Intrinsically Digital Radios

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Topic: Intrinsically Digital RadiosPI: Oliver CollinsProposal: ECS-0523324This integrative systems proposal focuses on building intrinsically digital radios. Most modern radios perform modulation in a DSP, but still require extensive analog hardware. Since analog devices are both big to begin with and will not scale with decreases in VLSI feature sizes, there has been an ongoing effort to realize signal-processing chains that generate the RF waveform directly. The fundamental problems with this approach are the limited accuracy available in high-speed multi-bit digital-to-analog converters (DACs) and the limited computational abilities of digital hardware. This proposal presents a radical new transmitter architecture that eliminates both of these deficiencies. The essential idea is that the branches in the trellis structure representing the modulator can be labeled with binary strings, which can be passed through a filter and then radiated directly. Thus, the entire problem of building high accuracy, high-speed converters is eliminated. These binary strings are generated offline by a list-decoding algorithm and the entire coder/modulator/transmitter is merely a look-up table. It is proposed to develop this idea further and to adapt it to receivers and other applications. Broader Impacts: The proposed research will have substantial broader impact since building higher dynamic range, lower power transmitters and receivers is key to the continued spread of wireless devices. Everything from military radars to structural monitoring systems could benefit. Furthermore, the list decoding approach will have applications beyond wireless communications. This interface is critical in today's digital world both to send and store information. Personal CD players, cellular telephones, high definition TV, computer modems, and deep space communication systems all use analog-to-digital and digital-to-analog conversion blocks. In addition, the project will enrich the department's curriculum and help train students in communication systems and VLSI circuit design.