Energy Benefits of Reconfigurable Hardware for Use in Underwater Sensor Nets

Small, dense underwater sensor networks have the potential to greatly improve undersea environmental and structural monitoring. However, few sensor nets exist because commercially available underwater acoustic modems are too costly and energy inefficient to be practical for this applications. Therefore, when designing an acoustic modem for sensor networks, the designer must optimize for low cost and low energy consumption at every level, from the analog electronics, to the signal processing scheme, to the hardware platform. In this paper we focus on the design choice of hardware platform: digital signal processors, microcontrollers, or reconfigurable hardware, to optimize for energy efficiency while keeping costs low. We implement one algorithm used in an acoustic modem design - matching pursuits for channel estimation - on all three platforms and perform a design space exploration to compare the timing, power and energy consumption of each implementation. We show that the reconfigurable hardware implementation can provide a maximum of 210 X and 52 X decrease in energy consumption over the microcontroller and DSP implementations respectively