase, according to Adolfo Recio, a Ph.D. student who developed the system with Jorge Suris (Ph.D. ’09) and Peter Athanas. “The framework guides the user through the process of determining the modulation type of an unknown signal, and then builds an FPGA-based receiver capable of demodulating that signal,” he explained. “The user needs only to be concerned with some of the signal analysis activities, and the framework will automatically identify the parameters of the physical link layer and build a receiver for it in a short time.”

The system, Recio emphasized, allows a “human in the loop.” The operator reviews the framework’s decisions and “if the user sees something obviously wrong, he or she can override that decision and have the framework do something else, or augment the modulation scheme database,” he said.

FPGAs are excellent candidates for receivers, but because of their complexity, designers have traditionally used them to implement only what is absolutely necessary and resorted to high-end processors for important parts of the signal processing, he said. “Off-loading the signal processing tasks from the processor permits a better workload distribution and enhances the overall performance.”

RapidRadio can abstract away most of the system architecture because of its radio component database and the use of a platform-independent XML-based radio description file. “A goal of the RapidRadio framework is to reduce the amount of FPGA knowledge necessary to create a system.” Preliminary tests were successful, transmitting and receiving signals using the BPSK, QPSK, 16QAM, and 32QAM modulation schemes, which encode 1, 2, 4, and 5 bits of data into a single radio symbol.

The framework successfully validated the signal constellation, reprogrammed the FPGAs appropriately, and properly resynchronized and received the transmitted symbols.

The team is building an Internet-controllable LEGO robot that carries an electromagnetically reflective foil shield to test the system’s ability to deal with channel attenuation and multipath. The project was supported by Harris Corp. and earned a Best Paper Award at the 2009 International Conference on ReConFigurable Computing and FPGAs.