Energy management in portable multimedia communications devices is becoming more and more critical and complex, with the convergence of computing and communication technologies, particularly when video signal processing and secure communications are integrated. There are many demands on the power supply of a portable information device, including the power supply, display, signal processing hardware, and modem. Our research attempts to prolong battery life by adapting the signal processing, radio transmission, encryption, and battery discharge operations of a wireless terminal to changing operating conditions. The operating conditions include wireless channel quality, network activity, and remaining battery charge.
Our work provides an approach for minimizing the total power consumption of a mobile transmitter due to source compression, channel coding and transmission subject to fixed end-to-end source distortion. We illustrate, both in an abstract setting and in a realistic H.263 compressed video over wireless, that an optimized system which adapts the transmission power, compression, and channel coding parameters to the channel conditions and the implementation platform prolongs the battery life considerably. We also investigate the effects of multiple interfering users on the power optimization problem, and how simultaneous transmission of video and data can be accomplished in a power limited environment. Our more recent work identifies the fundamental limits of energy efficient sensing and communication, and incorporates the energy harvesting capability of the wireless nodes into the energy optimization problem.
This research is partly funded by NSF through grants #0093163, #0219822, #0224387.