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Improving battery life

Masoud Sharif‘s research may provide a way to substantially increase the battery life of wireless devices like cellphones and laptops

Masoud Sharif, Assistant Professor of Electrical and Computer Engineering in the College of Engineering

How often have you gone to make that important call on your cell phone only to discover that its battery has run out? Probably more often than you would care to recall.  But the dismay and frustration that you had not remembered to charge it the night before may soon become a rarity, thanks to the award-winning work of Masoud Sharif.  An Assistant Professor of Electrical and Computer Engineering in the College of Engineering, Sharif has been awarded the 2006 Charles Wilts Prize for the doctoral thesis he completed at the California Institute of Technology.

His thesis, “Broadband Wireless Broadcast Channels: Throughput, Performance, and PAPR Reduction” explores the fundamental performance limits of communication and studies the practical schemes possible to achieve those limits.  “In my thesis, we proposed simple coding schemes for multi-antenna broadcast channels that significantly increase the capacity,” said Sharif. “These schemes are based on opportunistic beam-forming and offer the promise of substantial capacity improvement in cellular systems with little complexity.” 

Sharif’s research revealed the value of coding for peak to average power reduction (PAPR) of OFDM signals.  OFDM (short for orthogonal frequency division multiplexing) splits a radio signal into multiple smaller sub-signals that are then transmitted simultaneously at different frequencies, reducing the amount of disturbance in signal transmissions.  Sharif said the coding methods that his thesis proposes “could significantly reduce the cost of implementation of OFDM modulation and substantially increase the battery life of wireless devices such as cell phones and laptops.”

Sharif earned his Bachelor’s and Master’s degrees in electrical engineering from the Sharif University of Technology in Tehran, Iran, and his PhD from the California Institute of Technology. He joined the faculty at the College of Engineering this past January and will be teaching a course called “Digital Communications” (SC 515) this fall.