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Digital Fountains

Tiffany Jing Li, an associate professor of electrical and computer engineering, is hoping to answer some of the most pressing digital questions facing the world today. Her work investigates areas of coding and communication theory, wireless communications and networks, and digital data storage systems.

Li’s work on digital data storage systems comes as an explosion of digital data is exacting a steep energy price tag.

“The proliferation of information has created an exponential demand for digital storage,” says Li. “This requires the availability of massive data centers that are becoming notorious energy hogs.”

A PC or laptop by itself generates an inconsequential amount of heat, says Li. But when hundreds or thousands join forces to back up data at a bank, corporation or military base, cooling is essential. In 2006, the U.S. burned through 61 billion kilowatt-hours, at a cost of $4.5 billion, to power and cool data centers.

Much of that energy, she says goes to provide redundant data protection. “If you can reduce your storage disks without sacrificing reliability or robustness, you can cut costs significantly.”

Li, who has an EAGER (EArly Concept Grants for Exploratory Research) grant from NSF's Office of Cyberinfrastructure, proposes to cut energy consumption in data centers by making data storage itself more efficient. She designs erasure codes that restore lost data when storage disks fail, thus reducing the need for heavily redundant replacement schemes.

Li is also focusing on quantum computers, which may one day solve complex problems in optimization and encryption that now tie up supercomputers for years. But this will not happen without QEC codes that let quantum devices compute reliably in the fragile quantum world.

With the NSF’s support, Li has also invented several new classes of QEC codes.

Two years ago, Li and her group invented the first class of unrestricted (non-CSS) stabilizer LDPC (low-density parity-check) codes based on classical binary codes. In contrast to previously reported design methods, many of which resulted in only a single code with a fixed rate and length, the new design developed by Li’s group revealed a rich family of codes with a wide range of rates and lengths.

More recently, Li and her group have invented systematic ways of constructing unrestricted and restricted stabilizer codes. They have designed the first feasible quantum-decoding algorithm for unrestricted stabilizer convolutional error-correcting codes, and they have successfully simulated and demonstrated the codes’ error-correction performance.

Learn more about Tiffany Jing Li’s research at: http://www.ece.lehigh.edu/~jingli.